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   72395篇
  免费   2181篇
  国内免费   30篇
  74606篇
  2020年   554篇
  2019年   757篇
  2018年   4190篇
  2017年   3611篇
  2016年   3136篇
  2015年   988篇
  2014年   975篇
  2013年   4481篇
  2012年   2085篇
  2011年   3884篇
  2010年   3363篇
  2009年   2418篇
  2008年   3006篇
  2007年   3396篇
  2006年   1322篇
  2005年   1341篇
  2004年   1234篇
  2003年   1203篇
  2002年   1115篇
  2001年   1864篇
  2000年   1825篇
  1999年   1310篇
  1998年   615篇
  1997年   526篇
  1996年   521篇
  1992年   1102篇
  1991年   1062篇
  1990年   1022篇
  1989年   955篇
  1988年   946篇
  1987年   915篇
  1986年   895篇
  1985年   961篇
  1984年   770篇
  1983年   642篇
  1981年   493篇
  1979年   788篇
  1978年   577篇
  1977年   525篇
  1976年   501篇
  1975年   659篇
  1974年   745篇
  1973年   799篇
  1972年   642篇
  1971年   581篇
  1970年   555篇
  1969年   553篇
  1968年   697篇
  1967年   618篇
  1966年   638篇
排序方式: 共有10000条查询结果,搜索用时 15 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.
This study evaluated cardiovascular responses (CVR) to an active speech task with blatantly discriminatory (BRC) versus neutral (NRC) stimuli and an anger recall task in a sample of Black men (N = 73; age 18 to 47). Diastolic blood pressure scores were higher for NRC versus BRC stimuli during anger recall (p = .05). Moreover, persons in the NRC group who perceived high levels of racism (vs. no racism or BRC group) during active speech showed larger increases in blood pressure across postspeech rest, anger recall, and subsequent rest (p = .03). The notable elevation in CVR in response to an ambiguous event extends current models of racism suggesting that subtle racism is a psychosocial stressor that erodes health through chronically elevated CVR.  相似文献   
34.
35.
36.
37.
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   
38.
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   
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