大多数细胞产生静息电位的原因是A.细胞内高K+浓度和安静时膜主要对K+有通透性 B.

题型:单项选择题

问题:

大多数细胞产生静息电位的原因是

A.细胞内高K+浓度和安静时膜主要对K+有通透性

B.细胞内高K+浓度和安静时膜主要对Na+有通透性

C.细胞外高Na+浓度和安静时膜主要对K+有通透性

D.细胞外高Na+浓度和安静时膜主要对Na+有通透性

考点:普通考研西医综合西医综合
题型:单项选择题

片剂的湿润剂是()。

A.CMC-Na溶液 

B.L-HPC 

C.乳糖 

D.50%醇 

E.聚乙二醇

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阅读理解。

     One reaction to all the concern about tropical deforestation is a blank stare that asks the question,

"Since I don't live there, what does it have to do with me?"

     The answer is that your way of life, wherever you live in the world, is tied to the tropics in many

ways. If you live in a house, wash your hair, eat fruits and vegetables, drink soda, or drive a car, you

can be certain that you are affected by the loss of tropical forests.

    Biologically, we are losing the richest regions on earth when, each minute, a piece of tropical forest,

the size of ten city blocks, disappears. As many as five million species of plants, animals, and insects

(40 to 50 percent of all living things) live there, and are being lost faster than they can be found and

described. Their loss is immeasurable.

    Take rubber for example. For many uses, only natural rubber from trees will do. Synthetics are not

good enough. Today over half the world's commercial rubber is produced in Malaysia and Indonesia,

while the Amazon's rubber industry produces much of the world's four million tons. And rubber is an

important material in making gloves, balloons, footwear and many sporting goods. Thousands of other

tropical plants are valuable for their industrial use.

    Many scientists strongly believe that deforestation contributes to the greenhouse effect -or heating

of the earth from increased carbon dioxide in the atmosphere. As we destroy forests, we lose their

ability to change carbon dioxide into oxygen.

    Carbon dioxide levels could double within the next half-century, warming the earth by as much as

4.5 degrees. The result? A partial melt-down of polar ice caps, raising sea levels as much as 24 feet;

even 15 feet could threaten anyone living within 35 miles of the coast. Unbelievable? Maybe. But

scientists warn that by the time we realise the severe effects of tropical deforestation, it will be 20

years too late.

    Can tropical deforestation affect our everyday lives? Now, you should have got the answer.

1. The underlined word "synthetics" probably means               .     

A. natural rubber                  

B. tropical materials

C. man-made material              

D. commercial rubber

2. In the last paragraph the author tries to                  

A. tell people how to avoid the tropical deforestation

B. persuade people to buy something synthetic

C. show us how important it is to protect the tropical forests

D. let people realise the effect of tropical deforestation

3. According to the passage, which of the following is NOT true?

A. The forests are losing their function in turning carbon dioxide into oxygen.

B. Many of our daily uses are related to the tropical forests.

C. Tropical plants can be used to make industrial products.

D. High carbon dioxide levels will make the earth warmer.

4. The author's attitude towards the tropical deforestation is              .

A. puzzling        

B. cold          

C. supporting        

D. opposed

5. Which of the following might be the best title for the passage?

A. Tropical Forests                    

B. the value of Tropical Forests

C. Tropical Forests and Our Life        

D. The Greenhouse Effects W

题型:单项选择题

吗录贝胺

A.结石,损伤,肿瘤或结核
B.盆腔内疾病
C.先天性畸形
D.前列腺增生症
E.包皮过长

题型:单项选择题

公共就业服务

题型:单项选择题

可作为眼病外用的药物是()

A.芒硝

B.朴硝

C.玄明粉

D.玄参

E.巴豆

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