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   932027篇
  免费   66376篇
  国内免费   1343篇
耳鼻咽喉   12958篇
儿科学   24360篇
妇产科学   23232篇
基础医学   132906篇
口腔科学   28249篇
临床医学   80539篇
内科学   183285篇
皮肤病学   19384篇
神经病学   72194篇
特种医学   36815篇
外国民族医学   79篇
外科学   152087篇
综合类   18043篇
现状与发展   1篇
一般理论   234篇
预防医学   61744篇
眼科学   21307篇
药学   72532篇
  3篇
中国医学   2162篇
肿瘤学   57632篇
  2018年   8970篇
  2017年   7031篇
  2016年   7767篇
  2015年   8858篇
  2014年   11990篇
  2013年   17505篇
  2012年   24092篇
  2011年   25044篇
  2010年   14811篇
  2009年   14274篇
  2008年   24604篇
  2007年   25703篇
  2006年   26494篇
  2005年   25441篇
  2004年   24567篇
  2003年   23624篇
  2002年   23160篇
  2001年   54733篇
  2000年   56547篇
  1999年   46955篇
  1998年   10734篇
  1997年   9471篇
  1996年   9596篇
  1995年   8934篇
  1994年   8281篇
  1993年   7595篇
  1992年   35488篇
  1991年   33916篇
  1990年   32738篇
  1989年   31870篇
  1988年   28992篇
  1987年   28251篇
  1986年   26288篇
  1985年   25144篇
  1984年   17834篇
  1983年   15142篇
  1982年   7796篇
  1981年   6774篇
  1979年   15781篇
  1978年   10599篇
  1977年   9052篇
  1976年   7872篇
  1975年   8630篇
  1974年   10468篇
  1973年   9860篇
  1972年   9359篇
  1971年   8855篇
  1970年   8428篇
  1969年   7926篇
  1968年   7200篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Clinicopathological and electron microscopical findings of eight cases of enzootic nasal adenocarcinoma of sheep, diagnosed solely in one big flock in Slovenia between years 2001 and 2003 are described. All affected sheep were female, their mean age was 4.5 ± 1.5 years and they either belonged to the Istrian pramenka breed (five sheep) or were crossbreeds (three sheep). Tumours that arose from the ethmoid area of the nasal cavity were unilateral in six cases (75%) and bilateral in two cases (25%). All tumours were classified as adenocarcinomas by histopathological examination and they displayed either a combination of tubular and papillary growth or less often solely tubular proliferation. No metastases were detected in regional lymph nodes, brain or other organs. Electron microscopical studies performed on the reprocessed paraffin‐embedded tissues revealed the presence of the virus‐like particles with an average diameter between 70 and 90 nm.  相似文献   
32.
33.
34.
35.
Inter-individual variations in the development of silicosis, even within the same environments, have been reported, which suggest the contribution of genetic factors in silicosis aetiology. The aim of the present study was to determine whether there is any significant genetic influence on the development of silicosis. Furthermore, which genetic loci are responsible for the pulmonary response to silica exposure? Eight strains of inbred mice were used to examine the genetic influence on the lung fibrotic response to silica exposure. After intercross-breeding between the most susceptible and most resistant strains, a genome-wide linkage analysis of quantitative trait loci (QTL) was performed. Hydroxyproline was applied as an index, and genotypes of 167 marker genes were analysed by fragment analysis using a capillary-type sequencer. There was significant inter-strain difference in the mean concentration of hydroxyproline contents among the eight strains of mice. Breeding studies were conducted between the most susceptible, C57BL/6J, and the most resistant strain, CBA/J. A genome-wide linkage analysis of silica-exposed intercrossed cohorts identified significant QTL on chromosome 4 and suggestive QTL on chromosomes 3 and 18. The present study demonstrates that genetic factors may play a significant role in fibrotic-lung responses to silica; one significant and two suggestive quantitative trait loci were identified.  相似文献   
36.
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   
37.
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   
38.
39.
40.
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