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   87691篇
  免费   41772篇
  国内免费   51篇
耳鼻咽喉   1640篇
儿科学   4479篇
妇产科学   741篇
基础医学   17108篇
口腔科学   6500篇
临床医学   12919篇
内科学   25146篇
皮肤病学   7711篇
神经病学   13948篇
特种医学   2350篇
外科学   14818篇
综合类   66篇
一般理论   24篇
预防医学   5505篇
眼科学   1533篇
药学   6452篇
中国医学   1156篇
肿瘤学   7418篇
  2023年   148篇
  2022年   319篇
  2021年   1733篇
  2020年   5312篇
  2019年   11165篇
  2018年   10511篇
  2017年   11712篇
  2016年   12395篇
  2015年   12337篇
  2014年   12343篇
  2013年   12892篇
  2012年   5074篇
  2011年   5070篇
  2010年   9453篇
  2009年   5697篇
  2008年   2763篇
  2007年   1555篇
  2006年   1460篇
  2005年   1144篇
  2004年   1184篇
  2003年   1054篇
  2002年   1027篇
  2001年   927篇
  2000年   813篇
  1999年   399篇
  1998年   101篇
  1997年   56篇
  1996年   51篇
  1995年   42篇
  1994年   35篇
  1993年   26篇
  1992年   63篇
  1991年   60篇
  1990年   58篇
  1989年   56篇
  1988年   56篇
  1987年   53篇
  1986年   42篇
  1985年   41篇
  1984年   22篇
  1983年   29篇
  1982年   15篇
  1981年   14篇
  1980年   14篇
  1976年   13篇
  1974年   17篇
  1973年   19篇
  1971年   13篇
  1969年   13篇
  1966年   14篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
1. alpha 2-Adrenoceptors on platelet membranes and beta 2-adrenoceptors on lymphocytes were studied in 24 patients with primary Raynaud's phenomenon and in 24 age- and sex-matched control subjects. In two subgroups, a standardized mental arithmetic test and a finger-cooling test were performed. 2. Baseline blood pressure, heart rate and forearm blood flow did not differ between the two groups. 3. Baseline skin microcirculation (laser Doppler flux) was decreased in primary Raynaud's phenomenon (19 +/- 15 arbitrary units) compared with control subjects (33 +/- 14 arbitrary units) (P less than 0.01). 4. Baseline plasma noradrenaline concentration (2.00 +/- 1.44 versus 1.16 +/- 0.36 nmol/l) and alpha 2-adrenoceptor density (301 +/- 119 versus 210 +/- 82 fmol/mg) were increased in patients with primary Raynaud's phenomenon in comparison with the control subjects. The alpha 2-adrenoceptor density/beta 2-adrenoceptor density ratio in patients with primary Raynaud's phenomenon was, with a value of 0.37 +/- 0.04, higher than in the control subjects, where a value of 0.25 +/- 0.02 was measured (P less than 0.001). Plasma adrenaline concentration, beta 2-adrenoceptor density and the antagonist affinity to both receptor subtypes did not differ between both groups under baseline conditions. 5. Whereas during the finger-cooling test no differences were seen in the responses of the parameters measured, the mental arithmetic test induced an increase in laser Doppler flux in patients with primary Raynaud's phenomenon and a decrease in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
32.
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   
33.
34.
1 The internal anal sphincter (IAS) has a spontaneous tone and is the main contributor to the maintenance of faecal continence. The spontaneous resting tone exhibited by the sphincter can be modified by neurotransmitters from the autonomic and enteric nervous systems. 2 In this review, the influence of the sympathetic and parasympathetic nervous systems on IAS tone are discussed and the putative roles of nitric oxide, carbon monoxide, vasoactive intestinal peptide and adenosine triphosphate in non‐adrenergic non‐cholinergic transmission are considered. 3 Faecal incontinence is a common condition that places a heavy financial burden on the health service and severely affects patients’ quality of life. Resting anal pressure is reduced in patients with faecal incontinence and agents that increase sphincter tone tend to relieve symptoms. The results of clinical studies of the use of phenylephrine to treat faecal incontinence are reviewed. 4 It is concluded that the IAS is a potential target for drug development for the treatment of faecal incontinence.  相似文献   
35.
36.
37.
38.
39.
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   
40.
Selecting an appropriate working correlation structure is pertinent to clustered data analysis using generalized estimating equations (GEE) because an inappropriate choice will lead to inefficient parameter estimation. We investigate the well‐known criterion of QIC for selecting a working correlation structure, and have found that performance of the QIC is deteriorated by a term that is theoretically independent of the correlation structures but has to be estimated with an error. This leads us to propose a correlation information criterion (CIC) that substantially improves the QIC performance. Extensive simulation studies indicate that the CIC has remarkable improvement in selecting the correct correlation structures. We also illustrate our findings using a data set from the Madras Longitudinal Schizophrenia Study. Copyright © 2008 John Wiley & Sons, Ltd.  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