全文获取类型
收费全文 | 2528篇 |
免费 | 72篇 |
国内免费 | 39篇 |
专业分类
管理学 | 463篇 |
民族学 | 1篇 |
人口学 | 2篇 |
丛书文集 | 37篇 |
理论方法论 | 8篇 |
综合类 | 846篇 |
社会学 | 19篇 |
统计学 | 1263篇 |
出版年
2024年 | 7篇 |
2023年 | 16篇 |
2022年 | 42篇 |
2021年 | 26篇 |
2020年 | 40篇 |
2019年 | 75篇 |
2018年 | 78篇 |
2017年 | 137篇 |
2016年 | 78篇 |
2015年 | 75篇 |
2014年 | 87篇 |
2013年 | 381篇 |
2012年 | 178篇 |
2011年 | 118篇 |
2010年 | 103篇 |
2009年 | 89篇 |
2008年 | 130篇 |
2007年 | 123篇 |
2006年 | 113篇 |
2005年 | 112篇 |
2004年 | 108篇 |
2003年 | 70篇 |
2002年 | 53篇 |
2001年 | 54篇 |
2000年 | 66篇 |
1999年 | 59篇 |
1998年 | 41篇 |
1997年 | 30篇 |
1996年 | 35篇 |
1995年 | 26篇 |
1994年 | 19篇 |
1993年 | 8篇 |
1992年 | 20篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 12篇 |
1988年 | 7篇 |
1987年 | 3篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
排序方式: 共有2639条查询结果,搜索用时 15 毫秒
131.
Josef Kozák 《Statistics》2013,47(3):363-371
Working with the linear regression model (1.1) and having the extraneous information (1.2) about regression coefficients the problem exists how to build estimators (1.3) with the risk (1.4) which enable to utilize the known information in order to reduce their risk as compared with the risk (1.6) of the LSE (1.5). Solution of this problem is known for the positive definite matrix T, namely in form for estimators (1.8) and (1.10).First, it is shown that the proposed estimators (2.6),(2.9) and (2.16) based on psedoinversions of the matrix L represent the solution of the problem of the positive semidefinite matrix T=L'L.Further, the problem of interpretability of estimators in the sense of the inequality (3.1) exists; it is shown that all mentioned estimators are at least partially interpretable in the sense of requirements (3.2) or (3.10). 相似文献
132.
Ole Klungsøyr Joe Sexton Inger Sandanger Jan F. Nygård 《Journal of applied statistics》2013,40(4):843-861
A substantial degree of uncertainty exists surrounding the reconstruction of events based on memory recall. This form of measurement error affects the performance of structured interviews such as the Composite International Diagnostic Interview (CIDI), an important tool to assess mental health in the community. Measurement error probably explains the discrepancy in estimates between longitudinal studies with repeated assessments (the gold-standard), yielding approximately constant rates of depression, versus cross-sectional studies which often find increasing rates closer in time to the interview. Repeated assessments of current status (or recent history) are more reliable than reconstruction of a person's psychiatric history based on a single interview. In this paper, we demonstrate a method of estimating a time-varying measurement error distribution in the age of onset of an initial depressive episode, as diagnosed by the CIDI, based on an assumption regarding age-specific incidence rates. High-dimensional non-parametric estimation is achieved by the EM-algorithm with smoothing. The method is applied to data from a Norwegian mental health survey in 2000. The measurement error distribution changes dramatically from 1980 to 2000, with increasing variance and greater bias further away in time from the interview. Some influence of the measurement error on already published results is found. 相似文献
133.
Selecting an optimal 2k?pfractional factorial is structured as a mathematical programming problem. An algorithm is defined for the solution, and the case of additive costs is shown to have a known solution for resolution III designs. 相似文献
134.
It is well-known that the nonparametric maximum likelihood estimator (NPMLE) of a survival function may severely underestimate the survival probabilities at very early times for left truncated data. This problem might be overcome by instead computing a smoothed nonparametric estimator (SNE) via the EMS algorithm. The close connection between the SNE and the maximum penalized likelihood estimator is also established. Extensive Monte Carlo simulations demonstrate the superior performance of the SNE over that of the NPMLE, in terms of either bias or variance, even for moderately large Samples. The methodology is illustrated with an application to the Massachusetts Health Care Panel Study dataset to estimate the probability of being functionally independent for non-poor male and female groups rcspectively. 相似文献
135.
S. Kalke 《Journal of Statistical Computation and Simulation》2013,83(4):641-667
In this paper, we introduce the p-generalized polar methods for the simulation of the p-generalized Gaussian distribution. On the basis of geometric measure representations, the well-known Box–Muller method and the Marsaglia–Bray rejecting polar method for the simulation of the Gaussian distribution are generalized to simulate the p-generalized Gaussian distribution, which fits much more flexibly to data than the Gaussian distribution and has already been applied in various fields of modern sciences. To prove the correctness of the p-generalized polar methods, we give stochastic representations, and to demonstrate their adequacy, we perform a comparison of six simulation techniques w.r.t. the goodness of fit and the complexity. The competing methods include adapted general methods and another special method. Furthermore, we prove stochastic representations for all the adapted methods. 相似文献
136.
This paper evaluates the ability of a Markov regime-switching log-normal (RSLN) model to capture the time-varying features of stock return and volatility. The model displays a better ability to depict a fat tail distribution as compared with using a log-normal model, which means that the RSLN model can describe observed market behavior better. Our major objective is to explore the capability of the model to capture stock market behavior over time. By analyzing the behavior of calibrated regime-switching parameters over different lengths of time intervals, the change-point concept is introduced and an algorithm is proposed for identifying the change-points in the series corresponding to the times when there are changes in parameter estimates. This algorithm for identifying change-points is tested on the Standard and Poor's 500 monthly index data from 1971 to 2008, and the Nikkei 225 monthly index data from 1984 to 2008. It is evident that the change-points we identify match the big events observed in the US stock market and the Japan stock market (e.g., the October 1987 stock market crash), and that the segmentations of stock index series, which are defined as the periods between change-points, match the observed bear–bull market phases. 相似文献
137.
138.
139.
Li L 《Lifetime data analysis》2000,6(3):271-279
Suppose that when a unit operatesin a certain environment, its lifetime has distribution G,and when the unit operates in another environment, its lifetimehas a different distribution, say F. Moreover, supposethe unit is operated for a certain period of time in the firstenvironment and is then transferred to the second environment.Thus we observe a censored lifetime in the first environmentand a failure time of a ``used' unit in the second environment.We propose an EM algorithm approach for obtaining a self-consistentestimator of F. Moreover, suppose using observations from both environments.The case where failure times are subject to right censoring isconsidered as well. We also establish the maximum likelihoodestimator of F. Moreover, suppose when the unit is repairable. Applicationand simulation studies are presented to illustrate the methodsderived. 相似文献
140.
Toshimasa Ishii Hiroshi Nagamochi Toshihide Ibaraki 《Journal of Combinatorial Optimization》2000,4(1):35-77
Given an undirected multigraph G = (V, E) and two positive integers and k, we consider the problem of augmenting G by the smallest number of new edges to obtain an -edge-connected and k-vertex-connected multigraph. In this paper, we show that the problem can be solved in Õ(mn2) time for any fixed and k = 3 if an input multigraph G is 2-vertex-connected, where n = |V| and m is the number of pairs of adjacent vertices in G. 相似文献