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   1840328篇
  免费   133933篇
  国内免费   3144篇
耳鼻咽喉   25939篇
儿科学   61260篇
妇产科学   52210篇
基础医学   272978篇
口腔科学   52046篇
临床医学   160091篇
内科学   357308篇
皮肤病学   39763篇
神经病学   139305篇
特种医学   70676篇
外国民族医学   429篇
外科学   281617篇
综合类   39061篇
现状与发展   3篇
一般理论   436篇
预防医学   135009篇
眼科学   42514篇
药学   140334篇
  4篇
中国医学   4496篇
肿瘤学   101926篇
  2018年   18150篇
  2016年   15569篇
  2015年   17740篇
  2014年   24445篇
  2013年   37028篇
  2012年   50174篇
  2011年   53336篇
  2010年   31530篇
  2009年   29680篇
  2008年   50959篇
  2007年   54948篇
  2006年   56032篇
  2005年   53951篇
  2004年   52328篇
  2003年   50526篇
  2002年   49446篇
  2001年   86464篇
  2000年   88484篇
  1999年   74396篇
  1998年   20634篇
  1997年   18138篇
  1996年   18560篇
  1995年   17526篇
  1994年   16591篇
  1993年   15244篇
  1992年   59231篇
  1991年   58319篇
  1990年   57345篇
  1989年   56125篇
  1988年   52065篇
  1987年   50640篇
  1986年   48352篇
  1985年   45876篇
  1984年   34117篇
  1983年   29398篇
  1982年   17060篇
  1981年   15126篇
  1979年   31906篇
  1978年   22405篇
  1977年   19327篇
  1976年   18265篇
  1975年   20110篇
  1974年   23664篇
  1973年   22737篇
  1972年   21549篇
  1971年   20112篇
  1970年   18986篇
  1969年   18017篇
  1968年   16832篇
  1967年   14843篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
91.
Aging alters bladder functions where a decrease in filling, storage and emptying is observed. These changes cause urinary incontinence, especially in women. The aim of this study is to examine how aging affects the intracellular calcium movements due to agonist-induced contractions in permeabilized female rat bladder. Urinary bladder isolated from young and old female Sprague-Dawley rats were used. Small detrusor strips were permeabilized with β-escin. The contractile responses induced with agonists were compared between young and old groups. Carbachol-induced contractions were decreased in permeabilized detrusor from old rats compared to young group. Heparin and ryanodine decreased carbachol-induced contractions in young rats where only heparin inhibited these contractions in olds. Caffeine-induced contractions but not inositol triphosphate (IP3)-induced contractions were decreased in old group compared to youngs. The cumulative calcium response curves (pCa 8–4) were also decreased in old rats. Carbachol-induced calcium sensitization responses did not alter by age where GTP-β-S and GF-109203X but not Y-27632 inhibited these responses. Carbachol-induced contractions decrease with aging in rat bladder detrusor. It can be postulated as IP3-induced calcium release (IICR) is primarily responsible for the contractions in older rats where the decrease in carbachol contractions in aging may be as a result of a decrease in calcium-induced calcium release (CICR), rather than carbachol-induced calcium sensitization.  相似文献   
92.
The aim of the present study was to evaluate the antimicrobial activity of two synbiotic combinations, Lactobacillus fermentum with short-chain fructooligosaccharides (FOS-LF) and Bifidobacterium longum with isomaltooligosaccharides (IMO-BL), against enterohaemorrhagic Escherichia coli O157:H7 and enteropathogenic E. coli O86. Antimicrobial activity was determined (1) by co-culturing the synbiotics and pathogens in batch cultures, and (2) with the three-stage continuous culture system (gut model), inoculated with faecal slurry from an elderly donor. In the co-culture experiments, IMO-BL was significantly inhibitory to both E. coli strains, while FOS-LF was slightly inhibitory or not inhibitory. Factors other than acid production appeared to play a role in the inhibition. In the gut models, both synbiotics effectively inhibited E. coli O157 in the first vessel, but not in vessels 2 and 3. E. coli O86 was not significantly inhibited.  相似文献   
93.
94.
Farnesyltransferase (FTase) is one of the prenyltransferase family enzymes that catalyse the transfer of 15-membered isoprenoid (farnesyl) moiety to the cysteine of CAAX motif-containing proteins including Rho and Ras family of G proteins. Inhibitors of FTase act as drugs for cancer, malaria, progeria and other diseases. In the present investigation, we have developed two structure-based pharmacophore models from protein–ligand complex (3E33 and 3E37) obtained from the protein data bank. Molecular dynamics (MD) simulations were performed on the complexes, and different conformers of the same complex were generated. These conformers were undergone protein–ligand interaction fingerprint (PLIF) analysis, and the fingerprint bits have been used for structure-based pharmacophore model development. The PLIF results showed that Lys164, Tyr166, TrpB106 and TyrB361 are the major interacting residues in both the complexes. The RMSD and RMSF analyses on the MD-simulated systems showed that the absence of FPP in the complex 3E37 has significant effect in the conformational changes of the ligands. During this conformational change, some interactions between the protein and the ligands are lost, but regained after some simulations (after 2 ns). The structure-based pharmacophore models showed that the hydrophobic and acceptor contours are predominantly present in the models. The pharmacophore models were validated using reference compounds, which significantly identified as HITs with smaller RMSD values. The developed structure-based pharmacophore models are significant, and the methodology used in this study is novel from the existing methods (the original X-ray crystallographic coordination of the ligands is used for the model building). In our study, along with the original coordination of the ligand, different conformers of the same complex (protein–ligand) are used. It concluded that the developed methodology is significant for the virtual screening of novel molecules on different targets.  相似文献   
95.
96.

Background

Arterial vascular anomalies in patients undergoing kidney transplantation (KT) are correlated with a higher incidence of early surgical complications, potentially causing graft loss. Arterial reconstruction allows patients to overcome these surgical challenges, thus minimizing the risk of poor outcomes. The aim of the present study is to retrospectively investigate the safety and effectiveness of the multiple arterial reconstruction technique with a Teflon patch in case of an unavailable aortic patch: to do so, surgical complications, graft function, and patient survival were evaluated.

Methods

During the period January 2009 to August 2016, 202 adult deceased-donor KTs were performed at our center. Group A (n = 27; reconstruction of multiple arteries) and Group B (n = 175; control group) were compared.

Results

No differences were observed between the 2 groups in terms of early postoperative course, with no vascular complication observed in Group A. No vascular patch infections were reported, nor longer cold ischemia time rates. Similarly, long-term survival rates were similar between the 2 groups.

Conclusions

The Teflon-patch arterial reconstruction technique appears to be safe and effective, with an acceptable balance of benefits and potential risks of using a prosthetic material. Studies based on larger series are needed to further validate this approach.  相似文献   
97.
98.
99.
100.
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