共查询到20条相似文献,搜索用时 0 毫秒
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Marx JL 《Science (New York, N.Y.)》1973,182(4114):811-814
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[目的]研究比较豹猫和金猫针毛红外光谱。[方法]使用傅立叶红外光谱对豹猫和金猫两种野生动物毛发进行了检测和分析。[结果]在豹猫和金猫针毛的中部红外图谱及其二阶导数谱均具有明显的种间差异,如648 cm-1和654 cm-1波数处金猫出现明显 M 形双峰吸收峰,而豹猫没有;金猫的二阶导数谱在709-763 cm-1范围内以峰强较大的单峰为主,豹猫则以峰强较小的 M 形双峰为主,这均说明两种动物毛发的蛋白侧链的构成上则存在较大的差异。[结论]红外光谱分析方法可以应用于动物毛发的种间识别,在毛发的研究领域有较好的应用前景。 相似文献
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The evolutionary dynamics underlying the latitudinal gradient in biodiversity have been controversial for over a century. Using a spatially explicit approach that incorporates not only origination and extinction but immigration, a global analysis of genera and subgenera of marine bivalves over the past 11 million years supports an "out of the tropics" model, in which taxa preferentially originate in the tropics and expand toward the poles without losing their tropical presence. The tropics are thus both a cradle and a museum of biodiversity, contrary to the conceptual dichotomy dominant since 1974; a tropical diversity crisis would thus have profound evolutionary effects at all latitudes. 相似文献
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Koenig R 《Science (New York, N.Y.)》2000,289(5486):1863-1865
Bulgaria created a pioneering center in late 1990 to tackle the threat that its homegrown computer viruses posed to the world; according to experts, it has been a major force in reining in that threat. Now the lab is struggling to stave off obsolescence on a budget of roughly half of what a single Western whiz kid fresh out of college might earn in a year. 相似文献
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Kormendy J 《Science (New York, N.Y.)》2000,289(5484):1484-1485
Supermassive black holes (BHs) have long been implicated in explaining active galactic nuclei such as quasars. In his Perspective, Kormendy discusses recent work that suggests a larger role for these objects. The Hubble Space Telescope has provided many new detections of BHs, and these new results indicate that they play an important role in the galaxy formation processes. 相似文献
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Koenig R 《Science (New York, N.Y.)》2000,290(5496):1484-1487
Two decades after Iran's Islamic revolution, science in this politically isolated but oil-rich nation may be on the verge of resurgence. The nation's reform-minded president, Mohammad Khatami, and his allies are promising more money for R&D, reorganizing universities to beef up graduate education and research, and cracking open the door to closer cooperation with scientists abroad, including those in the United States. But Iran's government is walking a tightrope between hard-liners on the right who oppose reforms and liberal university students eager for change. 相似文献
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Service RF 《Science (New York, N.Y.)》2000,290(5491):425-427
This year's Nobel Prize in chemistry was awarded to a trio of researchers--Alan Heeger of the University of California, Santa Barbara; Alan MacDiarmid of the University of Pennsylvania in Philadelphia; and Hideki Shirakawa of the University of Tsukuba in Japan--for discovering that plastics can be made electrically conductive. The discovery paved the way for revolutionary applications such as full-color displays for cellular phones and plastic electronics for computerized merchandise. 相似文献
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观察分析了捕鼠猫对褐家鼠的控制能力,结果表明,当捕鼠猫覆盖度达8只/km<'2>左右时,可将褐家鼠控制在较低密度水平,且捕鼠猫覆盖度与平均捕鼠率及平均盗食率均呈显著负相关. 相似文献
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O'Shea JN 《Science (New York, N.Y.)》2005,310(5747):453-454
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The impact of gene patents on downstream research and innovation are unknown, in part because of a lack of empirical data on the extent and nature of gene patenting. In this Policy Forum, the authors show that 20% of human gene DNA sequences are patented and that some genes are patented as many as 20 times. Unsurprisingly, genes associated with health and disease are more patented than the genome at large. The intellectual property rights for some genes can become highly fragmented between many owners, which suggests that downstream innovators may face considerable costs to gain access to gene-oriented technologies. 相似文献
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张琳琳 《农业图书情报学刊》2010,22(7):198-200
剖析了图书馆在信息时代边缘化的现状,从"注意力的逃离"、"传统模式的弊端"和"Web2.0的冲击"三方面因素分析了网络时代图书馆出现边缘化走势的原因,在此基础上提出了扭转图书馆边缘化走势的对策。 相似文献
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Walsh J 《Science (New York, N.Y.)》1974,185(4157):1143-1193