全文获取类型
收费全文 | 6779篇 |
免费 | 322篇 |
国内免费 | 80篇 |
专业分类
管理学 | 440篇 |
劳动科学 | 27篇 |
民族学 | 165篇 |
人才学 | 4篇 |
人口学 | 87篇 |
丛书文集 | 1653篇 |
理论方法论 | 338篇 |
综合类 | 3617篇 |
社会学 | 333篇 |
统计学 | 517篇 |
出版年
2024年 | 14篇 |
2023年 | 37篇 |
2022年 | 113篇 |
2021年 | 142篇 |
2020年 | 101篇 |
2019年 | 110篇 |
2018年 | 122篇 |
2017年 | 160篇 |
2016年 | 120篇 |
2015年 | 231篇 |
2014年 | 272篇 |
2013年 | 372篇 |
2012年 | 356篇 |
2011年 | 481篇 |
2010年 | 500篇 |
2009年 | 496篇 |
2008年 | 503篇 |
2007年 | 492篇 |
2006年 | 508篇 |
2005年 | 424篇 |
2004年 | 236篇 |
2003年 | 234篇 |
2002年 | 227篇 |
2001年 | 199篇 |
2000年 | 139篇 |
1999年 | 123篇 |
1998年 | 74篇 |
1997年 | 68篇 |
1996年 | 62篇 |
1995年 | 57篇 |
1994年 | 36篇 |
1993年 | 43篇 |
1992年 | 29篇 |
1991年 | 19篇 |
1990年 | 25篇 |
1989年 | 18篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 1篇 |
排序方式: 共有7181条查询结果,搜索用时 15 毫秒
931.
Sliced inverse regression, a link-free and distribution-free method, is applied to binary response limited dependent variable models. An inverse regression property of binary response LDV model is found. Based on this property, if the distributions of X j (j = 1, 2,…, p) satisfy the linearity condition, then β can be estimated up to a positive multiplicative scalar without any assumptions on the distribution of error ε. Moreover, the estimator can be proved to be asymptotically normal based on which testing hypotheses are considered. Simulations results are reported. 相似文献
932.
This article is concerned with the parameter estimation in linear regression model when it is suspected that the regression coefficients are the subspace of the equality restrictions. The objective of this article is to introduce the preliminary test almost unbiased Liu estimators (PTAULE) based on the Wald (W), the likelihood ratio (LR), and the Lagrangian multiplier (LM) tests and compare the proposed estimators in the sense of the quadratic bias and mean square error (MSE) criterion. 相似文献
933.
AbstractIn this paper, assuming that the error terms follow a multivariate t distribution, we derive the exact formula for the predictive mean squared error (PMSE) of two different types of pretest estimators. It is shown analytically that one of the pretest estimator dominates the SR estimator if a critical value of the pretest is chosen appropriately. Also, we compare the PMSE of the pretest estimators with the MMSE, AMMSE, SR and PSR estimators by numerical evaluations. Our results show that the pretest estimators dominate the OLS estimator for all combinations when the degrees of freedom is not more than 5. 相似文献
934.
Kuan Xu 《Econometric Reviews》2013,32(5):567-577
U-statistics form a general class of statistics that have certain important features in common. This class arises as a generalization of the sample mean and the sample variance, and typically members of the class are asymptotically normal with good consistency properties. The class encompasses some widely used income inequality and poverty measures, in particular the variance, the Gini index, the poverty rate, the average poverty gap ratios, the Foster-Greer-Thorbecke index, and the Sen index and its modified form. This paper illustrates how these measures come together within the class of U-statistics, and thereby why U-statistics are useful in econometrics. 相似文献
935.
In this paper, we consider the following linear errors-in-variables regression model: , with independent identically distributed errors . The strong and weak consistency for the LS estimators and of the unknown parameters in this model are obtained, which weaken some known conditions and improve some known results. 相似文献
936.
Dinghai Xu 《统计学通讯:模拟与计算》2013,42(7):1403-1421
This article investigates an efficient estimation method for a class of switching regressions based on the characteristic function (CF). We show that with the exponential weighting function, the CF-based estimator can be achieved from minimizing a closed form distance measure. Due to the availability of the analytical structure of the asymptotic covariance, an iterative estimation procedure is developed involving the minimization of a precision measure of the asymptotic covariance matrix. Numerical examples are illustrated via a set of Monte Carlo experiments examining the implementation, finite sample property and the efficiency of the proposed estimator. 相似文献
937.
Przystalski and Krajewski (2007) proposed the restricted backfitting (RBCF) estimator and restricted Speckman (RSPC) estimator for the treatment effects in a partially linear model when some additional exact linear restrictions are assumed to hold. In this article, we introduce the preliminary test backfitting (PTBCF) estimator and preliminary test Speckman (PTSPC) estimator when the validity of the restrictions is suspected. Performances of the proposed estimators are examined with respect to the mean squared error (MSE) criterion. In addition, numerical behaviors of the proposed estimators are illustrated and compared via a Monte Carlo simulation study. 相似文献
938.
The Cox proportional hazards (PH) regression model has been widely used to analyze survival data in clinical trials and observational studies. In addition to estimating the main treatment or exposure group effect, it is common to adjust for additional covariates using the Cox model. It is well known that violation of the PH assumption can lead to estimates that are biased and difficult to interpret, and model checking has become a routine procedure. However, such checking might focus on the primary group comparisons, and the assumption can still be violated when adjusting for many of the potential covariates. We study the effect of violation of the PH assumption of the covariates on the estimation of the main group effect in the Cox model. The results are summarized in terms of the bias and the coverage properties of the confidence intervals. Overall in randomized clinical trials, the bias caused by misspecifying the PH assumption on the covariates is no more than 15% in absolute value regardless of sample size. In observational studies where the covariates are likely correlated with the group variable, however, the bias can be very severe. The coverage properties largely depend on sample size, as expected, as bias becomes dominating with increasing sample size. These findings should serve as cautionary notes when adjusting for potential confounders in observational studies, as the violation of PH assumption on the confounders can lead to erroneous results. 相似文献
939.
940.
基于2011—2019年我国277个市域农业的面板数据,运用反事实方法科学测度了其经济韧性水平,并借助系统GMM模型、中介模型和动态门槛模型等方法,实证检验了数字经济对市域农业经济韧性的影响效应及作用机理。研究发现:数字经济显著增强了市域农业经济韧性,这一结论经一系列稳健性检验后仍能成立;机制分析结果表明,农业资本深化是数字经济提升市域农业经济韧性的重要路径。异质性分析表明,在东部、中部、西部地区和人力资本水平较高的地区,数字经济对市域农业经济韧性的影响效应更为显著,而对东北部地区的提升效应则不显著。动态门槛检验进一步揭示,数字经济对市域农业经济韧性的影响呈现边际递增的非线性特征,当数字经济发展水平越过特定门槛值(0147)时,数字经济对市域农业经济韧性的促进作用显著增强。 相似文献