全文获取类型
收费全文 | 29653篇 |
免费 | 445篇 |
专业分类
管理学 | 4009篇 |
民族学 | 174篇 |
人口学 | 4080篇 |
丛书文集 | 102篇 |
教育普及 | 2篇 |
理论方法论 | 2179篇 |
综合类 | 707篇 |
社会学 | 13616篇 |
统计学 | 5229篇 |
出版年
2021年 | 111篇 |
2020年 | 304篇 |
2019年 | 370篇 |
2018年 | 2040篇 |
2017年 | 2204篇 |
2016年 | 1485篇 |
2015年 | 382篇 |
2014年 | 468篇 |
2013年 | 3279篇 |
2012年 | 970篇 |
2011年 | 1628篇 |
2010年 | 1393篇 |
2009年 | 1141篇 |
2008年 | 1189篇 |
2007年 | 1392篇 |
2006年 | 370篇 |
2005年 | 716篇 |
2004年 | 669篇 |
2003年 | 600篇 |
2002年 | 486篇 |
2001年 | 489篇 |
2000年 | 477篇 |
1999年 | 462篇 |
1998年 | 325篇 |
1997年 | 312篇 |
1996年 | 350篇 |
1995年 | 286篇 |
1994年 | 300篇 |
1993年 | 269篇 |
1992年 | 340篇 |
1991年 | 319篇 |
1990年 | 295篇 |
1989年 | 302篇 |
1988年 | 283篇 |
1987年 | 254篇 |
1986年 | 265篇 |
1985年 | 267篇 |
1984年 | 296篇 |
1983年 | 298篇 |
1982年 | 245篇 |
1981年 | 212篇 |
1980年 | 208篇 |
1979年 | 239篇 |
1978年 | 206篇 |
1977年 | 179篇 |
1976年 | 155篇 |
1975年 | 153篇 |
1974年 | 137篇 |
1973年 | 134篇 |
1971年 | 102篇 |
排序方式: 共有10000条查询结果,搜索用时 483 毫秒
31.
Yana Kucheva 《Demography》2018,55(2):617-642
Despite abundant evidence about the effect of children’s socioeconomic circumstances on their transition to adulthood, we know much less about the effect of social policy programs aimed at poor families with children in facilitating how and when children become adults. This issue is particularly important for the U.S. federal subsidized housing program given its long history of placing subsidized units in some of the poorest and most racially segregated neighborhoods. Using counterfactual causal methods that adjust for the length of receipt of subsidized housing, I estimate the effect of subsidized housing on teenage parenthood, household formation, and educational attainment. I find that the subsidized housing program has either null or positive effects on the transition to adulthood and that these effects vary by both race and gender. These results underscore the importance of considering whether social programs have differential effects on the life chances of individuals based on both race and gender. 相似文献
32.
Journal of Nonverbal Behavior - Age-related deficits are often observed in emotion categorization tasks that include negative emotional expressions like anger, fear, and sadness. Stimulus... 相似文献
33.
de Jong Petra W. Caarls Kim de Valk Helga A. G. 《Population research and policy review》2022,41(2):671-694
Population Research and Policy Review - The welfare state can be perceived as a safety net which helps individuals adjust to situations of risk or transition. Starting from this idea of the welfare... 相似文献
34.
Random effects regression mixture models are a way to classify longitudinal data (or trajectories) having possibly varying lengths. The mixture structure of the traditional random effects regression mixture model arises through the distribution of the random regression coefficients, which is assumed to be a mixture of multivariate normals. An extension of this standard model is presented that accounts for various levels of heterogeneity among the trajectories, depending on their assumed error structure. A standard likelihood ratio test is presented for testing this error structure assumption. Full details of an expectation-conditional maximization algorithm for maximum likelihood estimation are also presented. This model is used to analyze data from an infant habituation experiment, where it is desirable to assess whether infants comprise different populations in terms of their habituation time. 相似文献
35.
36.
There is considerable speculation that female political empowerment could improve population health. Yet, evidence to date is limited, and explanations for why political empowerment would matter and the conditions under which this might be enhanced or muted are not well understood. In this article, we draw on theoretical work on the politics of representation to frame an investigation of whether increases in the percentage of females in a country’s parliament influence mortality rates. We further examine whether the relationship is conditioned by extent of democracy and economic and social development. Through multivariate longitudinal regression, we analyze four indicators of mortality in 155 countries spanning 1990 to 2014 with controls for initial country conditions, time-stable structural predispositions to higher mortality, and a number of time-varying potential confounders. Results indicate that a high level of female representation—30 % or greater in our models—has large negative associations with mortality, that these are particularly strong in lesser developed and weak democratic contexts, that high female political representation effectively offsets liabilities associated with low development, and that the relationships are robust to various operationalizations of social development. In the end, our research provides a particularly thorough accounting of the relationship between female political representation and population health, particularly by specifying the conditions under which female representation is most salient. In doing so, the research suggests important links between issues of female empowerment, political context, and developmental trajectories of countries more generally. 相似文献
37.
As important members of research teams, statisticians bear an ethical responsibility to analyze, interpret, and report data honestly and objectively. One way of reinforcing ethical responsibilities is through required courses covering a variety of ethics-related topics at the graduate level. We assessed ethics requirements for graduate-level statistics training programs in the United States for the 2013–2014 academic year using the websites of 88 universities, examining 103 biostatistics programs, and 136 statistics degree programs. We categorized programs’ ethics training requirements as required or not required. Thirty-one (35.1%) universities required an ethics course for at least some degree students. Sixty-two (25.5%) degree programs required an ethics course for at least some students. The majority (77.4%) of required courses were worth 0 or 1 credit. Of the 177 programs without an ethics requirement, 19 (10.7%) listed an ethics elective. Although a single ethics course is insufficient for instilling an ethical approach to science, degree programs that model expectations through coursework point to the value of ethics in science. More training programs should prepare statisticians to consider the ethical dimensions of their work through required coursework. Supplementary materials for this article are available online. 相似文献
38.
Simulation results are reported on methods that allow both within group and between group heteroscedasticity when testing the hypothesis that independent groups have identical regression parameters. The methods are based on a combination of extant techniques, but their finite-sample properties have not been studied. Included are results on the impact of removing all leverage points or just bad leverage points. The method used to identify leverage points can be important and can improve control over the Type I error probability. Results are illustrated using data from the Well Elderly II study. 相似文献
39.
Serra Sónia R. Q. Calapez Ana Raquel Simões Nuno Eduardo Sá Marques José A. A. Laranjo Maria Feio Maria João 《Urban Ecosystems》2019,22(6):1173-1186
Urban Ecosystems - Urban streams provide important ecosystem services to cities’ population, from the maintenance of urban biodiversity, temperature, humidity and air quality to improving... 相似文献
40.
Public Organization Review - The organizational practices of government personnel are indispensable components of building public trust and confidence. The 56 department heads and 662 personnel... 相似文献