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   26440篇
  免费   2216篇
  国内免费   86篇
耳鼻咽喉   349篇
儿科学   602篇
妇产科学   543篇
基础医学   3681篇
口腔科学   775篇
临床医学   3041篇
内科学   5351篇
皮肤病学   251篇
神经病学   2919篇
特种医学   982篇
外国民族医学   2篇
外科学   3258篇
综合类   363篇
一般理论   24篇
预防医学   2095篇
眼科学   512篇
药学   2183篇
中国医学   27篇
肿瘤学   1784篇
  2023年   95篇
  2022年   163篇
  2021年   421篇
  2020年   290篇
  2019年   436篇
  2018年   486篇
  2017年   454篇
  2016年   513篇
  2015年   625篇
  2014年   816篇
  2013年   1204篇
  2012年   1707篇
  2011年   1848篇
  2010年   1155篇
  2009年   971篇
  2008年   1755篇
  2007年   1707篇
  2006年   1685篇
  2005年   1786篇
  2004年   1627篇
  2003年   1612篇
  2002年   1513篇
  2001年   335篇
  2000年   269篇
  1999年   337篇
  1998年   397篇
  1997年   287篇
  1996年   280篇
  1995年   264篇
  1994年   217篇
  1993年   189篇
  1992年   181篇
  1991年   163篇
  1990年   152篇
  1989年   154篇
  1988年   151篇
  1987年   144篇
  1986年   152篇
  1985年   149篇
  1984年   168篇
  1983年   165篇
  1982年   204篇
  1981年   178篇
  1980年   191篇
  1979年   101篇
  1978年   125篇
  1977年   119篇
  1976年   87篇
  1975年   92篇
  1974年   74篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Nidogen 1 (NID1) is a glycoprotein found in basement membranes involved in cross-linking collagen IV and laminin. The role of NID in breast cancer has only been evaluated in a small number of studies and the findings of these studies have been inconsistent. Our previous work revealed that highly tumorigenic murine mammary tumor cells express high levels of Nid1 while weakly tumorigenic mammary tumor cells express low levels of Nid1. To investigate Nid1, two stable knockdown lines were created, and Nid1 knockdown was confirmed at both the mRNA and protein level. Nid1 knockdown significantly reduced cell proliferation and migration/invasion and these reductions in proliferation and migration/invasion could be rescued by conditioned media containing NID1 protein. The reduced migration/invasion observed in the Nid1 knockdown cells was not associated with significant alterations in the epithelial gene Cdh1 or the mesenchymal genes Snai1, Snai2, Twist1, Twist2, Zeb1 and Zeb2. Therefore, suppression of Nid1 expression reduces proliferation and migration/invasion in claudin-low murine mammary tumor cells.  相似文献   
2.
3.
4.
ObjectivesTo fill an empirical gap in the literature by examining changes in quality of care measures occurring when multispecialty clinic systems were acquired by hospital-owned, vertically integrated health care delivery systems in the Twin Cities area.ConclusionsMoving a clinic system into a vertically integrated delivery system resulted in limited increases in quality of care indicators. Caution is warranted when the acquisition causes disruption in referral patterns.  相似文献   
5.
6.

Objective

Successful weight loss interventions for African-Americans adolescents are lacking. Cognitive-behavioral interventions seek to develop weight loss skills (e.g., counting calories, goal setting, managing one's environment). Little is known about how well adolescents implement such skills in their daily lives. Study aims were to (1) examine weight loss skills utilization at midpoint and end of a 6-month cognitive-behavioral/motivational interviewing weight loss sequential multiple assignment randomized trial (SMART), and (2) determine if greater skill utilization predicted weight loss at treatment end and 3 months post-treatment.

Method

One hundred and eighty six African-Americans adolescents with obesity and their caregiver were first randomly assigned to complete 3 months of cognitive-behavioral and motivational interviewing family-based weight loss treatment in their home or in the research office (Phase 1). Nonresponders (i.e., those who lost < 3% of initial weight, n?=?161) were rerandomized to 3 months of continued skills training (n?=?83) or contingency management (n?=?78) for Phase 2; responders were allocated to 3 months of relapse prevention (n?=?20). Adolescents’ frequency of weight loss skills utilization was assessed via questionnaire at treatment midpoint and end.

Results

Higher treatment attendance was associated with better skill utilization. Higher skill utilization was associated with more weight loss at treatment end, whereas higher baseline confidence was associated with more weight loss at follow-up.

Conclusions

This study indicates the importance of attending weight loss intervention sessions to develop and strengthen weight loss skills in African-American adolescents with obesity, and strengthening confidence to use such skills for continued weight loss.  相似文献   
7.
8.
9.
10.
Development of the Practical Solutions for Pesticide Safety guide used participatory research strategies to identify and evaluate solutions that reduce pesticide exposures for workers and their families and to disseminate these solutions. Project principles were (1) workplace chemicals belong in the workplace, and (2) pesticide handlers and farm managers are experts, with direct knowledge of production practices. The project’s participatory methods were grounded in self-determination theory. Practical solutions were identified and evaluated based on five criteria: practicality, adaptability, health and safety, novelty, and regulatory compliance. Research activities that had more personal contact provided better outcomes. The Expert Working Group, composed of farm managers and pesticide handlers, was key to the identification of solutions, as were farm site visits. Audience participation, hands-on testing, and orchard field trials were particularly effective in the evaluation of potential solutions. Small work groups in a Regional Advisory Committee provided the best direction and guidance for a “user-friendly” translational document that provided evidence-based practical solutions. The “farmer to farmer” format of the guide was endorsed by both the Expert Working Group and the Regional Advisory Committee. Managers and pesticide handlers wanted to share their solutions in order to “help others stay safe,” and they appreciated attribution in the guide. The guide is now being used in educational programs across the region. The fundamental concept that farmers and farmworkers are innovators and experts in agricultural production was affirmed by this study. The success of this process demonstrates the value of participatory industrial hygiene in agriculture.  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