2002年诺贝尔化学奖表彰了两项成果,其中一项是瑞士科学家库尔特·维特里希“发明

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问题:

2002年诺贝尔化学奖表彰了两项成果,其中一项是瑞士科学家库尔特·维特里希“发明了利用核磁共振技术测定溶液中生物大分子三维结构的方法”。在化学上经常使用的是氢核磁共振谱,它是根据不同化学环境的氢原子在氢核磁共振谱中给出的信号不同来确定有机物分子中氢原子种类的。下列有机物分子中,在氢核磁共振谱中信号强度(个数比)是1:3的是

A.1,2,3,—三甲基苯

B.丙烷

C.异丙醇

D.醋酸正丙酯

考点:结构简式结构式
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玉米的白化苗是变异个体,在光下也不能形成叶绿素,这种变异属于    (    )

A.有利的可遗传变异

B.不利的可遗传变异

C.有利的可遗传变异

D.不利的不遗传变异

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Europe’s deadly outbreak of a rare form of E. coli bacteria (大肠杆菌) has brought new attention to food safety issues. One of the problems when people get sick from food is that the simplest question is often difficult or even impossible to answer. Just what did the people eat that made them sick?

Of course, one way to avoid these medical mysteries is to keep dangerous organisms out of the food supply. This is easier said than done, but scientists keep looking for new ways.

Scientists in the United States have developed an experimental system that uses a high-tech optical scanner. The system is designed to identify the presence of contaminants(致污物) like soil or animal waste on fresh produce. These can be sources of E. coli. E. coli bacteria naturally live in the intestines(肠) of humans and many animals. Most kinds of E. coli are harmless but some can make people sick.

The new scanner can also show damage and imperfections that might make the produce unappealing to shoppers.

Scientists designed the system at a Department of Agriculture research center in Beltsville, Maryland. Moon Kim of the Agricultural Research Service led the team.

MOON KIM: “We were requested, we were asked, to develop a method to detect contamination in produce. So we started with the apple as the model sample.”

The scanner uses a high-speed camera placed over the conveyer belt that moves the produce along. As the apples move along the belt, the scanner captures images of each piece of fruit.

Moon Kim says the team hopes the system will be available before long.

MOON KIM: “We are targeting for development in commercial plants for the next several years.”

The scanner can direct a sorting machine to separate the bad apples from the good ones. The system is currently able to show the surface of only half the apple as it speeds by. The inventers hope to improve the process so it can show the whole surface.

小题1:What is the main topic of the text?

A.Bacteria.

B.A high-tech scanner.

C.A camera

D.Food safety.小题2:E. coli bacteria ______.

A.broke out all over the world

B.comes from soil or animal waste

C.is extremely harmful to health

D.does not cause illness小题3:The high-tech scanner ______.

A.can help to sort out different fruits

B.make the produce appeal to shoppers

C.can only capture images of the whole apple

D.can identify the presence of contaminants小题4:What can be inferred from the text?

A.The scanner needs to be improved.

B.The scanner will be available in the next several years.

C.Moon Kim is unwilling to develop the scanner.

D.The scanner is connected to a sorting machine.

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滚翻式货舱盖开舱时,在盖板进入舱口端收藏坡道后盖板便:()

A.顺序纵向叠加

B.顺序横向并靠

C.自动水平堆积

D.翻转成直立状态存放

题型:选择题

集中供热系统主要由()部分组成。

A.3

B.4

C.5

D.6

题型:选择题

业态信息分析的完整性原则是指()。

A、采用与具体情况相适应的分析方法对业态信息进行分析,形成最准确、最恰当的方法系统,取长补短、相互配合,从而形成全面、准确的分析结果

B、对业态信息进行多角度的全面分析,以反映和把握信息资料的总体特征

C、必须以客观的事实和资料作为分析的依据,不能受外来因素和主观倾向的影响

D、不但要把握分析现状,更要分析把握变化趋势,要注意分析各相关因素的变化特点,用发展的观点来把握问题

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