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   26401篇
  免费   1207篇
各国政治   1034篇
工人农民   1803篇
世界政治   1418篇
外交国际关系   892篇
法律   17216篇
中国共产党   2篇
中国政治   110篇
政治理论   5040篇
综合类   93篇
  2023年   88篇
  2021年   110篇
  2020年   469篇
  2019年   487篇
  2018年   1789篇
  2017年   1753篇
  2016年   1648篇
  2015年   632篇
  2014年   605篇
  2013年   2064篇
  2012年   762篇
  2011年   1437篇
  2010年   1512篇
  2009年   1130篇
  2008年   1232篇
  2007年   1206篇
  2006年   569篇
  2005年   529篇
  2004年   631篇
  2003年   521篇
  2002年   461篇
  2001年   700篇
  2000年   634篇
  1999年   498篇
  1998年   256篇
  1997年   190篇
  1996年   218篇
  1995年   222篇
  1994年   189篇
  1993年   179篇
  1992年   308篇
  1991年   315篇
  1990年   300篇
  1989年   281篇
  1988年   304篇
  1987年   263篇
  1986年   323篇
  1985年   317篇
  1984年   259篇
  1983年   240篇
  1982年   189篇
  1981年   157篇
  1980年   145篇
  1979年   227篇
  1978年   125篇
  1977年   100篇
  1975年   94篇
  1974年   124篇
  1973年   79篇
  1972年   78篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
While having a purpose in life has been theorized as a developmental asset, the extent to which adolescents cultivate a meaningful sense of direction is not well understood. In the present study, cluster analysis was used to classify adolescents by levels of purpose exploration and commitment. The sample (N = 318; 55% female) consisted of youth aged 14–18 and was predominantly White/non-Hispanic (76.3%). Results supported four meaningful yet distinguishable profiles of youth purpose that are largely consistent with theories on identity formation: Achieved, Foreclosed, Uncommitted, and Diffused. Hypothesized linkages with affect and hope were established across the profiles such that positive emotions and goal-directed thinking were most apparent among Achieved and Foreclosed youth and least apparent among Diffused and Uncommitted youth. Overall, findings demonstrate the inherent complexity in adolescents’ engagement with purpose and suggest a correspondence between stronger commitments to purpose and youths’ sense of personal agency and well-being.  相似文献   
972.
The main aim of this study was to investigate the causal nature of the relationship between adolescents’ risky sexual behavior on the internet and their perceptions of this behavior. Engagement in the following online behaviors was assessed: searching online for someone to talk about sex, searching online for someone to have sex, sending intimate photos or videos to someone online, and sending one’s telephone number and address to someone exclusively known online. The relationship between these behaviors and adolescents’ perceptions of peer involvement, personal invulnerability, and risks and benefits was investigated. A two-wave longitudinal study among a representative sample of 1,445 Dutch adolescents aged 12–17 was conducted (49% females). Autoregressive cross-lagged structural equation models revealed that perceived peer involvement, perceived vulnerability, and perceived risks were all significant predictors of risky sexual online behavior 6 months later. No reverse causal paths were found. When the relationships between perceptions and risky sexual online behavior were modeled simultaneously, only perceived peer involvement was a determinant of risky sexual online behavior. Findings highlight the importance of addressing peer involvement in future interventions to reduce adolescents’ risky sexual online behavior.  相似文献   
973.
Self-harm is widely recognized as a significant adolescent social problem, and recent research has begun to explore its etiology. Drawing from Agnew’s (1992) social psychological strain theory of deviance, this study considers this issue by testing three hypotheses about the effects of traditional and cyber bullying victimization on deliberate self-harm and suicidal ideation. The data come from a school-based survey of adolescents in a rural county of a southeastern state (n = 426); 50% of subjects are female, their mean age was 15 years, and non-Hispanic whites represent 66% of the sample. The analysis revealed that both types of bullying are positively related to self-harm and suicidal ideation, net of controls. Moreover, those relationships are partially mediated by the negative emotions experienced by those who are bullied and partially moderated by features of the adolescent’s social environment and self. Regarding the latter, exposure to authoritative parenting and high self-control diminished the harmful effects of bullying victimization on self-harm and suicidal ideation. The article concludes by discussing the implications of these conclusions for future research and for policy efforts designed to reduce self-harm.  相似文献   
974.
The present study examined the longitudinal links between perceptions of family connectedness and body satisfaction in 1,774 (52% female) adolescents. Participants (10–15 years of age at Time 1) completed self-report measures at three measurement occasions separated by 1 year each. Mean group difference results showed that both body satisfaction levels and perceived levels of family connectedness decreased over 2 years for the whole sample. As expected, girls were generally less satisfied with their bodies than boys, particularly in the older cohort. Structural equation modelling was used to assess stability coefficients and cross-lagged effects, and longitudinal bidirectional effects between perceptions of family connectedness and body satisfaction were found for girls, but not for boys. This result suggests that adolescent girls’ body satisfaction is both affected by and a predictor of perceived family connectedness.  相似文献   
975.
Extracurricular activities provide a key context for youth development, and participation has been linked with positive developmental outcomes. Using data from the 4-H Study of Positive Youth Development (PYD), this study explored how the intentional self regulation ability of youth interacted with participation in extracurricular activities to affect PYD among adolescents living in neighborhoods with relatively low ecological assets. In total, 545 youth were included in the study (50.3% female). Most of the youth were European American (41%) or Latino (37%; African American, 10%; Asian American, 7%; Native American, 4%; and other, 1%). In general, youth with the greatest capacity to self regulate benefitted the most, as compared to their peers with less capacity to self regulate, from involvement in extracurricular activities. Consistent with a developmental systems perspective, and specifically with bioecological theory, the findings from this study confirmed that, within lower asset settings, children with the most positive person-level factors (intentional self regulation) benefit the most from proximal processes such as extracurricular activity involvement.  相似文献   
976.
In an effort to increase both adolescents’ engagement with school and academic achievement, school districts across the United States have created small high schools. However, despite the widespread adoption of size reduction reforms, relatively little is known about the relationship between size, engagement and outcomes in high school. In response, this article employs a composite measure of engagement that combines organizational, sociological, and psychological theories. We use this composite measure with the most recent nationally-representative dataset of tenth graders, Educational Longitudinal Study: 2002, (N = 10,946, 46% female) to better assess a generalizable relationship among school engagement, mathematics achievement and school size with specific focus on cohort size. Findings confirm these measures to be highly related to student engagement. Furthermore, results derived from multilevel regression analysis indicate that, as with school size, moderately sized cohorts or grade-level groups provide the greatest engagement advantage for all students and that there are potentially harmful changes when cohorts grow beyond 400 students. However, it is important to note that each group size affects different students differently, eliminating the ability to prescribe an ideal cohort or school size.  相似文献   
977.
Few studies have examined risk factors of childhood and early adolescent depressive symptomatology trajectories. This study examined self-report depressive symptomatology across a 6-year time period from 2nd to 8th grade to identify latent groups of individuals with similar patterns of depressive phenomena in a sample of 951 children (440 girls, 511 boys). Analyses, using semiparametric group modeling (SGM), identified 5 trajectory groups for girls and boys: low depressed stables, low depressed risers, mildly depressed stables, moderately depressed changers, and moderately depressed risers. Individual risk factors, with the exception of shy/withdrawn behavior, were significantly different across trajectory group membership for boys and girls, as was low-income status for boys. Boys in the low depressed and mildly depressed stable trajectory groups had significantly higher levels of antisocial behavior, attention problems, and lower social competency compared to girls in similar groups. These results suggest that universal prevention programs implemented in early elementary school that target selected risk factors may be helpful in reducing future adolescent mental health problems, specifically depressive symptomatology.  相似文献   
978.
Much of the prior work on General Strain Theory (GST) has focused on how strain and negative emotions interrelate to produce criminal—especially violent—activity. Very little research has extended GST to examine other types of non-criminal, negative behavior, such as self-harming behaviors associated with disordered eating, a traditionally female-specific self-directed outcome. Using a sample of 338 young adults (54% female, 95% white), this article applies GST to disordered eating by examining how strain and negative emotions relate to this particular outcome across gender. Findings indicate that two types of strain measures predict depressive symptoms among males and females, that inequitable strainful experiences relate to disordered eating among females but not males, that depressive symptoms but not anger increase disordered eating for both males and females, and that membership in Greek organizations (sororities or fraternities) is associated with disordered eating but only for males. Implications for theory and directions for future research are highlighted.  相似文献   
979.
980.
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