共查询到20条相似文献,搜索用时 15 毫秒
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Montgomery DJ 《Science (New York, N.Y.)》1976,193(4256):836
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C E 《Science (New York, N.Y.)》1993,260(5106):406
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《Science (New York, N.Y.)》1966,152(3720):332-333
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Marshall E 《Science (New York, N.Y.)》1991,252(5013):1609
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Wolfle D 《Science (New York, N.Y.)》1957,126(3269):335-343
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图书馆——高校新生入馆教育必修第一课 总被引:1,自引:0,他引:1
陈国玲 《农业图书情报学刊》2010,22(2):182-184
新生入馆教育是高校图书馆读者服务工作的重要内容之一。论文探讨了新生入馆教育的必要性,提出了新生入馆教育的有效途径。 相似文献
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Walsh J 《Science (New York, N.Y.)》1975,187(4176):518-520
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Iron, calcium, aluminum, silicon, and sulfur are major elements in the first surface sample of Mars that has been analyzed by the Viking x-ray fluorescence spectrometer. Titanium is present in minor quantities. This is consistent with the sample being a mixture of fine silicate and oxide mineral grains, with a significant proportion of sulfates, possibly hydrated. Ferric oxide is regarded as the red pigmenting agent on the martian surface, but if it coats silicate grains, the coatings must be very thin (= 2 micrometers) or discontinuous. A high abundance of Fe, relatively low abundances of Al, Rb, Sr, and Zr, and a high Ca/K ratio are distinctive features of the spectra. Preliminary determinations indicate the following abundances (as percentages by weight): Fe, 14 +/- 2; Ti < 1; S, 2 to 5; the Ca/K ratio by weight is greater than 5. 相似文献
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First record of the little fire ant,Wasmannia auropunctata (Hymenoptera: Formicidae), in Chinese mainland
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In January 2022, we received ant specimens collected from three field colonies from Shantou City, Guangdong Province, China. They were identified as the little fire ant, Wasmannia auropunctata, through morphological and molecular analyses. Wasmannia auropunctata is listed as one of the 100 most dangerous invasive species by the International Union for Conservation of Nature (IUCN) and has spread from its native range in South America to every continent except Antarctica. DNA analysis of mitochondrial cytochrome c oxidase subunit I (COI) in nine specimens of W. auropunctata found that they had a close genetic relationship with specimens from Argentina. This study represents the first formal record of the establishment of W. auropunctata outdoor in Chinese mainland. However, the invasion stage and occurrence degree of W. auropunctata in China are not clear to date. The implementation of quarantine measures, investigation of the occurrence and distribution, and development of monitoring and control strategies are needed to actively respond to the threat posed by this highly invasive ant. 相似文献
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A fossil record of lampreys has previously been unknown. A new genus demonstrates the presence of this group in the Pennsylvanian. The body outline, parts of the head skeleton, rasping tongue mechanism, gill basket, and other internal organs are preserved. The fossils are very similar in structure to modern forms. The absence of hagfish characters in the fossil supports the view that the common ancestor of lampreys and hagfishes lived prior to the Pennsylvanian. 相似文献