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   232146篇
  免费   48474篇
  国内免费   1206篇
耳鼻咽喉   3562篇
儿科学   6985篇
妇产科学   4205篇
基础医学   38389篇
口腔科学   8060篇
临床医学   26955篇
内科学   51753篇
皮肤病学   11318篇
神经病学   24645篇
特种医学   10056篇
外科学   34278篇
综合类   2167篇
现状与发展   5篇
一般理论   101篇
预防医学   13614篇
眼科学   5455篇
药学   18658篇
  38篇
中国医学   2405篇
肿瘤学   19177篇
  2024年   338篇
  2023年   1166篇
  2022年   2784篇
  2021年   6223篇
  2020年   8008篇
  2019年   13576篇
  2018年   13759篇
  2017年   13794篇
  2016年   15304篇
  2015年   16627篇
  2014年   17811篇
  2013年   19693篇
  2012年   16272篇
  2011年   15842篇
  2010年   15402篇
  2009年   10873篇
  2008年   11014篇
  2007年   9795篇
  2006年   9100篇
  2005年   8492篇
  2004年   7641篇
  2003年   6743篇
  2002年   6003篇
  2001年   5090篇
  2000年   4669篇
  1999年   3498篇
  1998年   1329篇
  1997年   999篇
  1996年   962篇
  1995年   870篇
  1994年   762篇
  1993年   651篇
  1992年   1586篇
  1991年   1579篇
  1990年   1358篇
  1989年   1241篇
  1988年   1159篇
  1987年   1033篇
  1986年   1012篇
  1985年   882篇
  1984年   645篇
  1983年   564篇
  1982年   401篇
  1981年   379篇
  1980年   340篇
  1979年   520篇
  1978年   409篇
  1977年   389篇
  1976年   345篇
  1974年   359篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
OBJECTIVE: Outcomes analysis in congenital diaphragmatic hernia (CDH) requires a validated risk-adjustment tool. The purpose of this study was to use the Canadian Neonatal Network (CNN) database to validate the Score for Neonatal Acute Physiology, Version II (SNAP-II) for prediction of mortality among CDH infants admitted to a neonatal intensive care unit (NICU), and to compare this to the predictive equation recently developed by the Congenital Diaphragmatic Hernia Study Group (CDHSG). STUDY DESIGN: Infants with CDH in the CNN database were identified. Bivariate and multivariable logistic regression models were used to identify risk factors predictive of mortality. Model predictive performance and calibration were assessed using the area under the receiver operator characteristic curve and the technique of Hosmer-Lemeshow, respectively, and compared with the CDHSG predictive equation. RESULTS: There were 88 patients with CDH among 19,507 admissions to CNN hospitals. The mortality rate among CDH patients surviving to NICU admission was 17%, and 12.5% received extracorporeal membrane oxygenation therapy. Gestational age and admission SNAP-II score predicted mortality. Model predictive performance and calibration were optimized with these variables combined. The CDHSG equation was equally predictive of mortality, but was only marginally calibrated. CONCLUSIONS: SNAP-II is highly predictive of mortality among patients with CDH, and can be used to risk-adjust these patients.  相似文献   
42.
43.
The authors compared children (ages 7-13 years) of unipolar depressed mothers with children of nondepressed psychiatric patients, of nondepressed medical patients, and of nondepressed mothers in the community. The children's adjustment was rated by clinicians on the Child Adjustment Schedule and by the mothers on the Child Behavior Checklist. The highest proportion of clinically significant problems was found in the children of the depressed mothers. However, the overlap between the problems of these children and those of the children of the nondepressed psychiatric patients calls into question the formulation that children's adjustment difficulties are specific to parental depression.  相似文献   
44.
Abstract: We have designed and synthesized a new series of azapeptides which act as potential inhibitors of cathepsin B and/or cathepsin K. Their structures are based upon the inhibitory sites of natural cysteine protease inhibitors, cystatins. For the synthesized azapeptides, the equilibrium constants for dissociation of inhibitor–enzyme complex, Ki, were determined. Comparison of these values indicated that all of the azainhibitors act much stronger toward cathepsin B. Z‐Arg‐Leu‐His‐Agly‐Ile‐Val‐OMe ( 7 ) proved to be approximately 500 times more potent for cathepsin B than for cathepsin K. To be able to explain the obtained experimental values we used the molecular dynamics procedures to analyze the interactions between cathepsin B and compound 7 . We also determined the structure of the most potent and selective cathepsin B azainhibitor by means of NMR studies and theoretical calculations. In this report, we describe SAR studies of azapeptide inhibitors indicating the influence of the conformational flexibility of the examined compounds on inhibition of cathepsins B and K.  相似文献   
45.
46.
Bradyarrhythmia requiring permanent pacing after heart transplantation remains a common problem. Sinus node dysfunction is the most common indication, and late onset of atrioventricular (AV) block has rarely been reported. We report the case of a patient who developed advanced AV block at 41 months after transplantation. Right bundle branch block with progressive increase of QRS complex duration was noted in serial electrocardiograms. At the time of late AV block development, the patient did not have acute rejection and coronary angiogram was normal. The mechanism of late onset of AV block is unclear, but it may be caused by progressive conduction.  相似文献   
47.
48.
49.
50.
Abstract – Traumatic dental injuries often occur to the teeth and their supporting tissues and they are the main reasons for emergency visit to a dental clinic. Management of a fracture depends on its position and the extent of root involvement. Horizontal root fractures are not seen frequently and the treatment consists of reduction and long‐term rigid fixation of the coronal segment. The present case demonstrates the successful management of two horizontally fractured maxillary central incisors with a follow‐up period of 9 months.  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