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91.
92.
Prostate cancer (PrCA) is the most common cancer diagnosed in American men and the second leading cause of death from malignancies. There are large geographical variation and racial disparities existing in the survival rate of PrCA. Much work on the spatial survival model is based on the proportional hazards (PH) model, but few focused on the accelerated failure time (AFT) model. In this paper, we investigate the PrCA data of Louisiana from the Surveillance, Epidemiology, and End Results program and the violation of the PH assumption suggests that the spatial survival model based on the AFT model is more appropriate for this data set. To account for the possible extra-variation, we consider spatially referenced independent or dependent spatial structures. The deviance information criterion is used to select a best-fitting model within the Bayesian frame work. The results from our study indicate that age, race, stage, and geographical distribution are significant in evaluating PrCA survival. 相似文献
93.
In this study, we evaluate several forms of both Akaike-type and Information Complexity (ICOMP)-type information criteria, in the context of selecting an optimal subset least squares ratio (LSR) regression model. Our simulation studies are designed to mimic many characteristics present in real data – heavy tails, multicollinearity, redundant variables, and completely unnecessary variables. Our findings are that LSR in conjunction with one of the ICOMP criteria is very good at selecting the true model. Finally, we apply these methods to the familiar body fat data set. 相似文献
94.
95.
Joseph E. Cavanaugh Andrew A. Neath Simon L. Davies 《Journal of statistical planning and inference》2010
The conceptual predictive statistic, Cp, is a widely used criterion for model selection in linear regression. Cp serves as an estimator of a discrepancy, a measure that reflects the disparity between the generating model and a fitted candidate model. This discrepancy, based on scaled squared error loss, is asymmetric: an alternate measure is obtained by reversing the roles of the two models in the definition of the measure. We propose a variant of the Cp statistic based on estimating a symmetrized version of the discrepancy targeted by Cp. We claim that the resulting criterion provides better protection against overfitting than Cp, since the symmetric discrepancy is more sensitive towards detecting overspecification than its asymmetric counterpart. We illustrate our claim by presenting simulation results. Finally, we demonstrate the practical utility of the new criterion by discussing a modeling application based on data collected in a cardiac rehabilitation program at University of Iowa Hospitals and Clinics. 相似文献
96.
97.
We consider the calculation of power functions in classical multivariate analysis. In this context, power can be expressed
in terms of tail probabilities of certain noncentral distributions. The necessary noncentral distribution theory was developed
between the 1940s and 1970s by a number of authors. However, tractable methods for calculating the relevant probabilities
have been lacking. In this paper we present simple yet extremely accurate saddlepoint approximations to power functions associated
with the following classical test statistics: the likelihood ratio statistic for testing the general linear hypothesis in
MANOVA; the likelihood ratio statistic for testing block independence; and Bartlett's modified likelihood ratio statistic
for testing equality of covariance matrices. 相似文献
98.
This article has two objectives. First, it aims to complement and extend existing research on post-socialist demographic change, which has thus far tended to focus on Central and Eastern Europe. It does this by describing the nature of post-Soviet trends in nuptiality and fertility in Tajikistan, the republic with the highest rate of population growth during the Soviet period. It finds evidence for a decrease in period fertility after independence: initially, through a decline at higher orders; then, through a significant decrease in the rate of first births, associated with a dramatic decrease in the rate of first union formation since the mid-1990s. Second, it aims to contribute to the demography of conflict and of food crisis. Most clearly, it finds strong evidence for a decrease in nuptiality and fertility associated with the 1995 food crisis. 相似文献
99.
There is mixed evidence in the existing literature on whether children are associated with greater subjective well-being, with the correlation depending on which countries and populations are considered. We here provide a systematic analysis of this question based on three different datasets: two cross-national and one national panel. We show that the association between children and subjective well-being is positive only in developed countries, and for those who become parents after the age of 30 and who have higher income. We also provide evidence of a positive selection into parenthood, whereby happier individuals are more likely to have children. 相似文献
100.
We discuss the analysis of random effects in capture-recapture models, and outline Bayesian and frequentists approaches to their analysis. Under a normal model, random effects estimators derived from Bayesian or frequentist considerations have a common form as shrinkage estimators. We discuss some of the difficulties of analysing random effects using traditional methods, and argue that a Bayesian formulation provides a rigorous framework for dealing with these difficulties. In capture-recapture models, random effects may provide a parsimonious compromise between constant and completely time-dependent models for the parameters (e.g. survival probability). We consider application of random effects to band-recovery models, although the principles apply to more general situations, such as Cormack-Jolly-Seber models. We illustrate these ideas using a commonly analysed band recovery data set. 相似文献