单选题胆固醇生物合成时的限速酶是

单选题原核生物的释放因子RF-2可识别的终止密码是

单选题可促进多肽链折叠为天然构象的生物大分子不包括

单选题Fear seems to be the dominant mood of the moment. Hurricanes, tidal waves, floods, earthquakes and terrorism this year have all brought with them not only appalling scenes of devastation, death and suffering, but also outrage at the lack of preparations to avoid or cope with these disasters. Now even the birds of the air are a threat, we are told. That migrating flock visible On the horizon at sunset, once a consoling reminder of the eternal rhythms of nature, could be carrying the virus which might soon kill tens of millions of people. Given the many fingers pointed at governments in the wake of other disasters this year, it is hardly surprising that they are scrambling to respond to the threat posed by avian influenza. After confirmation this week that the HSN1 strain of bird flu, which has been spreading quickly in Asia, had been discovered in Romania and perhaps Greece, European Union foreign ministers convened an emergency meeting. President George Bush, still smarting from a torrent of criticism of his government's clumsy response to Hurricane Katrina, has promised to rush out emergency plans for dealing with an outbreak of pandemic flu which have been stalled for years. Countries around the world are hurrying to stockpile the only current antiviral drug, Tamifln, which might be effective in saving lives in any pandemic or curbing its spread. The World Health Organisation is calling for an internationally coordinated effort. Health ministers from around the globe are due to meet next week in Canada to discuss what steps to take. Is any of this eff6rt justified? Or are politicians simply helping to feed public panic, and then covering themselves by promising to spend lavishly against a threat which may never materialize and to reduce a risk which they do not understand? To ask these questions is not to counsel complacency, but to apply the kind of test which is required in any kind of disaster planning, not least because the world is an inherently dangerous place and it is impossible to plan against every possible disaster. With the media full of warnings of impending mass death, an overreaction is all too possible.

单选题合成dTMP的直接前体是( )(2007年)

单选题不能经转氨基作用生成相应α-酮酸的氨基酸是

单选题A．AMP类似物B．嘧啶类似物C．叶酸类似物D．次黄嘌呤类似物

单选题A．不可逆抑制B．竞争性抑制C．非竞争性抑制D．反竞争性抑制E．反馈抑制

单选题AATAAA是

单选题能催化错配二硫键断裂并形成正确二硫键连接的是

单选题下述哪项不符合G蛋白的特点

单选题下列哪项反应过程只在线粒体中进行

单选题关于p53基因叙述错误的是

单选题下列关于蛋白质结构的叙述中不正确的是

单选题A．7α-羟化酶B．胆绿素还原酶C．血红素加氧酶D．单胺氧化酶

单选题只有一个密码的氨基酸是

单选题血糖来源的叙述中不正确的是

单选题软脂酸合成的循环步骤是

单选题原核生物翻译过程中，促进核蛋白体大、小亚基分离的物质是

单选题蛋白质变性是由于( )(2007年)