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   2384712篇
  免费   195815篇
  国内免费   4226篇
耳鼻咽喉   34316篇
儿科学   73159篇
妇产科学   63336篇
基础医学   335970篇
口腔科学   67626篇
临床医学   217391篇
内科学   470081篇
皮肤病学   48051篇
神经病学   201656篇
特种医学   96129篇
外国民族医学   886篇
外科学   361230篇
综合类   56469篇
现状与发展   1篇
一般理论   999篇
预防医学   192420篇
眼科学   55595篇
药学   178200篇
  5篇
中国医学   4377篇
肿瘤学   126856篇
  2018年   24537篇
  2016年   20855篇
  2015年   23563篇
  2014年   33926篇
  2013年   51352篇
  2012年   69581篇
  2011年   73129篇
  2010年   42875篇
  2009年   41227篇
  2008年   69415篇
  2007年   73830篇
  2006年   74685篇
  2005年   72705篇
  2004年   69957篇
  2003年   67575篇
  2002年   66742篇
  2001年   112556篇
  2000年   116581篇
  1999年   98419篇
  1998年   27945篇
  1997年   25578篇
  1996年   25510篇
  1995年   24668篇
  1994年   23215篇
  1993年   21606篇
  1992年   79429篇
  1991年   76421篇
  1990年   73592篇
  1989年   70864篇
  1988年   65864篇
  1987年   64821篇
  1986年   61355篇
  1985年   58411篇
  1984年   44228篇
  1983年   37672篇
  1982年   22901篇
  1981年   20355篇
  1980年   19042篇
  1979年   41309篇
  1978年   28990篇
  1977年   24350篇
  1976年   22832篇
  1975年   23969篇
  1974年   29641篇
  1973年   28046篇
  1972年   26230篇
  1971年   24157篇
  1970年   22754篇
  1969年   21090篇
  1968年   19137篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
灾难的时代错误:灾害医学的过去、现在和将来(一)   总被引:1,自引:0,他引:1  
灾难,特别是地震、火山、洪水以及与战争有关的事件如饥饿和流行性传染病,是人类有记录的经历的一部分。从意大利庞贝的火山爆发,到约翰斯顿的洪水、第二次世界大战和黑色瘟疫,到西班牙流感,都发生了灾难,这不会被传说和历史书籍长期忘却。不过,在20世纪中叶以前,那些灾难的发生相对较少,且相距时间较长。从20世纪中叶以来,灾难的本质发生了变化。从恐怖分子使用“新技术”,到与气候有关的导致亿万美元经济损失的事件,表明这个世界正在发生变化。仅仅在最近的50~60年间,造成多种多样的伤亡事件,其危险性和频率的增加引人注目,并且注定要在接…  相似文献   
72.
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   
73.
74.
75.
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   
76.
77.
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   
78.
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   
79.
80.
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