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   46163篇
  免费   1928篇
  国内免费   15篇
  2020年   458篇
  2019年   579篇
  2018年   802篇
  2017年   799篇
  2016年   832篇
  2015年   597篇
  2014年   765篇
  2013年   3369篇
  2012年   1394篇
  2011年   1423篇
  2010年   884篇
  2009年   853篇
  2008年   1252篇
  2007年   1252篇
  2006年   1155篇
  2005年   1058篇
  2004年   1007篇
  2003年   899篇
  2002年   958篇
  2001年   1569篇
  2000年   1473篇
  1999年   1099篇
  1998年   528篇
  1997年   450篇
  1996年   452篇
  1992年   854篇
  1991年   827篇
  1990年   836篇
  1989年   793篇
  1988年   768篇
  1987年   742篇
  1986年   741篇
  1985年   797篇
  1984年   655篇
  1983年   604篇
  1982年   492篇
  1981年   452篇
  1979年   715篇
  1978年   528篇
  1976年   475篇
  1975年   592篇
  1974年   685篇
  1973年   693篇
  1972年   560篇
  1971年   541篇
  1970年   499篇
  1969年   558篇
  1968年   677篇
  1967年   589篇
  1966年   564篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
Maternal and adolescent depression are challenges that often co-occur. Many studies have drawn bivariate associations between maternal depressive symptoms, adolescent depressive symptoms, and family conflict, but few have examined reciprocal effects. Even among extant studies, there is a lack of clarity related to directionality of influence. Three competing theoretical models may explain the relationship between maternal depressive symptoms, adolescent depressive symptoms, and family conflict, and these processes may differ by adolescents’ sex. Using three time points of data from 187 diverse mother-adolescent dyads, we fit a taxonomy of autoregressive cross-lagged structural equation models to simultaneously evaluate the competing theoretical models and also examine differences by sex using multiple-group analyses. Results indicate a symptom-driven model whereby adolescent depressive symptoms predicted increases in family conflict. Sex differences were also found. For males, but not females, greater adolescent depressive symptoms predicted subsequent increases in maternal depressive symptoms, which then predicted lower family conflict—possibly indicating maternal disengagement/withdrawal. Our findings suggest addressing adolescent depressive symptoms in order to prevent family conflict and that distinctive targets for the prevention/intervention of family conflict should account for differences by adolescents’ sex.  相似文献   
962.
African Americans are at significantly greater risk of hypertension and worse cardiovascular outcomes than other racialized groups, yet hypertension intervention effects remain limited. Thus, it is necessary to understand the potential mechanisms whereby interventions may be more effectively targeted to improve health. Supported by prior research evidence and guided by the Biobehavioral Family Model, this study examined associations between family relationship quality, psychological wellbeing, and self-management behaviors for African Americans with hypertension. Data were pooled from three Midlife Development in the U.S. projects, resulting in a sample of 317 African Americans (63.4% female, Mage = 53.32) with self-reported high blood pressure in the past 12 months. We tested four cross-sectional multiple mediator models, with depressed mood and environmental mastery mediating associations between family strain and exercise, smoking, problematic alcohol use, and stress-eating. Environmental mastery mediated the association between greater family strain and decreased odds of achieving recommended exercise levels; greater odds of reporting problematic alcohol use; and greater stress-eating. Though family strain was associated with depressed mood in each model, this variable did not serve as an indirect pathway to self-management behaviors. Family strain, and the potential pathway identified via environmental mastery, may be a meaningful predictor of disease self-management for African Americans with hypertension. Longitudinal studies are needed to examine directionality and to support intervention trials for improving self-management and hypertension outcomes.  相似文献   
963.
Although several studies have addressed the relations between perceived parental warmth and social behaviours, few have distinguished their between- and within-person effects or explored their within-person mediating mechanisms. This study examined the transactional relations among perceived parental warmth (i.e. maternal warmth and paternal warmth), children's self-esteem and children's positive/negative social behaviours (i.e. prosocial behaviour and delinquent behaviour) along with the mediating role of self-esteem after disentangling between- and within-person effects. A total of 4315 Chinese elementary children (44.9% girls; Mage = 9.93 years, SD = 0.73) completed relevant measures on four occasions employing 6-month intervals. Results of random-intercept cross-lagged panel models showed that (a) perceived parental warmth reciprocally and positively predicted prosocial behaviour and self-esteem; (b) perceived paternal warmth reciprocally and negatively predicted delinquent behaviour; (c) self-esteem reciprocally predicted prosocial and delinquent behaviour; (d) perceived maternal warmth reciprocally and positively predicted prosocial behaviour through self-esteem; (e) perceived parental warmth reciprocally and negatively predicted delinquent behaviour through self-esteem; and (f) perceived maternal and paternal warmth differed in their relations with prosocial and delinquent behaviours through self-esteem. These findings illuminated the complicated longitudinal within-person interactions among perceived parental warmth, self-esteem, and social behaviours, the specific mediating mechanism of self-esteem, and the differing results associated with perceived maternal and paternal warmth, all of which yield significant implications for assessments and early interventions aimed to promote positive social behaviour.  相似文献   
964.
Christians are notably underrepresented in science in part due to long-standing public perceptions of science-religion incompatibility and antireligious bias in science. This research explores whether undergraduates at a Christian university perceive and impose anti-Christian cultural stigma in science. Survey results from 126 biology students revealed that though students generally perceived the culture of science to be anti-Christian, they perceived Christians to have equal opportunities for scientific achievement. Results from a quasi-experimental audit study, in which students evaluated one of two profiles for mock prospective Ph.D. applicants (Christian or undisclosed faith) showed that students did not project anti-Christian stereotypes in terms of competence, hireability, or likeability, but showed some evidence of pro-Christian favorability. Together, this study suggests that the affirmational community of a Christian University may alleviate some negative impacts of anti-Christian stereotypes in academic biology, even as students perceive discrimination against Christians in science and atheists as more scientifically competent.  相似文献   
965.
The other-race effect (ORE) is a longstanding phenomenon in experimental psychology, where recognition for same-race faces is superior than for other-race faces. The present research pits two competing theories of perceptual expertise and social motivation against each other to see which is the more robust predictor of the ORE. In Study 1, we measured Black and White participants' prior contact with individuals from the other-race (i.e. expertise) as well as their expected level of future interaction with other-race individuals (i.e. motivation). Of the two theories, anticipated interaction (i.e. motivation) emerged as a significant predictor of the ORE. Study 2 followed the same design, measuring motivation with a self-report assessment of how much participants are willing to have cross-race friendships. Here, neither experience nor motivation predicted the ORE, though an ORE was established. Differences in measures that assess motivation and the experience versus motivation debate are discussed.  相似文献   
966.
967.
Previous research has evaluated the effects of prompt rates on the rate of communicative behavior. More recent research has suggested that dense prompting can result in communicative behavior that is more resistant to change. However, existing research has not considered the impact that higher response rates had on reinforcement rate, a variable known to impact response persistence. The current study systematically replicated previous research by evaluating communicative responding in contexts associated with dense- and lean-prompt schedules and extended existing research by (a) holding reinforcement rates similar across the two prompting schedules (lean and dense), and (b) evaluating the persistence of communicative responding in the contexts associated with each prompting schedule. The results for Experiment 1 clearly replicated and extended previous research. The results for Experiment 2 were equivocal and suggested that previous reinforcement history and response class size impacted outcomes.  相似文献   
968.
Residents in juvenile residential treatment facilities (JRTFs) often display various emotional, behavioral, and educational needs. Researchers have recently developed behavioral interventions to increase residents' appropriate behavior such as cooperation with facility staff instructions, accepting feedback from facility staff, and tolerating unpleasant events. However, there is not a generally accepted tool for assessing the operant function of residents' problem behavior in JRTFs. For various logistical reasons, indirect functional assessments may be more appropriate in a JRTF than manipulating either antecedent or consequent events. This study obtained scores on the Questions About Behavior Function (QABF) assessment for 17 residents from two dormitory staff members for each resident. To increase the number of respondents, each resident completed a QABF for their own behavior. Results revealed moderate to high correspondence (i.e., agreement) for highest and lowest potential operant function of problem behavior between combinations of JRTF staff and residents. These preliminary findings suggest additional research with the QABF in JRTFs is warranted.  相似文献   
969.
Interruption and redirection (IR) procedures involve systematically disrupting an undesirable behavior and prompting an individual to engage in an alternative behavior. These procedures have been frequently assessed for reducing repetitive behaviors for autistic individuals. The primary purpose of this review was to assess IR interventions to determine whether outcomes vary according to intervention characteristics, dependent variable types, design quality, or publication status. A secondary purpose was to assess the extent to which generalization and maintenance outcomes were measured and whether characteristics of these conditions were related to outcomes. IR interventions were moderately successful for reducing repetitive behaviors but less effective for improving corollary variables such as appropriate vocalizations and functional engagement. Generalization and maintenance outcomes, when measured, were poor. Results indicate the need for alternative or augmentative procedures that focus on engagement in meaningful interactions and activities.  相似文献   
970.
When teaching infants new actions, parents tend to modify their movements. Infants prefer these infant-directed actions (IDAs) over adult-directed actions and learn well from them. Yet, it remains unclear how parents’ action modulations capture infants’ attention. Typically, making movements larger than usual is thought to draw attention. Recent findings, however, suggest that parents might exploit movement variability to highlight actions. We hypothesized that variability in movement amplitude rather than higher amplitude is capturing infants’ attention during IDAs. Using EEG, we measured 15-month-olds’ brain activity while they were observing action demonstrations with normal, high, or variable amplitude movements. Infants’ theta power (4–5 Hz) in fronto-central channels was compared between conditions. Frontal theta was significantly higher, indicating stronger attentional engagement, in the variable compared to the other conditions. Computational modelling showed that infants’ frontal theta power was predicted best by how surprising each movement was. Thus, surprise induced by variability in movements rather than large movements alone engages infants’ attention during IDAs. Infants with higher theta power for variable movements were more likely to perform actions successfully and to explore objects novel in the context of the given goal. This highlights the brain mechanisms by which IDAs enhance infants’ attention, learning, and exploration.  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