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   199911篇
  免费   4394篇
  国内免费   473篇
耳鼻咽喉   2823篇
儿科学   7523篇
妇产科学   5946篇
基础医学   25917篇
口腔科学   6075篇
临床医学   15629篇
内科学   36194篇
皮肤病学   4877篇
神经病学   12302篇
特种医学   10953篇
外国民族医学   97篇
外科学   29848篇
综合类   1109篇
一般理论   1篇
预防医学   16429篇
眼科学   4383篇
药学   13792篇
  2篇
中国医学   141篇
肿瘤学   10737篇
  2018年   3607篇
  2017年   3962篇
  2016年   3314篇
  2015年   4993篇
  2014年   4457篇
  2013年   3608篇
  2012年   10221篇
  2011年   5098篇
  2010年   2450篇
  2009年   4090篇
  2008年   2483篇
  2007年   3191篇
  2006年   3446篇
  2005年   11541篇
  2004年   12939篇
  2003年   8495篇
  2002年   3739篇
  2001年   4394篇
  2000年   1720篇
  1999年   5898篇
  1998年   600篇
  1995年   416篇
  1992年   6871篇
  1991年   7113篇
  1990年   7352篇
  1989年   6947篇
  1988年   6475篇
  1987年   6239篇
  1986年   5952篇
  1985年   5242篇
  1984年   3603篇
  1983年   2917篇
  1982年   1014篇
  1981年   776篇
  1980年   849篇
  1979年   3841篇
  1978年   2372篇
  1977年   1791篇
  1976年   1570篇
  1975年   2479篇
  1974年   3113篇
  1973年   2747篇
  1972年   2759篇
  1971年   2747篇
  1970年   2559篇
  1969年   2474篇
  1968年   2239篇
  1967年   2167篇
  1966年   1903篇
  1965年   1140篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
The prevalence of bronchial hyperresponsiveness (BHR) to methacholine inhalation in a consecutive series of 21 patients with primary Sjögren''s syndrome was studied prospectively. Slight to severe BHR was seen in 12/20 (60%) of the patients. Ten of 12 patients with BHR (83%) had a non-productive cough, wheezing, or intermittent breathlessness. Bronchial hyperresponsiveness was more common in patients with extraglandular symptoms (10/14, 71%) than in those with only glandular symptoms (29%). Spirometrically 29% (6/21) of the patients had ''small airways'' disease'', and all those had BHR. Of 6/21 (29%) who had diffuse interstitial lung disease, two had BHR. Three of the four patients with obstructive lung function were challenged with methacholine and two of them had BHR. Only two patients with BHR had normal spirometry findings. The data showed that respiratory disease--mostly mild or moderate but even severe bronchial hyperresponsiveness--is commonly seen in patients with primary Sjögren''s syndrome.  相似文献   
992.
A symmetrical view of the T-cell receptor-CD3 complex.   总被引:1,自引:0,他引:1  
  相似文献   
993.
Segmental aortic wall stiffness was calculated from intravascular ultrasound images and intravascular pressures in six pigs at normal and subnormal aortic pressures (21 sequences of pressures and areas before and after boli of intravenous nitroglycerin). The wall stiffness was expressed as the pressure-strain elastic modulus (Ep). The Ep was calculated from the formula: Ep = delta PR delta R-1 (P, pressure; R, radius) in two different ways. First from maximal and minimal values of pressure and area. Second as the slope of linear regression line of delta PR as a function of delta R from 29 simultaneous recorded pressures and images. The average Ep value for all sequences in the different segments was 0.58 +/- 0.55 10(5) Pa (Method 1) and 0.50 +/- 0.40 10(5) Pa (Method 2). Ep increased with the distance from the heart at normal aortic pressures. At subnormal aortic pressures after intravenous nitroglycerin this relationship was not so evident. At subnormal aortic pressures the calculated Ep values were significantly reduced in the lower half of the abdominal aorta. The phase lag, i.e. hysteresis, between pressure and diameter was demonstrated. Our study shows the applicability of intravascular ultrasound as a tool to evaluate arterial wall stiffness.  相似文献   
994.
Concentration and metabolic replacement (turnover) rate of glucose and ketone bodies were determined at intervals during a 52 day postweaning fast in five grey seal (Halichoerus grypus) pups, using bolus injections of radiotracers. Blood glucose was maintained at a high level throughout the fast, while beta-hydroxybutyrate increased 26 times from day 3 to day 37, whereafter it by and large was maintained. Glucose replacement rate decreased to 56% of the day 9 value at day 37 and dropped further to only 32% of the day 9 level at day 52 in two seals, while in another 2 seals it increased at this late stage. The average ketone body replacement rate ranged between 8.6 and 13.8 mumols min-1 kg-1, but did not change significantly (P greater than 0.05) during the fasting period. These results suggest a reduced gluconeogenesis from protein and increased production of ketone bodies, which may in part replace glucose as energy source during fasting.  相似文献   
995.
Interindividual variability of lung function responses to smoking is unexplained. The aim of the present study is to inquire about a possible role of personality factors for an explanation of interindividual differences of lung function responses in smokers of both sexes. The results of canonical correlation analyses showed that there are no substantial correlations of personality with smoking behavior and also no significant associations of smoking behavior with pulmonary function in a healthy sample of smokers. In males only, personality factors were related to breathing frequency, but not to static and dynamic lung volumes.  相似文献   
996.
997.
998.
999.
1000.
Amorphin--24-vicyanoside (C34H4O16(2)H2O)--in a dose of 10 mg/kg orally decreases the content of cholesterol, total lipids, atherogenic lipoproteids in the blood and organs of intact rats and rats with endogenous or ethanol hyperlipemia, inhibits the development of experimental atherosclerosis in rabbits induced by the combination of risk factors (cholesterol + glucose + hypodynamia), decreases the content of lipids in the blood and organs (especially in aorta), prevents the development of morphological manifestations of the aorta atherosclerosis.  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