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51.
Experimental adaptation of an influenza H5 HA confers respiratory droplet transmission to a reassortant H5 HA/H1N1 virus in ferrets 总被引:1,自引:0,他引:1
Imai M Watanabe T Hatta M Das SC Ozawa M Shinya K Zhong G Hanson A Katsura H Watanabe S Li C Kawakami E Yamada S Kiso M Suzuki Y Maher EA Neumann G Kawaoka Y 《Nature》2012,486(7403):420-428
Highly pathogenic avian H5N1 influenza A viruses occasionally infect humans, but currently do not transmit efficiently among humans. The viral haemagglutinin (HA) protein is a known host-range determinant as it mediates virus binding to host-specific cellular receptors. Here we assess the molecular changes in HA that would allow a virus possessing subtype H5 HA to be transmissible among mammals. We identified a reassortant H5 HA/H1N1 virus-comprising H5 HA (from an H5N1 virus) with four mutations and the remaining seven gene segments from a 2009 pandemic H1N1 virus-that was capable of droplet transmission in a ferret model. The transmissible H5 reassortant virus preferentially recognized human-type receptors, replicated efficiently in ferrets, caused lung lesions and weight loss, but was not highly pathogenic and did not cause mortality. These results indicate that H5 HA can convert to an HA that supports efficient viral transmission in mammals; however, we do not know whether the four mutations in the H5 HA identified here would render a wholly avian H5N1 virus transmissible. The genetic origin of the remaining seven viral gene segments may also critically contribute to transmissibility in mammals. Nevertheless, as H5N1 viruses continue to evolve and infect humans, receptor-binding variants of H5N1 viruses with pandemic potential, including avian-human reassortant viruses as tested here, may emerge. Our findings emphasize the need to prepare for potential pandemics caused by influenza viruses possessing H5 HA, and will help individuals conducting surveillance in regions with circulating H5N1 viruses to recognize key residues that predict the pandemic potential of isolates, which will inform the development, production and distribution of effective countermeasures. 相似文献
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Jin D Liu HX Hirai H Torashima T Nagai T Lopatina O Shnayder NA Yamada K Noda M Seike T Fujita K Takasawa S Yokoyama S Koizumi K Shiraishi Y Tanaka S Hashii M Yoshihara T Higashida K Islam MS Yamada N Hayashi K Noguchi N Kato I Okamoto H Matsushima A Salmina A Munesue T Shimizu N Mochida S Asano M Higashida H 《Nature》2007,446(7131):41-45
CD38, a transmembrane glycoprotein with ADP-ribosyl cyclase activity, catalyses the formation of Ca2+ signalling molecules, but its role in the neuroendocrine system is unknown. Here we show that adult CD38 knockout (CD38-/-) female and male mice show marked defects in maternal nurturing and social behaviour, respectively, with higher locomotor activity. Consistently, the plasma level of oxytocin (OT), but not vasopressin, was strongly decreased in CD38-/- mice. Replacement of OT by subcutaneous injection or lentiviral-vector-mediated delivery of human CD38 in the hypothalamus rescued social memory and maternal care in CD38-/- mice. Depolarization-induced OT secretion and Ca2+ elevation in oxytocinergic neurohypophysial axon terminals were disrupted in CD38-/- mice; this was mimicked by CD38 metabolite antagonists in CD38+/+ mice. These results reveal that CD38 has a key role in neuropeptide release, thereby critically regulating maternal and social behaviours, and may be an element in neurodevelopmental disorders. 相似文献
53.
An intronic SNP in a RUNX1 binding site of SLC22A4, encoding an organic cation transporter, is associated with rheumatoid arthritis 总被引:25,自引:0,他引:25
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Zusammenfassung Elektronenmikroskopische Untersuchung von B-Zellen der Pankreas eines diabetischen Stammes japanischer Mäuse erbrachte den Hinweis gesteigerter Insulin-Synthese, bzw. gesteigerten Insulin-Ausflusses. 相似文献
57.
Over the past 50 years there has been much speculation about the energetic cost of swimming and wave-riding by dolphins. When aligned properly in front of the bow of moving ships in the stern wake of small boats, on wind waves, and even in the wake of larger cetaceans, the animals appear to move effortlessly through the water without the benefit of propulsive strokes by the flukes. Theoretically, body streamlining as well as other anatomical and behavioural adaptations contribute to low transport costs in these animals. The economy of movement permitted by wave-riding has been perceived as an energetic advantage for the swimming dolphin, but has been hard to prove in the absence of physiological data for exercising cetaceans. Here we determine the aerobic and anaerobic costs of swimming and wave-riding in bottlenose dolphins and find that the minimum cost of transport for swimming dolphins is 1.29 +/- 0.05 J kg-1 m-1 at a cruising speed of 2.1 m s-1. Aerobic costs are nearly twice as high for swimming seals and sea lions, and 8-12 times higher for human swimmers. Wave-riding by dolphins provides additional benefits in terms of speed. The results indicate that behavioural, physiological and morphological factors make swimming an economical form of high-speed travel for dolphins. 相似文献
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Zusammenfassung Elektronenmikroskopisch konnten in den Langerhansschen Inseln im Pankreas von normalen und diabetischen Fischen bestimmte Typen von Drüsenzellen differenziert werden, nämlich A-, B- und D-Zellen sowie klare Zellen. Bei diabetischen Fischen ist vor allem die sehr starke Vermehrung sogenannter klarer Zellen typisch. 相似文献
60.
新型植物生长调节物质-Lepidimoide的生理作用及其与其它植物激素生理作用的比较 总被引:1,自引:0,他引:1
以燕麦、萝卜和水稻幼苗为材料,分析Lepidimoide的生理作用,并与其它激素的生理作用进行比较.研究结果表明:1Lepidimoide促进燕麦胚芽鞘切段的伸长,单侧处理燕麦胚芽鞘能产生弯曲生长,但作用效果略低于生长素;2Lepidimoide处理萝卜子叶能使叶绿素含量增加,但效果略低于BA,混合使用时作用效果高于单独使用BA或Lepidimoide;3Lepidimoide能促进水稻幼苗伸长,效果与GA3相似,但低浓度时效果不佳,混合使用时有一定的增效作用.上述结果表明,Lepidimoide是一种促进型生长调节物质,其作用与BA和GA3相似. 相似文献