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   1609781篇
  免费   132308篇
  国内免费   2595篇
耳鼻咽喉   21713篇
儿科学   53149篇
妇产科学   46462篇
基础医学   228941篇
口腔科学   47379篇
临床医学   141963篇
内科学   316114篇
皮肤病学   34197篇
神经病学   131003篇
特种医学   64976篇
外国民族医学   475篇
外科学   244816篇
综合类   39837篇
现状与发展   3篇
一般理论   553篇
预防医学   123854篇
眼科学   36618篇
药学   121781篇
  3篇
中国医学   2985篇
肿瘤学   87862篇
  2018年   14915篇
  2016年   13023篇
  2015年   15186篇
  2014年   20857篇
  2013年   31648篇
  2012年   43017篇
  2011年   45196篇
  2010年   26548篇
  2009年   25535篇
  2008年   43433篇
  2007年   45630篇
  2006年   46465篇
  2005年   45085篇
  2004年   44470篇
  2003年   42529篇
  2002年   41597篇
  2001年   75885篇
  2000年   78544篇
  1999年   66580篇
  1998年   17822篇
  1997年   16420篇
  1996年   16386篇
  1995年   16090篇
  1994年   15142篇
  1993年   14271篇
  1992年   55559篇
  1991年   53902篇
  1990年   52690篇
  1989年   50994篇
  1988年   47353篇
  1987年   46673篇
  1986年   44396篇
  1985年   42967篇
  1984年   32127篇
  1983年   27643篇
  1982年   16226篇
  1981年   14500篇
  1980年   13621篇
  1979年   30553篇
  1978年   21153篇
  1977年   17831篇
  1976年   16758篇
  1975年   17620篇
  1974年   21547篇
  1973年   20742篇
  1972年   18915篇
  1971年   17820篇
  1970年   16346篇
  1969年   15307篇
  1968年   13989篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
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   
82.
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   
83.
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   
84.
BACKGROUND: Obsessive-compulsive disorder (OCD) is a chronic, impairing and often comorbid disorder. METHODS: 1000 subjects who called the Anxiety Disorders Association of America (ADAA) were surveyed and divided in three groups: (a) callers with OCD (OCD) and two overlapping control groups: (b) callers with no axis I disorder (NAC) and (c) with no-OCD (NOC) using a 97-item questionnaire. RESULTS: The rate of OCD was 14.5% (N = 145). Relative to the NOC group, OCD subjects were more likely to be female, White, younger and not married. Relative to the NAC group, subjects with OCD were more likely to be White, not married and younger. OCD was accompanied by significant comorbidity and was associated with an increased number of visits to health professionals than NAC subjects. There was no significant difference regarding unemployment rates among the three groups. However, OCD callers were more likely than both control groups to have missed work or have decreased productivity due to their mental condition. OCD subjects took an average of 1 psychotropic medication in the past year and were statistically more likely than the control groups to experience sleepiness and nervousness as side effects. CONCLUSIONS: OCD was fairly prevalent among ADAA callers and presented high levels of comorbidity, impairment, health care utilization and sensitivity to psychotropic side effects.  相似文献   
85.
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   
86.
87.
88.
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   
89.
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