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   13186篇
  免费   699篇
  国内免费   95篇
耳鼻咽喉   89篇
儿科学   225篇
妇产科学   124篇
基础医学   2137篇
口腔科学   97篇
临床医学   1344篇
内科学   2928篇
皮肤病学   356篇
神经病学   1298篇
特种医学   523篇
外科学   2019篇
综合类   48篇
一般理论   2篇
预防医学   654篇
眼科学   215篇
药学   917篇
中国医学   40篇
肿瘤学   964篇
  2023年   62篇
  2022年   84篇
  2021年   256篇
  2020年   151篇
  2019年   224篇
  2018年   317篇
  2017年   202篇
  2016年   238篇
  2015年   268篇
  2014年   372篇
  2013年   511篇
  2012年   902篇
  2011年   1020篇
  2010年   604篇
  2009年   535篇
  2008年   870篇
  2007年   1008篇
  2006年   902篇
  2005年   941篇
  2004年   875篇
  2003年   858篇
  2002年   837篇
  2001年   132篇
  2000年   98篇
  1999年   141篇
  1998年   211篇
  1997年   163篇
  1996年   160篇
  1995年   109篇
  1994年   109篇
  1993年   108篇
  1992年   92篇
  1991年   54篇
  1990年   45篇
  1989年   57篇
  1988年   45篇
  1987年   40篇
  1986年   42篇
  1985年   29篇
  1984年   43篇
  1983年   37篇
  1982年   41篇
  1981年   30篇
  1980年   35篇
  1979年   23篇
  1978年   19篇
  1977年   16篇
  1976年   10篇
  1975年   8篇
  1974年   12篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
12.
Evaluative composite measurement scales (CMS) are increasingly used in medicine to measure complex constructs in the absence of a reference criterion or ‘gold standard’. However, the level of measurement provided by these instruments has usually been given little attention. This paper explores the influence of the characteristics of the item set and weighting on the level of measurment of an evaluative CMS. The approach is illustrated with an application to the scoring system of the Nottingham Health Profile. Simulations are provided to indicate when the composite score of item responses, on an ordinal or pass—fail scale, could be considered to achieve the properties of an interval scale.  相似文献   
13.
The diagnosis of nontraumatic intracranial hemorrhage is currently made by computed tomography and is rarely problematic. The causes of bleeding are very numerous. It is important to determine the cause of the hemorrhage promptly, because there may be a recurrence of bleeding. Guidelines for radiologists are proposed and discussed here.  相似文献   
14.
OBJECTIVES: This article examines the differences found between clientele with severe mental health problems and their key health workers in terms of assessing service users' needs in 6 Quebec service areas. METHOD: We questioned 165 pairs of users and staff, using the Camberwell Assessment of Needs questionnaire. The profile of serious and overall problems encountered by clientele from each of the sites was compared. RESULTS: The sites with the greatest degree of user-staff agreement in identifying problems were also the ones where users considered that local services best met their needs. CONCLUSIONS: The study demonstrated that, in needs assessment, major differences exist between the perceptions of users and their key workers in the various sites. These differences can be explained in part by users' individual characteristics, by types of needs, by local particularities, and by service use.  相似文献   
15.
16.
Suramin is an antitrypanosomal compound with confirmed efficacy against several human malignancies. It is generally assumed that its mechanism of action includes the interaction with different growth factors, unlike most of the anticancer drugs. Its anticancer activity has not been testedin vivo against squamous cell carcinoma. The purpose of this study was to assess the efficacy and toxicity of suraminin vivo andin vitro on the VX2 tumor model at therapeutic monitored plasma concentrations. We determined the pharmacokinetics of suramin in rabbits, and modelized its administration in order to obtain plasma concentrations between 150 and 300 μg/ml throughout the treatment course of 3 weeks. Under these conditions, antitumor effects of suramin were evaluatedin vivo by comparing liver tumor involvement in suramin-treated and control rabbits. Liver involvement was quantified by image analysis andin vitro effects were also determined at the same concentrations.In vivo, suramin promoted liver tumor growth significantly (p<0.05), compared to untreated controls.In vitro, suramin significantly stimulated tumor cell growth at concentrations above 200 μg/ml (p<0.01). Suramin may have stimulatory effects on tumor growth in squamous cell carcinoma at relevant plasma drug concentrations. Caution should be taken in further trials in patients with squamous cell carcinomas.  相似文献   
17.
18.
Two hundred aneurysms of the abdominal aorta were treated surgically from 1980 to 1987 by the same surgeon. There were 187 men and 13 women whose mean age was 66.1 years. Nine patients were 80-years-old or more. Eighty-seven percent of patients had preoperative risk factors, 30% of which were coronary artery disease. The operative approach was through a transverse laparotomy in 188 patients compared to 11 midline incisions and one lumbotomy. An aortoaortic tube was inserted in 87 patients, a bifurcated prosthesis in 99, and a tube bypass in 14. Five patients (2.5%) died within the 30 day perioperative period. Death was due to colonic necrosis, right heart chamber thrombosis, renal failure after repeat operation for acute lower limb ischemia, and myocardial infarction associated with renal and respiratory failure. The morbidity rate was 15.7% (31 patients) and included seven neurologic accidents, four respiratory complications, five ischemic events of the lower limbs requiring reoperation and one amputation, four cardiac complications, two renal failures, one reversible colonic ischemia, one revision for incomplete hemostasis, one phlebitis, one sliding syndrome, and five minor infections or cutaneous complications. Mean duration of hospital stay was 10.9 days. These results confirm that direct operation on aortic aneurysms can be performed in patients from all age groups and even with associated diseases. A rapid, simple technique based on a transverse approach, minimal dissection and insertion of aortoaortic tubes, whenever feasible, appears to reduce combined mortality-morbidity.Presented at the Annual Meeting of the Societé de Chirurgie Vasculaire de Langue Française, May 20–21, 1988, La Grande Motte, France.  相似文献   
19.
A single intramuscular injection of 2 mg estradiol valerate (EV) results in neuronal degeneration and β-endorphin depletion in the hypothalamic arcuate nucleus of adult female rats. We have hypothesized that peroxidase-positive astrocytes in this brain region oxidize estrogens and catecholestrogens to semiquinone radicals which mediate oxidative neuronal injury. In the present study, dietary administration of the potent antioxidant 21-aminosteroid, U-74389F, completely blocked EV-induced β-endorphin depletion in the hypothalami of adult female rats. Neither EV nor 21-aminosteroid treatment had any effect on hypothalamic concentrations of neuropeptide Y and Met-enkephalin, confirming that the estradiol lesion is fairly selective for the β-endorphin cell population. The present findings support the hypothesis that the toxic effect of estradiol on hypothalamic β-endorphin neurons is mediated by free radicals.  相似文献   
20.
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