问题 单项选择题

对流免疫电泳中,抗体向阴极移动的原因是()

A.抗体带正电

B.抗体带负电

C.扩散作用

D.电泳作用

E.电渗作用

答案

参考答案:E

解析:对流免疫电泳是将双向扩散试验与电泳相结合的免疫扩散技术,在琼脂板上打两排孔,左侧各孔加入待测抗原,右侧孔内加入相应抗体,抗原在阴极侧,抗体在阳极侧。通电后,在pH8.4缓冲液中带负电荷的蛋白质抗原泳向阳性抗体侧,而抗体借电渗作用流向阴极侧,在两者之间或抗体侧形成沉淀线。

阅读理解

阅读理解。

     The city of Venice,in  Italy,is one of a kind.It is built on more than 120 islands,just

off arrival.After explaining where my new house was,I told him that I had left the key under

the doormat.Since I knew it would be quite late before I could get back,I suggested that

be make himself at home and help himself to anything that was kept in the refrigerator(冰箱).

     Two hours later my friend phoned me from the house.At the moment,he said,he was

listening to some of my records after having had a nice meal.He had found the pan and meat

in the refrigerator.Now,he was drinking a cup of tea and hoped that I would join him soon.

When I asked him if he bad any difficulty finding the house,he answered that the only problem 

 was that he had not been able to find the key under the doormat,but luckily,the living room

window by the apple tree had been left open and  he had climbed in through the window.I

listened to all this in great surprise.There is no apple tree outside my window,but there is one

by the living room window of my next-door  neighbor’s house!

1.When my friend arrived,I could not go to meet him because________.

A.we were not good friends        

]B.I was busy at work

C.he had not told me that he would come  

D.I did not want to see him

2.A doormat is a mat______

A.used as a door        

B.for cleaning the bottom of shoes

C. put up on a door as an ornament(装饰物)

D.near a door under which people put their keys

3.I listened to my friend’s phone call in great surprise because____.

A.he had not waited for me to eat together

B.he had eaten too much of the food

C.he mistook my neighbor’s house for mine

D.he had left the house with the window open

4.At last my friend______.

A.did not enter my house

B.entered my house after he opened the door

C.entered my house by climbing through the window

D.entered my house with the help of my neighbor

5.The writer left the key under the doormat so that______.

A.nobody would find it

B.he might not lose it

C.his family could use the same key

D.his friend could easily get it

单项选择题