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问题 单项选择题

丙二酸对琥珀酸脱氢酶的抑制属于

A．反馈抑制
B．反竞争性抑制
C．竞争性抑制
D．非竞争性抑制
E．别构抑制

答案

参考答案：C

解析：丙二酸结构上类似琥珀酸，可与后者竞争与该酶活性中心结合；而其抑制程度取决于琥珀酸与丙二酸的相对浓度，故为竞争性抑制。

单项选择题

某女，平素情绪不畅，因生气诱发呃逆连声，胸胁满闷，脘腹胀满，嗳气纳呆，昏眩恶心，苔薄腻，脉弦滑，方宜选（）

A.丁香散

B.五磨饮子

C.竹叶石膏汤

D.旋覆代赭石汤

E.半夏白术天麻汤
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单项选择题

The history of African—Americans during the past 400 years is traditionally narrated (1) an ongoing struggle against (2) and indifference on the part of the American mainstream, and a struggle (3) as an upward movement is (4) toward ever more justice and opportunity.

Technology in and of (5) is not at fault; it’s much too simple to say that gunpowder or agricultural machinery or fiber optics (6) been the enemy of an (7) group of people. A certain machine is put (8) work in a certain way—the purpose (9) which it was designed. The people who design the machines are not intent on unleashing chaos; they are usually trying to (10) a task more quickly, cleanly, or cheaply, (11) the imperative of innovation and efficiency that has ruled Western civilization (12) the Renaissance.

Mastery of technology is second only (13) money as the true measure of accomplishment in this country, and it is very likely that by (14) this under-representation in the technological realm, and by not questioning and examining the folkways that have (15) it, blacks are allowing. (16) to be kept out of the mainstream once again. This time, however, they will be (17) from the greatest cash engine of the twenty-first century. Inner-city blacks in particular are in danger, and the beautiful suburbs (18) ring the decay of Hartford, shed the past and learn to exist without contemplating or encountering the tragedy of the inner city.

And blacks must change as well. The ways that (19) their ancestors through captivity and coming to freedom have begun to loose their utility. If blacks (20) to survive as full participants in this society, they have to understand what works now.

13（）

A.before

B.to

C.with

D.from
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