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   52488篇
  免费   1473篇
  国内免费   26篇
  2020年   381篇
  2019年   489篇
  2018年   3984篇
  2017年   3315篇
  2016年   2873篇
  2015年   653篇
  2014年   651篇
  2013年   2666篇
  2012年   1620篇
  2011年   3377篇
  2010年   3067篇
  2009年   2158篇
  2008年   2565篇
  2007年   3025篇
  2006年   844篇
  2005年   933篇
  2004年   873篇
  2003年   741篇
  2002年   726篇
  2001年   1110篇
  2000年   1123篇
  1999年   810篇
  1998年   360篇
  1997年   345篇
  1996年   312篇
  1995年   330篇
  1992年   646篇
  1991年   598篇
  1990年   581篇
  1989年   551篇
  1988年   550篇
  1987年   496篇
  1986年   491篇
  1985年   544篇
  1984年   450篇
  1983年   411篇
  1982年   320篇
  1979年   483篇
  1978年   342篇
  1976年   333篇
  1975年   375篇
  1974年   444篇
  1973年   480篇
  1972年   413篇
  1971年   359篇
  1970年   322篇
  1969年   343篇
  1968年   422篇
  1967年   378篇
  1966年   363篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
22.
Brain mapping studies using dynamic imaging methods demonstrate areas regional cerebral blood flow (rCBF) decreases, as well as areas where increases, during performance of various experimental tasks. Task holds for both sets of cerebral blood flow changes (CBF), providing the opportunity to investigate areas that become and “activated” in the experimental condition relative to control state. Such data yield the intriguing observation that in areas in emotional processing, such as the amygdala, the posteromedial cortex, and the ventral anterior cingulate cortex, although flow as expected during specific emotion-related tasks, flow decreases performance of some attentionally demanding, cognitive tasks. Conversely, in some of the areas that appear to subserve cognitive functions, as the dorsal anterior cingulate and the dorsolateral prefrontal cortices, increases while performing attentionally demanding cognitive tasks, but during some experimentally induced and pathological emotional Although the specific nature of such reciprocal patterns of regional remains unclear, they may reflect an important cross-modal interaction during mental operations. The possibility that neural activity is less in areas required in emotional processing during some higher cognitive processes holds implications for the mechanisms underlying interactions cognition and emotion. Furthermore, the possibility that neural in some cognitive-processing areas is suppressed during intense states suggests mechanisms by which extreme fear or severe may interfere with cognitive performance.  相似文献   
23.
24.
25.
It is widely assumed that reinforcers are biologically relevant stimuli, or stimuli that have been associated with biologically relevant stimuli. However, brief, arbitrary stimuli have also been reported to have reinforcement-like effects, despite being unrelated to biologically relevant stimuli like food. The present study explored the potential reinforcement-like effects of brief stimuli across 5 experiments. In Experiments 1 through 4, pigeon subjects responded for food reinforcement and brief stimulus presentations in a 2-component multiple schedule. Neither baseline response rates nor resistance to change during disruption tests were systematically greater in a component with versus without brief stimulus presentations. Increasing the rate and duration of brief stimulus presentations in Experiment 4 did not reveal reinforcement-like effects when compared directly with food. In Experiment 5, pigeons chose between independent terminal links in a concurrent-chains procedure. Across conditions, varying the location, duration, and rate of brief stimulus presentations in the terminal links had no systematic effects on preference. In contrast, varying rates of food reinforcers resulted in large and reliable shifts in preference. Therefore, the present study found no systematic evidence that brief stimuli unrelated to food reliably increase response rates, resistance to change, or preference. These data demonstrate the value of systematic replication, and a behavioral momentum approach to assessing potential reinforcement-like effects.  相似文献   
26.
27.
Early explications of family communication patterns (FCP) suggested that a family's communication pattern arises as a result of interactions in which parents and adolescents influence each other. In contrast, empirical research usually treats FCP as parent‐imposed norms that influence socialization outcomes in adolescents, without testing whether adolescents' socialization influences FCP. This study revisits the assumption that adolescents influence FCP, using data from a longitudinal quasi‐experimental evaluation of a school‐based civics curriculum intervention (N = 313 parent‐adolescent pairs). Results show that the intervention‐stimulated adolescents to initiate discussion of politics at home and that these adolescent‐initiated discussions influenced adolescents' and parents' perceptions of FCP 6 months later.  相似文献   
28.
29.
30.
Intention is theorized as the proximal determinant of behavior in some theories of motivation, but the need to understand predictors of action control (i.e., translating an intention into behavior) is warranted to tailor physical activity intervention efforts. The purpose of this study was to examine constructs of the transtheoretical model of behavior change (TTM) as predictors of physical activity intention-behavior profiles across 6 months in a large Canadian sample (N = 1,192). Results showed that 5 of the 8 possible intention-behavior profiles had a substantial number of participants: nonintenders, unsuccessful adopters, successful adopters, unsuccessful maintainers, and successful maintainers. Constructs of the TTM distinguished (p < .01) intention-behavior profiles. Self-efficacy and the behavioral processes of change were particularly good predictors of action control (p < .01), but disaggregated beliefs and processes identified specific intervention targets for successful physical activity adoption and maintenance. The results validate that both action planning and action control are important when understanding physical activity behavior.  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