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   2361889篇
  免费   172101篇
  国内免费   3375篇
耳鼻咽喉   32257篇
儿科学   76125篇
妇产科学   62797篇
基础医学   349621篇
口腔科学   63970篇
临床医学   212061篇
内科学   460470篇
皮肤病学   52131篇
神经病学   186015篇
特种医学   88495篇
外国民族医学   489篇
外科学   356026篇
综合类   47554篇
现状与发展   12篇
一般理论   851篇
预防医学   183039篇
眼科学   54435篇
药学   175814篇
  11篇
中国医学   4586篇
肿瘤学   130606篇
  2021年   19204篇
  2019年   19722篇
  2018年   27255篇
  2017年   20512篇
  2016年   22925篇
  2015年   25820篇
  2014年   36335篇
  2013年   54265篇
  2012年   75202篇
  2011年   79992篇
  2010年   47388篇
  2009年   44863篇
  2008年   75148篇
  2007年   80090篇
  2006年   80856篇
  2005年   78379篇
  2004年   74927篇
  2003年   72268篇
  2002年   69885篇
  2001年   109145篇
  2000年   111873篇
  1999年   93869篇
  1998年   27132篇
  1997年   23790篇
  1996年   24173篇
  1995年   22814篇
  1994年   20986篇
  1993年   19790篇
  1992年   72260篇
  1991年   70308篇
  1990年   68616篇
  1989年   65921篇
  1988年   60523篇
  1987年   59360篇
  1986年   55421篇
  1985年   53221篇
  1984年   39452篇
  1983年   33514篇
  1982年   19926篇
  1979年   35973篇
  1978年   25706篇
  1977年   21274篇
  1976年   20382篇
  1975年   21874篇
  1974年   26211篇
  1973年   24866篇
  1972年   23256篇
  1971年   22081篇
  1970年   20286篇
  1969年   19354篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
BackgroundHepatopancreatobiliary (HPB) surgery fellowship training has multiple paths. Prospective trainees and employers must understand the differences between training pathways. This study examines self-reported fellowship experiences and current scope of practice across three pathways.MethodsAn online survey was disseminated to 654 surgeons. These included active Americas Hepato-Pancreato-Biliary Association (AHPBA) members and recent graduates of HPB, transplant–HPB and HPB–heavy surgical oncology fellowships.ResultsA total of 416 (64%) surgeons responded. Most respondents were male (89%) and most were practising in an academic setting (83%). 290 (70%) respondents underwent formal fellowship training. Although fellowship experiences varied, current practice was largely similar. Minimally invasive surgery (MIS) and ultrasound were the most commonly identified areas of training deficiencies and were, respectively, cited as such by 47% and 34% of HPB-, 49% and 50% of transplant-, and 52% and 25% of surgical oncology-trained respondents. Non-HPB cases performed in current practice included gastrointestinal (GI) and general surgery cases (56% and 49%, respectively) for HPB-trained respondents, transplant and general surgery cases (87% and 21%, respectively) for transplant-trained respondents, and GI surgery and non-HPB surgical oncology cases (70% and 28%, respectively) for surgical oncology-trained respondents.ConclusionsFellowship training in HPB surgery varies by training pathway. Training in MIS and ultrasound is deficient in each pathway. The ultimate scope of non-transplant HPB practice appears similar across training pathways. Thus, training pathway choice is best guided by the training experience desired and non-HPB components of anticipated practice.  相似文献   
83.
84.
85.
86.
The hepatitis C virus (HCV) is a pandemic human pathogen posing a substantial health and economic burden in both developing and developed countries. Controlling the spread of HCV through behavioural prevention strategies has met with limited success and vaccine development remains slow. The development of antiviral therapeutic agents has also been challenging, primarily due to the lack of efficient cell culture and animal models for all HCV genotypes, as well as the large genetic diversity between HCV strains. On the other hand, the use of interferon-α-based treatments in combination with the guanosine analogue, ribavirin, achieved limited success, and widespread use of these therapies has been hampered by prevalent side effects. For more than a decade, the HCV RNA-dependent RNA polymerase (RdRp) has been targeted for antiviral development. Direct acting antivirals (DAA) have been identified which bind to one of at least six RdRp inhibitor-binding sites, and are now becoming a mainstay of highly effective and well tolerated antiviral treatment for HCV infection. Here we review the different classes of RdRp inhibitors and their mode of action against HCV. Furthermore, the mechanism of antiviral resistance to each class is described, including naturally occurring resistance-associated variants (RAVs) in different viral strains and genotypes. Finally, we review the impact of these RAVs on treatment outcomes with the newly developed regimens.  相似文献   
87.
88.
89.
Abstract

This study was undertaken to compare the concentrations of pro- and anti-angiogenic growth factors, nitric oxide (NO) stable metabolites in maternal serum and embryonic left ventricular (LV) isovolumic relaxation time (IRT, ms) during the first trimester in two groups of women: with pregnancy conceived by assisted reproductive technologies (ART, n?=?39) and normally conceived (control group, n?=?68) pregnancy. The concentration of vasoconstrictor endothelin 1 was 45.5 times more in ART than in control group. On the contrary, the concentrations of NO stable metabolites in ART were 1.9 times less than in control women. The assessment of angiogenic suppressors in ART women demonstrates the decrease in s-endoglin concentration was 1.6 times and in soluble receptor to vascular endothelial growth factor concentration was 2.0 times in comparison with control group. There was a significant increase in LV IRT in ART embryos in comparison to control ones. These data suggest significant changes in pro- anti-angiogenic factors balance and increase in vascular impedance in ART-conceived embryos.  相似文献   
90.
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