问题 单项选择题 A1/A2型题

下列对干扰素的描述中不正确的是()。

A.是病毒或其他干扰素诱生剂刺激细胞所产生的一类分泌性蛋白

B.IFN通过诱导细胞合成抗病毒蛋白可直接杀灭病毒

C.发挥作用迅速,病毒感染后几小时内就能起作用

D.IFN对多种病毒都有一定的作用

E.IFN有种属特异性

答案

参考答案:B

解析:干扰素是病毒或其他干扰素诱生剂(细菌内毒素、人工合成的双链RNA等)刺激细胞所产生的一类分泌性蛋白,具有抗病毒、抗肿瘤和免疫调节等多种生物学活性。分为IFNα、IFNβ和IFNγ。IFN不能直接灭活病毒,而是通过诱导细胞合成抗病毒蛋白(antiviralprotein,AVP)发挥抗病毒效应(抑制病毒复制和增殖);IFN的抗病毒作用是抑制,而不是杀灭;IFN作用具有广谱性,对多种病毒都有一定的作用;IFN有种属特异性,受种属特异性的限制,一般在同种细胞中活性高,对异种细胞无活性;发挥作用迅速,病毒感染后几小时内就能起作用。此外IFN还具有免疫调节活性及抗肿瘤活性。

单项选择题
单项选择题

It’s easy to get the sense these days that you’ve stumbled into a party with some powerful drug that dramatically alters identity. The faces are familiar, but the words coming out of them aren’t. Something has happened to a lot of people you used to think you knew. They’ve changed into something like their own opposite.

There’s Bill Gates, who these days is spending less time earning money than giving it away--and pulling other billionaires into the deep end of global philanthropy(慈善事业) with him. There’s historian Francis Fukuyama, leading a whole gang of disaffected fellow travelers away from neoconservatism. To flip-flopis human. It can still sometimes be a political liability, evidence of a flaky disposition or rank opportunism. But there are circumstances in which not to reverse course seems almost pathological(病态的). He’s a model of consistency, Stephen Colbert said last year of George W. Bush:" He believes the same thing Wednesday that he believed on Monday -- no matter what happened on Tuesday."

Over the past three years, I found people who had pulled a big U-turn in their lives. Often the insight came in a forehead-smiting moment in the middle of the night: I’ve got it all wrong.

It looked at first like a sprinkling of outliers beyond the curve of normal human experience. But when you stepped back, a pattern emerged. What these personal turns had in common was the apprehension that we’re all connected. Everything leans on something, is both dependent and depended on.

"The difference between you and me," a visiting Chinese student told University of Michigan psychologist Richard Nisbett not long ago," is that I think the world is a circle, and you think it’s a line." The remark prompted the professor to write a book, The Geography of Thought, about the differences between the Western and the Asian mind.

To Western thinking, the world is linear; you can chop it up and analyze it, and we can all work on our little part of the project independently until it’s solved. The classically Eastern mind, according to Nisbett, sees things differently: the world isn’t a length of rope but a vast, closed chain, incomprehensibly complex and ever changing. When you look at life from this second perspective, some unlikely connections reveal themselves.

I realized this was what almost all the U-turns had in common: people had swung around to face East. They had stopped thinking in a line and started thinking in a circle. Morality was looking less like a set of rules and more like a story, one in which they were part of an ensemble cast, no longer the star.

The underlined word" flip-flop" (Line 4, Paragraph 2) most probably means ()

A. reverse

B.flick

C. handspring

D. fail