- 慧慧
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你定义了基类的变量mybase
但也只是定义了而已
内存中并有开辟相应的内存空间
必须new
或者把他指向其他空间才能正常使用~所以你没给他赋值或者没new
是不能调用DoSomething()方法的~~
不同的类一般情况下是不能相互赋值的~但是有几个特例,比如
两个是继承关系
子类实例可以给父类变量赋值~或者两个类的实例类型相同等情况~
最后一个问题
~父类对象不能调用子类的属性方法
子类的对象可以调用父类的属性方法~如果你子类重写了父类的方法
你得到的是子类的方法值
但是你调用的仍然是父类的方法~只不过C#自己发现了重写后的值
取了一下而已。。。
补充一点
你子类没有用override重写方法
不可能得到Derived
imp
C++中类类型指针Base * ptr=new Derived是什么意思(注,Base和Derived都是类名,Derived公有继承Base类)
从本质来讲,指针只是一个地址,可以是任意类型。但是这样不好区分,所以才给指针加上了类型。此处ptr就是Base*,不能直接访问Derived类的成员函数,但是可以通过强制转换后访问Derived* d = (Derived*) ptr;2023-07-23 13:55:422
说明base类和derived类之间的关系
继承关系 base类就像一个怀孕的母亲 而derived类就是那个胎儿再举一个例子: 跑车属于车辆这个base类 卡车也属于车辆这个base 类他们都有共同点2023-07-23 13:55:491
求这个c++程序的详细注释!!
这行可能有点难度:derived(int x,int y,int z):base1(y),base2(z)这是derived的构造函数,它继承于base1和base2,然后把y和z分贝传送给base1和base2的构造函数,也就是说derived是先调用其基类base1和base2的构造函数,再调用自己的构造函数。derived ob(3,4,5);就是实例化,把具体的值传递给x,y,z其它都应该看的懂2023-07-23 13:56:162
C#中Base b1 = new Derived();
父类变量指向子类实例这是面向对象三大特征:多态的基本应用。假设Base 中有DoSth的虚方法,而且Derived类重写了该方法,那么b1.DoSth()执行的就是Derived重写之后的方法。想想看这样做的好处,如果某方法以Base实例作为参数,那么所有的Base子类实例都可以作为该方法的参数,而并不需要指明具体是哪一个子类实例。2023-07-23 13:56:232
解释一下经济中的“最终需求(final demand)”和“派生需求(derived demand)”
最终需求,就是对最终消费产品的需求,比如多吃的啊、穿的啊这些的。而派生需求,就是对生产要素的需求,因为它是由对最终消费品的需求引申出来的。比如,因为你需要衣服,所以,你需要布、棉花等各种原料,还需要生产衣服的劳动力,这就是派生出来的需求。也被成为引致需求。最终需求是在一般消费市场上的,派生需求是在生产要素市场上的。2023-07-23 13:56:432
C++ Base *p=new Derived
有2023-07-23 13:56:525
定义基类base,有两个公有成员函数fn1(),frn2(),私有派生出derived类,
#include<iostream>using namespace std;class Base{public:void fn1(){cout<<"a"<<endl;}void fn2(){cout<<"b"<<endl;}};class Derived:private Base{public:void fn1(){Base::fn1();}};int main(){Derived d;d.fn1();return 0;}2023-07-23 13:57:101
This file is derived. Do you really want to edit it?
文件夹已经建立,你真的想要编辑它吗2023-07-23 13:57:205
derived attribute是什么意思
derived attribute是派生属性的意思2023-07-23 13:57:372
C++代码问题请帮忙改错
base2 *pb=static_cast<base2* >(pv);这句是不是写错了?base2 *pb=static_cast<base2>(* pv);这样试下。2023-07-23 13:57:471
C++中的virtual关键字是什么?怎么用?
C++中的虚函数 虽然很难找到一本不讨论多态性的C++书籍或杂志,但是,大多数这类讨论使多态性和C++虚函数的使用看起来很难。我打算在这篇文章中通过从几个方面和结合一些例子使读者理解在C++中的虚函数实现技术。说明一点,写这篇文章只是想和大家交流学习经验因为本人学识浅薄,难免有一些错误和不足,希望大家批评和指正,在此深表感谢! 一、 基本概念 首先,C++通过虚函数实现多态."无论发送消息的对象属于什么类,它们均发送具有同一形式的消息,对消息的处理方式可能随接手消息的对象而变"的处理方式被称为多态性。"在某个基类上建立起来的类的层次构造中,可以对任何一个派生类的对象中的同名过程进行调用,而被调用的过程提供的处理可以随其所属的类而变。"虚函数首先是一种成员函数,它可以在该类的派生类中被重新定义并被赋予另外一种处理功能。 二、 虚函数的定义与派生类中的重定义 class 类名{public: virtual 成员函数说明;}class 类名:基类名{ public: virtual 成员函数说明;}三、 虚函数在内存中的结构1.我们先看一个例子:#include "iostream.h"#include "string.h"class A {public: virtual void fun0() { cout << "A::fun0" << endl; }};int main(int argc, char* argv[]){ A a; cout << "Size of A = " << sizeof(a) << endl; return 0;} 结果如下:Size of A = 42.如果再添加一个虚函数:virtual void fun1() { cout << "A::fun" << endl;}得到相同的结果。如果去掉函数前面的virtual修饰符 class A {public: void fun0() { cout << "A::fun0" << endl; }};int main(int argc, char* argv[]){ A a; cout << "Size of A = " << sizeof(a) << endl; return 0;} 结果如下:Size of A = 13.在看下面的结果: class A {public: virtual void fun0() { cout << "A::fun0" << endl; }int a;int b;};int main(int argc, char* argv[]){ A a; cout << "Size of A = " << sizeof(a) << endl; return 0;} 结果如下:Size of A = 12 其实虚函数在内存中结构是这样的:图一 在window2000下指针在内存中占4个字节,虚函数在一个虚函数表(VTABLE)中保存函数地址。在看下面例子。 class A {public: virtual void fun0() { cout << "A::fun0" << endl; }virtual void fun1() { cout << "A::fun1" << endl; }int a;int b;};int main(int argc, char* argv[]){ A a; cout << "Size of A = " << sizeof(a) << endl; return 0;}结果如下:结果如下: Size of A = 4 虚函数的内存结构如下,你也可以通过函数指针,先找到虚函数表(VTABLE),然后访问每个函数地址来验证这种结构,在国外网站作者是:Zeeshan Amjad写的"ATL on the Hood中有详细介绍"图二4.我们再来看看继承中虚函数的内存结构,先看下面的例子 class A {public: virtual void f() { }};class B {public: virtual void f() { }};class C {public: virtual void f() { }};class Drive : public A, public B, public C {};int main() { Drive d; cout << "Size is = " << sizeof(d) << endl; return 0;} 结果如下:Size is = 12 ,相信大家一看下面的结构图就会很清楚, 图三 5.我们再来看看用虚函数实现多态性,先看个例子:class A {public: virtual void f() { cout << "A::f" << endl; }};class B :public A{public: virtual void f() { cout << "B::f" << endl;}};class C :public A {public: virtual void f() { cout << "C::f" << endl;}};class Drive : public C {public: virtual void f() { cout << "D::f" << endl;}};int main(int argc, char* argv[]){ A a; B b; C c; Drive d; a.f(); b.f(); c.f(); d.f(); return 0;}结果:A::fB::fC::fD::f不用解释,相信大家一看就明白什么道理!注意:多态不是函数重载 6.用虚函数实现动态连接在编译期间,C++编译器根据程序传递给函数的参数或者函数返回类型来决定程序使用那个函数,然后编译器用正确的的函数替换每次启动。这种基于编译器的替换被称为静态连接,他们在程序运行之前执行。另一方面,当程序执行多态性时,替换是在程序执行期进行的,这种运行期间替换被称为动态连接。如下例子: class A{public: virtual void f(){cout << "A::f" << endl;};};class B:public A{public: virtual void f(){cout << "B::f" << endl;};};class C:public A{public: virtual void f(){cout << "C::f" << endl;};};void test(A *a){ a->f();};int main(int argc, char* argv[]){ B *b=new B; C *c=new C; char choice; do{ cout<<"type B for class B,C for class C:"<<endl; cin>>choice; if(choice==""b"") test(b); else if(choice==""c"") test(c); }while(1); cout<<endl<<endl; return 0;} 在上面的例子中,如果把类A,B,C中的virtual修饰符去掉,看看打印的结果,然后再看下面一个例子想想两者的联系。如果把B和C中的virtual修饰符去掉,又会怎样,结果和没有去掉一样。 7.在基类中调用继承类的函数(如果此函数是虚函数才能如此)还是先看例子: class A {public: virtual void fun() { cout << "A::fun" << endl; } void show() { fun(); }};class B : public A {public: virtual void fun() { cout << "B::fun" << endl; }};int main() { A a; a.show(); return 0;} 打印结果:A::fun 在6中的例子中,test(A *a)其实有一个继承类指针向基类指针隐式转化的过程。可以看出利用虚函数我们可以在基类调用继承类函数。但如果不是虚函数,继承类指针转化为基类指针后只可以调用基类函数。反之,如果基类指针向继承类指针转化的情况怎样,这只能进行显示转化,转化后的继承类指针可以调用基类和继承类指针。如下例子: class A {public: void fun() { cout << "A::fun" << endl; }};class B : public A {public: void fun() { cout << "B::fun" << endl; } void fun0() { cout << "B::fun0" << endl; }};int main() { A *a=new A; B *b=new B; A *pa; B *pb; pb=static_cast<B *>(a); //基类指针向继承类指针进行显示转化 pb->fun0(); pb->fun(); return 0;}2023-07-23 13:58:179
java 中什么是动态绑定!
一个例子:Java代码 class Base{ public void foo(Base x){ System.out.println("Base.Base"); } public void foo(Derived x){ System.out.println("Base.Derived"); } } class Base{ public void foo(Base x){ System.out.println("Base.Base"); } public void foo(Derived x){ System.out.println("Base.Derived"); }}Java代码 class Derived extends Base{ public void foo(Base x){ System.out.println("Derived.Base"); } public void foo(Derived x){ System.out.println("Derived.Derived"); } } class Derived extends Base{ public void foo(Base x){ System.out.println("Derived.Base"); } public void foo(Derived x){ System.out.println("Derived.Derived"); }}Java代码 class Main{ public static void whichFoo(Base arg1, Base arg2){ arg1.foo(arg2); } public static void main(String[] args)}{ Base b = new Base(); Derived d = new Derived(); whichFoo(b,b); whichFoo(b,d); whichFoo(d,b); whichFoo(d,d); } } class Main{ public static void whichFoo(Base arg1, Base arg2){ arg1.foo(arg2); } public static void main(String[] args)}{ Base b = new Base(); Derived d = new Derived(); whichFoo(b,b); whichFoo(b,d); whichFoo(d,b); whichFoo(d,d); }}因为参数通常在编译阶段被匹配,在whichFoo方法中,形式参数arg2的类型是Base, 因此不管arg2实际引用的是什么类型,arg1.foo(arg2)匹配的foo都将是:public void foo(Base x)惟一的问题在于用Base还是Derived版本中的foo(Base x)函数?当知道arg1引用的对象时,这是在运行阶段要决定的。精确使用的方法是编译器绑定,在编译阶段,最佳方法名依赖于参数的静态和控制引用的静态类型所适合的方法。在这一点上,设置方法的名称,这一步叫静态重载。决定方法是哪一个类的版本,这通过由虚拟机推断出这个对象的运行时类型来完成,一旦知道运行时类型,虚拟机就唤起继承机制,寻找方法的最终版本。这叫做动态绑定。在方法whichFoor的调用arg1.foo(arg2),将根据arg1的运行时类型是Base还是Derived来调用Base类或者Derived类中的foo(Base x)版本函数。由此理解方法的覆盖和重载。重载函数的实际调用版本由编译器绑定决定,而覆盖函数的实际调用版本由动态绑定决定。2023-07-23 13:59:343
输出的近义词是什么
问题一:输出的反义词是什么 输出的反义词――输入、引进、引入 输出:【拼音】:[shu chu] 【释义】:1.从内部送到外部。如:血液从心脏输出,经血管分布到全身组织。2.商品或资本从某一国销售或投放到国外。3.科学技术上指能量、信号等从某种机构或装置。 问题二:电压的输出功率的近义句 功耗。 问题三:近义词反义词大全 近义词大全 聚拢――聚集 俊俏――俊美 伶俐――机灵 偶尔――偶然 姿势――姿态 喜欢――喜爱 注视――凝视 锐利――锋利 舒适――舒服 疲劳――疲惫 温暖――暖和 清澈――明净 清新――清爽 赶快――赶紧 后悔――懊悔 奇怪――奇异 劝告――劝说 本事――本领 愈合――痊愈 裂开――破裂 孤单――孤独 悲惨――悲哀 叮嘱――叮咛 教诲――教导 相信――信任 准确――精确 称赞――赞扬 假若――如果 安慰――慰问 滋味――味道 哀痛――伤痛 持续――延续 受益――得益 讨论――议论 洪亮――响亮 沉默――沉寂 纠正――改正 隆重――庄重 故意――有意 急忙――匆忙 服侍――伺候 情形――情况 愤怒――愤恨 烦恼――苦恼 缓和――平和 安静――宁静 迅速――快速 掩盖――掩藏 轻柔――轻盈 周围――四周 治疗――医治 吸收――吸取 遐想――幻想 费解――难懂 协助――帮助 神奇――神秘 赞叹――赞美 处境――境况 平等――公平 犹豫――迟疑 吃力――费力 悲惨――凄惨 搜索――搜寻 祝愿――祝福 稀少――稀罕 打扮――装扮 收成――收获 灌溉――浇灌 寻求――寻访 *** ――暴露 绝招――绝技 调动――调换 同意――赞成 立刻――立即 终于――终究 新鲜――清新 恍然大悟――茅塞顿开 喜出望外――大喜过望 情不自禁――不由自主 无影无踪――踪迹全无 栩栩如生――活灵活现 名副其实――名不虚传 提心吊胆――心惊胆战 连绵不断――连绵起伏 禁不住――忍不住 挪移――挪动 偶尔――偶然 汲水――吸水 从容――镇静 启示――启迪 优雅――雅致 陶醉――沉醉 沉着――镇静 构造――结构 复杂――繁杂 机敏――敏捷 枯――萎 空虚――空乏 觉察――察觉 徘徊――彷徨 叹息――叹气 萦绕――缠绕 慌乱――慌忙 依然――依旧 歉疚――愧疚 消受――享受 扶衬――帮衬 差异――差别 机敏――机灵 聪明――聪慧 确乎――的确 踌躇――犹豫 痕迹――踪迹 奇怪――奇特 规律――规则 依赖――依靠 枯萎――干枯 感动――激动 锻炼――磨炼 精彩――优美 歉疚――歉意 纵使――即使 索性――干脆 考验――检验 自在――自由 姿态――姿势 屏障――屏风 秀丽――秀美 渺小――微小 觉察――察觉 惊恐――惊慌 遮挽――挽留 基业――基础 萦绕――萦回 歉疚――内疚 忘怀――忘记 喝彩――叫好 平衡――平稳 艰难――困难 喧哗――喧闹 责怪――责备 剧烈――猛烈 镇静――镇定 声息――声音 薄弱――微弱 差异――差别 幸而――幸好 复杂――繁复 预备――准备 光景――情景 吞噬――吞食 充足――充裕 间断――中止 娴熟――熟练 照旧――照常 招徕――招揽 布施――施舍 侵蚀――腐蚀 崇尚――推崇 纵使――即使 扼杀――抹杀 技能――技巧 吉祥――吉利 愿望――希望 严肃――肃穆 试图――打算 温顺――柔顺 敦厚――忠厚 雄浑――雄壮(浑厚) 稀奇――稀罕 压抑――压制 点缀――装饰 偏僻――偏远 骚扰――扰乱 排挤――排斥 隆重――庄重 兴旺――兴盛 宽敞――宽大 激昂――高昂 单调――单一 摇曳――摇荡 深邃――深奥 豁达――扩达 惊恐――恐惧 慈爱――慈祥 兴趣――兴致 僻静――幽静 剧烈――猛烈 欺负――欺侮 粗暴――粗鲁 残暴――残酷 歼灭――消灭 宏伟――雄伟 兴旺――兴盛 追悼――哀悼 奇异――奇特 刚毅――坚毅 侵蚀――腐蚀 恐怖――恐惧 注视――凝视 扼杀――抹杀 憧憬――向往 哀思――悼念 乖巧――机灵 精致――精巧 舒服――舒适 昏暗――幽暗 模糊――含糊 继续......>> 问题四:王者荣耀近站英雄和远程输出什么意思 近战英雄就是使用近身攻击的,坦克、刺客、战士这一类的都是近身的,远程输出就是法师、射手这一类,专门在队友后面负责输出的 问题五:议论的近义词 首先我们了解一下显卡的构成。显卡主要是由显示芯片、显存、输出接口、散热系统、显卡BIOS组成。如果要超频就要从这些方面下手。 显示芯片 目前主流显卡的显示芯片主要由NVIDIA和ATi两大厂商制造,提高显示芯片的核心频率可以提高显卡处理图像的性能。同一显示芯片一般有多个版本,比如RV350显示芯片,也就是我们说的Radeon9600系列(以下简称R9600,以此类推),有R9600XT,R9600 PRO, R9600 ,R9600SE ,R9550等几个版本,它们最主要的区别就是其额定的工作频率不同。一般高端产品的核心频率相应也高,超频比较困难,相对而言低端产品超频就比较容易,比如R9550。 显存 显卡超频一般就是提高显示芯片核心频率和提高显存频率。显存频率一般和显存的时钟周期有关,越低的时钟周期可以达到的频率就越高。显存的封装也和超频有关,一般来说,mBGA封装的显存比较容易超频,而TSOP封装的显存就差些。 散热系统 和CPU超频一样,提高显示芯片核心频率和显存频率会使它们的发热量增大。所以要适当地给GPU和显存加上散热系统。 PCB板,电容 高档显卡一般采用6层以上的PCB板以获得稳定的工作状态。电容也同样,它对显卡的供电起着决定性作用,好的电容供电不成问题,超频后才能保证显卡稳定工作。 显卡超频主要有两种方式:一种是通过软件超频;另一种则通过刷新显卡BIOS进行超频,或是直接使用高端显卡BIOS刷新低端显卡的方式来获得性能的提升。 1.软件超频 对显卡超频的软件种类非常多,常见的有Riva Tuner、Rege3D Tweak、PowerStrip等。以PowerStrip为例,它可以方便地在图形界面中对显卡核心和显存进行超频。 调整核心频率和显存频率时一般以5MHz为单位微调,且调一次后就用软件测试一次。如果这颗显存最高可以达到600MHz,一般设置到500MHz或550MHz就不要超了,给显存留点余地。 通过软件超频后如果显卡无法正常工作,一般有两种恢复方式。一是用超频软件将核心频率和显存的时钟频率设置回显卡出厂时的默认值。二是由于显卡故障无法通过软件更改,就可以考虑重新安装操作系统来恢复。 2.刷新BIOS超频 通过刷新显卡BIOS超频的方法比较专业,它的基本操作步骤如下: (1)备份显卡BIOS 这里我们需要使用到显卡BIOS的刷新工具。以NVIDIA的显卡为例,最常用的就是Nvflash。 Nvflash要在DOS下操作,进入DOS后,在存放Nvflash.exe的目录下输入nvflash -b old.rom,其中-b的参数就是进行BIOS的备份操作,而old.rom则是我们为原有显卡BIOS取的名字。执行上述指令后,硬盘中会生成一个old.rom文件这便是当前显卡的BIOS文件,将它备份起来。 (2)修改BIOS 备份了显卡BIOS之后,我们就要用NVIDIA BIOS Editor对显卡BIOS进行修改,这是一款应用非常广泛的超频工具,重要的是它可以修改显卡频率。 (3)刷新显卡BIOS 首先进入DOS,仍然使用我们刚才备份显卡BIOS的工具nvflash。在存放有nflash.exe的目录下,输入nvflash -f old.rom,将修改后的BIOS重新写回显卡重新启动后,显卡将按照我们设定的频率进行工作。至此,显卡超频完成。 显卡超频失败后,需要恢复显卡的工作状态。方法是首先让原有的AGP显卡不......>> 问题六:王者荣耀近站英雄和远程输出什么意思 近战就是要靠近打,远程就是想射手一样在很远地方就可以攻击了 问题七:中国近代列强输出华工是什么意思 据资料介绍,一战期间,英法两国在中国直隶、山东、江苏等8个省招募的华工近14万人,而自威海卫转运的华工即达54000多人,成为一战期间最大的华工输出地。华工到达法国即被编为华工军团(也称华工队),经过短期军训后配属到英法联军作战部队从事战地作业和后方战勤服务。据有关资料介绍,到达欧州的14万华工,其中有9.6万人被分配给英军,3.7万人由法军支配,1万人被“借给”美国赴欧远征军。华工们送上前线后,除承担挖战壕、运弹药、埋尸体、修路架桥等危险工作外,很多人被迫投入战斗。 问题八:derived什么意思及同义词 derived什么意思及同义词 副词 1.【医】衍生的 不及物动词: 1.起源,由来 2.衍生,导出 词形变化:形容词:derivable;名词:deriver;时态:derived,deriving,derives。反义词:underived。 英语句子 Derive Objects By 导入物体方式;导入物体依据 Financial derivatives 金融衍生物 derivation; descendent 派生物 Of,relating to,or derived from vanilla or vanillin. 香子兰的,香草的香子兰的,与香子兰有关的,或从香子兰得来的 Margarine is derived from vegetable oil. 人造奶油来源于植物油。 英语解释 formed or developed from something else; not original 相似短语 derived from 来源于 derived algebra 导出代数 derived density 导出密度 derived functor 导函子, 导出函子 derived constant 导出常数 问题九:返回的近义词是什么 返回的近义词――归来、回到、回来、折回 返回:【拼音】:[fǎn huí] 【释义】:回;回到原地。 问题十:返回的近义词是什么 返回的近义词: 归来 回到 返回 【拼音】:[fǎn huí] 【释义】:回;回到原地。2023-07-23 13:59:421
C++问题 求解!
答案是正确的,分析结果如下:首先搞清楚Base1(int i, int j=0) : Base(j)还有Base2(int i, int j=0) : Base(j) 还有Derived(int a, int b, int c, int d) :mem1(a), mem2(b), Base1(c), Base2(d), Base(a) 都是成员初始化列表,而且由题中的继承可知,当创建Derived对象时,会调用三次Base,分别是1,0,0。首先要清楚的是成员列表初始化时,是按照类中定义的顺序来进行初始化的,这是规则。因此题中首先是初始化Base2对象,这首先要先调用基类Base,由Base(a),知输出1,然后是调用Base2(d),输出4,然后是Base1(c),输出3,然后初始化men2(b),因为有默认形参,先调用Base(0)(0值是有Base1(int i, int j=0) : Base(j)得到的,j默认为0),输出0,然后输出2,men1(a),的过程也一样。输出0,1,最后输出2,解释的比较啰嗦,希望能帮助你2023-07-23 13:59:521
一个英语句子结构分析
n主要,移植的优点是文化和结果从效益来源于种植这种作物通过其早期阶段在一个更有利的环境下,磁场都是成熟的。2023-07-23 14:00:004
c++问题,急!明天就考了!看程序写结果,答案是XY 求指教!
唉,看不懂啊 我是外国读书的可能教的不一样吧。。。2023-07-23 14:00:104
crRNA的中文怎么说
此系统的工作原理是 crRNA( CRISPR-derived RNA )通过碱基配对与 tracrRNA (trans-activating RNA )结合形成 tracrRNA/crRNA 复合物,此复合物引导核酸酶 Cas9 蛋白在与 crRNA 配对的序列靶位点剪切双链 DNA。而通过人工设计这两种 RNA,可以改造形成具有引导作用的sgRNA (singleguide RNA ),足以引导 Cas9 对 DNA 的定点切割。 作为一种 RNA 导向的 dsDNA 结合蛋白,Cas9 效应物核酸酶是已知的第一个统一因子(unifying factor),能够共定位 RNA、DNA 和蛋白,从而拥有巨大的改造潜力。将蛋白与无核酸酶的 Cas9( Cas9 nuclease-null)融合,并表达适当的 sgRNA ,可靶定任何 dsDNA 序列,而 sgRNA 的末端可连接到目标DNA,不影响 Cas9 的结合。因此,Cas9 能在任何 dsDNA 序列处带来任何融合蛋白及 RNA,这为生物体的研究和改造带来巨大潜力。2023-07-23 14:00:213
mysql执行计划怎么看
MySQL 使用 EXPLAIN 后面跟SQL,就直接显示查询计划 下面是一个例子: mysql> EXPLAIN -> SELECT -> SALE_DATE, -> SUM(SALE_MONEY) AS SUM_MONEY -> FROM -> SALE_REPORT -> GROUP BY -> SALE_DATE -> ORDER BY -> SUM(SALE_MONEY) DESC;2023-07-23 14:01:101
Java编程问题
public class Base{ public void baseA(){ System.out.println("this is BaseA!!!!!!!!!!!"); } public void baseB(){ System.out.println("this is BaseB -----"); this.baseA(); }}public class Derived{ public void baseB(){ System.out.println("this is Derived"s BaseB--------"); }}public class TestClass{ public static void main(String[] args){ Derived d = new Derived(); Base b = d; b.baseA(); }}2023-07-23 14:01:223
帮忙分析一个英语句子,并翻译一下
令爱因斯坦高兴的是他的名誉可以让他帮助更多的人2023-07-23 14:01:317
Xcode 删除Derived Data缓存数据
Xcode -> Preferences -> location,然后点击 Derived Data路径后的小箭头,删除这个文件夹下的数据就可以了,如图: /用户/mac/资源库/Developer/Xcode/DerivedDatau2069 终端输入命令行,打开相应路径,手动删除2023-07-23 14:01:461
Base *b=new Derived和Base *b=new Derived()两种写法是一样的么?看得有点晕。请指点。
一样,前者隐式调用对象的默认构造函数,后者显示调用默认构造函数。2023-07-23 14:01:531
Derived demand or joint demand?
It should be derived demand. Firstly, you should know the definitions of both derived demand and joint demand. Derived demand refers to the demand for factors of production such as houses and cement. Joint demand me o goods are used together to satisfy human wants such as DVDs and DVD player. In this case, the taxi is the factor of the production of taxi service by the taxi driver. Your demand for taxi service is derived from your demand for taxi. It is not joint demand because when 2 goods A and B are in joint demand, A cannot be used to produce B and vice versa. Just like the example of DVDs and DVD player. Can you use DVDs to produce DVD player? Hence it is derived demand. Hope it helps.,参考: My Economics Knowledge,Joint demand is the wer. 对生产资料 (factor of production) 的需求是一种引申需求。 For example: 电脑硬件需要适当的电脑软件才能使用, however they are not derived demand but joint demand. For 引申需求,一件是 final good (最终物品),另一件为该 final good 的生产资料;For 辅助品 joint demand,两者都是 final good。 Taxi and Taxi driver are derived demand for Taxi service. We can view Taxi and Taxi driver as another sample of DVD and DVD player, i.e. bining it we can watch DVD or have taxi service. If DVD and DVD player are joint demand,why should we said Taxi and Taxi driver is derived demand?,I don"t agree with the wer above. For taxi SERVICE and taxi driver, they are in derived demand. People demand for taxi service. In order to provide taxi service we demand taxi drivers. That"s why the demand for taxi service derives the demand for taxi drivers. For taxi (the VEHICLE itself) and taxi driver, they must be USED TOGETHER to provide taxi SERVICE to satisfy wants, while either one of them cannot. So they are in joint demand instead. Joint demand does not mean that one good produces another!!!!,2023-07-23 14:02:001
Derived-from-seafood是什么意思
由海鲜做成的。2023-07-23 14:02:083
求高手帮忙看一下,怎么翻译
D级RF(倍频)功率放大器已被应用了较长的一段时间。该放大器有开关的特性,因此,在低功率(10 to 100W)获得80%效率;在高功率(100 to 500W)获得70%效率。然而,D级放大器的理论效率为100%。事实上的效率降低的原因是与RF工作相关的开关损耗的增加。以前D级放大器的论文忽略了这些开关损耗造成的的影响。本文论述RF开关功率放大器的损耗和频率依赖。所分析的损耗有开关损耗、传导损耗和门驱损耗。门驱损耗在低频应用中常被忽略,在本文针对的频率(>10MHz)下,必须计入该损耗。得出预言D级功率放大器效率方程式。 近年来,已有介绍D级回路,它应用停滞时间、零电压开关工作的。但并无论述设计方程式和给出零电压开关的条件。RF可用的停滞时间非常短,因此设计空间更受限。本文分析回路,预言停滞时间正确的大小,预言允许装置零电压开关的负载电流的大小。还提到以合理精度控制纳秒级的停滞时间。用方波门驱快速正时变得非常难,因为开关频率为兆赫兹级以上。提出一种方法,即正弦门电压幅度控制停滞时间。得出零电压开关D级回路的设计方程式。2023-07-23 14:02:272
C++ vector 里存放基类指针,指向派生类对象
楼上的回答只点出了你的C++使用的语法错误之处,但是他并没有给出能让你理解的你想要的解决方法,那么我下面便是:#include<iostream>#include<vector>usingnamespacestd;classBase{public:virtualvoidprint();};classDerived:publicBase{public:virtualvoidprint();};voidBase::print(){std::cout<<" INBase"<<std::endl;}voidDerived::print(){std::cout<<" INderived"<<std::endl;}intmain(){vector<Base*>baseclass;Base*ptrDerived=newDerived;baseclass.push_back(ptrDerived);Base*ptrBase=newBase;baseclass.push_back(ptrBase);baseclass.push_back(newDerived);vector<Base*>::const_iteratoriter;for(iter=baseclass.begin();iter!=baseclass.end();++iter){(*iter)->print();}system("pause");return0;}其运行结果就是先Derived,后Base,然后又是Derived。注意push_back是值传递。此处多态体现是标准C++语言本身就有的!2023-07-23 14:02:353
C++一道题 跪求解答
构造函数执行顺序:先按继承顺序执行基类的构造函数,再执行派生类中按子对象声明顺序的构造函数,最后再执行派生类自己的构造函数。而析构函数恰好是逆方向。2023-07-23 14:02:422
C++多继承方式构造函数的执行顺序
1.基类的构造函数.2.子对象的构造函数.3.成员初始化表中的其他项.4.派生类构造函数的函数体.2023-07-23 14:02:524
什么是构造函数?构造函数可以重载吗?为什么?
给你的例子,你应该就能明白拉public class Test{ Test(){ System.out.println("test"); } Test(String s){ System.out.println("test "+s); }public static void main (String main[]){ Test t=new Test(); Test t2=new Test("r");} }2023-07-23 14:03:035
C++派生类的复制构造函数的初始化为什么用基类,而不是派生类对象 他的复制过程是怎样的
构造函数要初始化的?你到底想表达什么?最好把你有疑问的代码发上来2023-07-23 14:03:223
r e d可以组成什么单词
red 红色的祝你学习进步,更上一层楼!(*^__^*) 有不会的可以再问我:)2023-07-23 14:03:317
ldentify the paragraph from which the information is derived
ldentify the paragraph 意思是“识别该段落”,后面的 from which the information is derived 是 paragraph 的定语从句,可以翻译为“请识别这个信息来源的段落”。2023-07-23 14:03:571
C#程序题 class Base{ public Base() { Console.WriteLi
先执行父类里的。2023-07-23 14:04:072
在java 中 父类定义的静态方法 子类 调用时候 如何 知道 是哪个子类调用的
在C1中重写(override)test方法2023-07-23 14:04:194
java这道基础题为什么是这样的结果 谁能给讲讲?
Dervied extends Base 继承Dervied复写两个方法 所以印出来的都一样!!Dervied.classBase.class 两个方法是一样的所以内容被复写了!!!这样你知道了吗???2023-07-23 14:04:393
找出下面程序中的错误,并进行改正
class derived: base{ int y; public: void setxy(int n,int m) { setx(n); y=m; } void showxy() { cout<<x<<; //这里 showx(); cout<<y<<endl;} };2023-07-23 14:05:481
C#中: 错误:错误 1 未能找到为 Main 方法指定的“new_test.DerivedClass” 练习3; 什么怎么回事~~求教
就是啊,要不这样谁能看懂啥意思啊。2023-07-23 14:05:564
c++继承,大虾空降救命
derived(int i,int a,int b,int c,int d,int e,int f,int g):base1(g,a),member2(e),member1(g,d),base2(b),member3(f),base3(c),member(i)仔细看看书!构造函数和析构函数是不被继承的!2023-07-23 14:06:192
C与C++的共性、C与Java的共性、C++与 Java共性。请详细的分析一下。谢谢!!
它们的关系很简单,简单的说: c是面向过程语言,c++与java都是由c发展进化来的面向对象语言,c++与java大同小异2023-07-23 14:06:293
patient-derived xenografts怎样翻译成中文
patient-derived及其临床意义2023-07-23 14:06:433
派生的读音派生的读音是什么
派生的读音是:pàishēng。派生的拼音是:pàishēng。注音是:ㄆㄞ_ㄕㄥ。结构是:派(左右结构)生(独体结构)。词性是:形容词。派生的具体解释是什么呢,我们通过以下几个方面为您介绍:一、词语解释【点此查看计划详细内容】派生pàishēng。(1)由某一根本事物的发展过程中分化出来。二、引证解释⒈本指江河的源头产生出支流。引南朝梁刘勰《文心雕龙·隐秀》:“源奥而派生,根盛而颖峻。”⒉引申为从一个主要事物的发展中分化出来。引《人民日报》1981.3.3:“在上述五个问题中,前两个是基本的,后三个是派生的,前两个问题一解决,后三个问题即可迎刃而解。”《新华文摘》1983年第12期:“一件艺术品的价值不仅仅在于它包含了多少思想,还在于它在被社会欣赏的过程中能激发出、派生出多少思想。”三、国语词典由一个主要事物中分生出来。词语翻译英语toproduce(fromsthelse)_,toderive(fromrawmaterial)_,derivative德语ableiten(V)_法语dériverde四、网络解释派生派生:汉语词汇派生:词法学造词法的一种派生:哲学名词派生(汉语词汇)派生是一个汉语词汇,读音为pàishēng,本指江河的源头产生出支流。引申为从一个主要事物的发展中分化出来。关于派生的近义词衍生关于派生的单词derivativederivedlawderivedkeyderivedline关于派生的成语道不行派拉帮结派关于派生的词语拉帮结派斯文一派道不行派鹰派人物源殊派异少壮派异派同源耍两面派风派人物枝源派本关于派生的造句1、在西方语言的影响下,派生词很少的汉语,也开始大量使用衍生词。2、港式菠萝油,从传统菠萝包派生出来港式新吃法,外酥里嫩,实在美味。3、还可以要求对作品的派生物使用与原版一样的条款。4、大篆的发展派生出了小篆和古隶,秦统一中国后,小篆成了惟一的官体文字。5、词干可以是一个黏着词根、自由语素或者本身就是一个派生词。点此查看更多关于派生的详细信息2023-07-23 14:06:501
C++程序解释
class Base{ //定义类bpublic: Base(int i=0) { x=i;} // 构造函数初始化 int sss() { return x;} // 公共成员sss,用来访问私有成员xprivate: int x;};class Derived:public Base //以base为基类派生derived类,公有继承{public: Derived(int i=0,int j=0):Base(i) {y=j;} //构造函数初始化 int sss() { return Base::x+y;} //公共成员sss,用来返回x+yprivate: int y;};void main(){ int x,y,z; Base b(5); //定义base类对象b Derived d(2,4); //类似上边 Derived g; //同上 x= b.sss(); //令x=base类对象b的私有成员x y=d.sss(); //类似以上 z=g.sss(); //类似以上}2023-07-23 14:06:583
jeonse造句 jeonseの例文 "jeonse"是什麼意思
Jeonse tenants are taking a short position in the housing market in some sense. Jeonse involves the tenant giving the landlord a large sum of " key money " when a lease is signed. However, there is a certain level of risks of which the tenants shall be aware for leasing an apartment by Jeonse . When the apartment price goes down the amount of Jeonse deposit goes down proportionally, although this may not always be the case. Depending on the area, " jeonse " prices can range as much as 80 % of the home"s sale price. The expensive Gangnam area"s " jeonse " is about 30 % of the sales price because those properties are so expensive. As Jeonse tenants are not obpgated to pay any monthly rent, it may lead them to bepeve that Jeonse is a great deal in all aspects. As Jeonse tenants are not obpgated to pay any monthly rent, it may lead them to bepeve that Jeonse is a great deal in all aspects. It is a mon practice that Jeonse tenants have the deposit ready by taking a loan from a bank due to the sheer amount of the deposit. Since the " jeonse " price reflects the actual demand of people who reside in the area, the gap beeen rental deposits for " jeonse " and the apartment sales price means there might be an economic bubble in the apartment price. It"s difficult to see jeonse in a sentence. 用 jeonse 造句挺难的 Since the " jeonse " price reflects the actual demand of people who reside in the area, the gap beeen rental deposits for " jeonse " and the apartment sales price means there might be an economic bubble in the apartment price. This unique way of renting a house is called " jeonse "; a renter makes a lump-sum deposit on a rental space instead of paying monthly rent, at anywhere from 50 to 100 % of the market value, and gets back the whole deposit when the rent contract ends.2023-07-23 14:06:361
zambia哪个国家?
zambia是赞比亚共和国。赞比亚共和国(The Republic of Zambia),是非洲中南部内陆国家,东接马拉维、莫桑比克,南接津巴布韦、博茨瓦纳和纳米比亚,西邻安哥拉,北靠刚果(金)及坦桑尼亚。大部分地区海拔1000~1500米。属热带草原气候,5~8月为干凉季,气温为15~27℃,9~11月为干热季,气温为26~36℃,12月至次年4月为雨季。年平均气温18℃~20℃。农业是赞国民经济的重要部门,产值约占国内生产总值的20%。全国80%以上人口从事农业。目前开发的可耕地面积为620万公顷,只占全部可耕地的14%。土地肥沃,气候温和,适合多种农作物生长。对外贸易:主要出口铜、钴、锌、木材、烟草、食糖、咖啡等,其中铜出口是赞主要的外汇来源。主要进口机械设备、石油、化工产品、医药和纺织品等。主要出口国为瑞士、中国、南非、刚果(金)和埃及等,主要进口国为南非、刚果(金)、中国、印度等。2020年,出口额为67.63亿美元,进口额为45.27亿美元。2023-07-23 14:06:371
2018-04-24 乔布斯斯坦福大学演讲原文
乔布斯斯坦福大学演讲英文原文: Stanford Report, June 14, 2005‘You"ve got to find what you love," Jobs saysThis is the text of the Commencement address by Steve Jobs, CEO of Apple Computer and of Pixar Animation Studios, delivered on June 12, 2005.I am honored to be with you today at your commencement from one of the finest universities in the world. I never graduated from college. Truth be told, this is the closest I"ve ever gotten to a college graduation. Today I want to tell you three stories from my life. That"s it. No big deal. Just three stories.The first story is about connecting the dots.I dropped out of Reed College after the first 6 months, but then stayed around as a drop-in for another 18 months or so before I really quit. So why did I drop out?It started before I was born. My biological mother was a young, unwed college graduate student, and she decided to put me up for adoption. She felt very strongly that I should be adopted by college graduates, so everything was all set for me to be adopted at birth by a lawyer and his wife. Except that when I popped out they decided at the last minute that they really wanted a girl. So my parents, who were on a waiting list, got a call in the middle of the night asking: “We have an unexpected baby boy; do you want him?” They said: “Of course.” My biological mother later found out that my mother had never graduated from college and that my father had never graduated from high school. She refused to sign the final adoption papers. She only relented a few months later when my parents promised that I would someday go to college.And 17 years later I did go to college. But I naively chose a college that was almost as expensive as Stanford, and all of my working-class parents" savings were being spent on my college tuition. After six months, I couldn"t see the value in it. I had no idea what I wanted to do with my life and no idea how college was going to help me figure it out. And here I was spending all of the money my parents had saved their entire life. So I decided to drop out and trust that it would all work out OK. It was pretty scary at the time, but looking back it was one of the best decisions I ever made. The minute I dropped out I could stop taking the required classes that didn"t interest me, and begin dropping in on the ones that looked interesting.It wasn"t all romantic. I didn"t have a dorm room, so I slept on the floor in friends" rooms, I returned coke bottles for the 5?? deposits to buy food with, and I would walk the 7 miles across town every Sunday night to get one good meal a week at the Hare Krishna temple. I loved it. And much of what I stumbled into by following my curiosity and intuition turned out to be priceless later on. Let me give you one example:Reed College at that time offered perhaps the best calligraphy instruction in the country. Throughout the campus every poster, every label on every drawer, was beautifully hand calligraphed. Because I had dropped out and didn"t have to take the normal classes, I decided to take a calligraphy class to learn how to do this. I learned about serif and san serif typefaces, about varying the amount of space between different letter combinations, about what makes great typography great. It was beautiful, historical, artistically subtle in a way that science can"t capture, and I found it fascinating.None of this had even a hope of any practical application in my life. But ten years later, when we were designing the first Macintosh computer, it all came back to me. And we designed it all into the Mac. It was the first computer with beautiful typography. If I had never dropped in on that single course in college, the Mac would have never had multiple typefaces or proportionally spaced fonts. And since Windows just copied the Mac, its likely that no personal computer would have them. If I had never dropped out, I would have never dropped in on this calligraphy class, and personal computers might not have the wonderful typography that they do. Of course it was impossible to connect the dots looking forward when I was in college. But it was very, very clear looking backwards ten years later.Again, you can"t connect the dots looking forward; you can only connect them looking backwards. So you have to trust that the dots will somehow connect in your future. You have to trust in something - your gut, destiny, life, karma, whatever. This approach has never let me down, and it has made all the difference in my life.My second story is about love and loss.I was lucky - I found what I loved to do early in life. Woz and I started Apple in my parents garage when I was 20. We worked hard, and in 10 years Apple had grown from just the two of us in a garage into a $2 billion company with over 4000 employees. We had just released our finest creation - the Macintosh - a year earlier, and I had just turned 30. And then I got fired. How can you get fired from a company you started? Well, as Apple grew we hired someone who I thought was very talented to run the company with me, and for the first year or so things went well. But then our visions of the future began to diverge and eventually we had a falling out. When we did, our Board of Directors sided with him. So at 30 I was out. And very publicly out. What had been the focus of my entire adult life was gone, and it was devastating.I really didn"t know what to do for a few months. I felt that I had let the previous generation of entrepreneurs down - that I had dropped the baton as it was being passed to me. I met with David Packard and Bob Noyce and tried to apologize for screwing up so badly. I was a very public failure, and I even thought about running away from the valley. But something slowly began to dawn on me - I still loved what I did. The turn of events at Apple had not changed that one bit. I had been rejected, but I was still in love. And so I decided to start over. I didn"t see it then, but it turned out that getting fired from Apple was the best thing that could have ever happened to me. The heaviness of being successful was replaced by the lightness of being a beginner again, less sure about everything. It freed me to enter one of the most creative periods of my life.During the next five years, I started a company named NeXT, another company named Pixar, and fell in love with an amazing woman who would become my wife. Pixar went on to create the worlds first computer animated feature film, Toy Story, and is now the most successful animation studio in the world. In a remarkable turn of events, Apple bought NeXT, I retuned to Apple, and the technology we developed at NeXT is at the heart of Apple"s current renaissance. And Laurene and I have a wonderful family together.I"m pretty sure none of this would have happened if I hadn"t been fired from Apple. It was awful tasting medicine, but I guess the patient needed it. Sometimes life hits you in the head with a brick. Don"t lose faith. I"m convinced that the only thing that kept me going was that I loved what I did. You"ve got to find what you love. And that is as true for your work as it is for your lovers. Your work is going to fill a large part of your life, and the only way to be truly satisfied is to do what you believe is great work. And the only way to do great work is to love what you do. If you haven"t found it yet, keep looking. Don"t settle. As with all matters of the heart, you"ll know when you find it. And, like any great relationship, it just gets better and better as the years roll on. So keep looking until you find it. Don"t settle.My third story is about death. When I was 17, I read a quote that went something like: “If you live each day as if it was your last, someday you"ll most certainly be right.” It made an impression on me, and since then, for the past 33 years, I have looked in the mirror every morning and asked myself: “If today were the last day of my life, would I want to do what I am about to do today?” And whenever the answer has been “No” for too many days in a row, I know I need to change something.Remembering that I"ll be dead soon is the most important tool I"ve ever encountered to help me make the big choices in life. Because almost everything - all external expectations, all pride, all fear of embarrassment or failure - these things just fall away in the face of death, leaving only what is truly important. Remembering that you are going to die is the best way I know to avoid the trap of thinking you have something to lose. You are already naked. There is no reason not to follow your heart.About a year ago I was diagnosed with cancer. I had a scan at 7:30 in the morning, and it clearly showed a tumor on my pancreas. I didn"t even know what a pancreas was. The doctors told me this was almost certainly a type of cancer that is incurable, and that I should expect to live no longer than three to six months. My doctor advised me to go home and get my affairs in order, which is doctor"s code for prepare to die. It means to try to tell your kids everything you thought you"d have the next 10 years to tell them in just a few months. It means to make sure everything is buttoned up so that it will be as easy as possible for your family. It means to say your goodbyes. I lived with that diagnosis all day. Later that evening I had a biopsy, where they stuck an endoscope down my throat, through my stomach and into my intestines, put a needle into my pancreas and got a few cells from the tumor. I was sedated, but my wife, who was there, told me that when they viewed the cells under a microscope the doctors started crying because it turned out to be a very rare form of pancreatic cancer that is curable with surgery. I had the surgery and I"m fine now.This was the closest I"ve been to facing death, and I hope its the closest I get for a few more decades. Having lived through it, I can now say this to you with a bit more certainty than when death was a useful but purely intellectual concept:No one wants to die. Even people who want to go to heaven don"t want to die to get there. And yet death is the destination we all share. No one has ever escaped it. And that is as it should be, because Death is very likely the single best invention of Life. It is Life"s change agent. It clears out the old to make way for the new. Right now the new is you, but someday not too long from now, you will gradually become the old and be cleared away. Sorry to be so dramatic, but it is quite true.Your time is limited, so don"t waste it living someone else"s life. Don"t be trapped by dogma - which is living with the results of other people"s thinking. Don"t let the noise of other"s opinions drown out your own inner voice. And most important, have the courage to follow your heart and intuition. They somehow already know what you truly want to become. Everything else is secondary. When I was young, there was an amazing publication called The Whole Earth Catalog, which was one of the bibles of my generation. It was created by a fellow named Stewart Brand not far from here in Menlo Park, and he brought it to life with his poetic touch. This was in the late 1960"s, before personal computers and desktop publishing, so it was all made with typewriters, scissors, and polaroid cameras. It was sort of like Google in paperback form, 35 years before Google came along: it was idealistic, and overflowing with neat tools and great notions.Stewart and his team put out several issues of The Whole Earth Catalog, and then when it had run its course, they put out a final issue. It was the mid-1970s, and I was your age. On the back cover of their final issue was a photograph of an early morning country road, the kind you might find yourself hitchhiking on if you were so adventurous. Beneath it were the words: “Stay Hungry. Stay Foolish.” It was their farewell message as they signed off. Stay Hungry. Stay Foolish. And I have always wished that for myself. And now, as you graduate to begin anew, I wish that for you.Stay Hungry. Stay Foolish.Thank you all very much.2023-07-23 14:06:461
如何在学信网查询自己的学历信息
品牌型号:联想小新Pro16 2022款系统版本:Windows10软件版本:百度浏览器8.7.5学历信息可通过学信网学生档案查询,具体操作步骤如下:学信网查询1、点击进入官网搜索学信网,点击进入学信网官网。2、点击登录在页面填写信息后点击登录。3、点击学信档案登录后在页面点击学信档案进入。4、点击学历信息在学信档案页面点击学历信息即可查看。法律依据《高等学校档案管理办法》第二十七条:高校档案机构应当按照国家有关规定公布档案。未经高等学校授权,其他任何组织或者个人无权公布学校档案。属下列情况之一者,不对外公布:(一)涉及国家秘密的;(二)涉及专利或者技术秘密的;(三)涉及个人隐私的;(四)档案形成单位规定限制利用的。2023-07-23 14:06:471
All Along The Watchtower 歌词
歌曲名:All Along The Watchtower歌手:Jimi Hendrix专辑:Smash HitsThere must be some kind of way out of heresaid the joker to the thiefThere"s too much confusionI can"t get no reliefBusinessen they (uh) drink my winePlowman dig my earthNone will level on the vineNobody of it is worthHey heyNo reason to get excited (uh) (huh)The thief he kindly spokeThere are many here among us (uh)who feel that life is but a jokeBut uhbut you and I we been through thatAnd this is not our fateSo let us not talk falsely nowThe hour"s getting lateHeyOoh All along the watchtowerPrinces kept their viewwhile all the women came and wentBarefoot servants tooWell uhooh Outside in the cold distancea wildcat did growlTwo riders were approachingand the wind began to howlGotta get awayAll Along The Watchtowerhttp://music.baidu.com/song/14637172023-07-23 14:06:351
万物互联时代 物联网将带来哪些变革
物联网产业链可以细分为标识、感知、处理和信息传送四个环节,每个环节的关键技术分别为RFID、传感器、智能芯片和电信运营商的无线传输网络。 EPoSS在《Internet of Things in 2020》报告分析预测,未来物联网的发展将经历四个阶段,2010年之前RFID被广泛应用于物流、零售和制药领域,2010-2015年物体互联,2015-2020年物体进入半智能化,2020年之后物体终端进入全智能化。 RFID是物联网发展的排头兵,RFID技术是一项利用射频信号通过空间耦合(交变磁场或电磁场)实现无接触信息传递并通过所传递的信息达到识别目的的技术,最简单的RFID系统由电子标签(Tag)、读写器(Reader)和天线(Antenna)三部分组成,在实际应用中还需要其他硬件和软件的支持。2009年中国RFID市场规模将达到50亿元,年复合增长率为33%,其中电子标签超过38亿元、读写器接近7亿元、软件和服务达到5亿元的市场格局。 MEMS传感器市场前景广阔 MEMS(Micro-Electro-Mechanical Systems)是微机电系统的缩写,MEMS技术建立在微米/纳米基础上,是对微米/纳米材料进行设计、加工、制造、测量和控制的技术,完整的MEMS是由微传感器、微执行器、信号处理和控制电路、通讯接口和电源等部件组成的一体化的微型器件系统。MEMS传感器目前主要应用在汽车和消费电子两大领域。任天堂公司的Wii无线游戏机允许使用者通过运动和点击互相沟通和在屏幕上处理一些需求,其原理是将运动(例如挥舞胳膊模仿网球球拍的运动)转化为屏幕上的游戏行为。在苹果公司的iPhone中,通过对旋转时运动的感知,iPhone可以自动地改变其显示格式,以便消费者能够以合适的水平和垂直视角看到完整的页面或者数字图片。根据ICInsight最新报告,预计在2007年至2012年间,全球基于MEMS的半导体传感器和制动器的销售额将达到19%的年均复合增长率(CAGR),与2007年的41亿美元相比,五年后将实现97亿美元的年销售额。目前上市公司中歌尔声学已经掌握MEMS芯片设计、MEMS半导体封装等多项核心技术,2008年申请相关专利高达44项,主要应用在MEMS麦克风的生产制造。我们认为公司将在物联网时代MEMS传感器领域占据竞争优势。 智能终端备受期待 法国Violet公司推出了Nabaztag小兔子,通过wi-fi路由连接网络,可为主人提供所需的各类新闻等,能够讲5国语言,在主人接收到邮件或信息时,会发出语音提醒。此外它还能识读Ztamps标签上的信息,并实时连网,随时呈现动态信息。我们认为随着物联网推进,家用电器的智能化将是未来发展趋势。上市公司中的拓邦电子是家电智能控制应用领域的行业先行者,未来发展值得关注。 集成电路产业有望迎来发展新机遇 2005年我国集成电路市场规模达到3800亿元,占全球比重达25%,成为全球仅次于美国的第二大集成电路市场。32位CPU芯片、网络路由交换芯片、GSM/GPRS手机基带芯片、TD-SCDMA基带芯片、数字音视频和多媒体处理芯片、第二代居民身份证芯片等一批中高端产品相继研发成功并投入市场,产品设计能力达到0.18微米,集成度超过千万门;集成电路芯片生产线工艺水平达到12英寸0.13微米,90纳米工艺技术研发取得进展,与国外先进水平之间的差距明显缩小。 电信设备商最受益于物联网 当下最大的投资机会在于电信设备商,物联网的商业建设尚处于萌芽阶段。电信运营商是物联网的积极推动者,物联网丰富电信网络的应用。就三家电信运营商而言,包含强势固网的全业务运营商中国电信和中国联通在行业用户的ICT(信息通信技术,Information and Communications Technology)建设中一直处于领导地位,其全业务模式十分便于将通信网络与物联网相关信息管理的企业内网实现对接,完成对物联网的全程管控。由于资源所限以及历史原因,单纯的移动运营商中国移动目前能够实现的物联网应用还处于初级阶段。具体而言,网络的升级换代对光纤产业将产生实质性利好,受益的公司包括烽火通信、中天科技、亨通光电、中兴通讯、光讯科技、三维通信等国内领先的光纤制造商、通信设备提供商。在物联网建设进程中,这些公司最先受益,确定性最高2023-07-23 14:06:341
宿州学院每年有多少学生拿不到学位证
20多个。根据查询宿州学院统计得知,宿州学院平均每年有20多人拿不到学位证。宿州学院,位于安徽省宿州市,是安徽省属综合性普通本科高校,是安徽省示范应用型本科高校。2023-07-23 14:06:321
鲍勃·迪伦的歌 All Along the Watchtower 歌词怎样翻译比较好
All Along The Watchtower沿着瞭望塔“There must be some way out of here,” said the joker to the thief“一定有逃离此处的办法,”小丑对小偷说“There"s too much confusion, I can"t get no relief“困惑围绕着我,我无法解脱Businessmen, they drink my wine, plowmen dig my earth商人们,他们喝着我的酒,农民们耕着我的地None of them along the line know what any of it is worth”此时此刻,他们却浑然不知这一切有何意义。 ”“No reason to get excited,” the thief, he kindly spoke“没有理由过于激动,”小偷侃侃说道“There are many here among us who feel that life is but a joke“周围很多人都觉得,生活只不过是一个玩笑But you and I, we"ve been through that, and this is not our fate但你和我,早已历经这风雨,命运不会如此之糟糕So let us not talk falsely now, the hour is getting late”所以,别这样假惺惺地说话,时候已经不早。”All along the watchtower, princes kept the view沿着瞭望塔方向,王子们凝视远方While all the women came and went, barefoot servants, too而夫人和赤脚侍从们,来来往往Outside in the distance a wildcat did growl塔外远处,野猫嚎叫Two riders were approaching, the wind began to howl一对骑手临近城下,狂风咆哮2023-07-23 14:06:271