首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   162篇
  免费   2篇
  国内免费   3篇
系统科学   2篇
丛书文集   2篇
现状及发展   34篇
研究方法   26篇
综合类   102篇
自然研究   1篇
  2020年   1篇
  2019年   2篇
  2018年   1篇
  2017年   1篇
  2016年   2篇
  2015年   2篇
  2014年   2篇
  2013年   2篇
  2012年   14篇
  2011年   11篇
  2010年   2篇
  2009年   2篇
  2008年   11篇
  2007年   8篇
  2006年   5篇
  2005年   8篇
  2004年   8篇
  2003年   7篇
  2002年   6篇
  2001年   2篇
  2000年   4篇
  1999年   5篇
  1998年   3篇
  1997年   3篇
  1996年   2篇
  1994年   1篇
  1993年   4篇
  1992年   3篇
  1991年   2篇
  1990年   3篇
  1989年   7篇
  1988年   3篇
  1987年   2篇
  1986年   5篇
  1985年   1篇
  1984年   2篇
  1983年   1篇
  1982年   1篇
  1980年   1篇
  1978年   1篇
  1974年   1篇
  1973年   3篇
  1972年   4篇
  1971年   3篇
  1969年   1篇
  1967年   1篇
  1966年   1篇
  1954年   1篇
  1948年   1篇
排序方式: 共有167条查询结果,搜索用时 31 毫秒
41.
本文将便于应用的胡海昌方程推广到各种常见的中厚板理论.广义胡海昌方程解的结构与弹性理论所得的结果一致.  相似文献   
42.
Antigen presenting function of class II MHC expressing pancreatic beta cells   总被引:17,自引:0,他引:17  
Class II major histocompatibility complex (MHC) gene expression in the mouse is generally limited to thymic epithelium and bone marrow-derived cells such as B lymphocytes and cells of the macrophage/dendritic cell lineage (M phi/DC). Class II-bearing B lymphocytes and M phi/DC possess antigen presenting cell (APC) function; that is, they can stimulate T lymphocytes reactive to either antigen plus MHC or foreign MHC alone. To assess whether non-bone-marrow-derived cells can acquire APC function and elicit graft rejection through expression of class II, we studied transgenic pancreatic islet beta cells that express a foreign class II (I-E) molecule. In vivo, grafts of I-E+ transgenic islets into I-E- naive hosts are not rejected unless the host is primed by an injection of I-E+ spleen cells. In vitro, the I-E+ beta cells are unable to stimulate T lymphocytes reactive to I-E plus a peptide antigen. Paradoxically, they induce antigen specific unresponsiveness in the T cells. We propose that expression of class II on non-lymphoid cells may serve as an extrathymic mechanism for maintaining self tolerance.  相似文献   
43.
Highly precise 40Ar-39Ar dating results demonstrate that the ages of potash-rich volcanic rocks in western Shandong Province are 114.7–124.3 Ma, and that of the lamprophyres is 119.6 Ma. The potash-rich volcanic rocks have relatively high (87Sr÷86Sr)i ratios (0.708715–0.711418) and distinctly negative εnd values (−11.47–−17.54), and are enriched in radiogenic lead (206Pb÷204Pb=17.341−17.622, 207Pb÷204Pb=15.525−15.538, 208Pb÷204Pb = 37.563−37.684). Similarly, the lamprophyres also have quite low εnd values (−11.57–−19.64). Based on the fact that the Sr, Nd and Pb isotopic compositions of potash-rich volcanic rocks are very consistent with that of the clinopyroxene separates, and by integrating comprehensive analyses of their tectonic settings, and extensive comparisons of the Sr, Nd isotopic compositions with that of the related simultaneous rocks, it is concluded that the potash-rich volcanic rocks and lamprophyres in western Shandong Province were most possibly derived from the partial melting of enriched mantle which was caused by source contamination and metasomatism of subducted continental crustal materials.  相似文献   
44.
45.
More than 1,000 susceptibility loci have been identified through genome-wide association studies (GWAS) of common variants; however, the specific genes and full allelic spectrum of causal variants underlying these findings have not yet been defined. Here we used pooled next-generation sequencing to study 56 genes from regions associated with Crohn's disease in 350 cases and 350 controls. Through follow-up genotyping of 70 rare and low-frequency protein-altering variants in nine independent case-control series (16,054 Crohn's disease cases, 12,153 ulcerative colitis cases and 17,575 healthy controls), we identified four additional independent risk factors in NOD2, two additional protective variants in IL23R, a highly significant association with a protective splice variant in CARD9 (P < 1 × 10(-16), odds ratio ≈ 0.29) and additional associations with coding variants in IL18RAP, CUL2, C1orf106, PTPN22 and MUC19. We extend the results of successful GWAS by identifying new, rare and probably functional variants that could aid functional experiments and predictive models.  相似文献   
46.
47.
48.
Summary The cytoskeletal proteins of the vertebrate lens fibre cell comprise polypeptides ranging in mol.wt from 43,000 to 250,000 daltons. The main intermediate filament polypeptide of the pickerel, Northern frog, chick, bovine, and human lens has a mol.wt of 54,000 daltons. Peptide analysis revealed that the chick 54,000 dalton protein was more similar to the bovine protein than to the pickerel protein.Supported by grants EY 01417 (H. Maisel) and HD-06390 (J.C. Brown, University of Virginia, Charlottesville) from the National Institutes of Health, U.S.P.H.S.  相似文献   
49.
50.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号