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   1349277篇
  免费   95073篇
  国内免费   2976篇
耳鼻咽喉   19779篇
儿科学   40735篇
妇产科学   38990篇
基础医学   189075篇
口腔科学   40062篇
临床医学   113922篇
内科学   265244篇
皮肤病学   30564篇
神经病学   107696篇
特种医学   53938篇
外国民族医学   435篇
外科学   209579篇
综合类   31117篇
现状与发展   6篇
一般理论   452篇
预防医学   93104篇
眼科学   31639篇
药学   100956篇
  4篇
中国医学   3010篇
肿瘤学   77019篇
  2018年   12168篇
  2016年   10932篇
  2015年   12297篇
  2014年   17254篇
  2013年   25985篇
  2012年   34137篇
  2011年   35936篇
  2010年   21359篇
  2009年   20766篇
  2008年   34468篇
  2007年   37570篇
  2006年   38115篇
  2005年   36793篇
  2004年   35853篇
  2003年   34763篇
  2002年   34156篇
  2001年   63679篇
  2000年   65380篇
  1999年   55476篇
  1998年   14752篇
  1997年   13546篇
  1996年   13021篇
  1995年   12283篇
  1994年   11516篇
  1992年   42806篇
  1991年   41313篇
  1990年   40572篇
  1989年   39570篇
  1988年   36983篇
  1987年   36429篇
  1986年   34915篇
  1985年   33124篇
  1984年   24843篇
  1983年   21068篇
  1982年   12681篇
  1981年   11578篇
  1979年   23933篇
  1978年   17075篇
  1977年   14840篇
  1976年   13391篇
  1975年   15270篇
  1974年   18081篇
  1973年   17565篇
  1972年   16817篇
  1971年   15722篇
  1970年   14915篇
  1969年   14346篇
  1968年   13460篇
  1967年   12017篇
  1966年   11261篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
目的:SCANDSTENT试验旨在评价西罗莫司洗脱支架(SES)在复杂冠状动脉病变中的应用。背景:与裸金属支架(BMS)相比,在简单冠状动脉病变中使用SES能够改善造影和临.床的结果,但是,有关在复杂病变中使用SES的安全性和有效性的证据有限。方法:322例有症状的复杂冠状动脉疾病患者被随机分配接受SES或BMS治疗。病变形态分别为全闭(36%)、分叉(34%)、开口(22%)或成角(8%)改变。主要终点为支架置入6个月后血管最小管腔直径的差别。  相似文献   
102.
To examine the prevalence of Internet sex networking among men who have sex with men (MSM) in Hong Kong and risk behaviors associated with the behavior, a telephone survey of 15,230 Hong Kong Chinese men aged 18-60 was conducted. Of the 283 active MSM (having engaged in some MSM behaviors in the last 6 months) identified, 17.7% had networked for MSM partners via the Internet in the last 6 months. Younger age (odds ratio [OR] for age < or = 25 vs. age >25 = 4.67, 95% confidence interval [CI] = 2.35-9.28) and being an anal-sex MSM (OR = 4.72, 95% CI=2.36-9.44) were independent predictors of Internet sex networking. Being an Internet sex networker was associated with some risk behaviors such as having contracted a sexually transmitted disease (adjusted OR = 4.79, 95% CI = 1.34-17.11), having had > or = 3 MSM partners (adjusted OR = 4.74, 95% CI = 2.20-10.23), and having engaged in anal sex (adjusted OR = 3.95, 95% CI = 1.89-8.23). HIV prevention programs for MSM should thereby include Internet-based interventions.  相似文献   
103.
The incidence of asthma has been reported to be associated with obesity. An alternative analysis, of net change in prevalence, does not require exclusion of those with asthma at baseline. Follow-up data were obtained from 9,552 participants in the European Community Respiratory Health Survey and the Swiss cohort Study on Air Pollution and Lung Disease in Adults. Incidence of asthma was analysed by proportional hazards regression, and net changes in symptoms and asthma status by generalised estimating equations, by obesity group. Incidence and net change in ever having had asthma were greater in females than in males, and in participants who remained obese compared with those who were never obese (hazard ratio 2.00, 95% confidence interval 1.25-3.20; excess net change 2.8%, 0.4-5.3% per 10 yrs). The effect of being obese on net change in diagnosed asthma was greater in females than in males, but for net change in wheeze without a cold it was greater in males. The present results are consistent with asthma being more frequently diagnosed in females, especially obese females. These findings may help to explain the reports of a stronger association between asthma and obesity in females than in males.  相似文献   
104.
105.
106.
The finer branches of the biliary tree (FBBT) contain a regenerative compartment. We hypothesized that preservation of the FBBT together with its microvasculature will lead to recovery of biliary damage and prolonged preservation of bile ductules during the development of chronic liver allograft rejection. The interlobular bile ducts, portal bile ductules and extraportal biliary cells with and without microvessels were studied in sequential biopsies in five patients who fulfilled the Banff criteria of early chronic rejection (CR) (imminence group). Biopsies of CR patients (n = 12) served as controls. Biopsies were double immunostained with CD34 (microvessels) and cytokeratin 7 (biliary structures). Proliferation and proangiogenic activity were assessed with Ki67 and VEGF-A immunostaining. Severe damage of bile ducts in the imminence group did not progress to significant bile duct loss. This was associated with a high proliferative activity in all biliary structures and preservation of the microvascular compartment. VEGF-A expression was increased in all but the reperfusion biopsies. In conclusion, both regenerative activity of the FBBT and an intact microvascular compartment are associated with less damage of the biliary tree and could therefore be prerequisites for biliary regeneration.  相似文献   
107.
108.
Atherosclerotic renal artery stenosis (ARAS) may cause hypertension, progressive renal failure, and recurrent pulmonary edema. It typically occurs in high risk patients with coexistent vascular disease elsewhere. Most patients with ARAS are likely to die from coronary heart disease or stroke before end-stage renal failure occurs. Recent controlled trials have shown that most patients undergoing angioplasty to treat renovascular hypertension still need antihypertensive agents 6 or 12 months after the procedure. Nevertheless, the number of antihypertensive agents required to control blood pressure adequately is lower following angioplasty than for medication alone. Trials assessing the value of revascularization for preserving renal function or preventing clinical events are only in the early recruitment phase. Revascularization should be undertaken in patients with ARAS and resistant hypertension or heart failure, and probably in those with rapidly deteriorating renal function or with an increase in plasma creatinine levels during angiotensin-converting enzyme inhibition. With or without revascularization, medical therapy using antihypertensive, hypolipidemic and antiplatelet agents is necessary in almost all cases.  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