全文获取类型
收费全文 | 8841篇 |
免费 | 258篇 |
专业分类
各国政治 | 448篇 |
工人农民 | 402篇 |
世界政治 | 506篇 |
外交国际关系 | 262篇 |
法律 | 5603篇 |
中国共产党 | 3篇 |
中国政治 | 57篇 |
政治理论 | 1742篇 |
综合类 | 76篇 |
出版年
2020年 | 108篇 |
2019年 | 143篇 |
2018年 | 204篇 |
2017年 | 221篇 |
2016年 | 215篇 |
2015年 | 150篇 |
2014年 | 153篇 |
2013年 | 966篇 |
2012年 | 230篇 |
2011年 | 228篇 |
2010年 | 191篇 |
2009年 | 213篇 |
2008年 | 261篇 |
2007年 | 223篇 |
2006年 | 258篇 |
2005年 | 227篇 |
2004年 | 231篇 |
2003年 | 204篇 |
2002年 | 214篇 |
2001年 | 266篇 |
2000年 | 267篇 |
1999年 | 193篇 |
1998年 | 119篇 |
1997年 | 121篇 |
1996年 | 111篇 |
1995年 | 99篇 |
1994年 | 96篇 |
1993年 | 112篇 |
1992年 | 184篇 |
1991年 | 200篇 |
1990年 | 180篇 |
1989年 | 181篇 |
1988年 | 162篇 |
1987年 | 180篇 |
1986年 | 176篇 |
1985年 | 164篇 |
1984年 | 157篇 |
1983年 | 167篇 |
1982年 | 96篇 |
1981年 | 91篇 |
1980年 | 77篇 |
1979年 | 106篇 |
1978年 | 76篇 |
1977年 | 74篇 |
1976年 | 60篇 |
1975年 | 59篇 |
1974年 | 63篇 |
1973年 | 73篇 |
1972年 | 63篇 |
1968年 | 53篇 |
排序方式: 共有9099条查询结果,搜索用时 15 毫秒
311.
312.
Michael J. Cleveland Mark E. Feinberg Mark T. Greenberg 《Journal of youth and adolescence》2010,39(2):114-126
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
313.
Susanne E. Baumgartner Patti M. Valkenburg Jochen Peter 《Journal of youth and adolescence》2010,39(10):1226-1239
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
314.
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
315.
Christopher C. Weiss Brian V. Carolan E. Christine Baker-Smith 《Journal of youth and adolescence》2010,39(2):163-176
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
316.
Tracy M. Scull Janis B. Kupersmidt Alison E. Parker Kristen C. Elmore Jessica W. Benson 《Journal of youth and adolescence》2010,39(9):981-998
Two cross-sectional studies investigated media influences on adolescents’ substance use and intentions to use substances in
the context of exposure to parental and peer risk and protective factors. A total of 729 middle school students (n = 351, 59% female in Study 1; n = 378, 43% female in Study 2) completed self-report questionnaires. The sample in Study 1 was primarily African-American
(52%) and the sample in Study 2 was primarily Caucasian (63%). Across the two studies, blocks of media-related cognitions
made unique contributions to the prediction of adolescents’ current substance use and intentions to use substances in the
future above and beyond self-reported peer and parental influences. Specifically, identification with and perceived similarity
to media messages were positively associated with adolescents’ current substance use and intentions to use substances in the
future, and critical thinking about media messages and media message deconstruction skills were negatively associated with
adolescents’ intention to use substances in the future. Further, peer influence variables (e.g., peer pressure, social norms,
peer substance use) acted as risk factors, and for the most part, parental influence variables (e.g., parental pressure to
not use, perceived parental reaction) acted as protective factors. These findings highlight the importance of developing an
increased understanding of the role of media messages and media literacy education in the prevention of substance use behaviors
in adolescence. 相似文献
317.
Nicole E. Werner Matthew F. Bumpus Daquarii Rock 《Journal of youth and adolescence》2010,39(6):607-619
The current study examined concurrent and longitudinal predictors of early adolescents’ involvement in Internet aggression.
Cross-sectional results (N = 330; 57% female) showed that the likelihood of reporting Internet aggression was higher among youth who spent more time
using Internet-based technologies to communicate with friends and who were themselves targets of Internet aggression. Offline
relational aggression and beliefs supportive of relational and physical aggression also predicted concurrent involvement in
Internet aggression. We used longitudinal data (N = 150; 51% female) to distinguish between youth who were aggressive in traditional contexts only (i.e., school) from those
who were aggressive both online and offline. These results indicated that youth who were aggressive both online and offline
were older at the initial assessment, were targets of Internet aggression, and held beliefs more supportive of relational
aggression than youth who were aggressive offline only. Implications and directions for future research are discussed. 相似文献
318.
Heidi E. Grunwald Brian Lockwood Philip W. Harris Jeremy Mennis 《Journal of youth and adolescence》2010,39(9):1067-1079
This study examined the effects of neighborhood context on juvenile recidivism to determine if neighborhoods influence the
likelihood of reoffending. Although a large body of literature exists regarding the impact of environmental factors on delinquency,
very little is known about the effects of these factors on juvenile recidivism. The sample analyzed includes 7,061 delinquent
male juveniles committed to community-based programs in Philadelphia, of which 74% are Black, 13% Hispanic, and 11% White.
Since sample youths were nested in neighborhoods, a hierarchical generalized linear model was employed to predict recidivism
across three general categories of recidivism offenses: drug, violent, and property. Results indicate that predictors vary
across the types of offenses and that drug offending differs from property and violent offending. Neighborhood-level factors
were found to influence drug offense recidivism, but were not significant predictors of violent offenses, property offenses,
or an aggregated recidivism measure, despite contrary expectations. Implications stemming from the finding that neighborhood
context influences only juvenile drug recidivism are discussed. 相似文献
319.
320.
Much economic policy is deliberately shifted away from direct political processes to administrative processes—political pressure deflection. Pressure deflection poses a puzzle to standard political economy models which suggest that having policies to ‘sell’ is valuable to politicians. The puzzle is solved here by showing that incumbents will favor pressure deflection since it can deter viability of a challenger, essentially like entry deterrence. U.S. trade policy since 1934 provides a prime example, especially antidumping law and its evolution. 相似文献