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   171677篇
  免费   7814篇
  国内免费   158篇
  2021年   1507篇
  2020年   2805篇
  2019年   3437篇
  2018年   3540篇
  2017年   3960篇
  2016年   4625篇
  2015年   3954篇
  2014年   4830篇
  2013年   23555篇
  2012年   4514篇
  2011年   3624篇
  2010年   3881篇
  2009年   4783篇
  2008年   3827篇
  2007年   3421篇
  2006年   4009篇
  2005年   3952篇
  2004年   3464篇
  2003年   3122篇
  2002年   2894篇
  2001年   3277篇
  2000年   3189篇
  1999年   3148篇
  1998年   2839篇
  1997年   2671篇
  1996年   2586篇
  1995年   2416篇
  1994年   2383篇
  1993年   2340篇
  1992年   2596篇
  1991年   2446篇
  1990年   2292篇
  1989年   2203篇
  1988年   2162篇
  1987年   2167篇
  1986年   2153篇
  1985年   2402篇
  1984年   2519篇
  1983年   2289篇
  1982年   2349篇
  1981年   2324篇
  1980年   2177篇
  1979年   2160篇
  1978年   2159篇
  1977年   2142篇
  1976年   1915篇
  1975年   1982篇
  1974年   2035篇
  1973年   1886篇
  1972年   1468篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
191.
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   
192.
193.
By roughly 6 years of age, children acquire the stereotype that men are more competent than women in science, technology, engineering, and mathematics (STEM), potentially leading to greater trust in scientific information provided by men. This study tested whether 3- to 8-year-old children differentially endorsed conflicting information about science and toys presented by male and female informants depicted as a ‘man’ and ‘woman’ (Exp1) or ‘scientists’ (Exp2). Children were expected to endorse toy testimony from gender-matched informants; thus, the key question concerned endorsement of science testimony. In Exp1 (N = 149), boys and girls showed a same-gender informant preference for toy testimony; however, girls endorsed the male informant's testimony more for science than for toys – but only when tested by a male experimenter. In Exp2 (N = 264), boys and girls showed a same-gender preference, irrespective of content. Findings suggest that STEM-related gender stereotypes might lead girls to trust scientific information presented by men over women in certain contexts.  相似文献   
194.
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   
195.
196.
197.
198.
199.
陈莲笙道长生于1917年10月25日,上海市人.历任中国道教协会副会长,中国道教协会顾问,上海市道教协会会长.上海市道教协会名誉会长,上海城隍庙住持,上海道学院院长,<上海道教>杂志主编,上海市宗教学会理事,上海市政协第七届委员,上海市政协第八、九届常委等职.  相似文献   
200.
This study addresses the demands of alternating bimanual syncopation, a coordination mode in which the two hands move in alternation while tapping in antiphase with a metronomic tone sequence. Musically trained participants were required to engage in alternating bimanual syncopation and five other coordination modes: unimanual syncopation where taps are made (with the left or right hand) after every tone; unimanual syncopation where taps are made after every other tone; bimanual synchronization with alternating hands; unimanual synchronized tapping with every tone; and unimanual tapping with every other tone. Variability in tap timing was greatest overall for alternating bimanual syncopation, indicating that it is the most difficult. This appears to be due to instability arising from the simultaneous presence of two levels of antiphase coordination (one between the pacing sequence and the hands, the other between the two hands) rather than factors relating to movement frequency or dexterity limits of the nonpreferred hand.  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