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  3. While chemists try to assemble molecules using a combination of theor

While chemists try to assemble molecules using a combination of theor

游客2024-01-11  44
问题            While chemists try to assemble molecules using a combination of theoretical
       principles and practical experience to mold molecules that have desired
       structural and chemical properties, nanotechonologists generally seek to make
Line    more than a single molecule. They build arrays of identical or complexed
(5)      molecules, sometimes on a scale that will transcend the boundaries of the
       microscopic and approach the macroscopic, using both top-down and bottom-up
       approaches. The first is exemplified by scientists who build objects and
       molecular arrays using the techniques of scanning probe microscopy, while the
       second is exemplified by investigators who design two-and three-dimensional
(10)     chemical systems that cohere according to the rules of chemical interactions.
       The top-down approach has exquisite precision, but its disadvantage is its lack
       of extensive parallelism; it requires manipulating atoms and molecules
       practically one by one, while the bottom-up approach is massively parallel. But
       in both cases, scientists are forced to use the difficult nanometer scale, i.e. the
(15)     level at which living systems tend to make their structural components, rather
       than the angstrom scale of chemistry. [br] Which of the following statements concerning nanotechnology research is most directly suggested in the passage?
选项 A、Nanotechnology research tends to be more focused on the process of building multiple molecules than chemistry research.
B、Nanotechnology research is increasingly less bound to operations on the microscopic level than it once was.
C、The practitioners of nanotechnology tend to be more optimistic than pragmatic in choosing its methodology.
D、Nanotechnology research involves a much greater level of technical knowledge, on the whole, than chemistry research.
E、Nanotechnology research tends to be more concerned at this stage with precision than convenient mass production.
答案 A
解析
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