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   3519606篇
  免费   272109篇
  国内免费   6869篇
耳鼻咽喉   49794篇
儿科学   112256篇
妇产科学   94748篇
基础医学   496198篇
口腔科学   103199篇
临床医学   321261篇
内科学   681691篇
皮肤病学   74941篇
神经病学   286531篇
特种医学   136631篇
外国民族医学   1084篇
外科学   531560篇
综合类   84197篇
现状与发展   5篇
一般理论   1398篇
预防医学   278951篇
眼科学   84386篇
药学   262611篇
  11篇
中国医学   7485篇
肿瘤学   189646篇
  2018年   37643篇
  2017年   28763篇
  2016年   31816篇
  2015年   36057篇
  2014年   51235篇
  2013年   77063篇
  2012年   104964篇
  2011年   110953篇
  2010年   65682篇
  2009年   62045篇
  2008年   104291篇
  2007年   111113篇
  2006年   112066篇
  2005年   108719篇
  2004年   104706篇
  2003年   100464篇
  2002年   98256篇
  2001年   166831篇
  2000年   172097篇
  1999年   144862篇
  1998年   41167篇
  1997年   36723篇
  1996年   36388篇
  1995年   35204篇
  1994年   32857篇
  1993年   30451篇
  1992年   114903篇
  1991年   111225篇
  1990年   107329篇
  1989年   103671篇
  1988年   95737篇
  1987年   94033篇
  1986年   88900篇
  1985年   84810篇
  1984年   63854篇
  1983年   54404篇
  1982年   32241篇
  1981年   28807篇
  1979年   58838篇
  1978年   41094篇
  1977年   34916篇
  1976年   32680篇
  1975年   34502篇
  1974年   42460篇
  1973年   40524篇
  1972年   37933篇
  1971年   35026篇
  1970年   32901篇
  1969年   30615篇
  1968年   28124篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
High levels of tumor necrosis factor-alpha (TNF-alpha), a pro-inflammatory cytokine, are present in the wound fluid of chronic nonhealing wounds. This leads to increased inflammation, cytokine expression, and ultimately results in impaired wound healing and tissue destruction. Etanercept is a recombinant fusion protein that consists of the soluble TNF receptor (p75) linked to the Fc portion of human IgG1. It is an effective inhibitor of TNF-alpha and has been shown to provide rapid and sustained improvement in rheumatoid arthritis by acting as a soluble receptor binding TNF-alpha and preventing its proinflammatory activities. Therefore, the aim of this study was to determine whether Etanercept could inhibit TNF-alpha activity in chronic wound fluid. Wound fluid was collected from the venous leg ulcers of 16 different patients. The effect of Etanercept on TNF-alpha activity was evaluated using both a TNF-alpha bioassay and an enzyme-linked immunoassay. Etanercept was found to reduce the cytotoxic effect of chronic wound fluid on L929 fibroblasts by approximately 30% and neutralized TNF-alpha binding in the enzyme-linked immunoassay by up to 80%. Direct application of Etanercept to chronic wounds may therefore reduce the inflammatory activity of TNF-alpha, which could reduce the chronicity of venous leg ulcers and thus aid in the healing of these wounds.  相似文献   
993.
994.
For many parents stopping life-sustaining medical treatment on their dying infant is psychologically impossible. Dostoevsky's insights into human behavior, particularly the fact that individuals do not want the anxiety and guilt associated with responsibility for making difficult decisions, might change the way physicians approach parents for permission to withdraw life-prolonging medical interventions on dying infants.  相似文献   
995.
A series of 1-alkyl-3,4-dihydroisoquinolines and the related 4-alkyl-1,2-dihydro-benzo[f]isoquinolines was synthesized using reactions of dialkylbenzylcarbinols and their naphthyl analogs with alkylcyanides. Experiments showed that 1-alkyl-6,7-dimethoxy-3,4-dihydroisoquinolines typically produce a hypotensive action, while the benzo-annelated structures usually exhibit a hypertensive effects. The most active compound decreases the arterial pressure in cats by 52 Torr and the effect lasts for about 4 hours. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 40, No. 3, pp. 15–17, March, 2006.  相似文献   
996.
997.
The authors discuss techniques for Monte Carlo (MC) cohort simulations that reduce the number of simulation replications required to achieve a given degree of precision for various output measures. Known as variance reduction techniques, they are often used in industrial engineering and operations research models, but they are seldom used in medical models. However, most MC cohort simulations are well suited to the implementation of these techniques. The authors discuss the cost of implementation versus the benefit of reduced replications.  相似文献   
998.
999.
1000.
Consecutive patients (n = 215) who were referred to optometric (55%) or multidisciplinary (45%) low-vision services and above 50 years of age were recruited from four hospitals in the Netherlands. They completed two vision-related quality of life questionnaires, the Vision Quality of Life Core Measure (VCM1) and the Low Vision Quality of Life Questionnaire (LVQOL), before their first visit with low-vision services and 1 year later. At follow-up, patients referred to multidisciplinary low-vision services had lower scores on the mobility subscale of the LVQOL than patients referred to optometric low-vision services [5.3 points; 95% confidence interval (CI): 0.2-10.5]. Paired sample t-tests for the two groups of patients taken together show improvement for the VCM1 (3.1 points; 95% CI: 0.6-5.6) and deterioration for the basic aspects of vision (3.5 points; 95% CI: 1.1-5.9) and the mobility (6.6 points; 95% CI: 3.7-9.5) subscales of the LVQOL. In conclusion, people referred to optometric services showed less deterioration in mobility than those referred to multidisciplinary services. No differences were observed for any of the other subscales of the LVQOL and the VCM1. Future research in this field should include randomized controlled designs comparing low-vision services with no treatment or placebo.  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