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   31117篇
  免费   944篇
  国内免费   3篇
管理学   4301篇
民族学   188篇
人才学   4篇
人口学   2762篇
丛书文集   165篇
教育普及   1篇
理论方法论   2950篇
综合类   423篇
社会学   15841篇
统计学   5429篇
  2023年   180篇
  2021年   201篇
  2020年   524篇
  2019年   786篇
  2018年   890篇
  2017年   1210篇
  2016年   935篇
  2015年   655篇
  2014年   845篇
  2013年   5379篇
  2012年   1114篇
  2011年   1046篇
  2010年   801篇
  2009年   705篇
  2008年   827篇
  2007年   807篇
  2006年   816篇
  2005年   722篇
  2004年   708篇
  2003年   580篇
  2002年   617篇
  2001年   764篇
  2000年   667篇
  1999年   619篇
  1998年   486篇
  1997年   426篇
  1996年   456篇
  1995年   444篇
  1994年   400篇
  1993年   431篇
  1992年   453篇
  1991年   452篇
  1990年   442篇
  1989年   398篇
  1988年   369篇
  1987年   351篇
  1986年   344篇
  1985年   395篇
  1984年   373篇
  1983年   330篇
  1982年   296篇
  1981年   234篇
  1980年   267篇
  1979年   289篇
  1978年   232篇
  1977年   206篇
  1976年   177篇
  1975年   198篇
  1974年   195篇
  1973年   134篇
排序方式: 共有10000条查询结果,搜索用时 671 毫秒
951.
952.
Sedentary behavior has already been associated with mortality, cardiovascular disease, and cancer. Questionnaires are an affordable tool for measuring sedentary behavior in large epidemiological studies. Here, we introduce and evaluate two statistical methods for quantifying measurement error in questionnaires. Accurate estimates are needed for assessing questionnaire quality. The two methods would be applied to validation studies that measure a sedentary behavior by both questionnaire and accelerometer on multiple days. The first method fits a reduced model by assuming the accelerometer is without error, while the second method fits a more complete model that allows both measures to have error. Because accelerometers tend to be highly accurate, we show that ignoring the accelerometer's measurement error, can result in more accurate estimates of measurement error in some scenarios. In this article, we derive asymptotic approximations for the mean-squared error of the estimated parameters from both methods, evaluate their dependence on study design and behavior characteristics, and offer an R package so investigators can make an informed choice between the two methods. We demonstrate the difference between the two methods in a recent validation study comparing previous day recalls to an accelerometer-based ActivPal.  相似文献   
953.
954.
With competing risks data, one often needs to assess the treatment and covariate effects on the cumulative incidence function. Fine and Gray proposed a proportional hazards regression model for the subdistribution of a competing risk with the assumption that the censoring distribution and the covariates are independent. Covariate‐dependent censoring sometimes occurs in medical studies. In this paper, we study the proportional hazards regression model for the subdistribution of a competing risk with proper adjustments for covariate‐dependent censoring. We consider a covariate‐adjusted weight function by fitting the Cox model for the censoring distribution and using the predictive probability for each individual. Our simulation study shows that the covariate‐adjusted weight estimator is basically unbiased when the censoring time depends on the covariates, and the covariate‐adjusted weight approach works well for the variance estimator as well. We illustrate our methods with bone marrow transplant data from the Center for International Blood and Marrow Transplant Research. Here, cancer relapse and death in complete remission are two competing risks.  相似文献   
955.
We examined whether adolescent sexual abstinence predicts better adult mental health. 1,917 adolescents, recruited from middle schools at age 13, were surveyed at ages 13, 18, 23, and 29. In bivariate analyses, adolescent sexual abstinence was associated with better mental health at age 29 for females, but not males; three adolescent factors, educational prospects, family bonding, and unconventionality were investigated as explanatory variables of this relationship. The abstinence-mental health relationship was nonsignificant when educational prospects was included in multivariate models, and marginally significant when family bonding and unconventionality were included; all three explanatory factors accounted for significant proportions of the variance in adult mental health. Girls who are uninvolved in school, have weak family backgrounds, and exhibit unconventionality may have poor adult mental health, whether or not they abstain from sex in adolescence. Interventions that strengthen adolescents' connections to families and schools may reduce risk for long-term mental health problems.  相似文献   
956.
This paper explores adolescents' definitions of what it means to be a man and a woman, the psycho-social context surrounding the formation of gender ideologies and their relationship to HIV/STI prevention. Semi-structured, in-depth interviews were conducted with fifty African-American adolescents living in Baltimore, Maryland. Female gender ideologies included economic independence, emotional strength and caretaking. Male gender ideologies emphasized financial responsibility, toughness and sexual prowess. Findings suggest that stronger adherence to male gender ideologies related to toughness and sexual prowess is influenced by male participants' perceived inability to fulfill their primary gender role as economic providers and the importance of gaining approval from male peers in the absence of adult male role models. Stronger adherence to female gender ideologies related to emotional strength and caretaking may be linked to a heightened desire for male intimacy and tolerance of male sexual risk behavior. Implications of the gender ideologies documented and their commonalities are discussed in terms of HIV/STI prevention.  相似文献   
957.
Three studies explored gender differences in explicit and implicit components of sexual arousal following brief exposure to a sexual stimulus. Whereas Study 1 assessed reports of sexual arousal following subliminal exposure to a sexual or a neutral picture, Studies 2 and 3 examined the effects of the same priming procedure on accessibility of sex-related thoughts assessed with a pictorial judgment task and a lexical decision task. The subliminal sexual prime did not have an effect on men's reports of sexual arousal, but caused women to report lower levels of sexual arousal. In contrast, the same subliminal sexual prime led to higher accessibility of sex-related thoughts in both men and women. It is therefore suggested that the subliminal sexual prime causes women to activate sex-related mental contents but to experience the result as somewhat aversive.  相似文献   
958.
Much research suggests that political experts are more likelyto structure attitudes toward different issues in an ideologicallyconsistent fashion. Based on recent studies of motivationalinfluences on social cognition, we hypothesize that only expertswith a high need to evaluate—a strong motivation to establishevaluations of social objects—may "apply" ideology toa variety of issues. Data from the 1998 NES Pilot and 2000 NESare used to examine this hypothesis. While experts do show moreideological constraint, this relationship appears to be limitedto individuals with a high need to evaluate. Additional analysesindicated that this interactive effect extended to other indicesof the use of ideology as well.  相似文献   
959.
Many child welfare systems are unable to effectively identify and address co-occurring domestic violence and child maltreatment. In response, the Dependency Court Intervention Program for Family Violence implemented a protocol to identify indicators of domestic violence in families involved with child protection proceedings. This article highlights data that demonstrate the ability of an outreach and screening process to identify adult victims of domestic violence in dependency court and to offer them appropriate intervention services.  相似文献   
960.
Every state requires a home study before the placement of foster children for adoption. This article examines the history of home studies, presents results from expert interviews on the changing processes and purposes of home studies, and explores current challenges for the field. The article also introduces the Structured Analysis Family Evaluation (SAFE), a uniform home study format that encourages consistent family evaluations across workers, agencies, and jurisdictions. The article clarifies how SAFE may address challenges facing foster care and adoption practice.  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