全文获取类型
收费全文 | 1810篇 |
免费 | 48篇 |
国内免费 | 7篇 |
专业分类
管理学 | 124篇 |
民族学 | 2篇 |
人口学 | 34篇 |
丛书文集 | 13篇 |
理论方法论 | 22篇 |
综合类 | 333篇 |
社会学 | 40篇 |
统计学 | 1297篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 12篇 |
2021年 | 14篇 |
2020年 | 29篇 |
2019年 | 48篇 |
2018年 | 58篇 |
2017年 | 93篇 |
2016年 | 53篇 |
2015年 | 57篇 |
2014年 | 75篇 |
2013年 | 552篇 |
2012年 | 159篇 |
2011年 | 49篇 |
2010年 | 62篇 |
2009年 | 48篇 |
2008年 | 69篇 |
2007年 | 58篇 |
2006年 | 50篇 |
2005年 | 52篇 |
2004年 | 27篇 |
2003年 | 33篇 |
2002年 | 32篇 |
2001年 | 28篇 |
2000年 | 28篇 |
1999年 | 26篇 |
1998年 | 19篇 |
1997年 | 19篇 |
1996年 | 15篇 |
1995年 | 9篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 10篇 |
1991年 | 5篇 |
1990年 | 9篇 |
1989年 | 6篇 |
1988年 | 9篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 3篇 |
排序方式: 共有1865条查询结果,搜索用时 15 毫秒
91.
Composite samples are formed by physically mixing samples. Usually, composite samples are used to reduce the overall cost associated with analytical procedures that must be performed on each sample, but they can also be used to protect the privacy of individuals. Composite sampling can reduce the cost of identifying individual cases that have a certain trait, such as those with a rare disease or those exceeding pollution-level standards. Not much is lost by applying this method as long as the trait is relatively rare. Composite sampling can reduce the cost of estimating the mean of some process. When samples are composited, the ability to estimate the variance is lost. In spite of this, the potential savings are so great that composite samples have been used. Much of this paper deasl with the variance of estimators based on composite sampling when the porportions of hte original samples comprising the composite sample are actually random. Taking repeated samples and measurements on several composite samples complicates the prodcedure, but allows the estimation of between and within variation as well as measurement error. 相似文献
92.
For square contingency tables with ordered categories, there may be some cases that one wants to analyze them by considering collapsed tables with some adjacent categories combined in the original table. This paper proposes three kinds of new models which have the structure of point-symmetry (PS), quasi point-symmetry and marginal point-symmetry for collapsed square tables. This paper also gives a decomposition of the PS model for collapsed square tables. The father's and his daughter's occupational mobility data are analyzed using new models. 相似文献
93.
94.
The paper aims to find variance balanced and variance partially balanced incomplete block designs when observations within blocks are autocorrelated and we call them BIBAC and PBIBAC designs. Orthogonal arrays of type I and type II when used as BIBAC designs have smaller average variance of elementary contrasts of treatment effects compared to the corresponding Balanced Incomplete Block (BIB) designs with homoscedastic, uncorrelated errors. The relative efficiency of BIB designs compared to BIBAC designs depends on the block size k and the autocorrelation ρ and is independent of the number of treatments. Further this relative efficiency increases with increasing k. Partially balanced incomplete block designs with autocorrelated errors are introduced using partially balanced incomplete block designs and orthogonal arrays of type I and type II. 相似文献
95.
Kōsei Iwase 《统计学通讯:理论与方法》2013,42(12):3559-3566
The uniformly minimum variance unbiased estimator of the cumulative hazard function in the Pareto distribution of the first kind is derived. The variance of the estimator is also obtained in an analytic form, and for some cases its values are compared numerically with mean square errors of the maximum likelihood estimator. 相似文献
96.
In a series of papers, Kshirsagar (1964, 1971) and McHenry and Kshirsagar (1977), factorize Wilks' A into a number of factors and find the independent null multivariate beta densities of these factors. These factors are the likelihood ratio test criteria for testing the goodness of fit of certain assigned discriminant functions or canonical variables either in the space of independent or dependent variables. Essentially the factors of Wilks' A are the factors of certain multivariate beta distributed matrix or its determinant. The Bartlett decomposition of the underlying multivariate beta distribution into independent factors determines the distribution of these factors. The present paper generalizes Kshirsagar's (1971) normal theory to the elliptically contoured model, and shows that his results are null robust for the elliptically contoured model. 相似文献
97.
Zhijie Xiao 《Econometric Reviews》2013,32(6):643-667
In this paper, we show that the widely used stationarity tests such as the Kwiatkowski Phillips, Schmidt, and Shin (KPSS) test have power close to size in the presence of time-varying unconditional variance. We propose a new test as a complement of the existing tests. Monte Carlo experiments show that the proposed test possesses the following characteristics: (i) in the presence of unit root or a structural change in the mean, the proposed test is as powerful as the KPSS and other tests; (ii) in the presence of a changing variance, the traditional tests perform badly whereas the proposed test has high power comparing to the existing tests; (iii) the proposed test has the same size as traditional stationarity tests under the null hypothesis of stationarity. An application to daily observations of return on U.S. Dollar/Euro exchange rate reveals the existence of instability in the unconditional variance when the entire sample is considered, but stability is found in subsamples. 相似文献
98.
汉代黑河(删丹河,或名张掖河,又名弱水)与北大河(金河,又名呼蚕水)交汇入注居延海,汉代以后直到唐代之前都没有记载.<元和郡县图志>记载两水分流,金河流注白亭海,张掖河流注居延海.敦煌文献记载晚唐时金河与张掖河交汇流注居延海,使居延海湖面出现一个恢复期.此外,金河和黑河流域地区居民结构变化、农业人口和用水量减少、黑河径流量增加也是居延海湖面增加的原因. 相似文献
99.
Abstract. Estimating higher‐order moments, particularly fourth‐order moments in linear mixed models is an important, but difficult issue. In this article, an orthogonality‐based estimation of moments is proposed. Under only moment conditions, this method can easily be used to estimate the model parameters and moments, particularly those of higher order than the second order, and in the estimators the random effects and errors do not affect each other. The asymptotic normality of all the estimators is provided. Moreover, the method is readily extended to handle non‐linear, semiparametric and non‐linear models. A simulation study is carried out to examine the performance of the new method. 相似文献
100.