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   62345篇
  免费   2352篇
  国内免费   26篇
  2020年   689篇
  2019年   810篇
  2018年   1104篇
  2017年   1202篇
  2016年   1270篇
  2015年   914篇
  2014年   1093篇
  2013年   4906篇
  2012年   1922篇
  2011年   1947篇
  2010年   1244篇
  2009年   1222篇
  2008年   1764篇
  2007年   1721篇
  2006年   1500篇
  2005年   1365篇
  2004年   1299篇
  2003年   1258篇
  2002年   1263篇
  2001年   1761篇
  2000年   1728篇
  1999年   1288篇
  1998年   619篇
  1997年   603篇
  1992年   1139篇
  1991年   1037篇
  1990年   1100篇
  1989年   1001篇
  1988年   988篇
  1987年   961篇
  1986年   1000篇
  1985年   968篇
  1984年   873篇
  1983年   810篇
  1982年   598篇
  1981年   617篇
  1979年   953篇
  1978年   686篇
  1977年   604篇
  1976年   573篇
  1975年   822篇
  1974年   906篇
  1973年   943篇
  1972年   760篇
  1971年   753篇
  1970年   698篇
  1969年   755篇
  1968年   895篇
  1967年   842篇
  1966年   764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.
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   
56.
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   
57.
Previous work on children's intuitive knowledge about the natural world has documented their difficulty in acquiring an overarching concept of biological life that includes plants as well as humans and non‐human animals. It has also suggested that the acquisition of fundamental biological concepts like alive and die may be influenced by the language used to describe them, as evidenced by differences between English‐ and Indonesian‐speaking children's performance in tasks involving these concepts. Here, we examine one particularly important source of linguistic information available to children during this acquisition process: everyday conversations with their parents. We take a cross‐linguistic approach in analysing the evidence available to English‐ and Indonesian‐speaking children as they acquire meanings for words corresponding to the concepts alive and die . Our analysis illustrates that young children acquiring English and Indonesian are faced with distinct problems, but that parental input in both languages does little to support the acquisition of broad, inclusive biological concepts.  相似文献   
58.
The current study was designed to gain a better understanding of the nature of the relationship between substance use and sexual risk taking within a community sample of women (N = 1,004). Using confirmatory factor analysis, the authors examined the factor structure of sexual risk behaviors and substance use to determine whether they are best conceptualized as domains underlying a single, higher order, risk-taking propensity. A 2 higher order factor model (sexual risk behavior and substance use) provided the best fit to the data, suggesting that these 2 general risk domains are correlated but independent factors. Sensation seeking had large general direct effects on the 2 risk domains and large indirect effects on the 4 first-order factors and the individual indicators. Negative affect had smaller, yet still significant, effects. Impulsivity and anxiety were unrelated to sexual health risk domains.  相似文献   
59.
60.
The purpose of this study was to examine speech convergence and speech evaluation in fact-finding interviews conducted in the field. Forty interviewers (ERs), undergraduates enrolled in a class on interviewing processes, conducted 20–30 minute interviews with selected interviewees (EEs), business persons and professionals in fields of interest to the ERs. Speech behaviors examined included response latency, speech rate, and turn duration; these were coded per one minute intervals of each interaction. Time series regression procedures indicated that both ERs and EEs converged speech rate and response latency toward their interlocutors' performances of these behaviors. Although turn duration convergence did not characterize the entire data set, male-male dyads did converge significantly and male (ER)-female (EE) dyads significantly diverged turn duration. Regarding speech evaluation, there was some evidence that greater response latency similarity, greater speech rate and response latency convergence, and faster ER speech and slower EE speech were positively related to the competence and social attractiveness judgments of participants. Limitations and implications are discussed.  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