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   3691篇
  免费   115篇
  国内免费   15篇
管理学   380篇
民族学   6篇
人口学   69篇
丛书文集   54篇
理论方法论   95篇
综合类   351篇
社会学   250篇
统计学   2616篇
  2023年   27篇
  2022年   21篇
  2021年   38篇
  2020年   61篇
  2019年   108篇
  2018年   154篇
  2017年   226篇
  2016年   114篇
  2015年   118篇
  2014年   121篇
  2013年   854篇
  2012年   271篇
  2011年   140篇
  2010年   123篇
  2009年   154篇
  2008年   146篇
  2007年   143篇
  2006年   118篇
  2005年   133篇
  2004年   111篇
  2003年   92篇
  2002年   71篇
  2001年   74篇
  2000年   67篇
  1999年   55篇
  1998年   50篇
  1997年   38篇
  1996年   19篇
  1995年   16篇
  1994年   27篇
  1993年   17篇
  1992年   19篇
  1991年   13篇
  1990年   11篇
  1989年   8篇
  1988年   12篇
  1987年   7篇
  1986年   4篇
  1985年   8篇
  1984年   6篇
  1983年   9篇
  1982年   8篇
  1981年   1篇
  1980年   2篇
  1979年   2篇
  1978年   2篇
  1977年   1篇
  1976年   1篇
排序方式: 共有3821条查询结果,搜索用时 15 毫秒
111.
Measuring school effectiveness using student test scores is controversial and some methods used for this can be inaccurate in some situations. The validity of two statistical models – the Student Growth Percentile (SGP) model and a multilevel gain score model – are evaluated. The SGP model conditions on previous test scores thereby unblocking a backdoor path between true school/teacher effectiveness and student test scores. When the product of the coefficients that make up this unblocked backdoor path is positive, the SGP estimates can be inaccurate. The accuracy of the multilevel gain score model was not associated with the product of this backdoor path. The gain score model appears promising in these situations where the SGP and other covariate adjusted models perform poorly.  相似文献   
112.
By examining the association between employees' perceptions of job security and central labor market policies and characteristics, this paper seeks to understand the mechanisms through which institutions generate confidence and positive expectations among individuals regarding their economic future. The analyses distinguish between different facets of perceived job security and different institutional mechanisms. My multilevel analyses of a data set that contains information on 12,431 individuals and 23 countries show that some labor market policies and characteristics are more likely than others to provide workers with subjective security. Unemployment assistance in particular is an effective means of reducing workers' worries about job loss. Dismissal protection, by contrast, only unleashes its psychologically protective effects under certain conditions. The paper's main conclusion is that the effectiveness of policies varies and that different types of labor market institutions serve as complements rather than as substitutes.  相似文献   
113.
Understanding how wood develops has become an important problematic of plant sciences. However, studying wood formation requires the acquisition of count data difficult to interpret. Here, the annual wood formation dynamics of a conifer tree species were modeled using generalized linear and additive models (GLM and GAM); GAM for location, scale, and shape (GAMLSS); a discrete semiparametric kernel regression for count data. The performance of models is evaluated using bootstrap methods. GLM was useful to describe the wood formation general pattern but had a lack of fitting, while GAM, GAMLSS, and kernel regression had a higher sensibility to short-term variations.  相似文献   
114.
This paper considers quantile regression for a wide class of time series models including autoregressive and moving average (ARMA) models with asymmetric generalized autoregressive conditional heteroscedasticity errors. The classical mean‐variance models are reinterpreted as conditional location‐scale models so that the quantile regression method can be naturally geared into the considered models. The consistency and asymptotic normality of the quantile regression estimator is established in location‐scale time series models under mild conditions. In the application of this result to ARMA‐generalized autoregressive conditional heteroscedasticity models, more primitive conditions are deduced to obtain the asymptotic properties. For illustration, a simulation study and a real data analysis are provided.  相似文献   
115.
In this article, we propose the non parametric mixture of strictly monotone regression models. For implementation, a two-step procedure is derived. We further establish the asymptotic normality of the resultant estimator and demonstrate its good performance through numerical examples.  相似文献   
116.
No satisfactory goodness of fit test is available for multilevel survival data which occur when survival data are clustered or hierarchical in nature. Hence the aim of this research is to develop a new goodness of fit test for multilevel survival data and to examine the properties of the newly developed test. Simulation studies were carried out to evaluate the type ? error and the power. The results showed that the type I error holds for every combination tested and that the test is powerful against the alternative hypothesis of nonproportional hazards for all combinations tested.  相似文献   
117.
Igor Linkov 《Risk analysis》2012,32(8):1349-1368
Recent severe storm experiences in the U.S. Gulf Coast illustrate the importance of an integrated approach to flood preparedness planning that harmonizes stakeholder and agency efforts. Risk management decisions that are informed by and address decision maker and stakeholder risk perceptions and behavior are essential for effective risk management policy. A literature review and two expert models/mental models studies were undertaken to identify areas of importance in the flood risk management process for layperson, non‐USACE‐expert, and two USACE‐expert groups. In characterizing and mapping stakeholder beliefs about risks in the literature onto current risk management practice, recommendations for accommodating and changing stakeholder perceptions of flood risks and their management are identified. Needs of the U.S. Army Corps of Engineers (USACE) flood preparedness and response program are discussed in the context of flood risk mental models.  相似文献   
118.
We introduce the problem of estimation of the parameters of a dynamically selected population in an infinite sequence of random variables and provide its application in the statistical inference based on record values from a non stationary scheme. We develop unbiased estimation of the parameters of the dynamically selected population and evaluate the risk of the estimators. We provide comparisons with natural estimators and obtain asymptotic results. Finally, we illustrate the applicability of the results using real data.  相似文献   
119.
ABSTRACT

In this paper, we are interested in nonparametric inference issues for stochastic damping hamiltonian systems under the fluctuation-dissipation condition. This condition relates the magnitude of the dissipative term and the magnitude of the random term. The precise balance between the drift term which removes energy in average and the stochastic term provided by the fluctuation-dissipation relation insures that the canonical measure is preserved by the dynamics. In this framework, it is possible to give an explicit construction of a Lyapunov function and thus to prove exponential ergodicity. Then, we consider various estimation procedures and provide also a numerical section, where simulations are conducted.  相似文献   
120.
This paper presents a study of D- and A-optimality of direct sum designs for additive mixture models when the errors are heteroscedastic. Sufficient conditions are given so that D- and A-optimal designs for additive mixture models can be constructed from the D- and A-optimal designs for homogeneous models in sub-mixture systems.  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