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   31890篇
  免费   2797篇
  国内免费   27篇
  2023年   143篇
  2022年   266篇
  2021年   783篇
  2020年   417篇
  2019年   551篇
  2018年   661篇
  2017年   544篇
  2016年   975篇
  2015年   1647篇
  2014年   1726篇
  2013年   2043篇
  2012年   2664篇
  2011年   2699篇
  2010年   1643篇
  2009年   1373篇
  2008年   2044篇
  2007年   2013篇
  2006年   1955篇
  2005年   1689篇
  2004年   1710篇
  2003年   1498篇
  2002年   1472篇
  2001年   296篇
  2000年   221篇
  1999年   292篇
  1998年   303篇
  1997年   218篇
  1996年   197篇
  1995年   171篇
  1994年   152篇
  1993年   148篇
  1992年   134篇
  1991年   162篇
  1990年   117篇
  1989年   103篇
  1988年   98篇
  1987年   79篇
  1986年   97篇
  1985年   102篇
  1984年   104篇
  1983年   101篇
  1982年   115篇
  1981年   116篇
  1980年   91篇
  1979年   67篇
  1978年   52篇
  1977年   51篇
  1976年   55篇
  1975年   50篇
  1974年   49篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
2.
3.
Immunological memory for T and B cells was studied in an in vitro culture system with spleen cells from mice primed with bovine serum albumin (BSA). Spleen cells taken from mice immunized at various times previously with a single intravenous injection of alum-precipitated (AP) BSA and bacterial endotoxin (ET) were cultured in Marbrook's system with dinitrophenylated (DNP) BSA as the in vitro antigen. In the cultures of spleen cells obtained from mice primed more than 14 days previously, an IgG-predominant anti-BSA response was generated. However, no anti-BSA response was observed in the culture of spleen cells taken from mice primed 7 days previously (day 7 spleen cells). The failure of day 7 spleen cells to generate an antibody response in vitro was shown to be attributable to both the lack of B memory cells and the effect of “suppressive” macrophages induced by ET. On the other hand, anti-BSA memory in the spleen of mice primed with AP-BSA plus ET and 2 months later challenged with AP-BSA matured within 7 days and declined rather quickly by 30 days after the challenge. The difference in the time course of the generation of memory between the spleen cells from primary and from secondary immunized mice might be attributable to the difference in the maturation of memory B cells, since the time course of the development of memory T cells after the secondary immunization was similar to that observed after primary immunization.  相似文献   
4.
5.
For decades, the bio-duck sound has been recorded in the Southern Ocean, but the animal producing it has remained a mystery. Heard mainly during austral winter in the Southern Ocean, this ubiquitous sound has been recorded in Antarctic waters and contemporaneously off the Australian west coast. Here, we present conclusive evidence that the bio-duck sound is produced by Antarctic minke whales (Balaenoptera bonaerensis). We analysed data from multi-sensor acoustic recording tags that included intense bio-duck sounds as well as singular downsweeps that have previously been attributed to this species. This finding allows the interpretation of a wealth of long-term acoustic recordings for this previously acoustically concealed species, which will improve our understanding of the distribution, abundance and behaviour of Antarctic minke whales. This is critical information for a species that inhabits a difficult to access sea-ice environment that is changing rapidly in some regions and has been the subject of contentious lethal sampling efforts and ongoing international legal action.  相似文献   
6.
7.
Metabolism is recognized as an important driver of cancer progression and other complex diseases, but global metabolite profiling remains a challenge. Protein expression profiling is often a poor proxy since existing pathway enrichment models provide an incomplete mapping between the proteome and metabolism. To overcome these gaps, we introduce multiomic metabolic enrichment network analysis (MOMENTA), an integrative multiomic data analysis framework for more accurately deducing metabolic pathway changes from proteomics data alone in a gene set analysis context by leveraging protein interaction networks to extend annotated metabolic models. We apply MOMENTA to proteomic data from diverse cancer cell lines and human tumors to demonstrate its utility at revealing variation in metabolic pathway activity across cancer types, which we verify using independent metabolomics measurements. The novel metabolic networks we uncover in breast cancer and other tumors are linked to clinical outcomes, underscoring the pathophysiological relevance of the findings.  相似文献   
8.
Connective tissue growth factor (CTGF/CCN2) is overexpressed in diabetes. Diabetic rats possess myocardial and cardiomyocyte hypertrophy. In a recent report, Wang and colleagues (Am J Physiol Cell Physiol. 2009 Jul 22. [Epub ahead of print]) show that CCN2 directly mediates cardiomyocyte hypertrophy as well as that induced by high glucose and fatty acid. CCN2 acted via the TrkA receptor. These data are the subject of this commentary, and emphasize that CCN2 may be an excellent target for therapy in diabetes.  相似文献   
9.
10.
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