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   2350204篇
  免费   171658篇
  国内免费   3331篇
耳鼻咽喉   32054篇
儿科学   75920篇
妇产科学   62687篇
基础医学   348242篇
口腔科学   63644篇
临床医学   211412篇
内科学   457318篇
皮肤病学   51749篇
神经病学   185327篇
特种医学   88058篇
外国民族医学   489篇
外科学   353904篇
综合类   47517篇
现状与发展   12篇
一般理论   848篇
预防医学   182751篇
眼科学   54334篇
药学   175112篇
  11篇
中国医学   4576篇
肿瘤学   129228篇
  2021年   18985篇
  2019年   19543篇
  2018年   27067篇
  2017年   20359篇
  2016年   22749篇
  2015年   25647篇
  2014年   36106篇
  2013年   53965篇
  2012年   74698篇
  2011年   79423篇
  2010年   47066篇
  2009年   44579篇
  2008年   74624篇
  2007年   79485篇
  2006年   80304篇
  2005年   77794篇
  2004年   74385篇
  2003年   71701篇
  2002年   69388篇
  2001年   108749篇
  2000年   111460篇
  1999年   93514篇
  1998年   26993篇
  1997年   23666篇
  1996年   24054篇
  1995年   22716篇
  1994年   20898篇
  1993年   19719篇
  1992年   72008篇
  1991年   70084篇
  1990年   68400篇
  1989年   65677篇
  1988年   60308篇
  1987年   59137篇
  1986年   55224篇
  1985年   53018篇
  1984年   39319篇
  1983年   33405篇
  1982年   19864篇
  1979年   35871篇
  1978年   25652篇
  1977年   21232篇
  1976年   20337篇
  1975年   21819篇
  1974年   26148篇
  1973年   24809篇
  1972年   23202篇
  1971年   22038篇
  1970年   20248篇
  1969年   19319篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
At the time of hire, 4059 of 6522 healthcare workers required a 2-step tuberculin skin test; 114 workers (2.8%) demonstrated a boosted reaction after the second step. Boosted reactions were significantly associated with male sex and older age. A verbal history of previous tuberculin skin test results was not a reliable indicator of baseline tuberculin skin test status at the time of hire.  相似文献   
82.
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   
83.
84.
OBJECTIVE: To determine whether under-reporting of rheumatic fever occurs at hospital, municipal, provincial and national levels of the South African health system. BACKGROUND: Information on the incidence of rheumatic fever (RF) and the prevalence of rheumatic heart disease (RHD) is required for the prevention of valvular heart disease in developing countries. In South Africa, RF was made a notifiable condition in 1989. It has recently been suggested that the reporting of RF cases may be incomplete, possibly because of underreporting by health care professionals and deficient administration of the disease notification system in South Africa. METHOD AND RESULTS: We assessed whether underreporting of RF cases occurs by comparing the numbers of RF cases reported per year at hospital, municipal, provincial and national levels from 1990 to 2004. There was a fall in the number of RF cases reported per year at national and provincial level over the 15 years of observation. A detailed analysis of the number of RF cases reported at hospital, municipal and provincial level for a 5-year period showed that more cases were diagnosed in one hospital (serving a smaller population) than were captured at municipal and provincial level (serving a larger population), suggesting underreporting by health care professionals. There were discrepancies in the number of cases reported at municipal, provincial and national level, suggesting poor administration of the notification system. CONCLUSION: There appears to be underreporting of RF cases by health care professionals, and poor administration of the RF notification system. Health care professionals need to be educated about the statutory requirement to notify all RF cases in South Africa. An effective national disease notification system is required.  相似文献   
85.
86.
87.
Traumatic injuries of the elbow are frequent in patients of all ages but are particularly common in young children and adolescents engaged in normal play and athletic competition. Injury may result primarily due to direct trauma or may be secondary to transmission of forces through the elbow following a fall on an outstretched hand. In middle-aged and older individuals, chronic repetitive injuries tend to predominate. In all patients, radiographs remain the initial imaging study of choice. Many patients, however, may need advanced cross-sectional imaging (i.e. MRI, CT, or ultrasound) either at presentation or during the course of their treatment and follow-up. This article reviews the imaging appearance of common acute and chronic traumatic disorders of the elbow.  相似文献   
88.
89.
Both vascular surgery and endovascular interventions traumatise the arterial wall, especially the endothelium. The vessel responds with neointimal hyperplasia and/or constrictive remodelling, and this is still the limiting factor in curative interventions. Stent placement prevents constrictive remodelling but is the main trigger for in-stent restenosis. Hyperproliferation of neointimal tissue is the main response to arterial thrombosis, local inflammation or medio-intimal injury such as occurs, for example, after balloon dilatation in the region of arterial anastomoses or of a thrombectomy (Fogarty-manoeuvre). At present, research on prevention of restenosis is focused on inhibiting neointimal hyperproliferation by using drug-eluting stents, and especially sirolimus- or paclitaxel-eluting stents. In addition, further experimental research work is in progress, with the aim of esablishing new treatment regimens and solving the problem of neointimal formation, thrombosis and constrictive remodelling. These include both local and systemic pharmacological therapy, brachy- and laser therapy, and many genetic treatment options, some of which are currently the subjects of experimental studies and early-stage clinical trials. Gene therapy seems like a promising way of preventing restenosis, but has not yet been tested in clinical trials. In the near future, selective, simultaneous, and perhaps even polyphasic regulation for gene silencing of two or more genes involved in the development of restenosis could improve the long-term patency rate.  相似文献   
90.
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