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   3712859篇
  免费   321293篇
  国内免费   13753篇
耳鼻咽喉   51031篇
儿科学   118878篇
妇产科学   97652篇
基础医学   582372篇
口腔科学   103060篇
临床医学   333030篇
内科学   663512篇
皮肤病学   95488篇
神经病学   318249篇
特种医学   148869篇
外国民族医学   497篇
外科学   573893篇
综合类   113958篇
现状与发展   23篇
一般理论   2404篇
预防医学   311145篇
眼科学   86047篇
药学   260574篇
  22篇
中国医学   10134篇
肿瘤学   177067篇
  2021年   55124篇
  2020年   35134篇
  2019年   58087篇
  2018年   71567篇
  2017年   54595篇
  2016年   60384篇
  2015年   74360篇
  2014年   108641篇
  2013年   173863篇
  2012年   98166篇
  2011年   98807篇
  2010年   118141篇
  2009年   122350篇
  2008年   86548篇
  2007年   89991篇
  2006年   100918篇
  2005年   95982篇
  2004年   98485篇
  2003年   88894篇
  2002年   78708篇
  2001年   120981篇
  2000年   115277篇
  1999年   111857篇
  1998年   67098篇
  1997年   64644篇
  1996年   62627篇
  1995年   58246篇
  1994年   52405篇
  1993年   48937篇
  1992年   83052篇
  1991年   79506篇
  1990年   76065篇
  1989年   74720篇
  1988年   69525篇
  1987年   68219篇
  1986年   65017篇
  1985年   64887篇
  1984年   56633篇
  1983年   51330篇
  1982年   44801篇
  1981年   41944篇
  1980年   39541篇
  1979年   49020篇
  1978年   40988篇
  1977年   36813篇
  1976年   34120篇
  1975年   32884篇
  1974年   35577篇
  1973年   34231篇
  1972年   31736篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
891.
892.
893.
ObjectiveClinical specialty societies recommend long-acting reversible contraceptives (LARCs) as first-line contraception for adolescent women. We evaluated whether a combined educational and process improvement intervention enhanced LARC placement in primary care within an integrated health care system.MethodsThe intervention included journal clubs, live continuing education, point-of-care guidelines, and new patient materials. We conducted a retrospective cohort study across 3 time periods: baseline (January 2013?September 2015), early implementation (October 2015–March 2016), and full implementation (April 2016–June 2017). The primary outcome was the proportion of LARCs placed by primary care clinicians among women aged 13 to 18 years compared with gynecology clinicians.ResultsKaiser Foundation Health Plan of Colorado cared for approximately 20,000 women aged 13 to 18 years in each calendar quarter between 2013 and 2017. Overall, LARC placement increased from 7.0 per 1000 members per quarter at baseline to 13.0 per 1000 during the full intervention. Primary care clinicians placed 6.2% of all LARCs in 2013, increasing to 32.1% by 2017 (P < .001), including 45.5% of contraceptive implants. Clinicians who attended educational sessions were more likely to adopt LARCs than those who did not (17.9% vs 6.4% respectively, P = .009). Neither overall LARC placement rates (relative risk, 1.9; 95% confidence interval, 0.7?5.6) nor contraceptive implant rates (relative risk, 3.0; 95% confidence interval, 0.9?9.8) increased significantly in clinicians who attended educational activities.ConclusionsThis multimodal intervention was associated with increased LARC placement for adolescent women in primary care. The combination of education and process improvement is a promising strategy to promote clinician behavior change.  相似文献   
894.
895.
896.
897.
898.
899.
Understanding the contribution of endothelial cells to the progenitor pools of adult tissues has the potential to inform therapies for human disease.To address whether endothelial cells transdifferentiate into non-vascular cell types,we performed cell lineage tracing analysis using transgenic mice engineered to express a fluorescent marker following activation by tamoxifen in vascular endothelial cadherin promoter-expressing cells(VEcad-CreERT2;B6 Cg-Gt(ROSA)26Sortm9(CAG-tdTomato)Hze).Activation of target-cell labeling following 1.5 months of ad libitum feeding with tamoxifen-laden chow in 4–5 month-old mice resulted in the tracing of central nervous system and peripheral cells that include:cerebellar granule neurons,ependymal cells,skeletal myocytes,pancreatic beta cells,pancreatic acinar cells,tubular cells in the renal cortex,duodenal crypt cells,ileal crypt cells,and hair follicle stem cells.As Nestin expression has been reported in a subset of endothelial cells,Nes-CreERT2 mice were also utilized in these conditions.The tracing of cells in adult Nes-CreERT2 mice revealed the labeling of canonical progeny cell types such as hippocampal and olfactory granule neurons as well as ependymal cells.Interestingly,Nestin tracing also labeled skeletal myocytes,ileal crypt cells,and sparsely marked cerebellar granule neurons.Our findings provide support for endothelial cells as active contributors to adult tissue progenitor pools.This information could be of particular significance for the intravenous delivery of therapeutics to downstream endothelial-derived cellular targets.The animal experiments were approved by the Boise State University Institute Animal Care and Use Committee(approval No.006-AC15-018)on October 31,2018.  相似文献   
900.
ABSTRACT

Abortion is legal in South Africa, but negative abortion attitudes remain common and are poorly understood. We used nationally representative South African Social Attitudes Survey data to analyze abortion attitudes in the case of fetal anomaly and in the case of poverty from 2007 to 2016 (n = 20,711; ages = 16+). We measured correlations between abortion attitudes and these important predictors: religiosity, attitudes about premarital sex, attitudes about preferential hiring and promotion of women, and attitudes toward family gender roles. Abortion acceptability for poverty increased over time (b = 0.05, p < .001), but not for fetal anomaly (b = ?0.008, p = .284). Highly religious South Africans reported lower abortion acceptability in both cases (Odds Ratio (OR)anomaly = 0.85, p = .015; ORpoverty = 0.84, p = .02). Premarital sex acceptability strongly and positively predicted abortion acceptability (ORanomaly = 2.63, p < .001; ORpoverty = 2.46, p < .001). Attitudes about preferential hiring and promotion of women were not associated with abortion attitudes, but favorable attitudes about working mothers were positively associated with abortion acceptability for fetal anomaly ((ORanomaly = 1.09, p = .01; ORpoverty = 1.02, p = .641)). Results suggest negative abortion attitudes remain common in South Africa and are closely tied to religiosity, traditional ideologies about sexuality, and gender role expectations about motherhood.  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