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   12457篇
  免费   1371篇
  国内免费   1813篇
  2024年   14篇
  2023年   216篇
  2022年   330篇
  2021年   799篇
  2020年   623篇
  2019年   768篇
  2018年   667篇
  2017年   484篇
  2016年   613篇
  2015年   864篇
  2014年   1068篇
  2013年   1054篇
  2012年   1241篇
  2011年   1151篇
  2010年   711篇
  2009年   618篇
  2008年   699篇
  2007年   585篇
  2006年   500篇
  2005年   448篇
  2004年   439篇
  2003年   396篇
  2002年   329篇
  2001年   204篇
  2000年   181篇
  1999年   135篇
  1998年   102篇
  1997年   63篇
  1996年   55篇
  1995年   53篇
  1994年   38篇
  1993年   47篇
  1992年   30篇
  1991年   17篇
  1990年   20篇
  1989年   23篇
  1988年   12篇
  1987年   9篇
  1986年   6篇
  1985年   9篇
  1984年   4篇
  1983年   4篇
  1982年   6篇
  1981年   2篇
  1980年   2篇
  1970年   1篇
  1950年   1篇
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
1.
2.
Phenotypes of inter-alpha-trypsin-inhibitor (ITI) have been determined by isoelectric focusing on polyacrylamide gels followed by immunofixation. The phenotype frequencies of ITI in the Han population in Chengdu, P. R. China have been investigated using this method. In addition, family studies have been conducted in 21 families. The results show that ITI is polymorphic in the Han population in Chengdu, China. The allele frequencies are as follows: ITI*1 = 0.5763. ITI*2 = 0.4107, ITI*3 = 0.0130. ITI is thus a new and promising genetic marker that can be used in the field of forensic haematogenetics.  相似文献   
3.
Brucella cell surface protein (BCSP31) is potentially useful for diagnosing brucellosis. We aimed to establish a monoclonal antibody (MAb) against Brucella melitensis BCSP31 and to investigate its distribution in diagnosis. Soluble recombinant BCSP31 was successfully expressed and purified. Two MAbs (1F1 and 1E5) against B. melitensis BCSP31, effective in detecting both recombinant and cellular proteins, were obtained and characterized. The MAbs did not react with Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Mycobacterium tuberculosis, or Bacillus aeruginosus, but strongly reacted with BCSP31 and B. melitensis by ELISA and Western blot analysis. We also tested different Brucella species and brucellosis using the prepared anti-BCSP31 MAbs. BCSP31 and anti-BCSP31 MAbs may play important roles in future research in diagnosing brucellosis.  相似文献   
4.
ObjectiveWe investigated whether glutamate, NMDA receptors, and eukaryote elongation factor-2 kinase (eEF-2K)/eEF-2 regulate P-glycoprotein expression, and the effects of the eEF-2K inhibitor NH125 on the expression of P-glycoprotein in rat brain microvessel endothelial cells (RBMECs).MethodsCortex was obtained from newborn Wistar rat brains. After surface vessels and meninges were removed, the pellet containing microvessels was resuspended and incubated at 37°C in culture medium. Cell viability was assessed by the MTT assay. RBMECs were identified by immunohistochemistry with anti-vWF. P-glycoprotein, phospho-eEF-2, and eEF-2 expression were determined by western blot analysis. Mdr1a gene expression was analyzed by RT-PCR.ResultsMdr1a mRNA, P-glycoprotein and phospho-eEF-2 expression increased in L-glutamate stimulated RBMECs. P-glycoprotein and phospho-eEF-2 expression were down-regulated after NH125 treatment in L-glutamate stimulated RBMECs.ConclusionseEF-2K/eEF-2 should have played an important role in the regulation of P-glycoprotein expression in RBMECs. eEF-2K inhibitor NH125 could serve as an efficacious anti-multidrug resistant agent.  相似文献   
5.
6.
7.
8.
9.
10.
Suspension culture of Ajuga lobata D. Don cells provides a method of synthesis of the phytoecdysteroid 20-hydroxyecdysone (20E) which can regulate the molting process of larvae. We characterized the culture conditions to optimize 20E production. Growth of A. lobata D. Don cells fits the logistic equation curve with a growth cycle of 19 days. Medium conductivity was negatively correlated with dry cell weight and 20E accumulation, thus could be used to determine the optimal time for cell harvest. Continuous subculture reduced 20E synthesis, but supplementing medium with 20E precursors mevalonic (MVA), α-Pinene, and nitric oxide (NO) can significantly promote cell growth and influence 20E accumulation. Combination of α-Pinene, MVA, and SNP significantly elevated 20E accumulation, thus may synergistically enhance 20E synthesis in A. lobata D. Don. The optimal concentrations of α-Pinene, MVA, and NO donor SNP in suspension culture were 50 μL L?1, 10 mg L?1, and 80 μmol L?1.  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