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   26617篇
  免费   1445篇
各国政治   1061篇
工人农民   981篇
世界政治   2167篇
外交国际关系   827篇
法律   17321篇
中国共产党   3篇
中国政治   156篇
政治理论   5302篇
综合类   244篇
  2020年   509篇
  2019年   552篇
  2018年   658篇
  2017年   764篇
  2016年   806篇
  2015年   649篇
  2014年   693篇
  2013年   2685篇
  2012年   629篇
  2011年   737篇
  2010年   796篇
  2009年   785篇
  2008年   676篇
  2007年   672篇
  2006年   715篇
  2005年   598篇
  2004年   582篇
  2003年   606篇
  2002年   553篇
  2001年   1007篇
  2000年   883篇
  1999年   728篇
  1998年   409篇
  1997年   348篇
  1996年   295篇
  1995年   320篇
  1994年   370篇
  1993年   320篇
  1992年   503篇
  1991年   542篇
  1990年   484篇
  1989年   528篇
  1988年   471篇
  1987年   463篇
  1986年   483篇
  1985年   479篇
  1984年   432篇
  1983年   442篇
  1982年   346篇
  1981年   329篇
  1980年   275篇
  1979年   366篇
  1978年   236篇
  1977年   209篇
  1976年   186篇
  1975年   173篇
  1974年   197篇
  1973年   172篇
  1972年   155篇
  1971年   143篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
971.
This study used data from a sample of 6th to 12th grade students (N = 48,641, 51% female), nested in 192 schools, to determine if the influence of family-based protective factors varied across different school contexts. Hierarchical logistic regression models were used to examine the effects of individual-level family protective factors, relative to school-level aggregates of the same factors, on recent (past 30 days) use of cigarettes, alcohol, and marijuana. Cross-level interactions indicated that the effect of the student’s level of family protection, relative to other students in their school, differed depending on the aggregated school level of family protection. The results suggested that the benefit of belonging to a well-functioning family was more influential for students attending schools characterized by higher-than-average aggregated levels of protection compared to students attending schools of lower-than-average protection. Thus, family-level factors offered less protection for students in relatively high-risk school contexts. These results were consistent with a protective–reactive interaction and suggest that a thorough understanding of adolescent substance use must consider the complex interplay among adolescents, their families, and their social environments.  相似文献   
972.
Studies using valid measures of monitoring activities have not found the anticipated main effects linking greater monitoring activity with fewer behavioral problems. This study focused on two contexts in which monitoring activities may be particularly influential. Early adolescents (n = 218, M age = 11.5 years, 51% female, 49% European American, 47% African American) reported their unsupervised time, beliefs about the legitimacy of their parents’ authority, and their own involvement in antisocial behavior. Mothers and adolescents reported their perceptions of adolescent disclosure and parental solicitation and control. Adolescents’ perceptions of greater parental solicitation at age 11 were associated with less antisocial behavior at age 12 (when controlling for age 11 antisocial behavior) among adolescents reporting large amounts of unsupervised time and weak legitimacy beliefs. Perceived parental solicitation may be an effective deterrent of antisocial behavior when adolescents spend a lot of time unsupervised and for adolescents who are likely to challenge the legitimacy of their parents’ authority.  相似文献   
973.
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   
974.
The purpose of this study was to investigate how different types of child maltreatment, independently and collectively, impact a wide range of risk behaviors that fall into three domains: sexual risk behaviors, delinquency, and suicidality. Cumulative classification and Expanded Hierarchical Type (EHT) classification approaches were used to categorize various types of maltreatment. Data were derived from Wave III of the National Longitudinal Study of Adolescent Health (Add Health). Our sample consisted of White, Black, Hispanic, and Asian females ages 18 to 27 (n = 7,576). Experiencing different kinds of maltreatment during childhood led to an extensive range of risk behaviors within the three identified domains. Women experiencing sexual abuse plus other maltreatment types had the poorest outcomes in all three domains. These findings illustrate that it may no longer be appropriate to assume that all types of maltreatment are equivalent in their potential contribution to negative developmental sequelae.  相似文献   
975.
976.
This study documents state implementation of mechanisms designed to promote public participation in agency rulemaking. Many scholars have questioned the effectiveness of such mechanisms, arguing that they fail to encourage greater participation or that increased participation does not affect the substance of administrative rules. Using data from a unique survey of state administrators, the author employs multivariate analyses to assess the relationship between these measures and the perceived influence of external actors. The results suggest that critics may understate the importance of public notification and access procedures. These devices are associated with increases in the impact that a wide variety of actors are perceived to have on the content of agency rules.  相似文献   
977.
978.
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