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   2652篇
  免费   194篇
  2846篇
  2024年   8篇
  2023年   31篇
  2022年   50篇
  2021年   77篇
  2020年   113篇
  2019年   127篇
  2018年   176篇
  2017年   173篇
  2016年   146篇
  2015年   113篇
  2014年   117篇
  2013年   296篇
  2012年   189篇
  2011年   179篇
  2010年   91篇
  2009年   106篇
  2008年   131篇
  2007年   132篇
  2006年   97篇
  2005年   78篇
  2004年   77篇
  2003年   50篇
  2002年   53篇
  2001年   23篇
  2000年   14篇
  1999年   21篇
  1998年   20篇
  1997年   12篇
  1996年   10篇
  1995年   8篇
  1994年   11篇
  1993年   12篇
  1992年   8篇
  1991年   9篇
  1990年   10篇
  1989年   8篇
  1988年   5篇
  1987年   6篇
  1986年   9篇
  1985年   5篇
  1984年   6篇
  1983年   5篇
  1982年   11篇
  1981年   3篇
  1980年   4篇
  1979年   3篇
  1978年   2篇
  1977年   2篇
  1974年   3篇
  1972年   2篇
排序方式: 共有2846条查询结果,搜索用时 15 毫秒
941.
It has long been understood that food deliveries may act as signals of future food location, and not only as strengtheners of prefood responding as the law of effect suggests. Recent research has taken this idea further—the main effect of food deliveries, or other “reinforcers”, may be signaling rather than strengthening. The present experiment investigated the ability of food deliveries to signal food contingencies across time after food. In Phase 1, the next food delivery was always equally likely to be arranged for a left‐ or a right‐key response. Conditions were arranged such that the next food delivery was likely to occur either sooner on the left (or right) key, or sooner on the just‐productive (or not‐just‐productive) key. In Phase 2, similar contingencies were arranged, but the last‐food location was signaled by a red keylight. Preference, measured in 2‐s bins across interfood intervals, was jointly controlled by the likely time and location of the next food delivery. In Phase 1, when any food delivery signaled a likely sooner next food delivery on a particular key, postfood preference was strongly toward that key, and moved toward the other key across the interreinforcer interval. In other conditions in which food delivery on the two keys signaled different subsequent contingencies, postfood preference was less extreme, and quickly moved toward indifference. In Phase 2, in all three conditions, initial preference was strongly toward the likely‐sooner food key, and moved to the other key across the interfood interval. In both phases, at a more extended level of analysis, sequences of same‐key food deliveries caused a small increase in preference for the just‐productive key, suggesting the presence of a “reinforcement effect”, albeit one that was very small.  相似文献   
942.
Many studies have examined the accuracy of predictions of future memory performance solicited through judgments of learning (JOLs). Among the most robust findings in this literature is that delaying predictions serves to substantially increase the relative accuracy of JOLs compared with soliciting JOLs immediately after study, a finding termed the delayed JOL effect. The meta-analyses reported in the current study examined the predominant theoretical accounts as well as potential moderators of the delayed JOL effect. The first meta-analysis examined the relative accuracy of delayed compared with immediate JOLs across 4,554 participants (112 effect sizes) through gamma correlations between JOLs and memory accuracy. Those data showed that delaying JOLs leads to robust benefits to relative accuracy (g = 0.93). The second meta-analysis examined memory performance for delayed compared with immediate JOLs across 3,807 participants (98 effect sizes). Those data showed that delayed JOLs result in a modest but reliable benefit for memory performance relative to immediate JOLs (g = 0.08). Findings from these meta-analyses are well accommodated by theories suggesting that delayed JOL accuracy reflects access to more diagnostic information from long-term memory rather than being a by-product of a retrieval opportunity. However, these data also suggest that theories proposing that the delayed JOL effect results from a memorial benefit or the match between the cues available for JOLs and those available at test may also provide viable explanatory mechanisms necessary for a comprehensive account.  相似文献   
943.
944.
Previous research has linked higher levels of hopelessness about one's future to violent behavior during adolescence; however, little is known about this relationship over time for adolescents. Using growth curve modeling, we tested the association between future orientation and violent behavior across the high school years of adolescence in a sample of African American youth (n = 681). Variation based on demographic characteristics (i.e., sex, SES, previous violence) was explored. At baseline, differences in violent behavior varied by demographic characteristics. Overall, violent behavior decreased with age. Higher levels of future orientation were associated with greater decreases in violent behavior over time. Demographic characteristics were not associated with change in violent behavior overtime. Our findings suggest that future orientation can act as a promotive factor for at risk African American youth. Interventions that help support the development of future goals and aspirations could play a vital role in violence prevention efforts.  相似文献   
945.
In much of the youth empowerment literature, researchers focus on the relationship between youth and adults involved in empowerment programs while neglecting the broader social framework in which these relationships and the program itself functions. Utilizing an ecological model, the current research examines the tensions that surfaced in attempts to create an empowering setting in an after-school PAR program with fifth-graders. Challenging assumptions about youth, structural challenges, and conflicting theories of change are highlighted. Results examine the role of sociocultural context as PAR researchers attempt to create a setting in which students gain skills to become change agents within their school. The study suggests that youth empowerment is a context dependent process that requires attention to a multiplicity of factors that influence possibilities for empowerment via second order change.  相似文献   
946.
This study investigated the extent to which trait anxiety and state anxiety in response to stress are associated with the cortisol awakening response (CAR).Fifty-one healthy participants were recruited. State anxiety measures were taken in anticipation of and during a laboratory stressor. Salivary cortisol levels were measured immediately upon awakening (at 0, 15, 30, and 45 min) on two consecutive mornings. Cortisol awakening response was assessed by the area under the curve with respect to zero (AUCG).The magnitude of the CAR was found to be negatively associated with both trait anxiety and anticipatory anxiety. Moreover, regression analysis showed that the effects of trait anxiety on the AUCG were mediated by anticipatory anxiety.These results suggest that the CAR is influenced by trait anxiety. Moreover, the effect of trait anxiety on the CAR seems to operate by impacting on psychological stress reactivity (i.e., anticipatory anxiety).  相似文献   
947.
The Trail-Making Test (TMT) is a widely used neuropsychological measure that assesses visuomotor abilities and cognitive flexibility. For the TMT-A condition participants are required to locate and connect numbers (i.e. 1-2-3…) while in the TMT-B condition participants perform the set-shifting task of locating and connecting numbers and letters (i.e. 1-A-2-B…). The TMT-B condition has shown impairments in many clinical populations, particularly schizophrenia patients, but the neurobiological underpinning of the task can be difficult to discern given pragmatic obstacles in adapting the task for neuroimaging. In a behavioural testing experiment we demonstrated a close correspondence between performance on the standard TMT and a novel, computer programmed adaptation of the TMT (pcTMT). The pcTMT was designed for functional magnetic resonance imaging (fMRI) administration and neuroimaging data for this task were obtained in. A whole brain analysis revealed significantly greater activation during the pcTMT-B relative to the pcTMT-A in right inferior/middle frontal cortices, right precentral gyrus, left angular gyrus/left middle temporal gyrus. These results identify the regions that most likely underlie cognitive flexibility during the TMT and are candidate regions underlying the impairment of groups with poor set-shifting abilities.  相似文献   
948.
In two experiments we examined the role of visual horizon information on absolute egocentric distance judgments to on-ground targets. Sedgwick [1983, in Human and Machine Vision (New York: Academic Press) pp 425-458] suggested that the visual system may utilize the angle of declination from a horizontal line of sight to the target location (horizon distance relation) to determine absolute distances on infinite ground surfaces. While studies have supported this hypothesis, less is known about the specific cues (vestibular, visual) used to determine horizontal line of sight. We investigated this question by requiring observers to judge distances under degraded vision given an unaltered or raised visual horizon. The results suggest that visual horizon information does influence perception of absolute distances as evident through two different action-based measures: walking or throwing without vision to previously viewed targets. Distances were judged as shorter in the presence of a raised visual horizon. The results are discussed with respect to how the visual system accurately determines absolute distance to objects on a finite ground plane and for their implications for understanding space perception in low-vision individuals.  相似文献   
949.
This study reviewed 4,457 articles from 1998 to 2007 in American Counseling Association division‐affiliated journals to identify research articles published in counseling; 1,139 articles (25.6%) were quantitatively research based. The authors provide details related to quantitative research publications, including individual journal contribution to the research base, focus areas for research, and independent and dependent variables highlighted by researchers. One summary finding was that only 6% of counseling research articles explored effectiveness of counseling interventions.  相似文献   
950.
Support from a partner can play a key role in a woman's emotional adjustment to breast cancer. However, little is known about the influence of partner behaviours on a woman's sexual adjustment. This study examined the prospective relationship between baseline levels of several types of perceived partner support (instrumental, informational, emotional and negative) and psychosexual adjustment (sexual functioning and relationship satisfaction) over the course of 12 months post-surgery in a sample of 130 women with breast cancer. Results indicated that perceptions of greater emotional and informational support from the partner at baseline were associated with less sexual difficulties among breast cancer patients concurrently and 6 months post-surgery. Baseline perceptions of greater emotional and instrumental support from a partner were associated with greater relationship satisfaction at all time points. Perceptions of informational support at baseline were related to greater concurrent relationship satisfaction. Baseline perceptions of negative partner support were related to less relationship satisfaction, but only concurrently. These findings suggest that the perception of a partner's provision of emotional, instrumental and informational support may each play a role in facilitating sexual adjustment and relationship satisfaction.  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