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单选题RNAi技术的基本程序主要为 A.siRNA对目标RNA的干扰、确定干扰靶点、合成siRNA B.确定干扰靶点、合成siRNA、siRNA对目标RNA的干扰 C.siRNA对目标RNA的干扰、合成siRNA、确定干扰靶点 D.确定干扰靶点、siRNA对目标RNA的干扰、合成siRNA E.合成siRNA、确定干扰靶点、siRNA对目标RNA的干扰

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单选题严重肝病时，机体各器官会发生出血倾向，主要原因是 A.维生素A减少 B.维生素B6减少 C.维生素C减少 D.维生素E减少 E.维生素K减少

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单选题Prince Klemens Von Metternich, foreign minister of the Austrian Empire during the Napoleonic era and its aftermath, would have no trouble recognizing Google. To him, the world's most popular web-search engine would closely resemble the Napoleonic France that in his youth humiliated Austria and Europe's other powers. Its rivals—Yahoo!, the largest of the traditional web gateways, eBay, the biggest online auction and trading site, and Microsoft, a software empire that owns MSN, a struggling web portal—would look a lot like Russia, Prussia, and Austria. Metternich responded by forging an alliance among those three monarchies to create a "balance of power" against France. Google's enemies, he might say, ought now to do the same thing. Google announced two new conquests on August 7th. It struck a deal with Viacom, an "old" media firm, under which it will syndicate video clips from Viacom brands such as MTV and Nickelodeon to other websites, and integrate advertisements into them. This makes Google the clear leader in the fledgling but promising market for web-video advertising. It also announced a deal with News Corporation, another media giant, under which it will pro-vide all the search and text-advertising technology on News Corporation's websites, including My Space, an enormously popular social-networking site. These are hard blows for Yahoo! and MSN, which had also been negotiating with News Corporation. Both firms have been losing market share in web search to Google over the past year—Google now has half the market. They have also fallen further behind in their advertising technologies and networks, so that both make less money than Google does from the same number of searches. Safa Rashtchy, an analyst at Piper Jaffray, a securities firm, estimates that for every advertising dollar that Google makes on a search query, Yahoo! makes only 60-70cents. Last month Yahoo! said that a new advertising algorithm that it had designed to close the gap in profitability will be delayed, and its share price fell by 22% , its biggest-ever one-day drop. MSN is further behind Google than Yahoo! in search, and its parent, Microsoft, faces an even more fundamental threat from the expansionist new power. Many of Google's new ventures beyond web search enable users to do things free of charge through their web browsers that they now do using Microsoft software on their personal computers. Google offers a rudimentary but free online word processor and spreadsheet, for instance. The smaller eBay, on the other hand, might in one sense claim Google as an ally. Google's search results send a lot of traffic to eBay's auction site, and eBay is one of the biggest advertisers on Google's network. But the relationship is imbalanced. An influential re-cent study from Berkeley's Haas School of Business estimated that about 12% of eBay's revenues come indirectly from Google, whereas Google gets only 3% of its revenues from eBay. Worst of all for eBay, Google is starting to undercut its core business. Sellers are setting up their own websites and buying text advertisements from Google, and buyers are using its search rather than eBay to connect with sellers directly. As a result, "eBay would be wise to strike a deep partnership with Yahoo! or Microsoft in order to regain a balance of power in the industry," said the study's authors, Julien Decot and Steve Lee, sounding like diplomats at the Congress of Vienna in 1814.

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单选题真核起始因子eIF-3的作用是： A、帮助形成亚基起始复合物（eIF-3，GTP，Met-tRNA，40S） B、帮助亚基起始复合物（三元复合物，40S）与mRNA5′端的结合 C、若与40S亚基结合，防止40S与60S亚基的结合 D、与mRNA5′端帽子结构相结合以解开二级结构 E、激活核糖体GTP酶，使亚基结合可在GTP水解时结合，同时释放eIF-2

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