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   3063301篇
  免费   240730篇
  国内免费   6265篇
耳鼻咽喉   43501篇
儿科学   97462篇
妇产科学   82868篇
基础医学   435044篇
口腔科学   88706篇
临床医学   280137篇
内科学   592576篇
皮肤病学   64558篇
神经病学   255503篇
特种医学   121239篇
外国民族医学   1148篇
外科学   459291篇
综合类   72662篇
现状与发展   2篇
一般理论   1356篇
预防医学   250139篇
眼科学   72056篇
药学   226536篇
  7篇
中国医学   5850篇
肿瘤学   159655篇
  2018年   32268篇
  2017年   24915篇
  2016年   27810篇
  2015年   31287篇
  2014年   44694篇
  2013年   67946篇
  2012年   91357篇
  2011年   96341篇
  2010年   56945篇
  2009年   54346篇
  2008年   90794篇
  2007年   96533篇
  2006年   97415篇
  2005年   94484篇
  2004年   91169篇
  2003年   87794篇
  2002年   85897篇
  2001年   139074篇
  2000年   143793篇
  1999年   121485篇
  1998年   35706篇
  1997年   32299篇
  1996年   31902篇
  1995年   30859篇
  1994年   28994篇
  1993年   26887篇
  1992年   98079篇
  1991年   95020篇
  1990年   92080篇
  1989年   88782篇
  1988年   82006篇
  1987年   81141篇
  1986年   76682篇
  1985年   73515篇
  1984年   55720篇
  1983年   47568篇
  1982年   29008篇
  1981年   25868篇
  1979年   52339篇
  1978年   36975篇
  1977年   31274篇
  1976年   29432篇
  1975年   30947篇
  1974年   38093篇
  1973年   36261篇
  1972年   33884篇
  1971年   31481篇
  1970年   29399篇
  1969年   27385篇
  1968年   25026篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
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   
102.
103.
104.
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   
105.
106.
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   
107.
Molecular characterization of Wuchereria bancrofti is essential to develop suitable anti-filarial drugs and vaccines. We describe here isolation, sequence analysis and cloning of a partial cDNA of an enzyme superoxide dismutase from this parasite. The immunoscreening of a lambda zap W. bancrofti microfilarial (Mf) cDNA library with microfilaremic sera had resulted in the isolation of several seroreactive clones including, WbSOD. This clone contained a 309 bp insert and showed significant nucleotide and deduced amino acid sequence homologies to the superoxide dismutases of other nematode parasites. The antioxidant property of this enzyme may have important contribution in the defense mechanism of the parasite against host immune response.  相似文献   
108.
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   
109.
110.
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