问题 单项选择题 B型题

进行血液常规细胞计数时使用的抗凝剂为()。

A.EDTA盐

B.草酸钠

C.枸橼酸钠

D.肝素

E.双草酸盐

答案

参考答案:A

解析:1.EDTA盐对血细胞形态和血小板计数影响很小,故特别适用于全血细胞计数分析及血细胞比容测定。2.肝素可加强抗凝血酶Ⅲ灭活丝氨酸蛋白酶,从而具有阻止凝血酶形成、对抗凝血酶和阻止血小板聚集等多种作用。肝素抗凝血常用于快速生化测定。3.枸橼酸钠可与血中钙离子形成可溶性螯合物,从而起到阻止血液凝固的作用。枸橼酸钠对凝血Ⅴ因子有较好的保护作用,使其活性减低缓慢,故常用于凝血象的检查,也用于红细胞沉降率的测定。因其毒性小,也是输血保养液中的成分之一。

阅读理解

阅读理解。

     A fish that lives in America can live out. of water for months at a time, similar to how animals got used

to land millions of years ago, a new study shows.

     The Mangrove Rivulus, a kind of little fish, lives in small pools of water. When their living place dries up,

they live. on the land, said Scott Taylor, a researcher in Florida.

     The fish can grow as large as three inches. They group together and breathe air through their skin before

they can find water again.

     The new scientific discovery came during a trip.

     "We were travelling for fun. and one day I kicked over a log (圆木) and the fish came out," Taylor told

reporters by telephone. He said he would make his study on the fish known to the public in an American

magazine early next year.

     In lab tests, Taylor said he found the fish can live up to 66 days out of water without eating.

     Some other fish can live out of water for a short period of time. The walking catfish found in Southeast

Asia can stay on land for hours at a time, while lungfish (肺鱼) found in Australia, Africa and South America

can live out of water, but only in a not active (活波的) way. But no other known fish can be out of water as

long as the Mangrove Rivulus and keep active, according to Patricia Wright, a biologist at a Canadian

University.

     More studies of the fish may tell how animals changed over time.

     "These animals live in conditions similar to those millions of years ago, when animals began to move from

water onto land," Wright said.

1. The Mangrove Rivulus is a type of fish that _____.

A. lives on land in Africa

B. can stay alive for months out of water

C. prefers living in dry places

D. is the longest living fish on earth 

2. Who will write a report on Mangrove Rivulus?

A. Scott Taylor.

B. Some reporters.

C. Patricia Wright.

D. Scientists from Europe.

3. According to the passage, lungfish can _____.

A. breathe through its skin

B. be found in Asia

C. keep alive out of water

D. keep alive and walk on land

4. Which one of the sentences below is not true?

A. The Mangrove Rivulus fish can live out of water as long as other animals if it has something to eat.

B. Millions of years ago, animals began to live onto land from water.

C. Lungfish found in Australia, Africa and South America can live out of water in a not active way.

D. The walking catfish found in Southeast Asia can stay on land for hours at a time.

5. What can we say about the discovery of Mangrove Rivulus?

A. ft was made by Scott Taylor, a researcher in New York.

B. It was helped by an American magazine.

C. It was helped by Patricia Wright.

D. It was made by a researcher while travelling.

判断题