问题 单项选择题

已知某理想气体的压强为p,体积为V,温度为T,K为玻尔兹曼常量,R为摩尔气体常量,则该理想气体单位体积内的分子数为()。

A.pV/(kT)

B.p/(kT)

C.pV/(RT)

D.p/(RT)

答案

参考答案:B

阅读理解

阅读理解

     The Ivy League is an athletic conference comprising eight private institutions of higher education in the

Northeastern United States.The term is most commonly used to refer to those eight schools considered as

a group.The term is also connected with academic excellence,selectivity in admissions,and social elitism

(精英主义).

     The term became official,especially in sports terminology,after the formation of the NCAA Division I

athletic conference in 1954,when much of the nation polarized around favorite college teams."IV" was used

because originally the league consisted only of four members.The use of the phrase is no longer limited to a

thletics,and now represents an educational philosophy inherent to the nation's oldest schools.In addition,Ivy

League schools are often viewed by the public as some of the most prestigious universities worldwide and

are often ranked amongst the best universities in the United States and worldwide.The eight institutions are

Brown University,Columbia University,Cornell University,Dartmouth College,Harvard University,Princeton

University,the University of Pennsylvania,and Yale University.

     All of the Ivy League's institutions place near the top in the US News & World Report college and

university rankings and rank within the top one percent of the world's academic institutions in terms of

financial endowment (捐助).Seven of the eight schools were founded during America's colonial period;

the exception is Cornell,which was founded in 1865.Ivy League institutions,therefore,account for seven of

the nine Colonial Colleges chartered before the American Revolution.The Ivies are all in the Northeast

geographic region of the United States.All eight schools receive millions of dollars in research grants and

other subsidies from federal and state government.

      Undergraduate enrollments among the Ivy League schools range from about 4,000 to 14,000,making

them  larger than those of  a typical private liberal arts college and smaller than a  typical public state

university.Ivy League university financial endowments range from Brown's $2.01 billion to Harvard's $26

billion,the largest financial endowment of any academic institution in the world.

1.From the passage,we know the word "Ivy" in "the Ivy League" was first chosen to refer to________.

A.a plant  

B.a number  

C.a sport  

D.a spirit

2.What is special about Cornell University in the League?

A.It is the oldest one.

B.It was founded by colonists.

C.It has the smallest endowment.

D.It is the youngest one.

3.Which meaning can the term "the Ivy League" convey today?

A.The largest enrollment.

B.The strongest government support.

C.The most expensive schools.

D.Firstclass education.

4.Which of the following statements is true?

A.There is no longer sports competition in the Ivy League.

B.Seven colleges were set up before the USA was founded.

C.Brown University has the smallest number of students.

D.Typical public state universities are larger than the Ivies.

5.Which of the following can be the best title of the passage?

A.The ABC of "The Ivy League"

B.Best Universities in the USA

C.The Financial Income of American Universities

D.How to Apply to an Ivy League University

单项选择题

阅读下面短文,回答下 * * 道题。
目前,制造微型电子元件的方法一般是从大块的半导体材料上切割下所需要的原料,然后在上面刻蚀出电路。美国得克萨斯大学奥斯汀分校的安杰拉·贝尔彻等人最近在英国《自然》杂志上发表报告说,他们的新研究成果使制造更复杂、更精密的电子元件成为可能。
科学家已经掌握了制造半导体纳米晶体的技术。半导体纳米晶体是一种分子团,仅有几纳米大小,比目前微电路中使用的晶体管小得多。一块纳米晶体能够充当一个开关或一个存储单元,将它们组合起来就能制造出电子元件。但纳米晶体比细菌还小,如何对它们进行挑选、传送和拼装等操作呢在生命体中,有时候一个细胞会发送出一个小型分子团,蛋白质则像“交通工具”一样将其运送到另一个细胞。科学家想,如果给蛋白质装备能选择不同半导体材料的分子,就可以利用这一原理对半导体纳米晶体进行操作。
贝尔彻等人通过化学反应随机产生了约10亿种不同的多肽分子,从中筛选出了那些能与半导体材料表面结合的分子,然后对这些分子进行结构改造,使其与半导体的亲和力更强。经过5轮筛选和培育,他们已经获得了能与镓砷半导体紧密结合而不与硅等其他材料结合的多肽分子。
理论上,将这种多肽分子与蛋白质结合,就能从半导体材料“仓库”中挑选出镓砷纳米晶体,运送到“建筑工地”,添加在未完成的“建筑物”上。如果进一步筛选出与其他半导体材料或掺杂剂结合的多肽分子,就能组成一支完整的“施工队”,从事微电子元件的组装工作。不过专家表示,这一技术离实用化尚有相当长的距离。

根据原文提供的信息,以下推断正确的一项是______。

A.用多肽分子运送镓砷纳米晶体到“建筑工地”,将是今后组装微电子元件的主要方法

B.组装微电子元件,还需要进一步筛选出能与其他半导体材料或掺杂剂结合的多肽分子

C.科学家利用半导体纳米晶体技术,制造出比一般晶体管体积更小、功能更强的电子设备

D.未来的微电子元件,一个开关或一个存储单元,都将由比细菌还小的纳米晶体来充当