单选题A．α-螺旋B．左手双螺旋C．右手双螺旋D．三叶草E．倒L型

单选题临床上出现黄疸时，尿中可检出的化合物是 A.胆红素 B.尿胆素原 C.尿胆素 D.尿胆红素 E.粪胆素

单选题催化聚合酶链式反应的酶是______ A.DNA连接酶 B.反转录酶 C.末端转移酶 D.DNA聚合酶I E.TaqDNA聚合酶

单选题In old days, when a glimpse of stocking was looked upon as something far too shocking to distract the serious work of an office, secretaries were men. Then came the first World War and the male secretaries were replaced by women. A man's secretary became his personal servant, charged with remembering his wife's birthday and buying her presents; taking his suits to the dry cleaners; telling lies on the telephone to keep people he did not wish to speak to at bay and, of course, typing and filing and taking shorthand. Now all this may be changing again. The microchip and high technology is sweeping the British office, taking with it much of the routine clerical work that secretaries did. "Once office technology takes over generally, the status of the job will rise again because it will involve only the high-powered work-and then men will want to do it again." That was said by one of the executives(male) of one of the biggest secretarial agencies in this country. What he has predicted is already under way in the US. One girl described to me a recent temporary job placing men in secretarial jobs in San Francisco. She noted that all the men she dealt with appeared to be gay so possibly that is just a new twist to the old story. Over here, though, there are men coming onto the job market as secretaries. Classically, girls have learned shorthand and typing and gone into a company to seek their fortune from the bottom——and that's what happened to John Bowman. Although he joined a national grocery chain as secretary to its first woman senior manager, he has since been promoted to an administration job. "I filled in the application form and said I could do audio/typing, and in fact I was the only applicant. The girls were reluctant to work for this young, glamorous new woman with all this power in the firm. " "I did typing at school, and then a commercial course. I just thought it would be useful finding a job. I never got any funny treatment from the girls, though I admit I've never met another male secretary. But then I joined the Post Office as a clerk and carelessly played with the typewriter, and wrote letters, and thought that after all secretaries were getting a good ￡1,000 a year more than clerks like me. There was a shortage at that time, you see. " "It was simpler working for a woman than for a man. I found she made decisions, she told everybody what she thought, and there was none of that stuff' ring this number for me dear, which men go in for." "Don't forget, we were a team—that's how I about it—not boss and servant but two people doing different things for the same purpose." Once high technology has made the job of secretary less routine, will there be male takeover? Men should beware of thinking that they can walk right into the better jobs. There are a lot of women secretaries who will do the job as well as they because they are as efficient and well trained to cope with word processors and computers, and men.

单选题能编码具有酪氨酸蛋白激酶活性的癌基因是

单选题磷酸化时活性增高

单选题有一糖蛋白经测定其含氮量为0.5mol，那么其蛋白质含量为多少?______

单选题 下列病毒中属双链RNA病毒的是 A、流感病毒 B、乙型脑炎病毒 C、麻疹病毒 D、疤疹病毒 E、轮状病毒

单选题白喉毒素抑制的过程是 A.翻译起始过程 B.翻译延长过程 C.翻译终止过程 D.DNA拓扑异构酶反应 E.核酶反应

单选题已知某种酶的K m 值为25mmol／L，欲使酶促反应达到最大反应速度的50％，该底物浓度应为( )(2003年)

单选题目前基因治疗主要采用的方法是

单选题人体不能合成的脂肪酸是

单选题下列DNA分子中，可以使T m 值达到最高的是

单选题下列配对不正确的是

单选题下列关于胆固醇的说法，不正确的叙述是

单选题胞浆中NADH经α-磷酸甘油穿梭作用进入线粒体内完成氧化磷酸化，其P／O比值为

单选题有关mRNA的叙述正确的是______ A.hnRNA中只含有基因编码区转录的序列 B.在3'端具有SD序列 C.mRNA的遗传密码方向是5'→3' D.在细胞内总RNA含量中所占比例很大 E.mRNA碱基序列与DNA双链中的反义链一致

单选题在生理pH条件下，具有缓冲作用的氨基酸残基是( )。

单选题有关生物氧化描述错误的是 A.生物氧化是在体温下、pH7.35～7.45的生理条件下进行的 B.生物氧化是一系列酶促反应 C.生物氧化过程是逐步氧化、逐步释放能量的 D.生物氧化过程消耗氧，氧化的终产物是H2O、CO2和能量 E.生物氧化过程中产生的能量都以ATP的形式储存和利用

单选题关于β-折叠，下列说法正确的是