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A.氢 H
B.氮 N
C.氧 O
D.磷 P
E.碳 C
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更多“目前MRI主要用哪种元素来成像 Which element is currently used for MRI imaging？”相关的问题
Polygraphs, which have been used for decades, have been joined by new systems that purportedly analyze a person's voice, blush, pupil size and even brain waves for signs of deception. The devices range from costly experimental devices that use strings of electrodes or thermal imaging to ＄19. 95 palm-sized versions.
No studies have ever proven that lie detectors work. Many show that they assess truth as accurately as a coin flip; in other words, not at all. Still, some people have come to depend on them. The recent proliferation of lie detectors has reignited a decades-old debate over the ethics and politics of when and how they should be used and whether such important questions as guilt or innocence should be left to machines.
Mankind has looked for centuries for a physical indicator that would expose a liar. The Romans studied the entrails of suspected liars. In China, rice was shoved into the mouths of interviewees to measure how dry they were -- the drier the mouth, the more likely the person was lying, it was thought. Other cultures tried various chemical concoctions, but they worked no better than chance.
Especially since September 11, law enforcement agencies consider lie detection systems critical to their investigations. The CIA, FBI and Defense Department have spent millions of dollars on them. In an unusual plea made soon after the terrorist attacks, the government asked for the public's help in building counterterrorism technologies, among them a portable polygraph.
In the United States, there is a double standard when it comes to the use of polygraphs. Although the so-called lie detector is considered an important law enforcement tool, polygraph data are inadmissible as evidence in a court of law. The US Supreme Court forbade private companies from using them to screen job applicants, but allowed the government to use them for the same purpose.
As debate about polygraphs rages, the devices are being phased out in favor of voice analyzers, which are more portable and easier to use. A voice analyzer device typically consists of a telephone and microphone attached to a computer that packs neatly in a briefcase, or attached to any PC with the proper software installed. Most of the analyzers can be used in person or over the phone. Conversations can be tested in real time or recorded for later analysis.
First, the questioner asks an interviewee about something he or she would have no reason to lie about, such as "When's your birthday？" Then he asks what he really wants to ask. The device makes an assessment about whether the subject is telling the truth based on the differences between the inaudible microtremors in the voice during the first round of questioning and those in the second.
The federal government officially says it does not use these voice lie detectors. Still, the voice technology has its true believers, among them more than 1,200 police departments nationwide and tens of thousands of consumers.
The slightly more sophisticated Truster software program that runs on a desktop computer gives text rating of truthfulness. The companies that market these technologies say they are more than 80 percent accurate.
Though skeptical, Rick Garloff, a 35-year-old American, still said even if the systems are not great lie detectors, they are wonderful lie deterrents. He once used the Truster on his 9-year-old son, to see if he had forgotten to close a door, accidentally letting the d
| 阅读理解。 |
| Among the most popular books being written today are those which are usually classified as science fiction. Hundreds of titles are published every year and are read by all kinds of people. Furthermore, some of the most successful films in recent years have been based on science fiction stories. It is often thought that science fiction is a fairly new development in literature, but it can be found in books written hundreds of years ago. These books were often concerned with the presentation of some form of ideal society, a theme which is still often found in modern stories. Most of the classics of science fiction, however, have been written within the last one hundred years. Books by writers such as Jules Verne and H. Wells, to mention just two well-known authors, have been translated into many languages. Modern science fiction writers don't write about men from Mars or space adventure stories. They are more interested in predicting the results of technical developments on society and the human mind or in imagining future world which results the world we live in now. Because of this their writing has obvious political undertones. In an age where science fact frequently overtakes science fiction, the writers may find it difficult to keep ahead of scientific advances.Those who see the future clearly can teach us how to master new technology and live in a rapidly changing world. |
| 1. You can find science fiction ______. |
| A. only in modern literature B. only in books written for children C. in books written today and hundreds of years ago D. as a new development in literature |
| 2. Modern science fiction writers are interested in ______. |
| A. writing about men from Mars B. writing about everything but politics C. imagining future world with the results of technical developments D. writing space adventure stories |
| 3. It can be concluded that modern science fiction____________. |
| A. reflects social political reform B. shows the writer's viewpoints C. is not as good as that in the past D. is better than other literary forms |
| 4. Science fiction writers may provide a valuable lesson on how to deal with the problems of ______. |
| A. conflict used by different political theories B. adopting new technology and adapting quickly to its effect on society C. conflict caused by different religious beliefs D. space adventure |
| 5. Which of the following statements is NOT true？ |
| A. Science fiction often overtakes science fact. B. Writers may find it hard to keep ahead of scientific advances. C. Some of the most successful films of recent years have been based on science fiction stories. D. Those writers who can see clearly the way we are going will give us valuable instructions. |
A、稳定的主磁场 Stable magnetic field
B、具有一定能量的射频脉冲 RF pulse with a certain energy
C、梯度磁场 Gradient magnetic field
D、磁矩不为零的自旋核 Spin nuclei with non-zero magnetic moment
E、感应线圈 Induction coil
A、低活度核素 Low activity nuclides
B、短半衰期核素 Short half-life nuclides
C、高活度核素 High activity nuclides
D、长寿命核素 Long half-life nuclides
A、反映人体的新陈代谢信息 Showing metabolism information of human body
B、图像分辨率高 Images with high resolution
C、分子水平成像 molecular imaging
D、可以检测早期肿瘤 Detecting tumor at early stage
A、电脑产生的辐射 Radiation generated by computer
B、电吹风产生的辐射 Radiation generated by hair drier
C、手机产生的辐射 Radiation generated by mobilephone
D、DR产生的辐射 Radiation generated by DR
A、单位体积内放射性核素的数目 Number of radionuclides per unit volume
B、单位时间内发生核衰变的次数 Number of radionuclide decay per unit time
C、单位时间内核衰变释放的能量 Energy released by radionuclide decay per unit time
D、核素半衰期的2倍 2 times the half-life of the radionuclide
E、放射性核素半衰期 Half-life of radionuclides
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