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   114093篇
  免费   8995篇
  国内免费   9343篇
  2024年   161篇
  2023年   1331篇
  2022年   2855篇
  2021年   5763篇
  2020年   3964篇
  2019年   4914篇
  2018年   4695篇
  2017年   3414篇
  2016年   4854篇
  2015年   7060篇
  2014年   8279篇
  2013年   8730篇
  2012年   10578篇
  2011年   9553篇
  2010年   5870篇
  2009年   5257篇
  2008年   6075篇
  2007年   5436篇
  2006年   4733篇
  2005年   3740篇
  2004年   3168篇
  2003年   2869篇
  2002年   2427篇
  2001年   2023篇
  2000年   1834篇
  1999年   1821篇
  1998年   1106篇
  1997年   1074篇
  1996年   1006篇
  1995年   898篇
  1994年   861篇
  1993年   669篇
  1992年   901篇
  1991年   689篇
  1990年   533篇
  1989年   484篇
  1988年   406篇
  1987年   377篇
  1986年   307篇
  1985年   334篇
  1984年   181篇
  1983年   175篇
  1982年   118篇
  1981年   95篇
  1980年   64篇
  1979年   88篇
  1978年   63篇
  1977年   69篇
  1975年   59篇
  1974年   63篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
A Melanesian variant of the genetic disease α-thalassemia has recently been shown to be due to a single-nucleotide polymorphism located between the adult α-globin genes and their enhancers. The finding that this mutation creates a novel promoter provides support for a mechanism of gene regulation by facilitated chromatin looping.  相似文献   
75.
76.
77.
78.
In chloroplasts, tetramethyl-p-hydroquinone supports high rates of phosphorylation-coupled, noncyclic electron flow through Photosystem I to methylviologen. The reaction is totally sensitive to dibromothymoquinone, indicating an electron donation to the plastoquinone region of the photosynthetic chain. The uncoupled electron flow rate exceeds 1000 μequivalents per hour per mg chlorophyll. The phosphorylation efficiency (Pe2) at the optimal pH of 8 is 0.6–0.65. Presumably this ratio represents the efficiency of energy coupling in the electron transfer step plastoquinone → cytochrome f.  相似文献   
79.

Background  

Meiotic prophase is a critical stage in sexual reproduction. Aberrant chromosome recombination during this stage is a leading cause of human miscarriages and birth defects. However, due to the experimental intractability of mammalian gonads, only a very limited number of meiotic genes have been characterized. Here we aim to identify novel meiotic genes important in human reproduction through computational mining of cross-species and cross-sex time-series expression data from budding yeast, mouse postnatal testis, mouse embryonic ovary, and human fetal ovary.  相似文献   
80.
Intestinal mucosal injuries are directly or indirectly related to many common acute and chronic diseases. Long non-coding RNAs (lncRNAs) are expressed in many diseases, including intestinal mucosal injury. However, the relationship between lncRNAs and intestinal mucosal injury has not been determined. Here, we investigated the functions and mechanisms of action of lncRNA Bmp1 on damaged intestinal mucosa. We found that Bmp1 was increased in damaged intestinal mucosal tissue and Bmp1 overexpression was able to alleviate intestinal mucosal injury. Bmp1 overexpression was found to influence cell proliferation, colony formation, and migration in IEC-6 or HIEC-6 cells. Moreover, miR-128-3p was downregulated after Bmp1 overexpression, and upregulation of miR-128-3p reversed the effects of Bmp1 overexpression in IEC-6 cells. Phf6 was observed to be a target of miR-128-3p. Furthermore, PHF6 overexpression affected IEC-6 cells by activating PI3K/AKT signaling which was mediated by the miR-128-3p/PHF6 axis. In conclusion, Bmp1 was found to promote the expression of PHF6 through the sponge miR-128-3p, activating the PI3K/AKT signaling pathway to promote cell migration and proliferation.Subject terms: Cell growth, Cell migration  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