全文获取类型
收费全文 | 24675篇 |
免费 | 418篇 |
国内免费 | 2篇 |
专业分类
管理学 | 3326篇 |
民族学 | 177篇 |
人才学 | 4篇 |
人口学 | 3674篇 |
丛书文集 | 103篇 |
教育普及 | 1篇 |
理论方法论 | 2055篇 |
综合类 | 556篇 |
社会学 | 11889篇 |
统计学 | 3310篇 |
出版年
2021年 | 77篇 |
2020年 | 209篇 |
2019年 | 323篇 |
2018年 | 1949篇 |
2017年 | 2111篇 |
2016年 | 1383篇 |
2015年 | 306篇 |
2014年 | 367篇 |
2013年 | 2490篇 |
2012年 | 789篇 |
2011年 | 1598篇 |
2010年 | 1377篇 |
2009年 | 1151篇 |
2008年 | 1194篇 |
2007年 | 1380篇 |
2006年 | 410篇 |
2005年 | 605篇 |
2004年 | 603篇 |
2003年 | 504篇 |
2002年 | 417篇 |
2001年 | 362篇 |
2000年 | 328篇 |
1999年 | 286篇 |
1998年 | 230篇 |
1997年 | 221篇 |
1996年 | 266篇 |
1995年 | 205篇 |
1994年 | 207篇 |
1993年 | 202篇 |
1992年 | 195篇 |
1991年 | 184篇 |
1990年 | 192篇 |
1989年 | 192篇 |
1988年 | 176篇 |
1987年 | 171篇 |
1986年 | 162篇 |
1985年 | 193篇 |
1984年 | 194篇 |
1983年 | 175篇 |
1982年 | 144篇 |
1981年 | 119篇 |
1980年 | 139篇 |
1979年 | 148篇 |
1978年 | 129篇 |
1977年 | 102篇 |
1976年 | 107篇 |
1975年 | 113篇 |
1974年 | 99篇 |
1973年 | 69篇 |
1972年 | 67篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
This paper investigates the impact of pension income on living arrangements of the elderly. Taking advantage of a unique opportunity due to the recent establishment and expansion of the New Rural Pension Scheme in China, we explicitly address the endogeneity of pension status and pension income through a fixed-effect model with instrumental variable approach by exploiting exogenous time variation in the program implementation at county level. We find an overall positive effect of pension income on independent living as well as considerable heterogeneity. The positive income effects of the NRPS are concentrated among the elderly with adult children living nearby, of higher socio-economic status, and with better health at baseline; for other groups, the effects are insignificant. We also find that more generous programs exhibit larger effects. Our results highlight that living arrangement is multidimensional in rural China. 相似文献
12.
Tyson E. Lewis 《Race Ethnicity and Education》2018,21(1):118-131
In this article, I call for a phenomenological turn in educating white, pre-service teachers. As opposed to dominant pedagogical models which focus on changing one’s beliefs about race, phenomenology points toward the importance of pre-conceptual, pre-critical forms of racial embodiment. Here I draw upon recent work on the different between body image (beliefs about the body) and body schema (what the body can do). The worry is that existing forms of anti-oppressive education miss the centrality of the schema, and thus do not go far enough in uncovering the embodied, perceptual roots of racism. 相似文献
13.
Ryan D. Edwards 《Demography》2018,55(2):403-434
Starting in 2006, respondents in the biennial U.S. Health and Retirement Study were asked to submit biomarkers every other wave and were notified of several results. Rates of undiagnosed high blood pressure and diabetes according to these biomarkers were 1.5 % and 0.7 %, respectively. An intent-to-treat analysis suggests that collection and notification had small effects on the average respondent and may have reduced health care utilization. Among respondents who received notification of potentially dangerous biomarker levels, subsequent rates of new diagnosis and associated pharmaceutical usage increased by 20 to 40 percentage points, an order of magnitude above baseline. High blood glucose A1C was associated with a 2.2 % drop in weight and an increase in exercise among respondents without a previous diagnosis of diabetes. Notifications appear also to have altered health behaviors by spouses, suggesting household responses to health maintenance. Biomarker collection seems to have altered circumstances for an interesting minority of HRS respondents. 相似文献
14.
15.
16.
Cancho Vicente G. Macera Márcia A. C. Suzuki Adriano K. Louzada Francisco Zavaleta Katherine E. C. 《Lifetime data analysis》2020,26(2):221-244
Lifetime Data Analysis - Frailty models are generally used to model heterogeneity between the individuals. The distribution of the frailty variable is often assumed to be continuous. However, there... 相似文献
17.
18.
Mark A. van de Wiel Dennis E. Te Beest Magnus M. Münch 《Scandinavian Journal of Statistics》2019,46(1):2-25
Empirical Bayes is a versatile approach to “learn from a lot” in two ways: first, from a large number of variables and, second, from a potentially large amount of prior information, for example, stored in public repositories. We review applications of a variety of empirical Bayes methods to several well‐known model‐based prediction methods, including penalized regression, linear discriminant analysis, and Bayesian models with sparse or dense priors. We discuss “formal” empirical Bayes methods that maximize the marginal likelihood but also more informal approaches based on other data summaries. We contrast empirical Bayes to cross‐validation and full Bayes and discuss hybrid approaches. To study the relation between the quality of an empirical Bayes estimator and p, the number of variables, we consider a simple empirical Bayes estimator in a linear model setting. We argue that empirical Bayes is particularly useful when the prior contains multiple parameters, which model a priori information on variables termed “co‐data”. In particular, we present two novel examples that allow for co‐data: first, a Bayesian spike‐and‐slab setting that facilitates inclusion of multiple co‐data sources and types and, second, a hybrid empirical Bayes–full Bayes ridge regression approach for estimation of the posterior predictive interval. 相似文献
19.
Stephen J. Ruberg Frank E. Harrell Jr. Margaret Gamalo-Siebers Lisa LaVange J. Jack Lee Karen Price 《The American statistician》2019,73(1):319-327
ABSTRACTThe cost and time of pharmaceutical drug development continue to grow at rates that many say are unsustainable. These trends have enormous impact on what treatments get to patients, when they get them and how they are used. The statistical framework for supporting decisions in regulated clinical development of new medicines has followed a traditional path of frequentist methodology. Trials using hypothesis tests of “no treatment effect” are done routinely, and the p-value < 0.05 is often the determinant of what constitutes a “successful” trial. Many drugs fail in clinical development, adding to the cost of new medicines, and some evidence points blame at the deficiencies of the frequentist paradigm. An unknown number effective medicines may have been abandoned because trials were declared “unsuccessful” due to a p-value exceeding 0.05. Recently, the Bayesian paradigm has shown utility in the clinical drug development process for its probability-based inference. We argue for a Bayesian approach that employs data from other trials as a “prior” for Phase 3 trials so that synthesized evidence across trials can be utilized to compute probability statements that are valuable for understanding the magnitude of treatment effect. Such a Bayesian paradigm provides a promising framework for improving statistical inference and regulatory decision making. 相似文献
20.
In the partial degree bounded edge packing problem (PDBEP), the input is an undirected graph \(G=(V,E)\) with capacity \(c_v\in {\mathbb {N}}\) on each vertex v. The objective is to find a feasible subgraph \(G'=(V,E')\) maximizing \(|E'|\), where \(G'\) is said to be feasible if for each \(e=\{u,v\}\in E'\), \(\deg _{G'}(u)\le c_u\) or \(\deg _{G'}(v)\le c_v\). In the weighted version of the problem, additionally each edge \(e\in E\) has a weight w(e) and we want to find a feasible subgraph \(G'=(V,E')\) maximizing \(\sum _{e\in E'} w(e)\). The problem is already NP-hard if \(c_v = 1\) for all \(v\in V\) (Zhang in: Proceedings of the joint international conference on frontiers in algorithmics and algorithmic aspects in information and management, FAW-AAIM 2012, Beijing, China, May 14–16, pp 359–367, 2012). In this paper, we introduce a generalization of the PDBEP problem. We let the edges have weights as well as demands, and we present the first constant-factor approximation algorithms for this problem. Our results imply the first constant-factor approximation algorithm for the weighted PDBEP problem, improving the result of Aurora et al. (FAW-AAIM 2013) who presented an \(O(\log n)\)-approximation for the weighted case. We also study the weighted PDBEP problem on hypergraphs and present a constant factor approximation if the maximum degree of the hypergraph is bounded above by a constant. We study a generalization of the weighted PDBEP problem with demands where each edge additionally specifies whether it requires at least one, or both its end-points to not exceed the capacity. The objective is to pick a maximum weight subset of edges. We give a constant factor approximation for this problem. We also present a PTAS for the weighted PDBEP problem with demands on H-minor free graphs, if the demands on the edges are bounded by polynomial. We show that the PDBEP problem is APX-hard even for bipartite graphs with \(c_v = 1, \; \forall v\in V\) and having degree at most 3. 相似文献