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   13012篇
  免费   1031篇
  国内免费   1101篇
  2024年   28篇
  2023年   208篇
  2022年   502篇
  2021年   843篇
  2020年   473篇
  2019年   640篇
  2018年   621篇
  2017年   419篇
  2016年   609篇
  2015年   865篇
  2014年   998篇
  2013年   1015篇
  2012年   1222篇
  2011年   1122篇
  2010年   662篇
  2009年   581篇
  2008年   659篇
  2007年   568篇
  2006年   468篇
  2005年   374篇
  2004年   328篇
  2003年   331篇
  2002年   273篇
  2001年   187篇
  2000年   167篇
  1999年   169篇
  1998年   86篇
  1997年   88篇
  1996年   81篇
  1995年   64篇
  1994年   53篇
  1993年   31篇
  1992年   54篇
  1991年   41篇
  1990年   45篇
  1989年   52篇
  1988年   29篇
  1987年   23篇
  1986年   26篇
  1985年   32篇
  1984年   19篇
  1983年   11篇
  1982年   8篇
  1981年   8篇
  1979年   5篇
  1971年   5篇
  1969年   4篇
  1968年   7篇
  1967年   4篇
  1937年   5篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
  相似文献   
2.
Yan  Xue  Liu  Jia  Wu  Ke-Xin  Yang  Nan  Pan  Li-Ben  Song  Ying  Liu  Yang  Tang  Zhong-Hua 《Journal of Plant Growth Regulation》2022,41(6):2421-2434
Journal of Plant Growth Regulation - Early-spring plants are a special type of plant that complete their life cycle promptly in cold, early spring. Very little effort has been made into researching...  相似文献   
3.
4.
In the fruitfly, Drosophila melanogaster, autophagy and caspase activity function in parallel in the salivary gland during metamorphosis and in a common regulatory hierarchy during oogenesis. Both autophagy and caspase activity progressively increase in the remodeling fat body, and they are induced by a pulse of the molting hormone (20-hydroxyecdysone, 20E) during the larval-prepupal transition. Inhibition of autophagy and/or caspase activity in the remodeling fat body results in 25–40% pupal lethality, depending on the genotypes. Interestingly, a balancing crosstalk occurs between autophagy and caspase activity in this tissue: the inhibition of autophagy induces caspase activity and the inhibition of caspases induces autophagy. The Drosophila remodeling fat body provides an in vivo model for understanding the molecular mechanism of the balancing crosstalk between autophagy and caspase activity, which oppose with each other and are induced by the common stimulus 20E, and blockage of either path reinforces the other path.  相似文献   
5.
6.
7.
The bioinorganic complexes of europium with N-acetyl-DL-alanine, N-acetyl-DL-valine, and DL-alanyl-DL-alanine have been synthesized and the M?ssbauer spectra at room temperature have been measured for these solid state complexes. The M?ssbauer parameters indicate that the water molecules in these complexes are not directly linked to the central europium ion and are outside the coordination sphere of europium and biological ligands, and that the chemical bond between the europium ion and the ligands may be predominantly ionic in character, with the possibility of partial covalent contribution.  相似文献   
8.
The chemiluminescence (CL) of bis(2,4,6‐trichlorophyenyl) oxalate with hydrogen peroxide in the present of cationic surfactant and gold nanoparticles was studied. The CL emission was obviously enhanced in the presence of surfactant at a suitable concentration, with a synergetic catalysis effect exhibited. Different sizes of gold nanoparticles (15 and 50 nm) showed different effects on CL intensity. Mechanisms of the CL reaction and sensitization effect are discussed. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
9.
We developed highly sensitive shuttle vector systems for detection of mutations formed in human cells using autonomously replicating derivatives of Epstein-Barr virus (EBV). EBV vectors carrying the bacterial lacI gene as the target for mutation were established in human cells and later returned to Escherichia coli for rapid detection and analysis of lacI mutations. The majority of the clonal cell lines created by establishment of the lacI-EBV vector show spontaneous LacI- frequencies of less than 10(-5) and are suitable for studies of induced mutation. The ability to isolate clonal lines represents a major advantage of the EBV vectors over transiently replicating shuttle vectors (such as those derived from simian virus 40) for the study of mutation. The DNA sequence changes were determined for 61 lacI mutations induced by exposure of one of the cell lines to N-nitroso-N-methylurea. A total of 33 of 34 lacI nonsense mutations and 26 of 27 missense mutations involve G X C to A X T transitions. These data provide support for the mutational theory of cancer.  相似文献   
10.
Mutation in a heat-regulated hsp70 gene of Ustilago maydis.   总被引:9,自引:2,他引:7       下载免费PDF全文
  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