全文获取类型
收费全文 | 18962篇 |
免费 | 200篇 |
国内免费 | 1篇 |
专业分类
管理学 | 2812篇 |
民族学 | 134篇 |
人口学 | 3188篇 |
丛书文集 | 35篇 |
理论方法论 | 1113篇 |
综合类 | 440篇 |
社会学 | 8078篇 |
统计学 | 3363篇 |
出版年
2023年 | 54篇 |
2020年 | 144篇 |
2019年 | 186篇 |
2018年 | 1863篇 |
2017年 | 1920篇 |
2016年 | 1297篇 |
2015年 | 201篇 |
2014年 | 263篇 |
2013年 | 1494篇 |
2012年 | 618篇 |
2011年 | 1364篇 |
2010年 | 1211篇 |
2009年 | 957篇 |
2008年 | 979篇 |
2007年 | 1175篇 |
2006年 | 206篇 |
2005年 | 421篇 |
2004年 | 422篇 |
2003年 | 368篇 |
2002年 | 263篇 |
2001年 | 230篇 |
2000年 | 218篇 |
1999年 | 184篇 |
1998年 | 133篇 |
1997年 | 131篇 |
1996年 | 159篇 |
1995年 | 110篇 |
1994年 | 110篇 |
1993年 | 98篇 |
1992年 | 144篇 |
1991年 | 124篇 |
1990年 | 118篇 |
1989年 | 114篇 |
1988年 | 105篇 |
1987年 | 91篇 |
1986年 | 97篇 |
1985年 | 111篇 |
1984年 | 115篇 |
1983年 | 127篇 |
1982年 | 99篇 |
1981年 | 89篇 |
1980年 | 86篇 |
1979年 | 95篇 |
1978年 | 92篇 |
1977年 | 81篇 |
1976年 | 70篇 |
1975年 | 70篇 |
1974年 | 59篇 |
1973年 | 63篇 |
1971年 | 53篇 |
排序方式: 共有10000条查询结果,搜索用时 781 毫秒
921.
Zdeněk Hlávka Marie Hušková Claudia Kirch Simos G. Meintanis 《Econometric Reviews》2017,36(4):468-492
We develop testing procedures which detect if the observed time series is a martingale difference sequence. Furthermore, tests are developed that detect change–points in the conditional expectation of the series given its past. The test statistics are formulated following the approach of Fourier–type conditional expectations first proposed by Bierens (1982) and have the advantage of computational simplicity. The limit behavior of the test statistics is investigated under the null hypothesis as well as under alternatives. Since the asymptotic null distribution contains unknown parameters, a bootstrap procedure is proposed in order to actually perform the test. The performance of the bootstrap version of the test is compared in finite samples with other methods for the same problem. A real–data application is also included. 相似文献
922.
The paper entitled “Bivariate and Multivariate Normal Characterizations: A Brief Survey,” by Hamedani, which was published in 1992, covered the published characterizations of bivariate and multivariate normal (MVN) distributions from 1941 to 1991. The present work is a follow-up to the 1991/1992 survey which includes not only characterizations of the bivariate and MVN distributions, but also characterizations of the matrix variate normal distribution, which have appeared from 1991/1992 to the present. 相似文献
923.
924.
Gap times between recurrent events are often of primary interest in medical and observational studies. The additive hazards model, focusing on risk differences rather than risk ratios, has been widely used in practice. However, the marginal additive hazards model does not take the dependence among gap times into account. In this paper, we propose an additive mixed effect model to analyze gap time data, and the proposed model includes a subject-specific random effect to account for the dependence among the gap times. Estimating equation approaches are developed for parameter estimation, and the asymptotic properties of the resulting estimators are established. In addition, some graphical and numerical procedures are presented for model checking. The finite sample behavior of the proposed methods is evaluated through simulation studies, and an application to a data set from a clinic study on chronic granulomatous disease is provided. 相似文献
925.
Several variable selection procedures are available for continuous time-to-event data. However, if time is measured in a discrete way and therefore many ties occur models for continuous time are inadequate. We propose penalized likelihood methods that perform efficient variable selection in discrete survival modeling with explicit modeling of the heterogeneity in the population. The method is based on a combination of ridge and lasso type penalties that are tailored to the case of discrete survival. The performance is studied in simulation studies and an application to the birth of the first child. 相似文献
926.
A common objective of cohort studies and clinical trials is to assess time-varying longitudinal continuous biomarkers as correlates of the instantaneous hazard of a study endpoint. We consider the setting where the biomarkers are measured in a designed sub-sample (i.e., case-cohort or two-phase sampling design), as is normative for prevention trials. We address this problem via joint models, with underlying biomarker trajectories characterized by a random effects model and their relationship with instantaneous risk characterized by a Cox model. For estimation and inference we extend the conditional score method of Tsiatis and Davidian (Biometrika 88(2):447–458, 2001) to accommodate the two-phase biomarker sampling design using augmented inverse probability weighting with nonparametric kernel regression. We present theoretical properties of the proposed estimators and finite-sample properties derived through simulations, and illustrate the methods with application to the AIDS Clinical Trials Group 175 antiretroviral therapy trial. We discuss how the methods are useful for evaluating a Prentice surrogate endpoint, mediation, and for generating hypotheses about biological mechanisms of treatment efficacy. 相似文献
927.
This paper is about satisficing behaviour. Rather tautologically, this is when decision-makers are satisfied with achieving some objective, rather than in obtaining the best outcome. The term was coined by Simon (Q J Econ 69:99–118, 1955), and has stimulated many discussions and theories. Prominent amongst these theories are models of incomplete preferences, models of behaviour under ambiguity, theories of rational inattention, and search theories. Most of these, however, seem to lack an answer to at least one of two key questions: when should the decision-maker (DM) satisfice; and how should the DM satisfice. In a sense, search models answer the latter question (in that the theory tells the DM when to stop searching), but not the former; moreover, usually the question as to whether any search at all is justified is left to a footnote. A recent paper by Manski (Theory Decis. doi: 10.1007/s11238-017-9592-1, 2017) fills the gaps in the literature and answers the questions: when and how to satisfice? He achieves this by setting the decision problem in an ambiguous situation (so that probabilities do not exist, and many preference functionals can therefore not be applied) and by using the Minimax Regret criterion as the preference functional. The results are simple and intuitive. This paper reports on an experimental test of his theory. The results show that some of his propositions (those relating to the ‘how’) appear to be empirically valid while others (those relating to the ‘when’) are less so. 相似文献
928.
Nobuo Koida 《Theory and Decision》2017,83(3):407-430
In this study, we analyze choice in the presence of some conflict that affects the decision time (response time), a subject that has been documented in the literature. We axiomatize a multiattribute decision time (MDT) representation, which is a dynamic extension of the classic multiattribute expected utility theory that allows potentially incomplete preferences. Under this framework, one alternative is preferred to another in a certain period if and only if the weighted sum of the attribute-dependent expected utility induced by the former alternative is larger than that induced by the latter for all attribute weights in a closed and convex set. MDT uniquely determines the decision time as the earliest period at which the ranking between alternatives becomes decisive. The comparative statics result indicates that the decision time provides useful information to locate indifference curves in a specific setting. MDT also explains various empirical findings in economics and other relevant fields. 相似文献
929.
Raphael Thiele 《Theory and Decision》2017,83(3):355-364
A jury and two valid options are given. Each agent of the jury picks exactly one of these options. The option with the most votes will be chosen by the jury. In the N-couple model of Althöfer and Thiele (Theory and Decision 81:1–15, 2016), the jury consisted of 2N agents. These agents form N independent couples, with dependencies within the couples. The authors assumed that the agents who form a couple have the same competence level. In this note, we relax this assumption by allowing different competence levels within the couples. We show that the theoretical results of Althöfer and Thiele remain valid under this relaxation. 相似文献
930.
This paper has a twofold scope. The first one is to clarify and put in evidence the isomorphic character of two theories developed in quite different fields: on one side, threshold logic, on the other side, simple games. One of the main purposes in both theories is to determine when a simple game is representable as a weighted game, which allows a very compact and easily comprehensible representation. Deep results were found in threshold logic in the sixties and seventies for this problem. However, game theory has taken the lead and some new results have been obtained for the problem in the past two decades. The second and main goal of this paper is to provide some new results on this problem and propose several open questions and conjectures for future research. The results we obtain depend on two significant parameters of the game: the number of types of equivalent players and the number of types of shift-minimal winning coalitions. 相似文献