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   378657篇
  免费   24871篇
  国内免费   2801篇
耳鼻咽喉   5221篇
儿科学   8210篇
妇产科学   10083篇
基础医学   53112篇
口腔科学   11786篇
临床医学   30081篇
内科学   78288篇
皮肤病学   8546篇
神经病学   27264篇
特种医学   13936篇
外国民族医学   82篇
外科学   60679篇
综合类   9951篇
现状与发展   1篇
一般理论   64篇
预防医学   17444篇
眼科学   9470篇
药学   30990篇
  1篇
中国医学   2195篇
肿瘤学   28925篇
  2021年   2621篇
  2019年   2724篇
  2018年   4525篇
  2017年   3436篇
  2016年   3526篇
  2015年   4024篇
  2014年   5699篇
  2013年   7396篇
  2012年   10039篇
  2011年   10216篇
  2010年   6205篇
  2009年   5850篇
  2008年   9466篇
  2007年   10301篇
  2006年   10221篇
  2005年   9293篇
  2004年   8792篇
  2003年   8535篇
  2002年   8214篇
  2001年   28298篇
  2000年   28808篇
  1999年   23672篇
  1998年   5172篇
  1997年   4250篇
  1996年   3832篇
  1995年   3485篇
  1994年   3106篇
  1993年   2845篇
  1992年   16065篇
  1991年   14827篇
  1990年   14160篇
  1989年   13969篇
  1988年   12587篇
  1987年   12070篇
  1986年   11108篇
  1985年   10329篇
  1984年   6915篇
  1983年   5602篇
  1982年   2723篇
  1979年   5481篇
  1978年   3352篇
  1977年   2975篇
  1975年   2642篇
  1974年   3066篇
  1973年   2866篇
  1972年   2831篇
  1971年   2774篇
  1970年   2513篇
  1969年   2546篇
  1968年   2250篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
Abstract

This study was undertaken to compare the concentrations of pro- and anti-angiogenic growth factors, nitric oxide (NO) stable metabolites in maternal serum and embryonic left ventricular (LV) isovolumic relaxation time (IRT, ms) during the first trimester in two groups of women: with pregnancy conceived by assisted reproductive technologies (ART, n?=?39) and normally conceived (control group, n?=?68) pregnancy. The concentration of vasoconstrictor endothelin 1 was 45.5 times more in ART than in control group. On the contrary, the concentrations of NO stable metabolites in ART were 1.9 times less than in control women. The assessment of angiogenic suppressors in ART women demonstrates the decrease in s-endoglin concentration was 1.6 times and in soluble receptor to vascular endothelial growth factor concentration was 2.0 times in comparison with control group. There was a significant increase in LV IRT in ART embryos in comparison to control ones. These data suggest significant changes in pro- anti-angiogenic factors balance and increase in vascular impedance in ART-conceived embryos.  相似文献   
53.
54.
Digestive Diseases and Sciences - To determine whether the presence of portal vein thrombosis (PVT) where venous flow within the liver may be altered may delay the diagnosis of HCC and be...  相似文献   
55.
56.
ABSTRACT

Purpose

To investigate the effect of 1% tropicamide on anterior chamber aqueous flare (ACAF) measurements acquired with laser flare meter in patients with pseudoexfoliation.  相似文献   
57.
58.
International Journal of Legal Medicine - Sex identification is a primary step in forensic analysis of skeletal remains. The accuracy of sex estimation methods greatly depends on the sexual...  相似文献   
59.
60.
Inflammation, an important contributory factor of muscle and bone aging, is potentially modulated by diet. This study examined the associations of dietary inflammatory index (DII) score with musculoskeletal parameters and related disease outcomes in 3995 community-dwelling Chinese men and women aged ≥65 years in Hong Kong. DII score at baseline was estimated from a food frequency questionnaire. Bone mineral density (BMD) and muscle mass estimated by dual-energy X-ray absorptiometry (DXA), hand grip strength, gait speed, and chair stand test were measured at baseline, year 4, and year 14. The associations of DII score with the longitudinal changes of musculoskeletal parameters, and incidence of osteoporosis, sarcopenia, and fractures were examined by using general linear model, multinomial logistic regression model, and Cox proportional hazards regression model, respectively. After multiple adjustments, each tertile increase in DII score in men was associated with 0.37 (95% confidence interval [CI], 0.10–0.64) kg loss in grip strength and 0.02 (95% CI, 0.01–0.03) m/s loss in gait speed over 4 years. In men, the highest tertile of DII was associated with a higher risk of incident fractures, with adjusted and competing death adjusted hazard ratio (HR) (95% CI) of 1.56 (1.14–2.14) and 1.40 (1.02–1.91), respectively. In women, DII score was not significantly associated with any muscle-related outcomes or incidence of fracture, but a significant association between higher DII score and risk of osteoporosis at year 14 was observed, with the highest tertile of DII score having adjusted odds ratio (OR) (95% CI) of 1.90 (1.03–3.52). In conclusion, pro-inflammatory diet consumption promoted loss of muscle strength and physical function, and increased risk of fractures in older Chinese men. Pro-inflammatory diets had no significant association with muscle related outcomes but increased the long-term risk of osteoporosis in older Chinese women. © 2022 American Society for Bone and Mineral Research (ASBMR).  相似文献   
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