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   2771828篇
  免费   194617篇
  国内免费   7736篇
耳鼻咽喉   37326篇
儿科学   91956篇
妇产科学   77004篇
基础医学   391357篇
口腔科学   74919篇
临床医学   250042篇
内科学   547603篇
皮肤病学   66510篇
神经病学   226428篇
特种医学   106951篇
外国民族医学   768篇
外科学   415298篇
综合类   55665篇
现状与发展   6篇
一般理论   1098篇
预防医学   209527篇
眼科学   61524篇
药学   201426篇
  8篇
中国医学   5801篇
肿瘤学   152964篇
  2019年   21953篇
  2018年   31339篇
  2017年   24054篇
  2016年   27940篇
  2015年   31435篇
  2014年   43076篇
  2013年   64798篇
  2012年   85469篇
  2011年   90061篇
  2010年   54715篇
  2009年   52384篇
  2008年   84080篇
  2007年   89439篇
  2006年   91134篇
  2005年   87051篇
  2004年   83901篇
  2003年   80979篇
  2002年   77963篇
  2001年   135228篇
  2000年   138406篇
  1999年   116492篇
  1998年   33007篇
  1997年   29513篇
  1996年   29700篇
  1995年   28790篇
  1994年   26407篇
  1993年   24709篇
  1992年   89901篇
  1991年   86502篇
  1990年   83755篇
  1989年   80952篇
  1988年   74054篇
  1987年   72429篇
  1986年   67762篇
  1985年   64664篇
  1984年   48028篇
  1983年   40598篇
  1982年   24117篇
  1981年   21386篇
  1979年   42079篇
  1978年   29706篇
  1977年   25222篇
  1976年   23246篇
  1975年   24865篇
  1974年   29283篇
  1973年   27922篇
  1972年   26177篇
  1971年   24203篇
  1970年   22370篇
  1969年   21432篇
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
11.
12.
13.
14.
15.
Sinus venosus atrial septal defect (SV‐ASD) usually coexists with partial anomalous pulmonary vein connection (PAPVC). It is a difficult diagnosis in transthoracic echocardiography (TTE) due to eccentric position of defects. We present a rare case of atypical anatomical variation in PAPVC, which was never described before. Two right pulmonary veins drained into superior vena cava, which overrode SV‐ASD and interatrial septum, a third pulmonary vein into the right atrium. Complete diagnosis could not be set after TTE, nor transesophageal echocardiography, whereas angio‐CT was finally conclusive. This diagnostic approach allowed the surgical planning.  相似文献   
16.
17.
In the current immunosuppressive therapy era, vessel thrombosis is the most common cause of early graft loss after renal transplantation. The prevalence of IgA anti–β2-glycoprotein I antibodies (IgA-aB2GPI-ab) in patients on dialysis is elevated (>30%), and these antibodies correlate with mortality and cardiovascular morbidity. To evaluate the effect of IgA-aB2GPI-ab in patients with transplants, we followed all patients transplanted from 2000 to 2002 in the Hospital 12 de Octubre prospectively for 10 years. Presence of IgA-aB2GPI-ab in pretransplant serum was examined retrospectively. Of 269 patients, 89 patients were positive for IgA-aB2GPI-ab (33%; group 1), and the remaining patients were negative (67%; group 2). Graft loss at 6 months post-transplant was significantly higher in group 1 (10 of 89 versus 3 of 180 patients in group 2; P=0.002). The most frequent cause of graft loss was thrombosis of the vessels, which was observed only in group 1 (8 of 10 versus 0 of 3 patients in group 2; P=0.04). Multivariate analysis showed that the presence of IgA-aB2GPI-ab was an independent risk factor for early graft loss (P=0.04) and delayed graft function (P=0.04). There were no significant differences regarding patient survival between the two groups. Graft survival was similar in both groups after 6 months. In conclusion, patients with pretransplant IgA-aB2GPI-ab have a high risk of early graft loss caused by thrombosis and a high risk of delayed graft function. Therefore, pretransplant IgA-aB2GPI-ab may have a detrimental effect on early clinical outcomes after renal transplantation.  相似文献   
18.
Animal and human studies suggest fish oil and green tea may have protective effect on prostate cancer. Fatty acid synthase (FAS) has been hypothesized to be linked to chemoprotective effects of both compounds. This study evaluated the independent and joint effects of fish oil (FO) and green tea supplement (epigallocatechin-3-gallate, EGCG) on FAS and Ki-67 levels in prostate tissue. Through a double-blinded, randomized controlled trial with 2 × 2 factorial design, 89 men scheduled for repeat prostate biopsy following an initial negative prostate biopsy were randomized into either FO alone (1.9 g DHA + EPA/day), EGCG alone (600 mg/day), a combination of FO and EGCG, or placebo. We used linear mixed-effects models to test the differences of prostate tissue FAS and Ki-67 by immunohistochemistry between pre- and post-intervention within each group, as well as between treatment groups. Results did not show significant difference among treatment groups in pre-to-post-intervention changes of FAS (P = 0.69) or Ki-67 (P = 0.26). Comparing placebo group with any of the treatment groups, we did not find significant difference in FAS or Ki-67 changes (all P > 0.05). Results indicate FO or EGCG supplementation for a short duration may not be sufficient to produce biologically meaningful changes in FAS or Ki-67 levels in prostate tissue.  相似文献   
19.
20.
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