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   93635篇
  免费   295篇
  国内免费   813篇
  2022年   8篇
  2021年   20篇
  2020年   6篇
  2019年   14篇
  2018年   11844篇
  2017年   10674篇
  2016年   7454篇
  2015年   599篇
  2014年   304篇
  2013年   321篇
  2012年   4232篇
  2011年   12828篇
  2010年   12010篇
  2009年   8237篇
  2008年   9800篇
  2007年   11372篇
  2006年   267篇
  2005年   518篇
  2004年   972篇
  2003年   1033篇
  2002年   797篇
  2001年   278篇
  2000年   177篇
  1999年   35篇
  1998年   16篇
  1997年   28篇
  1996年   9篇
  1994年   8篇
  1993年   33篇
  1992年   23篇
  1991年   41篇
  1990年   15篇
  1989年   12篇
  1988年   29篇
  1987年   18篇
  1984年   16篇
  1983年   21篇
  1979年   7篇
  1978年   8篇
  1975年   8篇
  1973年   6篇
  1972年   250篇
  1971年   276篇
  1970年   6篇
  1968年   6篇
  1965年   13篇
  1962年   25篇
  1956年   5篇
  1944年   12篇
  1940年   10篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
901.
902.
“Taxonomics” is proposed as a short name for the discipline of discovering, recognising, describing and classifying biological entities.  相似文献   
903.
Reproductive functions are closely related to nutritional status. Recent studies suggest that adiponectin may be a hormonal link between them. Adiponectin is an adipocytokine, abundantly expressed in adipose tissues. It plays a dominant role in lipid and carbohydrate metabolism by stimulating fatty acid oxidation, decreasing plasma triglycerides, and increasing cells’ sensitivity to insulin and has direct antiatherosclerotic effects. The hormone is also postulated to play a modulatory role in the regulation of the reproductive system. The aim of this study was to identify differentially expressed genes (DE-genes) in response to adiponectin treatment of porcine luteal ovarian cells. The global expression of genes in the porcine ovary was investigated using the Porcine (V2) Two-color gene expression microarray, 4?×?44 (Agilent, USA). Analysis of the microarray data showed that 701 genes were differentially expressed and 389 genes showed a fold change greater than 1.2 (p?<?0.05). Among this number, 186 genes were up-regulated and 203 were down-regulated. The list of DE-genes was used for gene ontology analyses. The biological process list was generated from up-regulated and down-regulated DE-genes. We found that up-regulated products of DE-genes take part in 30 biological processes and down-regulated products in 9. Analysis of the interaction network among DE-genes showed that adiponectin interacts with genes involved in important processes in luteal cells. These results provide a basis for future work describing the detailed interactions and relationships explaining local regulation of adiponectin actions in the ovary of pigs.  相似文献   
904.
905.
906.
Several studies have supported the hypoxia mimetic roles and cytoprotective properties of cobalt chloride in vitro and in vivo. However, a clear understanding of biological process-based mechanism that integrates the available information remains unknown. This study was aimed to explore the potential mechanism of cobalt chloride deciphering its benefits and well-known physiological challenge caused by hypobaric hypoxia that reportedly affects nearly 24 % of the global population. In order to explore the mechanism of CoCl2, we used global proteomic and systems biology approach in rat model to provide a deeper insight into molecular mechanisms of preconditioning. Furthermore, key conclusions were drawn based on biological network analysis and their enrichment with ontological overlaps. The study was further strengthened by consistent identification of validation of proteins using immunoblotting. CoCl2-pretreated animals exposed to hypoxia showed two significant networks, one lipid metabolism and other cell cycle associated, with a total score of 23 and eight focus molecules. In this study, we delineated two primary routes: one, by direct modulation of reactive oxygen species metabolism and, second, by regulation of lipid metabolism which was not known until now. The previously known benefits of cobalt chloride during physiological challenge by hypobaric hypoxia are convincing and could be explained by some basic set of metabolic and molecular reorganization within the hypoxia model. Interestingly, we also observed some of the completely unknown roles of cobalt chloride such as regulation of lipid that could undulate the translational roles of cobalt chloride supplementation beyond hypoxia preconditioning.  相似文献   
907.
908.
Members of Cnidaria Medusozoa are known for their wide morphological variation, which is expressed on many different levels, especially in different phases of the life cycle. Difficulties in interpreting morphological variations have posed many taxonomic problems, since intraspecific morphological variations are often misinterpreted as interspecific variations and vice-versa, hampering species delimitation. This study reviews the patterns of morphological variation in the Medusozoa, to evaluate how different interpretations of the levels of variation may influence the understanding of the patterns of diversification in the group. Additionally, we provide an estimate of the cryptic diversity in the Hydrozoa, based on COI sequences deposited in GenBank. Morphological variations frequently overlap between microevolutionary and macroevolutionary scales, contributing to misinterpretations of the different levels of variation. In addition, most of the cryptic diversity described so far for the Medusozoa is a result of previously overlooked morphological differences, and there is still great potential for discovering cryptic lineages in the Hydrozoa. We provide evidence that the number of species in the Medusozoa is misestimated and emphasize the necessity of examining different levels of morphological variations when studying species boundaries, in order to avoid generalizations and misinterpretations of morphological characters.  相似文献   
909.
910.
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