问题 问答题 简答题

免疫印迹法原理和需注意问题。

答案

参考答案:

免疫印迹法是在蛋白质电泳分离和抗原抗体检测的基础上发展起来一项检测蛋白质的技术,它将SDS聚丙烯酰胺凝胶电泳的高分辨力与抗原抗体反应的特异性相结合,其操作可分成三个阶段:

第一阶段为SDS-聚丙烯酰胺凝胶电泳(SDS-PACE);第二阶段为电转移;第三阶段为酶免疫定位。

需注意问题:

①许多单克隆抗体不能与变性抗原反应,因此免疫印迹实验中常选用多克隆抗体。

②在电泳之前应用免疫沉淀法将抗原进行纯化和浓缩可提高免疫印迹的灵敏度。

③IBT法在临床应用中存在一定的局限性:不同分子量的蛋白质出现电泳距离一致的条带;IBT法一般不能检出针对构象依赖表位的抗体,造成某些抗体漏检。

阅读理解

D

“You’re going to the United States to live? How wonderful! You’re really lucky!”

Does this sound familiar? Perhaps your family and friends said similar things to you when you left home. But does it seem true all the time? Is your life in this new country always wonderful and exciting? A great many facts show that it’s not easy for newcomers to adjust to life in a new culture. They have to experience culture shock.

What causes culture shock? Maybe the weather is unpleasant.  Perhaps the customs are different. Perhaps the public service systems such as the telephone, post office, or transportation are difficult to figure out and you make mistakes. The simplest things seem difficult. The language may be difficult. The food may seem strange to you. If you don’t look similar to the natives, you may feel strange. You may feel as ff everyone is watching you. In fact, you are always watching yourself.

Everyone experiences culture shock in some form or another. But culture shock comes as a surprise to most people. A lot of the time, the people with the worst culture shock are the people who never had any difficulties in their own countries. They were active and successful in their community(社区). They had hobbies or pastimes which they enjoyed. When they come to a new country, they do not have the same positions or hobbies as they already had in their countries. They find themselves without a role, almost without an identity. They have to build a new self-image.

Culture shock produces a feeling of disorientation(晕头转向), which may be homesickness, imagined illness, or even paranoia(偏执症). When people feel the disorientation of culture shock, they sometimes feel like staying inside all the time. They want to protect themselves from the unfamiliar environment. They want to create an escape within their room to give themselves a sense of security. This escape does solve the problem of culture shock for the short term, but it does nothing to familiarize the person more with the culture. Familiarity and experience are the long-term ways to settle the problem of culture shock.

67. Who is the passage mainly for?

A. The family and friends of those who came to the US.

B. Those who have got rid of culture shock.

C. People who have just moved to a foreign country.

D. People who can easily adjust their life in the US.

68. The underlined part “you are always watching yourself’” (in Paragraph 3) means         .

A. you are always feeling homesick

B. you are always worried too much about yourself

C. you are always looking at yourself in the mirror

D. you are always nervous about meeting other people

69. Which of the following would be a case of culture shock for newcomers?

A. They have trouble using public telephones.

B. Their positions or hobbies stay the same.

C. They are active and successful in the new community.

D. They have got used to the life in the new country.

70. Which of the following may cause newcomers to lack a sense of security?

A. A new identity.                                      B. Local food.

C. A new serf-image.                                    D. Strange environment.

71. The best way for the newcomers to overcome culture shock is         .

A. to stay inside to protect themselves

B. to make a study of the new hobbies

C. to adapt themselves to the new environment

D. to ask people for help when having difficulties

问答题 简答题