全文获取类型
收费全文 | 1270567篇 |
免费 | 94993篇 |
国内免费 | 1625篇 |
专业分类
耳鼻咽喉 | 16387篇 |
儿科学 | 41129篇 |
妇产科学 | 35220篇 |
基础医学 | 190219篇 |
口腔科学 | 34848篇 |
临床医学 | 118359篇 |
内科学 | 249311篇 |
皮肤病学 | 27377篇 |
神经病学 | 102424篇 |
特种医学 | 46977篇 |
外国民族医学 | 265篇 |
外科学 | 179587篇 |
综合类 | 25778篇 |
现状与发展 | 3篇 |
一般理论 | 572篇 |
预防医学 | 104983篇 |
眼科学 | 28209篇 |
药学 | 93045篇 |
6篇 | |
中国医学 | 2041篇 |
肿瘤学 | 70445篇 |
出版年
2018年 | 13728篇 |
2017年 | 10550篇 |
2016年 | 11494篇 |
2015年 | 13255篇 |
2014年 | 18232篇 |
2013年 | 27811篇 |
2012年 | 38065篇 |
2011年 | 40455篇 |
2010年 | 23355篇 |
2009年 | 22495篇 |
2008年 | 38148篇 |
2007年 | 40771篇 |
2006年 | 40350篇 |
2005年 | 39472篇 |
2004年 | 37893篇 |
2003年 | 36260篇 |
2002年 | 35112篇 |
2001年 | 56123篇 |
2000年 | 57119篇 |
1999年 | 48165篇 |
1998年 | 13445篇 |
1997年 | 12255篇 |
1996年 | 12682篇 |
1995年 | 11952篇 |
1994年 | 11148篇 |
1993年 | 10431篇 |
1992年 | 38245篇 |
1991年 | 37699篇 |
1990年 | 36480篇 |
1989年 | 35300篇 |
1988年 | 32719篇 |
1987年 | 32055篇 |
1986年 | 30536篇 |
1985年 | 28806篇 |
1984年 | 21962篇 |
1983年 | 19200篇 |
1982年 | 11372篇 |
1981年 | 10335篇 |
1979年 | 20961篇 |
1978年 | 15405篇 |
1977年 | 12796篇 |
1976年 | 11851篇 |
1975年 | 12816篇 |
1974年 | 15596篇 |
1973年 | 15368篇 |
1972年 | 14518篇 |
1971年 | 13564篇 |
1970年 | 12795篇 |
1969年 | 12078篇 |
1968年 | 11238篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
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
102.
103.
104.
105.
106.
107.
The association between family affluence and smoking among 15‐year‐old adolescents in 33 European countries,Israel and Canada: the role of national wealth
下载免费PDF全文
![点击此处可从《Addiction (Abingdon, England)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
108.
109.
110.
Stuart J. Dilley Tracey J. Weiland Robert O’Brien Neil J. Cunningham Julian E. Van Dijk Rosie M. Mahoney 《Teaching and learning in medicine》2015,27(1):71-79
Theory: Immersive simulation is a common mode of education for medical students. Observation of clinical simulations prior to participation is believed to be beneficial, though this is often a passive process. Active observation may be more beneficial. Hypotheses: The hypothesis tested in this study was that the active use of a simple checklist during observation of an immersive simulation would result in better participant performance in a subsequent scenario compared with passive observation alone. Methods: Medical students were randomized to either passive or active (with checklist) observation of an immersive simulation involving cardiac arrest prior to participating in their own simulation. Performance measures included time to cardiopulmonary resuscitation (CPR) and time to defibrillation and were compared between first and second scenarios as well as between passive and active observers. Results: Seventy-nine simulations involving 232 students were conducted. Mean time to CPR was 18 seconds (SD = 11.6) for those using the checklist and 24 seconds (SD = 15.8) for those who observed passively (M difference = 6 seconds), t(35) = 1.46, p =.153. Time to defibrillation was 94 seconds (SD = 26.4) for those using the checklist and 92 seconds (SD = 23.8) for those who observed passively (M difference = –2 seconds), t(38) =.21, p =.837. Time to CPR was 24 seconds (SD = 15.8) for passive observers and 31 seconds (SD = 21.0; M difference = 7 seconds), t(35) = 1.13, p =.265, for their first scenario counterparts. Time to CPR was 18 seconds (SD = 11.6) for active observers and 36 seconds (SD = 26.2; M difference = 18 seconds), t(24) = 2.81, p =.010, for their first scenario counterparts. Time to defibrillation was 92 seconds (SD = 23.8) for passive observers and 125 seconds (SD = 32.2; M difference = 33 seconds), t(33) = 3.63, p =.001, for their first scenario counterparts. Time to defibrillation was 94 seconds (SD = 26.4) for the active observers and 132 seconds (SD = 52.9; M difference = 38 seconds), t(28) =.46, p =.008, for their first scenario counterparts. Conclusions: Observation alone leads to improved performance in the management of a simulated cardiac arrest. The active use of a simple skills-based checklist during observation did not appear to improve performance over passive observation alone. 相似文献