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   204216篇
  免费   8829篇
  国内免费   500篇
耳鼻咽喉   3408篇
儿科学   7319篇
妇产科学   5225篇
基础医学   27443篇
口腔科学   5840篇
临床医学   15716篇
内科学   38351篇
皮肤病学   5254篇
神经病学   17714篇
特种医学   9952篇
外国民族医学   28篇
外科学   34414篇
综合类   1917篇
现状与发展   3篇
一般理论   63篇
预防医学   10404篇
眼科学   5881篇
药学   14480篇
  1篇
中国医学   607篇
肿瘤学   9525篇
  2023年   1131篇
  2022年   1512篇
  2021年   2797篇
  2020年   2052篇
  2019年   2490篇
  2018年   4328篇
  2017年   3404篇
  2016年   4402篇
  2015年   4876篇
  2014年   5378篇
  2013年   7263篇
  2012年   11177篇
  2011年   10511篇
  2010年   6151篇
  2009年   5045篇
  2008年   9701篇
  2007年   10607篇
  2006年   10366篇
  2005年   10534篇
  2004年   9952篇
  2003年   9634篇
  2002年   9325篇
  2001年   6519篇
  2000年   6536篇
  1999年   5664篇
  1998年   1749篇
  1997年   1421篇
  1996年   1117篇
  1995年   898篇
  1994年   834篇
  1992年   2529篇
  1991年   2470篇
  1990年   2394篇
  1989年   2241篇
  1988年   1955篇
  1987年   1939篇
  1986年   1790篇
  1985年   1754篇
  1984年   1356篇
  1983年   1073篇
  1979年   1425篇
  1978年   1046篇
  1977年   882篇
  1975年   1113篇
  1974年   1148篇
  1973年   1049篇
  1972年   1048篇
  1971年   1010篇
  1970年   897篇
  1969年   835篇
排序方式: 共有10000条查询结果,搜索用时 644 毫秒
21.
22.
23.

Objective

Arch obstruction after the Norwood procedure is common and contributes to mortality. We determined the prevalence, associated factors, and practice variability of arch reintervention and assessed whether arch reintervention is associated with mortality.

Methods

From 2005 to 2017, 593 neonates in the Congenital Heart Surgeons' Society Critical Left Heart Obstruction cohort underwent a Norwood procedure. Median follow-up was 3.7 years. Multivariable parametric models, including a modulated renewal analysis, were performed.

Results

Of the 593 neonates, 146 (25%) underwent 218 reinterventions for arch obstruction after the Norwood procedure: catheter-based (n = 168) or surgical (n = 50) at a median age of 4.3 months (quartile 1-quartile 3, 2.6-5.7). Interdigitation of the distal aortic anastomosis was protective against arch reintervention. Development of ≥ moderate tricuspid valve regurgitation and right ventricular dysfunction at any point was associated with arch reintervention. Nonsignificant variables for arch reintervention included shunt type and preoperative aortic measurements. Surgical arch reintervention was protective against arch reintervention, but transcatheter reintervention was associated with increased reintervention. Arch reintervention was not associated with increased mortality. There was wide institutional variation in incidence of arch reintervention (range, 0-40 reinterventions per 100 years patient follow-up) and in preintervention gradient (range, 0-64 mm Hg).

Conclusions

Interdigitation of the distal aortic anastomosis during the Norwood procedure decreased the risk of arch reintervention. Surgical arch reintervention is more definitive than transcatheter. Arch reintervention after the Norwood procedure is not associated with increased mortality. Serial surveillance for arch obstruction, integrated with changes in right ventricular function and tricuspid valve regurgitation, is recommended after the Norwood procedure to improve outcomes.  相似文献   
24.
25.
26.
27.
The present investigation was aimed at studying the possible role of curcumin against N-nitrosodiethylamine (NDEA)-induced toxicity in albino rats. Administration of NDEA to rats at a concentration of 0.1 mg/ml in drinking water ad libitum for 21 days produced toxicity in them, which was evident from histopathological changes in the rat livers, and increased levels of blood serum enzyme markers, i.e. aspartate transaminase, alanine transaminase, alkaline phosphatase, and lactate dehydrogenase. In addition, the levels of oxidative stress markers like lipid peroxidation (LPO), protein carbonyl (PCC), and glutathione-S-transferase (GST) activity were elevated and the total glutathione (GSH) content was reduced in the livers. The administration of curcumin to rats at concentrations of 10, 20, and 40 mg/ml in drinking water along with 0.1 mg/ml of NDEA for 21 days effectively suppressed NDEA-induced toxicity and also resulted in a dose-dependent reduction in the levels of blood serum enzyme markers (AST, ALT, ALP, and LDH). Moreover, LPO, PCC, and GST activity were reduced and the GSH level was increased upon the administration of curcumin along with NDEA. The results obtained for the comet assay in rat hepatocytes and blood lymphocytes showed a significant dose-dependent decrease in the mean tail length. The micronucleus assay performed on rat hepatocytes also showed a dose-dependent reduction in the frequency of micronucleated cells along with curcumin administration. These results suggest that curcumin has a protective role against NDEA-induced toxicity in albino rats.  相似文献   
28.
29.
30.
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