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   54798篇
  免费   1330篇
  国内免费   20篇
  2020年   354篇
  2019年   495篇
  2018年   3988篇
  2017年   3364篇
  2016年   2825篇
  2015年   696篇
  2014年   670篇
  2013年   2964篇
  2012年   1578篇
  2011年   3430篇
  2010年   3124篇
  2009年   2162篇
  2008年   2617篇
  2007年   3065篇
  2006年   912篇
  2005年   965篇
  2004年   881篇
  2003年   852篇
  2002年   725篇
  2001年   1272篇
  2000年   1264篇
  1999年   915篇
  1998年   437篇
  1997年   350篇
  1996年   333篇
  1994年   339篇
  1993年   329篇
  1992年   752篇
  1991年   721篇
  1990年   702篇
  1989年   630篇
  1988年   609篇
  1987年   604篇
  1986年   579篇
  1985年   644篇
  1984年   506篇
  1983年   404篇
  1982年   329篇
  1979年   489篇
  1978年   375篇
  1977年   351篇
  1976年   338篇
  1975年   449篇
  1974年   451篇
  1973年   502篇
  1972年   405篇
  1969年   339篇
  1968年   392篇
  1967年   343篇
  1966年   392篇
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
31.
32.
Although perceived health risk plays a prominent role in theories of health behavior, its empirical role in risk taking is less clear. In Study 1 (N = 129), 2 measures of drivers' risk-taking behavior were found to be unrelated to self-estimates of accident concern but to be related to self-ratings of driving skill and the perceived thrill of driving. In Study 2 (N = 405), out of a wide range of potential influences, accident concern had the weakest relationship with risk taking. The authors concluded that although health risk is a key feature in many theories of health behavior and a central focus for researchers and policy makers, it may not be such a prominent factor for those actually taking the risk.  相似文献   
33.
34.
35.
OBJECTIVE: This report reviews the evidence that informs the role of health and mental health care providers in addressing youth smoking cessation. DESIGN: Qualitative literature review. RESULTS: Physicians do not consistently screen adolescents for tobacco use and fail to provide recommended cessation advice. Challenges to addressing smoking cessation include the need for procedures to ensure confidentiality and the existence of competing demands to provide other services. Few published studies have specifically addressed the effectiveness of clinical interventions. Interventions that require return visits or follow-up phone contacts are technically difficult to implement in this population. Successful interventions may require resources not available in nonresearch settings. Most studies have used brief clinical intervention as a control condition, making it impossible to evaluate its effectiveness. CONCLUSION: There is little evidence that supports current clinical smoking cessation guidelines for adolescents. More research is needed to develop inexpensive, efficient clinical interventions that can provide youths access to smoking cessation help. Future challenges include reorganizing clinical systems to offer greater counseling by support staff or in electronic formats and to provide effective booster messages and follow-up care in a population that is difficult to track.  相似文献   
36.
An electronic apparatus using infrared beams for monitoring the movements of individual bees under dark conditions is described. The searching behavior of workers in an arena was monitored over 2-h periods. Mean ambulatory velocity for one bee over a distance of 100 mm was 45.6±1.51 mm/sec (n=45). Thigmokinesis and temporal activity patterns are illustrated.  相似文献   
37.
38.
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