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   1140445篇
  免费   73005篇
  国内免费   1768篇
耳鼻咽喉   14802篇
儿科学   37410篇
妇产科学   28760篇
基础医学   181715篇
口腔科学   30520篇
临床医学   102572篇
内科学   215092篇
皮肤病学   25737篇
神经病学   79431篇
特种医学   42223篇
外国民族医学   126篇
外科学   169566篇
综合类   21626篇
现状与发展   3篇
一般理论   251篇
预防医学   83230篇
眼科学   26410篇
药学   86689篇
  4篇
中国医学   3244篇
肿瘤学   65807篇
  2021年   8658篇
  2018年   12562篇
  2017年   9481篇
  2016年   10732篇
  2015年   11987篇
  2014年   16216篇
  2013年   24320篇
  2012年   33552篇
  2011年   35972篇
  2010年   21028篇
  2009年   19474篇
  2008年   33157篇
  2007年   36010篇
  2006年   35920篇
  2005年   33932篇
  2004年   33035篇
  2003年   31633篇
  2002年   30695篇
  2001年   54892篇
  2000年   55784篇
  1999年   46147篇
  1998年   12256篇
  1997年   10360篇
  1996年   10649篇
  1995年   10030篇
  1994年   9172篇
  1992年   34737篇
  1991年   35351篇
  1990年   34688篇
  1989年   34324篇
  1988年   31286篇
  1987年   30662篇
  1986年   28901篇
  1985年   27372篇
  1984年   20213篇
  1983年   17182篇
  1982年   9365篇
  1979年   18806篇
  1978年   13255篇
  1977年   10941篇
  1976年   10946篇
  1975年   12542篇
  1974年   14479篇
  1973年   13940篇
  1972年   13009篇
  1971年   12307篇
  1970年   11765篇
  1969年   10880篇
  1968年   10123篇
  1967年   9022篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
Case report 506   总被引:1,自引:0,他引:1  
  相似文献   
74.
Electrocardiographic symptoms were evaluated in 53 patients with an additional left-ventricular chorda (ALVC), detected by two-dimensional echocardiography. Signs of early ventricular repolarization (EVR) were identified in 45 (84.9%) patients. A transverse ALVC was more common in EVR-free patients (87.5%), as compared to patients with ALVC + EVR combinations (51.1%; p less than 0.05).  相似文献   
75.
In the isolated perfused rat pancreas, D,L-difluoromethylornithine, tested at a concentration of 3 mmol/L, failed to affect the release of glucagon and insulin caused, over 15 min stimulation, by either L-arginine or L-ornithine (2.0, 5.0 or 10.0 mmol/L) in the presence of either 3.3 or 5.6 mmol/L D-glucose. The inhibition of ornithine decarboxylase also failed to affect the release of glucagon provoked by either L-leucine (2 or 3 mmol/L) or L-glutamine (2 mmol/L) and the secretion of insulin stimulated by a rise in glucose concentration from 5.6 to 10.6 mmol/L. These data are interpreted to suggest that the rapid generation of polyamines from either L-arginine or L-ornithine does not play any significant role in the immediate glucagonotropic and insulinotropic action of these cationic amino acids.  相似文献   
76.
Eighty-nine cases of chronic bronchitis were matched against167 asymptomatic controls from the glass bangle industry ofFirozabad. Factors of age, social status, smoking habit andduration of exposure were studied. Duration of exposure wasfound to be a factor contributing significantly to the causationof disease. Requests for reprints should be addressed to: Dr B. N. Gupta, Division of Epidemilogy, Industrial Toxicology Research Centre, Mahatma Gandhi Marg, Lucknow P.O. Box 80, 226001, India  相似文献   
77.
78.
. Neutrophil-mediated tissue damage has been implicated in the pathogenesis of diarrhoea-associated haemolytic uraemic syndrome (D+ HUS). This study evaluates priming and activation of the neutrophil oxidative burst in D+ HUS using chemiluminescent techniques. Peripheral blood neutrophils from 11 children with acute D+ HUS were examined. No difference was found in the oxidative burst of neutrophils from patients and controls. Serum elastase levels were measured in 8 patients and found to be significantly elevated. Although elastase results suggest neutrophil activation, chemiluminescence studies do not confirm this in the peripheral blood neutrophil. This does not support a significant role for circulating agents in priming and activating the peripheral blood neutrophil. Received August 17, 1995; received in revised form and accepted November 27, 1995  相似文献   
79.
The role of caffeine or coffee in causing or promoting the incidence of serious disease is equivocal. Two design factors may account for the discrepancies in reported findings on the effects of coffee drinking: (a) imprecision of measurement and (b) confounding variables. A study of 2,714 white U.S. adults disclosed that, of 32 risk factors analyzed by linear and logistic regression, only sex and cigarette smoking were found to be important potential confounders of caffeine and coffee intake. Partial R2 values of the other 30 risk factors were relatively small and were inconsistent for each sex. It is unlikely that any of these factors could explain any of the reported associations between caffeine or coffee consumption and certain diseases. However, certain weak associations with caffeine or coffee intake should be included in the study design when they are known to be risk factors of a disease under investigation. These factors for men are dietary fat intake, vitamin C intake, and body mass index; and for women are vitamin use, alcohol intake, stress, and perceived health status.  相似文献   
80.
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