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   27058篇
  免费   418篇
  国内免费   2篇
  2023年   40篇
  2021年   63篇
  2020年   119篇
  2019年   150篇
  2018年   3620篇
  2017年   3002篇
  2016年   2445篇
  2015年   358篇
  2014年   268篇
  2013年   877篇
  2012年   859篇
  2011年   2676篇
  2010年   2683篇
  2009年   1669篇
  2008年   1939篇
  2007年   2420篇
  2006年   272篇
  2005年   461篇
  2004年   410篇
  2003年   330篇
  2002年   291篇
  2001年   153篇
  2000年   181篇
  1999年   145篇
  1998年   123篇
  1997年   110篇
  1996年   109篇
  1995年   92篇
  1994年   84篇
  1993年   71篇
  1992年   92篇
  1991年   76篇
  1990年   74篇
  1989年   69篇
  1988年   55篇
  1987年   53篇
  1986年   57篇
  1985年   71篇
  1984年   67篇
  1983年   57篇
  1982年   78篇
  1981年   78篇
  1980年   58篇
  1979年   56篇
  1978年   45篇
  1977年   72篇
  1976年   44篇
  1975年   49篇
  1974年   42篇
  1973年   50篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Twin and family studies have shown that genetic factors play a role in the development of conduct disorder (CD). The purpose of this study was to identify genetic variants associated with CD using a family-based association study. We used 4,720 single nucleotide polymorphisms (SNPs) from the Illumina Panel and 11,120 SNPs from the Affymetrix 10K GeneChips genotyped in 155 Caucasian nuclear families from Genetic Analysis Workshop (GAW) 14, a subset from the Collaborative Study on the Genetics of Alcoholism (COGA). 20 SNPs had suggestive associations with CD (p < 10−3), nine of which were located in known genes, including ADAM10 (rs383902, p = 0.00036) and CAMK2A (rs2053053, p = 0.00098). Our results were verified using the International Multi-Center ADHD Genetics Project (IMAGE) dataset. In conclusion, we identified several loci associated with CD. Especially, the two genes (ADAM10 and CAMK2A) have been reported to be associated with Alzheimer’s disease, bipolar disorder and depression. These findings may serve as a resource for replication in other populations.  相似文献   
942.
Socially anxious feelings sharply increase during adolescence and such feelings have been associated with interpretive biases. Studies in adults have shown that interpretive biases can be modified using Cognitive Bias Modification procedures (CBM-I) and subsequent effects on anxiety have been observed. The current study was designed to examine whether the CBM-I procedure has similar effects in adolescents. Unselected adolescents were randomly allocated to either a positive interpretation training (n = 88) or a placebo-control condition (n = 82). Results revealed that the training was successful in modifying interpretations and effects generalized to a new task. The interpretive bias effects were most pronounced in individuals with a threat-related interpretive bias at pre-test. No effects on state anxiety were observed. The current findings are promising with regard to applying bias modification procedures to adolescents, while further research is warranted regarding emotional effects.  相似文献   
943.
944.
Attention-Deficit/Hyperactivity Disorder (ADHD) is a prime candidate for exploration of gene-by-environment interaction (i.e., G x E), particularly in relation to dopamine system genes, due to strong evidence that dopamine systems are dysregulated in the disorder. Using a G x E design, we examined whether the DRD4 promoter 120-bp tandem repeat polymorphism, previously associated with ADHD, moderated the effects of inconsistent parenting and marital conflict on ADHD or Oppositional-Defiant Disorder (ODD). Participants were 548 children with ADHD and non-ADHD comparison children and their parents. Homozygosity for the DRD4 promoter 120-bp tandem repeat insertion allele increased vulnerability for ADHD and ODD only in the presence of inconsistent parenting and appeared to increase susceptibility to the influence of increased child self-blame for marital conflict on ADHD inattention. DRD4 genotypes may interact with these proximal family environmental risk factors by increasing the individual’s responsivity to environmental contingencies.  相似文献   
945.
This study examined transactional associations between responses to peer stress and depression in youth. Specifically, it tested the hypotheses that (a) depression would predict fewer effortful responses and more involuntary, dysregulated responses to peer stress over time; and (b) fewer adaptive and more maladaptive responses would predict subsequent depression. Youth (M age = 12.41; SD = 1.19; 86 girls, 81 boys) and their maternal caregivers completed semi-structured interviews and questionnaires at three annual waves. Multi-group comparison path analyses were conducted to examine sex and stress-level differences in the proposed reciprocal-influence model. In girls and in youth exposed to high levels of peer stress, maladaptive stress responses predicted more depressive symptoms and adaptive stress responses predicted fewer depressive symptoms at each wave. These findings suggest the utility of preventive interventions for depression designed to enhance the quality of girls’ stress responses. In boys, depression predicted less adaptive and more maladaptive stress responses, but only at the second wave. These findings suggest that interventions designed to reduce boys’ depressive symptoms may help them develop more adaptive stress responses.  相似文献   
946.
Building on interpersonal theories of depression, the current study sought to explore whether early childhood social withdrawal serves as a risk factor for depressive symptoms and diagnoses in young adulthood. The researchers hypothesized that social impairment at age 15 would mediate the association between social withdrawal at age 5 and depression by age 20. This mediational model was tested in a community sample of 702 Australian youth followed from mother’s pregnancy to youth age 20. Structural equation modeling analyses found support for a model in which childhood social withdrawal predicted adolescent social impairment, which, in turn, predicted depression in young adulthood. Additionally, gender was found to moderate the relationship between adolescent social impairment and depression in early adulthood, with females exhibiting a stronger association between social functioning and depression at the symptom and diagnostic level. This study illuminates one potential pathway from early developing social difficulties to later depressive symptoms and disorders.  相似文献   
947.
The goal of the current study was to determine the extent to which the perceived self-regulation deficits across behavioral, cognitive, and emotional domains seen in children with ADHD explain the association between the severity of ADHD symptoms and parenting stress. Participants for this study included 80 children (mean age = 10 years, 9 months) with a DSM-IV diagnosis of ADHD confirmed by a comprehensive clinical diagnostic assessment. Parents reported their own stress levels as well as the severity of their children’s ADHD symptoms, aggression, emotional lability, and executive functioning difficulties. Results indicated that the severity of children’s hyperactivity/impulsivity symptoms but not their inattention related to parenting stress. Multiple mediational analyses indicated that the association between hyperactivity/impulsivity and parenting stress was explained by children’s perceived comorbid aggression levels, emotional lability, and executive functioning difficulties. No significant differences in the strength of the mediators were found. The current study provides initial data showing that the perceived impairments in children’s self-regulation across emotional, cognitive, and behavioral domains are what parents report as stressful, not simply the severity of ADHD symptoms. Due to the cross-sectional nature of this study and shared variance from relying solely on parent report, it will be critical for future research to replicate our findings using longitudinal and multi-informant data such as teacher reports and standardized assessments.  相似文献   
948.
This study examined whether children’s biased self-perceptions of peer acceptance are associated in a linear or curvilinear fashion with aggression, whether associations are moderated by peer rejection status, and whether associations apply uniquely to reactive aggression. Children in the 4th through 7th grades completed a self-report measure on their social functioning (SPPC; Harter 1982), and teachers reported on children’s social functioning and aggression. Self-perceptual bias was operationalized as the standardized residual difference between children’s self-perceptions and their teachers’ perceptions of their peer acceptance. Rejected status moderated associations between biased self-perceptions and reactive aggression. Among non-rejected children, biased perceptions were not significantly associated with reactive aggression. In contrast, among peer-rejected children, reactive aggression was elevated in those who greatly underestimated as well as in those who even modestly overestimated their peer acceptance. This pattern was observed whether or not proactive aggression was statistically controlled. In contrast, biased self-perceptions were not associated with proactive aggression for rejected or nonrejected children. Implications are discussed with regard to future research and potential interventions for aggressive children.  相似文献   
949.
Evidence suggests that parental marital discord contributes to the development of internalizing and externalizing symptoms in children and adolescents. Few studies, however, have examined the association between parental marital discord and youth’s response to treatment. The present study examined the impact of interparental discord on treatment response in a randomized control trial of adolescents with major depression enrolled in the Treatment for Adolescents with Depression Study (TADS). Participants were 260 adolescents from two-parent households randomly assigned to one of four treatment groups: fluoxetine (FLX), cognitive behavior therapy (CBT), their combination (COMB), or placebo (PBO). Logistic regressions revealed that parental marital discord interacted with youth gender and co-morbid oppositionality symptoms to predict group differences in treatment response.  相似文献   
950.
This longitudinal study examined processes that mediate the association between maternal depressive symptoms and peer social preference during the early school years. Three hundred and fifty six kindergarten children (182 boys) and their mothers participated in the study. During kindergarten, mothers reported their level of depressive symptomatology. In first grade, teachers rated children’s emotion regulation at school and observers rated the affective quality of mother-child interactions. During second grade, children’s social preference was assessed by peer nomination. Results indicated that mothers’ level of depressive symptomatology negatively predicted their child’s social preference 2 years later, controlling for the family SES and teacher-rated social preference during kindergarten. Among European American families, the association between maternal depressive symptoms and social preference was partially mediated by maternal warmth and the child’s emotion regulation. Although the relation between maternal depressive symptoms and children peer preference was stronger among African American families than Europrean American families, its mediation by the maternal warmth and child’s emotion regulation was not found in African American families.  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