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   2526093篇
  免费   203945篇
  国内免费   5467篇
耳鼻咽喉   36329篇
儿科学   75814篇
妇产科学   66667篇
基础医学   356621篇
口腔科学   70705篇
临床医学   230150篇
内科学   496883篇
皮肤病学   51798篇
神经病学   212801篇
特种医学   102798篇
外国民族医学   886篇
外科学   380633篇
综合类   58174篇
现状与发展   7篇
一般理论   1065篇
预防医学   200870篇
眼科学   59471篇
药学   190409篇
  4篇
中国医学   5872篇
肿瘤学   137548篇
  2021年   21041篇
  2019年   20791篇
  2018年   28470篇
  2017年   21901篇
  2016年   24634篇
  2015年   28707篇
  2014年   40282篇
  2013年   59074篇
  2012年   81178篇
  2011年   84507篇
  2010年   49707篇
  2009年   46966篇
  2008年   78091篇
  2007年   82419篇
  2006年   82521篇
  2005年   80268篇
  2004年   76663篇
  2003年   73424篇
  2002年   71919篇
  2001年   114507篇
  2000年   118319篇
  1999年   100104篇
  1998年   29026篇
  1997年   26445篇
  1996年   26343篇
  1995年   25369篇
  1994年   23825篇
  1993年   22122篇
  1992年   80299篇
  1991年   77284篇
  1990年   74364篇
  1989年   71585篇
  1988年   66554篇
  1987年   65467篇
  1986年   61987篇
  1985年   58993篇
  1984年   44697篇
  1983年   38112篇
  1982年   23278篇
  1979年   41653篇
  1978年   29295篇
  1977年   24665篇
  1976年   23115篇
  1975年   24210篇
  1974年   29904篇
  1973年   28282篇
  1972年   26446篇
  1971年   24307篇
  1970年   22913篇
  1969年   21214篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
The aim of the present study was to explore differences in the clinical expression, clinical diagnoses and management of airway diseases in a primary-care setting. Patients aged >or=35 yrs who had ever smoked were enrolled when they presented for any reason to one of eight rural primary-care practices. Respiratory symptom questionnaires and spirometry were administered. In total, 1,034 patients had acceptable and reproducible spirometry, of whom 550 (53%) were males and 484 (47%) were females. Males smoked more than females (41.2 versus 29.2 pack-yrs) respectively, and were more likely to have a pre-bronchodilator forced expiratory volume in one second/forced vital capacity <0.70 at 22.4 versus 11.8%, respectively. However, more females than males reported breathlessness (51.0 versus 42.8%, respectively), a prior diagnosis compatible with airflow obstruction and taking respiratory medications (23.4 versus 14.9%, respectively). In conclusion, the current results suggest that females are more likely than males to report breathlessness and be prescribed respiratory medications independent of differences in the severity of airflow obstruction.  相似文献   
82.
83.
84.
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   
85.
86.
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   
87.
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   
88.
89.
90.
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