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101.
We introduce a general class of continuous univariate distributions with positive support obtained by transforming the class of two-piece distributions. We show that this class of distributions is very flexible, easy to implement, and contains members that can capture different tail behaviours and shapes, producing also a variety of hazard functions. The proposed distributions represent a flexible alternative to the classical choices such as the log-normal, Gamma, and Weibull distributions. We investigate empirically the inferential properties of the proposed models through an extensive simulation study. We present some applications using real data in the contexts of time-to-event and accelerated failure time models. In the second kind of applications, we explore the use of these models in the estimation of the distribution of the individual remaining life. 相似文献
102.
《Journal of Statistical Computation and Simulation》2012,82(12):1145-1161
The Perron test which is based on a Dickey–Fuller test regression is a commonly employed approach to test for a unit root in the presence of a structural break of unknown timing. In the case of an innovational outlier (IO), the Perron test tends to exhibit spurious rejections in finite samples when the break occurs under the null hypothesis. In the present paper, a new Perron-type IO unit root test is developed. It is shown in Monte Carlo experiments that the new test does not over-reject the null hypothesis. Even for the case of a level and slope break for trending data, the empirical size is near its nominal level. The test distribution equals the case of a known break date. Furthermore, the test is able to identify the true break date very accurately even for small breaks. As an application serves the Nelson–Plosser data set. 相似文献
103.
《统计学通讯:理论与方法》2012,41(13-14):2437-2444
We propose a new approach to estimate the parameters of the Cox proportional hazards model in the presence of collinearity. Generally, a maximum partial likelihood estimator is used to estimate parameters for the Cox proportional hazards model. However, the maximum partial likelihood estimators can be seriously affected by the presence of collinearity since the parameter estimates result in large variances. In this study, we develop a Liu-type estimator for Cox proportional hazards model parameters and compare it with a ridge regression estimator based on the scalar mean squared error (MSE). Finally, we evaluate its performance through a simulation study. 相似文献
104.
周晨虹 《广州大学学报(社会科学版)》2014,(5):59-64
"大学社区参与"是20世纪90年代以来美国兴起的新型大学社会服务模式。这一模式在大学与社区的合作伙伴关系基础上,以社区需求和社会发展为动力,旨在推进大学教学、科研与服务功能的综合发展,具有学术性、综合性、互惠性、公共性等特征。大学领导层、组织机构、教师参与、组织文化以及大学与社区的权力关系等因素共同决定着"大学社区参与"模式的运行状况。"大学社区参与"模式对我国大学社会服务的现代发展具有借鉴意义。 相似文献
105.
For decision purpose, one of the commonly used statistical applications is the comparison of two or more objects or characteristics. Sometimes, it is not possible to compare the objects at a time or when the number of objects under study is large and the differences between the objects become small, then a useful way is to compare them in pairwise manner. Because of its practical nature, the fields in which paired comparison techniques are being used are numerous. Many Bayesian statisticians have focused their attention on the practical and usable paired comparison technique and have successfully performed the Bayesian study of many of the paired comparison models. In the current study, analysis of the amended Davidson model (ADM) which has been extended after incorporating the order effect parameter is narrated. For this intention, both the informative and non informative priors are used. The said model is studied for the case of four treatments which are compared pairwise. 相似文献
106.
《Journal of the Korean Statistical Society》2014,43(3):339-353
Conditionally autoregressive (CAR) models are often used to analyze a spatial process observed over a lattice or a set of irregular regions. The neighborhoods within a CAR model are generally formed deterministically using the inter-distances or boundaries between the regions. To accommodate directional and inherent anisotropy variation, a new class of spatial models is proposed that adaptively determines neighbors based on a bivariate kernel using the distances and angles between the centroid of the regions. The newly proposed model generalizes the usual CAR model in a sense of accounting for adaptively determined weights. Maximum likelihood estimators are derived and simulation studies are presented for the sampling properties of the estimates on the new model, which is compared to the CAR model. Finally the method is illustrated using a data set on the elevated blood lead levels of children under the age of 72 months observed in Virginia in the year of 2000. 相似文献
107.
We present influence diagnostics for linear measurement error models with stochastic linear restrictions using the corrected likelihood of Nakamura in 1990. The case deletion and mean shift outlier models are developed to identify outlying and influential observations. We derive a corrected score test statistic for outlier detection based on mean shift outlier models. The analogs of Cook's distance and likelihood distance are proposed to determine influential observations based on case deletion models. A parametric bootstrap procedure is used to obtain empirical distributions of the test statistics and a simulation study has been used to evaluate the performance of the proposed estimators based on the mean squares error criterion and the score test statistic. Finally, a numerical example is given to illustrate the theoretical results. 相似文献
108.
Daniel B. Wright 《Journal of applied statistics》2018,45(14):2536-2547
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
109.
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
110.
Henri E. Cuny 《统计学通讯:模拟与计算》2016,45(5):1748-1762
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