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   8210篇
  免费   497篇
  国内免费   27篇
耳鼻咽喉   123篇
儿科学   226篇
妇产科学   237篇
基础医学   1476篇
口腔科学   279篇
临床医学   848篇
内科学   1392篇
皮肤病学   215篇
神经病学   827篇
特种医学   371篇
外科学   908篇
综合类   37篇
一般理论   1篇
预防医学   529篇
眼科学   120篇
药学   541篇
中国医学   10篇
肿瘤学   594篇
  2023年   61篇
  2022年   81篇
  2021年   172篇
  2020年   129篇
  2019年   136篇
  2018年   166篇
  2017年   137篇
  2016年   201篇
  2015年   196篇
  2014年   263篇
  2013年   360篇
  2012年   532篇
  2011年   564篇
  2010年   354篇
  2009年   344篇
  2008年   496篇
  2007年   509篇
  2006年   432篇
  2005年   453篇
  2004年   439篇
  2003年   420篇
  2002年   392篇
  2001年   135篇
  2000年   104篇
  1999年   139篇
  1998年   107篇
  1997年   77篇
  1996年   52篇
  1995年   67篇
  1994年   50篇
  1993年   47篇
  1992年   99篇
  1991年   55篇
  1990年   67篇
  1989年   61篇
  1988年   39篇
  1987年   43篇
  1986年   44篇
  1985年   54篇
  1984年   41篇
  1983年   26篇
  1982年   40篇
  1981年   22篇
  1978年   34篇
  1977年   27篇
  1976年   28篇
  1974年   25篇
  1973年   21篇
  1972年   32篇
  1971年   29篇
排序方式: 共有8734条查询结果,搜索用时 15 毫秒
991.
992.
993.
Novel orthobunyavirus in Cattle, Europe, 2011   总被引:4,自引:0,他引:4  
In 2011, an unidentified disease in cattle was reported in Germany and the Netherlands. Clinical signs included fever, decreased milk production, and diarrhea. Metagenomic analysis identified a novel orthobunyavirus, which subsequently was isolated from blood of affected animals. Surveillance was initiated to test malformed newborn animals in the affected region.  相似文献   
994.
995.
996.
997.
If CC chemokine receptor 5 (CCR5)-dependent mechanisms at the time of initial virus exposure are important determinants of virus entry and disease outcome, then the polymorphisms in CCR5 that influence risk of transmission and disease progression should be similar; this hypothesis was tested in a cohort of 649 Argentinean children exposed perinatally to human immunodeficiency virus type 1 (HIV-1). Two lines of evidence support this hypothesis. First, CCR5 haplotype pairs associated with enhanced risk of transmission were the chief predictors of a faster disease course. Second, some of the haplotype pairs associated with altered rates of transmission and disease progression in children were similar to those that we previously found influenced outcome in European American adults. This concordance suggests that CCR5 haplotypes may serve as genetic rheostats that influence events occurring shortly after initial virus exposure, dictating not only virus entry but, by extension, also the extent of early viral replication.  相似文献   
998.
Summary UDP-glucuronosyltransferase (UDPGT) was studied immunohistochemically in hepatic foci and nodules of N-nitrosomorpholine-treated mice. Serial sections were stained for glucose-6-phosphatase (G6Pase). It was found that a high percentage of G6Pase-negative liver foci and nodules were also UDPGT-negative (34%). In addition, G6Pase-negative foci without altered UDPGT phenotype (30%) and UDPGT-negative foci without altered G6Pase phenotype (8%) were detected. G6Pase-positive foci were also present (24%). Interestingly, most G6Pasepositive foci were UDPGT-positive (16%). Some G6Pase-positive lesions without altered UDPGT phenotype were also found (8%). The major phenotype observed in rat hepatocarcinogenesis models (UDPGT-positive/G6Pase-negative foci) was not detectable in the mouse model. These results demonstrate heterogeneous alterations of UDPGTs in mouse hepatic foci. They furthermore suggest marked differences between the mouse and the rat in the regulation of UDPGTs in similarly induced rat hepatic foci.Abbreviations UDPGT UDP-glucuronosyltransferase - G6Pase glucose-6-phosphatase Dedicated to Professor Dr. med. Dr. med. h.c. Herbert Remmer on the occasion of his 70th birthday  相似文献   
999.
1000.
The inward rectifier K+ current (K(ir)) determines the resting membrane potential of endothelial cells. Basic fibroblast growth factor (bFGF) has been shown to activate K(ir) and acts as angiogenic factor and vasodilator. In contrast, nicotine has been demonstrated to reduce endothelium-dependent vasorelaxation by increasing radical formation. Aim of the present study was to investigate whether nicotine modulates K(ir) and if this plays a role in bFGF-mediated proliferation, migration and nitric oxide (NO)-formation of endothelial cells. Using the patch-clamp technique in cultured endothelial cells of human umbilical cord veins (HUVEC), we found characteristic K(ir), which were blocked by extracellular barium (100 micromol/l). Perfusion with nicotine (1 nmol/l-10 micromol/l) revealed a dose-dependent reduction of K(ir). The simultaneous perfusion with bFGF (50 ng/ml) and nicotine (10 micromol/l) still significantly reduced K(ir) (n = 8; P < 0.01). Cell counts revealed that bFGF-mediated proliferation of HUVEC was significantly inhibited when using 1-10 micromol/l nicotine (n = 8, P < 0.01). The bFGF-induced endothelial cell migration--examined using the "Fences-Migration-Assay"--was significantly reduced by 10 mumol/l nicotine (n = 12; P < 0.05). NO-production was examined using a cGMP-Radioimmunoassay. The significant bFGF-induced increase of cGMP-levels was reduced by nicotine (n = 10; P < 0.05). Our data indicate that the modulation of K(ir) seems to be an essential pathway in the antagonistic effects of nicotine on bFGF-mediated endothelial cell growth, migration and NO-formation.  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