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
70
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.
It can be inferred from the passage that the author believes which of the following concerning the top-down method of nanotechnology?
选项
A、The top-down method tends to be accurate but highly inefficient, resulting in a process that takes a great deal of time and energy.
B、The top-down method, unlike the bottom-up method, tends to disobey the rules of many chemical interactions.
C、The top-down method requires a greater level of technological involvement than does the bottom-up method.
D、The top-down method shows the limits of nanotechnology methods that rely too heavily on parallel processes.
E、The top-down method is fairly useless when applied to the problem of creating a single molecule.
答案
A
解析
转载请注明原文地址:https://kaotiyun.com/show/2hjO777K
本试题收录于:
GRE VERBAL题库GRE分类
0
GRE VERBAL
GRE
相关试题推荐
Itisestimatedthatthedisease______bypollutedwaterwillkill1outofevery100children.
Thegovernmentwillconsider______futureactionsagainstterroristbombers.
Hermindwassobythediseasethatshecouldnotrememberwhatshehaddone.
Seldomdidwerealizethatmanyofourhairproblems______whatweeat.
Proteinsynthesisbeginswhenthegeneencodingaproteinisactivated.Thegene’ssequenceofnucleotidesistranscribedinto
Thefactthatsuperiorservicecangenerateacompetitiveadvantageforacompanydoesnotmeanthateveryattemptatimproving
MarissauseswhichofthefollowingtechniquesinattemptingtorefuteWalter’sargument?
STIMULATE:TONIC::
SUMMARY:
TocallCarlos______wouldbetomistakehisnaturalself-confidenceandyouthfulhighspiritsforwillfuldefiance.
随机试题
抑郁症的自杀率为()
企业防御战略类型包括( )
其清除率可用来代表肾小球滤过率的物质是
女性,28岁。因“抽搐、意识不清、高热3天”入院。病程中抽搐表现为双上肢弯曲,双下肢伸直,神志不清,伴有瞳孔扩大,舌咬伤及尿失禁。每次持续5~10min不等,发作间歇期意识不恢复,处于昏迷状态。同时伴有高热,体温达38.2℃~39.7℃。既往有头部外伤史。
屋面均布荷载设计值(包括檩条自重)q=1.5kN/m2。试问,多跨(≥五跨)连续檩条支座最大弯矩设计值(kN·m)与下列( )项数值最为接近。提示:可按M=0.105ql2计算。60m跨度托架端斜杆1的轴心拉力设计值(kN)与下列( )项数
马克思主义中国化的理论成果包括()
材料一《义务教育生物学课程标准(2011版)》对“开花和结果”部分内容标准如下:材料二某教材的相关内容如下:想一想,议一议许多植物的花色彩鲜艳,气味芬芳,让行人禁不住驻足观赏,甚至要凑上去闻一闻那沁人心脾的花香。
IseeabrokenuplandinthefarNorthwest.Itsgrayandpurplerocksareinterpatchedwithcolorsrichandwarm,thenew-bornc
ThenumberofwomendirectorsappointedtocorporateboardsintheUnitedStateshasincreaseddramatically,buttheratiooffe
SharingEconomicLossesThroughInsuranceEachminuteofthedayornight,everyonefacesapossiblefinancialloss.Ahome
最新回复
(
0
)