全文获取类型
收费全文 | 2615篇 |
免费 | 78篇 |
国内免费 | 46篇 |
专业分类
管理学 | 494篇 |
民族学 | 1篇 |
人口学 | 2篇 |
丛书文集 | 42篇 |
理论方法论 | 4篇 |
综合类 | 761篇 |
社会学 | 12篇 |
统计学 | 1423篇 |
出版年
2024年 | 7篇 |
2023年 | 15篇 |
2022年 | 42篇 |
2021年 | 26篇 |
2020年 | 38篇 |
2019年 | 79篇 |
2018年 | 96篇 |
2017年 | 168篇 |
2016年 | 88篇 |
2015年 | 81篇 |
2014年 | 97篇 |
2013年 | 369篇 |
2012年 | 184篇 |
2011年 | 120篇 |
2010年 | 104篇 |
2009年 | 94篇 |
2008年 | 126篇 |
2007年 | 141篇 |
2006年 | 125篇 |
2005年 | 109篇 |
2004年 | 106篇 |
2003年 | 82篇 |
2002年 | 57篇 |
2001年 | 56篇 |
2000年 | 66篇 |
1999年 | 54篇 |
1998年 | 42篇 |
1997年 | 28篇 |
1996年 | 32篇 |
1995年 | 25篇 |
1994年 | 17篇 |
1993年 | 8篇 |
1992年 | 20篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 10篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1981年 | 2篇 |
排序方式: 共有2739条查询结果,搜索用时 203 毫秒
191.
Saieed F. Ateya 《Journal of applied statistics》2013,40(12):2720-2734
In this paper, the maximum likelihood (ML) and Bayes, by using Markov chain Monte Carlo (MCMC), methods are considered to estimate the parameters of three-parameter modified Weibull distribution (MWD(β, τ, λ)) based on a right censored sample of generalized order statistics (gos). Simulation experiments are conducted to demonstrate the efficiency of the proposed methods. Some comparisons are carried out between the ML and Bayes methods by computing the mean squared errors (MSEs), Akaike's information criteria (AIC) and Bayesian information criteria (BIC) of the estimates to illustrate the paper. Three real data sets from Weibull(α, β) distribution are introduced and analyzed using the MWD(β, τ, λ) and also using the Weibull(α, β) distribution. A comparison is carried out between the mentioned models based on the corresponding Kolmogorov–Smirnov (K–S) test statistic, {AIC and BIC} to emphasize that the MWD(β, τ, λ) fits the data better than the other distribution. All parameters are estimated based on type-II censored sample, censored upper record values and progressively type-II censored sample which are generated from the real data sets. 相似文献
192.
Estimating the propagation rate of a viral infection of potato plants via mixtures of regressions 总被引:2,自引:0,他引:2
T. Rolf Turner 《Journal of the Royal Statistical Society. Series C, Applied statistics》2000,49(3):371-384
A problem arising from the study of the spread of a viral infection among potato plants by aphids appears to involve a mixture of two linear regressions on a single predictor variable. The plant scientists studying the problem were particularly interested in obtaining a 95% confidence upper bound for the infection rate. We discuss briefly the procedure for fitting mixtures of regression models by means of maximum likelihood, effected via the EM algorithm. We give general expressions for the implementation of the M-step and then address the issue of conducting statistical inference in this context. A technique due to T. A. Louis may be used to estimate the covariance matrix of the parameter estimates by calculating the observed Fisher information matrix. We develop general expressions for the entries of this information matrix. Having the complete covariance matrix permits the calculation of confidence and prediction bands for the fitted model. We also investigate the testing of hypotheses concerning the number of components in the mixture via parametric and 'semiparametric' bootstrapping. Finally, we develop a method of producing diagnostic plots of the residuals from a mixture of linear regressions. 相似文献
193.
CHRISTOPHE BIERNACKI 《Scandinavian Journal of Statistics》2007,34(3):569-586
Abstract. In the context of the univariate Gaussian mixture with grouped data, it is shown that the global maximum of the likelihood may correspond to a situation where a Dirac lies in any non-empty interval. Existence of a domain of attraction near such a maximizer is discussed and we establish that the expectation-maximization (EM) iterates move extremely slowly inside this domain. These theoretical results are illustrated both by some Monte-Carlo experiments and by a real data set. To help practitioners identify and discard these potentially dangerous degenerate maximizers, a specific stopping rule for EM is proposed. 相似文献
194.
Nowadays, it is popular that the dealer makes profits by selling a kind of discount coupons, which can be used as money to
purchase commodities with total cost less than or equal to the face value of the coupon. We can purchase a coupon at a price
of 0<s≤1 times its face value and the number of potential purchasable coupons is a given integer l. The customer has the option to buy the goods by cash completely or by a discount coupon. However, each piece of goods can
only use one coupon and the coupon used must have enough balance for the goods. The objective is to minimize the total cost
for purchasing all the goods. In this paper, we reduce the problem to a special bin packing model. We consider the online
problems for all 0<s≤1 and 1≤l≤∞. We present optimal online algorithms for all 0<s≤1 when l=∞ and l=1. For 2≤l<∞, we give both a lower bound and an algorithm, and show the algorithm is optimal for l=2.
A preliminary version of this paper appeared in the proceedings of the 1st International Symposium on Combinatorics, Algorithms,
Probabilistic and Experimental Methodologies, Lecture Notes in Computer Science.
Y. Jiang supported by Natural Science Foundation of Zhejiang Province (Y605316).
Z. Tan supported by Natural Science Foundation of China (10671177, 60021201). 相似文献
195.
模拟电路故障诊断的神经网络方法 总被引:6,自引:0,他引:6
李春明 《内蒙古工业大学学报》2000,19(2):130-133
提出了一种采用改进的BP快速算法实现模拟电路软故障诊断的方法。文中对构造神经网络交流故障字典的过程给出了详细说明,特别是隐层节点数确定,测试信号频率的优选及MATLAB神经网络工具箱的使用。实例表明,人工神经网络技术可应用于有容差模拟电路的故障诊断。 相似文献
196.
For clustering mixed categorical and continuous data, Lawrence and Krzanowski (1996) proposed a finite mixture model in which component densities conform to the location model. In the graphical models literature the location model is known as the homogeneous Conditional Gaussian model. In this paper it is shown that their model is not identifiable without imposing additional restrictions. Specifically, for g groups and m locations, (g!)m–1 distinct sets of parameter values (not including permutations of the group mixing parameters) produce the same likelihood function. Excessive shrinkage of parameter estimates in a simulation experiment reported by Lawrence and Krzanowski (1996) is shown to be an artifact of the model's non-identifiability. Identifiable finite mixture models can be obtained by imposing restrictions on the conditional means of the continuous variables. These new identified models are assessed in simulation experiments. The conditional mean structure of the continuous variables in the restricted location mixture models is similar to that in the underlying variable mixture models proposed by Everitt (1988), but the restricted location mixture models are more computationally tractable. 相似文献
197.
ABSTRACTEconomic statistical designs aim at minimizing the cost of process monitoring when a specific scenario or a set of estimated process and cost parameters is given. But, in practice the process may be affected by more than one scenario which may lead to severe cost penalties if the wrong design is used. Here, we investigate the robust economic statistical design (RESD) of the T2 chart in an attempt to reduce these cost penalties when there are multiple scenarios. Our method is to employ the genetic algorithm (GA) optimization method to minimize the total expected monitoring cost across all distinct scenarios. We illustrate the effectiveness of the method using two numerical examples. Simulation studies indicate that robust economic statistical designs should be encouraged in practice. 相似文献
198.
When an appropriate parametric model and a prior distribution of its parameters are given to describe clinical time courses of a dynamic biological process, Bayesian approaches allow us to estimate the entire profiles from a few or even a single observation per subject. The goodness of the estimation depends on the measurement points at which the observations were made. The number of measurement points per subject is generally limited to one or two. The limited measurement points have to be selected carefully. This paper proposes an approach to the selection of the optimum measurement point for Bayesian estimations of clinical time courses. The selection is made among given candidates, based on the goodness of estimation evaluated by the Kullback-Leibler information. This information measures the discrepancy of an estimated time course from the true one specified by a given appropriate model. The proposed approach is applied to a pharmacokinetic analysis, which is a typical clinical example where the selection is required. The results of the present study strongly suggest that the proposed approach is applicable to pharmacokinetic data and has a wide range of clinical applications. 相似文献
199.
模糊教学法是针对竞技体育教育思想提出的一种新的教学方法 ,它符合现代学校体育改革与发展的思想观念 .研究表明 ,模糊教学法在女大学生体育课中效果良好 ,值得推广 . 相似文献
200.
一种新的GPS导航卫星选择算法 总被引:2,自引:0,他引:2
针对利用全球定位系统(GPS)进行定位导航时对实时性的要求,提出了一种新的导航卫星选择算法。该算法比传统算法的计算量小得多。仿真结果表明,该算法所得出的结果与传统算法很接近,能满足导航定位的实时性精度要求。 相似文献