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   1742565篇
  免费   159763篇
  国内免费   4750篇
耳鼻咽喉   26232篇
儿科学   57750篇
妇产科学   48431篇
基础医学   231293篇
口腔科学   48780篇
临床医学   165751篇
内科学   357852篇
皮肤病学   41085篇
神经病学   143872篇
特种医学   70633篇
外国民族医学   474篇
外科学   281641篇
综合类   40025篇
现状与发展   75篇
一般理论   547篇
预防医学   129864篇
眼科学   39663篇
药学   122597篇
  3篇
中国医学   2990篇
肿瘤学   97520篇
  2018年   21484篇
  2017年   18336篇
  2016年   20426篇
  2015年   22606篇
  2014年   34766篇
  2013年   45612篇
  2012年   47786篇
  2011年   50038篇
  2010年   35858篇
  2009年   38376篇
  2008年   48512篇
  2007年   49184篇
  2006年   52280篇
  2005年   48376篇
  2004年   47140篇
  2003年   44221篇
  2002年   43457篇
  2001年   79249篇
  2000年   81146篇
  1999年   69418篇
  1998年   21087篇
  1997年   19472篇
  1996年   19301篇
  1995年   18897篇
  1994年   16818篇
  1993年   15606篇
  1992年   56692篇
  1991年   55072篇
  1990年   53567篇
  1989年   51945篇
  1988年   48151篇
  1987年   47395篇
  1986年   45131篇
  1985年   43553篇
  1984年   32582篇
  1983年   28068篇
  1982年   16651篇
  1981年   14831篇
  1979年   30779篇
  1978年   21376篇
  1977年   18156篇
  1976年   16935篇
  1975年   17844篇
  1974年   21719篇
  1973年   20893篇
  1972年   19161篇
  1971年   17979篇
  1970年   16537篇
  1969年   15362篇
  1968年   13987篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
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   
72.
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   
73.
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   
74.
75.
76.
Research coordinators in intensive care are a growing specialty about which little is known. This cross-sectional study surveyed the Australia and New Zealand Intensive Care Research Coordinators' Group (n = 49) regarding demographics, education, employment history, job structure, and role content. Most research coordinators were highly qualified and experienced nurses who undertake pharmaceutical trials, multicenter projects, departmental medical and nursing research, audits and data registries, and their own projects.  相似文献   
77.
78.
79.
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   
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