全文获取类型
收费全文 | 386篇 |
免费 | 0篇 |
专业分类
系统科学 | 5篇 |
教育与普及 | 2篇 |
现状及发展 | 91篇 |
研究方法 | 50篇 |
综合类 | 227篇 |
自然研究 | 11篇 |
出版年
2018年 | 2篇 |
2017年 | 2篇 |
2014年 | 3篇 |
2013年 | 7篇 |
2012年 | 14篇 |
2011年 | 23篇 |
2010年 | 7篇 |
2009年 | 2篇 |
2008年 | 16篇 |
2007年 | 17篇 |
2006年 | 18篇 |
2005年 | 14篇 |
2004年 | 16篇 |
2003年 | 12篇 |
2002年 | 17篇 |
2001年 | 17篇 |
2000年 | 7篇 |
1999年 | 8篇 |
1998年 | 2篇 |
1996年 | 2篇 |
1992年 | 7篇 |
1991年 | 9篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 11篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 9篇 |
1978年 | 8篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1974年 | 8篇 |
1972年 | 2篇 |
1971年 | 6篇 |
1970年 | 11篇 |
1969年 | 8篇 |
1968年 | 14篇 |
1967年 | 8篇 |
1966年 | 4篇 |
1965年 | 9篇 |
1960年 | 2篇 |
1959年 | 1篇 |
1957年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有386条查询结果,搜索用时 406 毫秒
381.
S Guioli B Incerti E Zanaria B Bardoni B Franco K Taylor A Ballabio G Camerino 《Nature genetics》1992,1(5):337-340
The X-linked Kallmann syndrome gene was recently cloned and homologous sequences of unknown functional significance identified on the Y chromosome. We now describe a patient with Kallmann syndrome carrying an X;Y translocation resulting from abnormal pairing and precise recombination between the X-linked Kallmann syndrome gene and its homologue on the Y. The translocation created a recombinant, non-functional Kallmann syndrome gene identical to the normal X-linked gene with the exception of the 3' end which is derived from the Y. Our findings indicate that the 3' portion of the Kallmann syndrome gene is essential for its function and cannot be substituted by the Y-derived homologous region, although a 'position' effect remains a formal possibility. 相似文献
382.
Nomenclature of the pepsins 总被引:10,自引:0,他引:10
383.
384.
S. E. Taylor M. A. Gafur A. K. Choudhury F. J. Evans 《Cellular and molecular life sciences : CMLS》1981,37(7):681-682
Summary From the unripe fruits ofSapium indicum, an irritant compound, sapintoxin, was isolated. Spectroscopic data together with selective hydrolysis and partial synthesis confirmed sapintoxin as 12-O-[N-methylaminobenzoyl]-13-O-acetyl-4-deoxyphorbol. 相似文献
385.
A suite of observations suggests that the northern plains of Mars, which cover nearly one third of the planet's surface, may once have contained an ocean. Perhaps the most provocative evidence for an ancient ocean is a set of surface features that ring the plains for thousands of kilometres and that have been interpreted as a series of palaeoshorelines of different age. It has been shown, however, that topographic profiles along the putative shorelines contain long-wavelength trends with amplitudes of up to several kilometres, and these trends have been taken as an argument against the martian shoreline (and ocean) hypothesis. Here we show that the long-wavelength topography of the shorelines is consistent with deformation caused by true polar wander--a change in the orientation of a planet with respect to its rotation pole--and that the inferred pole path has the geometry expected for a true polar wander event that postdates the formation of the massive Tharsis volcanic rise. 相似文献
386.
Kleinman ME Yamada K Takeda A Chandrasekaran V Nozaki M Baffi JZ Albuquerque RJ Yamasaki S Itaya M Pan Y Appukuttan B Gibbs D Yang Z Karikó K Ambati BK Wilgus TA DiPietro LA Sakurai E Zhang K Smith JR Taylor EW Ambati J 《Nature》2008,452(7187):591-597
Clinical trials of small interfering RNA (siRNA) targeting vascular endothelial growth factor-A (VEGFA) or its receptor VEGFR1 (also called FLT1), in patients with blinding choroidal neovascularization (CNV) from age-related macular degeneration, are premised on gene silencing by means of intracellular RNA interference (RNAi). We show instead that CNV inhibition is a siRNA-class effect: 21-nucleotide or longer siRNAs targeting non-mammalian genes, non-expressed genes, non-genomic sequences, pro- and anti-angiogenic genes, and RNAi-incompetent siRNAs all suppressed CNV in mice comparably to siRNAs targeting Vegfa or Vegfr1 without off-target RNAi or interferon-alpha/beta activation. Non-targeted (against non-mammalian genes) and targeted (against Vegfa or Vegfr1) siRNA suppressed CNV via cell-surface toll-like receptor 3 (TLR3), its adaptor TRIF, and induction of interferon-gamma and interleukin-12. Non-targeted siRNA suppressed dermal neovascularization in mice as effectively as Vegfa siRNA. siRNA-induced inhibition of neovascularization required a minimum length of 21 nucleotides, a bridging necessity in a modelled 2:1 TLR3-RNA complex. Choroidal endothelial cells from people expressing the TLR3 coding variant 412FF were refractory to extracellular siRNA-induced cytotoxicity, facilitating individualized pharmacogenetic therapy. Multiple human endothelial cell types expressed surface TLR3, indicating that generic siRNAs might treat angiogenic disorders that affect 8% of the world's population, and that siRNAs might induce unanticipated vascular or immune effects. 相似文献