首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
While chemists try to assemble molecules using a combination of theoretical principles and practical experience to mold m
While chemists try to assemble molecules using a combination of theoretical principles and practical experience to mold m
admin
2011-01-17
38
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.
The primary purpose of the passage is to
选项
A、indicate some possible technological benefits to the development of new and varied techniques in nanotechnology
B、argue that science involving the macroscopic tends to be exponentially more difficult than the science of the microscopic
C、defend the use of the bottom-up approach of building molecules as more efficient relative to the top-down approach
D、distinguish two different approaches in nanotechnology and comment on their differences and similarities
E、correct the misconception that the benefits of nanotechnology are likely to be seen in the near future
答案
D
解析
转载请注明原文地址:https://kaotiyun.com/show/1hjO777K
本试题收录于:
GRE VERBAL题库GRE分类
0
GRE VERBAL
GRE
相关试题推荐
Haveyoueverheardofapawpaw(木瓜)?Ifnot,donotfeelbad.ManyAmericansdonotknowofthefruit,althoughitisnativeto
Inancienttimesthemostimportantexaminationswerespoken,notwritten.IntheschoolsofancientGreeceandRome,testingus
Overtheyears,collegestudentshavestoodtogetherforwhattheybelievein,fromcivilrightstoanti-warpoliciestothemor
Overtheyears,collegestudentshavestoodtogetherforwhattheybelievein,fromcivilrightstoanti-warpoliciestothemor
Bytheendofthismonth,wesurely______asatisfactorysolutiontotheproblem.
Mistakesarethethingsthatnobodywants,butwestillmakemistakesatanyage.Somemistakeswemakeareaboutmoney.Somear
InspectionsystemXandinspectionsystemY,thoughbasedondifferentprinciples,eachdetectallproductflaws,buttheyeach
Nostatelawforbidsanemployerfromrejectingajobapplicantortodismissanemployeebasedontheresultsofaliedetector
In1971researchershopingtopredictearthquakesintheshorttermbyidentifyingprecursoryphenomena(thosethatoccurafew
In1971researchershopingtopredictearthquakesintheshorttermbyidentifyingprecursoryphenomena(thosethatoccurafew
随机试题
简述宗法观念对秦汉以后国家政治结构的渗透。
一女性患者胆囊切除术后一年,屡感上腹部不适,超声示近段胆管扩张,胆管内径10mm,壁轻度增厚,回声增强,并可显示局部狭窄,肝脏稍增大,呈淤胆表现,其最可能的诊断是
宅基地使用权属于民事权利的范畴。宅基地使用权人的权利主要体现在()。
项目评估的一般方法论原则包括动态分析与静态分析,以()为主。
有耐磨要求的混凝土优先选用的常用水泥有()。
下列关于品种法的表述不正确的是()。
设D=则A31+A32+A33=______.
Communicationisfarmorethanspeechandwriting.Mostofusareawarethatwearecommunicatinginmanydifferentwayseven【S1
A、Thenorthernreasonsforthewar.B、Topreservedemocracy.C、Todeterminethefutureofdemocracythroughouttheworld.D、The
Mostpeopledon’twakeupinthemorning,combtheirhair,andwalkoutthefrontdoorandontotheworldstage.ButBritain’sP
最新回复
(
0
)