并行技术可使系统各种硬件资源尽量并行工作,这样的程序执行环境具有独立性、随机性和A.

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问题:

并行技术可使系统各种硬件资源尽量并行工作,这样的程序执行环境具有独立性、随机性和

A. 封闭性

B. 多发性

C. 顺序性

D. 资源共享性

考点:计算机等级考试计算机等级考试四级计算机四级真题2002年09月
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A向B发送消息P,并使用公钥体制进行数字签名。设E表示公钥,D表示私钥,则B要保留的证据是 (49) 。基于数论原理的RSA算法的安全性建立在 (50) 的基础上。 Kerberos是MIT为校园网设计的身份认证系统,该系统利用智能卡产生 (51) 密钥,可以防止窃听者捕获认证信息。为了防止会话劫持,Kerberos提供了 (52) 机制,另外报文中还加入了 (53) ,用于防止重发攻击(Replay Attack)。

51()

A.私有

B.加密

C.一次性

D.会话

题型:单项选择题

化简a-(a-b+c)的结果是(  )

A.b+c

B.-b+c

C.b-c

D.-b-c

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工艺卡片实行分级管理,对关键性操作参数或对安全运行、质量控制有重要影响的操作参数,列入单元级控制指标,对一般性操作参数或对生产运行有较大影响的指标列为公司级控制指标。

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自动化仪表工程,检测回路的试验应符合的要求不包括()。

A.在检测回路的信号输入端输入模拟被测变量的标准信号,回路的显示仪表部分的示值误差,不应超过回路内各单台仪表允许基本误差平方和的平方根值

B.温度检测回路可在检测元件的输出端向回路输入电阻值或mV值模拟信号

C.现场不具备模拟被测变量信号的回路,应在其可模拟输入信号的最前端输入信号进行回路试验

D.输入信号确保为4~20mA交流信号

题型:单项选择题

If there is one thing scientists have to hear, it is that the game is over. Raised on the belief of an endless voyage of discovery, they recoil from the suggestion that most of the best things have already been located. If they have, today’s scientists can hope to contribute no more than a few grace notes to the symphony of science.

A book to be published in Britain this week, The End of Science, argues persuasively that this is the case. Its author, John Horgan, is a senior writer for Scientific American magazine, who has interviewed many of today’s leading scientists and science philosophers. The shock of realizing that science might be over came to him, he says, when he was talking to Oxford mathematician and physicist Sir Roger Penrose.

The End of Science provoked a wave of denunciation in the United States last year. "The reaction has been one of complete shock and disbelief, "Mr. Horgan says.

The real question is whether any remaining unsolved problems, of which there are plenty, lend themselves to universal solutions. If they do not, then the focus of scientific discovery is already narrowing. Since the triumphs of the 1960s—the genetic code, plate tectonics, and the microwave background radiation that went a long way towards proving the Big Bang—genuine scientific revolutions have been scarce. More scientists are now alive, spending more money on research, that ever. Yet most of the great discoveries of the 19th and 20th centuries were made before the appearance of state sponsorship, when the scientific enterprise was a fraction of its present size.

Were the scientists who made these discoveries brighter than today’s That seems unlikely. A far more reasonable explanation is that fundamental science has already entered a period of diminished returns. "Look, don’t get me wrong," says Mr Horgan. "There are lots of important things still to study, and applied science and engineering can go on for ever. I hope we get a cure for cancer, and for mental disease, though there are few real signs of progress.

The term "the Big Bang" probably refers to()

A. the genetic code theory

B. a geological theory

C. a theory of the origin of the universe

D. the origin and the power of atomic energy

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