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   95929篇
  免费   29183篇
  国内免费   1061篇
耳鼻咽喉   2384篇
儿科学   2560篇
妇产科学   2273篇
基础医学   2397篇
口腔科学   5045篇
临床医学   25775篇
内科学   24068篇
皮肤病学   3279篇
神经病学   12074篇
特种医学   3526篇
外科学   17436篇
综合类   113篇
现状与发展   40篇
一般理论   1篇
预防医学   13299篇
眼科学   2115篇
药学   1015篇
中国医学   10篇
肿瘤学   8763篇
  2024年   741篇
  2023年   5027篇
  2022年   1103篇
  2021年   2691篇
  2020年   5295篇
  2019年   1959篇
  2018年   6833篇
  2017年   7292篇
  2016年   7866篇
  2015年   7978篇
  2014年   10320篇
  2013年   12002篇
  2012年   3613篇
  2011年   3362篇
  2010年   6707篇
  2009年   8993篇
  2008年   3350篇
  2007年   2250篇
  2006年   3451篇
  2005年   2019篇
  2004年   1406篇
  2003年   1078篇
  2002年   1008篇
  2001年   1789篇
  2000年   1116篇
  1999年   1658篇
  1998年   2056篇
  1997年   1887篇
  1996年   1938篇
  1995年   1679篇
  1994年   1075篇
  1993年   905篇
  1992年   733篇
  1991年   617篇
  1990年   497篇
  1989年   509篇
  1988年   493篇
  1987年   369篇
  1986年   347篇
  1985年   294篇
  1984年   246篇
  1983年   295篇
  1982年   223篇
  1981年   197篇
  1980年   120篇
  1978年   120篇
  1977年   115篇
  1976年   83篇
  1974年   73篇
  1972年   73篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Using an earlier model, which described the critical contact angle for binding from second-order angulation alone, a more generalized model is derived that combines the effects of angulation and torque. From this vantage point, the onset of binding is evaluated for 3 scenarios: second-order angulation alone, third-order torque only, and a combination of second-order angulation and third-order torque. These scenarios are detailed by plotting the critical contact angle for binding against the torque angle as a function of 10 wire dimensions (16 x 16, 16 x 22, 17 x 17, 17 x 22, 17 x 25, 18 x 18, 18 x 22, 18 x 25, 19 x 25, and 21 x 25 mil), 4 bracket widths (70, 100, 130, and 160 mil), and 4 bracket slots (18, 20.5, 22, and 24.5 mil). From these plots, we learn that each wire base dimension (eg, an 18-mil base as found in 18 x 18-mil, 18 x 22-mil and 18 x 25-mil archwires) has a common maximum critical contact angle for binding. Moreover, each wire-slot combination has a common maximum torque angle, which is independent of bracket width. Finally, we learn that archwire-bracket combinations that use a metric 0.5-mm slot might have some advantages with regard to torquing--given the current philosophy that light, continuous forces are more favorable.  相似文献   
32.
33.
34.
The alphavbeta6 integrin is an exclusively epithelial integrin that is highly expressed during fetal development. In adult tissue, alphavbeta6 integrin is expressed during inflammation, carcinogenesis, and in wound healing. We previously reported that alphavbeta6 integrin is highly expressed in poorly healing human wounds and its over-expression is associated with chronic wounds in a mouse model. The objective of this study was to investigate the role of alphavbeta6 integrin in compromised wound healing induced by hydrocortisone treatment or aging by using young and old mice deficient in or overexpressing the beta6 integrin subunit in the epidermis. Untreated aged beta6 integrin-deficient (beta6-/-) animals showed a significant delay in wound healing when compared to their age-matched controls or younger beta6-/- mice. The most significant delay was observed at the stages where granulation tissue deposition was occurring. Hydrocortisone treatment significantly delayed wound healing in wild-type and beta6 integrin-deficient mice in comparison with the untreated controls. However, hydrocortisone treatment in beta6 integrin overexpressing animals did not cause a significant delay in wound healing. The results of this study suggest that alphavbeta6 integrin plays an important role in wound healing in animals compromised by either age or stress mimicked by hydrocortisone.  相似文献   
35.
36.
37.
PROBLEM: Recent developments in providing care to children with emotional and behavioral disorders, especially those with serious emotional disturbance, have included the establishment of systems of care. Guided by a set of principles and values, these systems of care have organized and delivered services to children and families with complex needs. To date, nurses have not had a salient role in systems of care. RESULTS: It is estimated that 20% of American children and adolescents have an emotional or mental disorder. As many as two thirds of these children are not receiving services. Systems of care have been funded to provide services for these children, particularly for the most severely affected. To date, nursing has not had a prominent role in these systems of care. CONCLUSIONS: Based on their knowledge, skills, and holistic approach to care, nurses could better integrate nursing care into systems of care. Possible roles as case managers, primary therapists, in-home interventionists, and in educational programs are suggested.  相似文献   
38.
Recent New Labour policy for the ‘modernisation’ of Government places a good deal of emphasis on decentralisation. This emphasis is particularly marked in relation to the organisation of primary care. However, like hospitals and other National Health Service institutions, primary care trusts (PCTs) are subject to a substantial raft of centrally established performance targets and indicators, including those which contribute to the public award of between zero and three performance ‘stars’. This raises questions about the extent to which employees can exercise autonomy in the context of rigid top‐down directives. This paper presents findings from a study using participant observation and interviews to examine the impact of a training course aimed ostensibly at increasing employee autonomy in an English PCT. The suggestion is that attempts to make employees more autonomous can be seen as a strategy for increasing central control based upon the internalisation by the employees of centrally promulgated values. The attraction of such strategies is that they may be potentially more effective and less costly than alternative strategies of direct control. However, the study suggests that the outcome of attempts by such methods as programmes to increase employee autonomy may be very different from those intended.  相似文献   
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