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   9792篇
  免费   744篇
  国内免费   1篇
  10537篇
  2023年   70篇
  2022年   131篇
  2021年   298篇
  2020年   185篇
  2019年   205篇
  2018年   237篇
  2017年   212篇
  2016年   337篇
  2015年   546篇
  2014年   575篇
  2013年   700篇
  2012年   898篇
  2011年   816篇
  2010年   515篇
  2009年   438篇
  2008年   618篇
  2007年   536篇
  2006年   525篇
  2005年   449篇
  2004年   408篇
  2003年   322篇
  2002年   328篇
  2001年   94篇
  2000年   105篇
  1999年   92篇
  1998年   57篇
  1997年   46篇
  1996年   48篇
  1995年   56篇
  1994年   31篇
  1993年   31篇
  1992年   60篇
  1991年   62篇
  1990年   33篇
  1989年   55篇
  1988年   28篇
  1987年   34篇
  1986年   31篇
  1985年   42篇
  1984年   26篇
  1983年   21篇
  1982年   16篇
  1981年   16篇
  1980年   20篇
  1979年   15篇
  1978年   13篇
  1977年   15篇
  1975年   16篇
  1973年   18篇
  1972年   15篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.

Introduction  

Sj?gren's syndrome (SS) is a systemic autoimmune disease that mainly targets the exocrine glands. The aim of this study was to investigate the involvement of 87 proteins measured in serum and 75 proteins analyzed in saliva in spontaneous experimental SS. In addition, we intended to compute a model of the immunological situation representing the overt disease stage of SS.  相似文献   
4.
5.
6.
Understanding drivers of biodiversity patterns is of prime importance in this era of severe environmental crisis. More diverse plant communities have been postulated to represent a larger functional trait‐space, more likely to sustain a diverse assembly of herbivore species. Here, we expand this hypothesis to integrate environmental, functional and phylogenetic variation of plant communities as factors explaining the diversity of lepidopteran assemblages along elevation gradients in the Swiss Western Alps. According to expectations, we found that the association between butterflies and their host plants is highly phylogenetically structured. Multiple regression analyses showed the combined effect of climate, functional traits and phylogenetic diversity in structuring butterfly communities. Furthermore, we provide the first evidence that plant phylogenetic beta diversity is the major driver explaining butterfly phylogenetic beta diversity. Along ecological gradients, the bottom up control of herbivore diversity is thus driven by phylogenetically structured turnover of plant traits as well as environmental variables.  相似文献   
7.
Detection of Infectious Astroviruses in Water   总被引:3,自引:2,他引:1       下载免费PDF全文
A method based on the infection of CaCo-2 cells and molecular hybridization with a specific cDNA probe has been developed for the detection of infectious astroviruses in environmental samples. By this procedure wild-type astroviruses have been detected in water from an area where a concurrent gastroenteritis outbreak was reported.  相似文献   
8.
Mice inoculated with an artificially constructed retrovirus carrying the middle T gene of polyomavirus develop acute myeloproliferative disease with severe thrombotic and hemorrhagic disorder and impaired platelet function. The megakaryocytic lineage appears to be a target for polyoma-murine leukemia virus infection and middle T gene expression. This newly described disease represents a unique model system for studying disorders of the megakaryocytic lineage.  相似文献   
9.
10.
We report in this paper the presence of fluorescence bands of tryptophan and tyrosine solutions centered above 550 nm. This long-wavelength fluorescence is of much lower intensity, (0.4-2.7)%, than the UV fluorescence of these aromatic aminoacids. The basic characteristic of these fluorescence bands are: (a) tyrosine: lambda em = 600 nm with two excitation peaks centered at 453 nm and 550 nm (b) tryptophan: lambda em = 675 nm with two excitation peaks centered at 455 and 560 nm. It has been found that irradiation of tyrosine solutions with a potent UV lamp promotes an important increase of absorption at 310 nm and above 400 nm.  相似文献   
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