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   62110篇
  免费   2443篇
  国内免费   25篇
  2020年   594篇
  2019年   829篇
  2018年   1101篇
  2017年   1181篇
  2016年   1146篇
  2015年   834篇
  2014年   989篇
  2013年   4792篇
  2012年   1789篇
  2011年   1934篇
  2010年   1221篇
  2009年   1217篇
  2008年   1744篇
  2007年   1654篇
  2006年   1569篇
  2005年   1376篇
  2004年   1294篇
  2003年   1255篇
  2002年   1259篇
  2001年   2031篇
  2000年   1918篇
  1999年   1444篇
  1998年   727篇
  1997年   596篇
  1992年   1196篇
  1991年   1152篇
  1990年   1108篇
  1989年   1071篇
  1988年   1047篇
  1987年   1006篇
  1986年   1006篇
  1985年   1097篇
  1984年   886篇
  1983年   772篇
  1982年   621篇
  1981年   603篇
  1979年   950篇
  1978年   698篇
  1977年   622篇
  1976年   642篇
  1975年   817篇
  1974年   863篇
  1973年   942篇
  1972年   756篇
  1971年   666篇
  1970年   655篇
  1969年   693篇
  1968年   839篇
  1967年   725篇
  1966年   773篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
55.
56.
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   
57.
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   
58.
59.
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   
60.
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