学科分类

已选分类 理学生物学生物化学与分子生物学
单选题下列哪一种化合物与琥珀酰CoA生成有关
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单选题不易逆行的糖酵解反应是( )(1989年)
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单选题转录延长中,RNA聚合酶与DNA模板的结合是
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单选题下列哪项不是合成嘌呤的原料
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单选题DNA复制时不需要以下哪种酶
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单选题下述哪一生化反应主要在线粒体内进行
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单选题离体肝线粒体中加入氰化物和丙酮酸,其P/O比值是
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单选题下列哪项不属于蛋白质分子的二级结构
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单选题可作为磷脂骨架的化合物是
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单选题People don't want to buy information online. Why? Because they don't have to. No more than that because they're used to not paying for it. That's the conventional wisdom. Slate, Microsoft's online politics-and-culture magazine, is an oft-cited example of the failed attempts to charge a fee for access to content. So far, for most publishers, it hasn't worked. But nothing on the Web is a done deal. In September graphics-soft-ware powerhouse Adobe announced new applications that integrate commerce into downloading books and articles online, with Simon Schuster, Barnes and Noble, and Salon. corn among its high-profile partners. Some analysts put the market for digitized publishing at more than $100 billion. Of course, if the Internet can generate that kind of money—some might say almost any kind of money—people want in. And this couldn't come at a better time. Newspaper and magazine writers in particular are increasingly frustrated by their publishers, which post their writings online but frequently don't pay them extra. So here's the good news: Fathrain. com, the third biggest book-seller on the Net—after Amazon. com and Barnesandnoble. corn—is now doing just what the publishing industry that made it a success fears., it's offering a secure way to pay for downloadable manuscripts online. Fatbrain calls it offshoot eMatter. With it, the company's executives have the radical notion of ousting publishers from the book-selling business altogether by giving writers 50% of each and every sale (To reel in authors, eMatter is running a 100% royalty promotion until the end of the year. ) Suggested prices to consumers range from a minimum $ 2 to $ 20, depending on the size of the book to download. "This will change publishing forever!" Chris MaeAskill, co-founder and chief executive of Fatbrain, declares with the bravado of an interior decorator. "With eBay, anybody could sell antiques. Now anybody can be published. " There's been no shortage of authors wanting in. Within a few weeks, according to the company, some 2,000 writers signed on to publish their works. Some of this is technical stuff—Fatbrain got where it is by specializing in technical books—but there are some well-known writers like Catherine Lanigan, author of Romancing the Stone, who has put her out-of-print books and a new novella on the site. Another popular draw is Richard Bach, who agreed to post a 23-page short story to the site. Not everyone thinks downloadable documents are the biggest thing in publishing since Oprah's Book Club. "I think it will appeal to sellers more than buyers," says Michael May, a digitalcommerce analyst at Jupiter Communications, which released a report that cast doubt on the market's potential. "A lot of people are going to publish gibberish. The challenge is to ensure the quality of the work. " Blaine Mathieu, an analyst at Gartner Group's Dataquest, says, "Most people who want digital content want it immediately, I don't know if this model would satisfy their immediate need. Even authors may not find that Web distribution of their works is going to bring them a pot of gold. For one thing, it could undermine sales rather than enhance them. For another, anybody could e-mail downloaded copies of manuscripts around town or around the world over the Net without the writer's ever seeing a proverbial dime. " Softlock. com, Authentica and Fatbrain are trying to head this problem off by developing encryption padlocks that would allow only one hard drive to receive and print the manuscripts. For now, the problem persists.
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单选题K m 值的概念应是
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单选题下述有关生物转化作用的论述恰当的是
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单选题A.单体酶B.寡聚酶C.多酶体系D.单纯酶
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单选题下列物质中,不属于高能化合物的是
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单选题下列哪种物质脱下的一对氢经呼吸链传递后P/O比约为2.5
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单选题嘌呤、嘧啶合成的共同原料是( )(1998年)
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单选题下列哪条途径与核酸合成密切相关
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单选题设计PCR引物时
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单选题A.甘氨酸B.缬氨酸C.酪氨酸D.丝氨酸E.精氨酸
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单选题下列哪种物质缺乏可引起血液丙酮酸含量升高
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