全文获取类型
| 收费全文 | 3425篇 |
| 免费 | 26篇 |
专业分类
| 管理学 | 368篇 |
| 民族学 | 37篇 |
| 人口学 | 443篇 |
| 丛书文集 | 7篇 |
| 理论方法论 | 237篇 |
| 综合类 | 54篇 |
| 社会学 | 1529篇 |
| 统计学 | 776篇 |
出版年
| 2024年 | 31篇 |
| 2023年 | 46篇 |
| 2022年 | 35篇 |
| 2021年 | 47篇 |
| 2020年 | 126篇 |
| 2019年 | 152篇 |
| 2018年 | 207篇 |
| 2017年 | 233篇 |
| 2016年 | 219篇 |
| 2015年 | 112篇 |
| 2014年 | 171篇 |
| 2013年 | 641篇 |
| 2012年 | 178篇 |
| 2011年 | 96篇 |
| 2010年 | 82篇 |
| 2009年 | 60篇 |
| 2008年 | 74篇 |
| 2007年 | 70篇 |
| 2006年 | 39篇 |
| 2005年 | 46篇 |
| 2004年 | 49篇 |
| 2003年 | 36篇 |
| 2002年 | 40篇 |
| 2001年 | 45篇 |
| 2000年 | 34篇 |
| 1999年 | 32篇 |
| 1998年 | 35篇 |
| 1997年 | 22篇 |
| 1996年 | 19篇 |
| 1995年 | 25篇 |
| 1994年 | 18篇 |
| 1993年 | 19篇 |
| 1992年 | 28篇 |
| 1991年 | 26篇 |
| 1990年 | 17篇 |
| 1989年 | 18篇 |
| 1988年 | 28篇 |
| 1987年 | 23篇 |
| 1986年 | 20篇 |
| 1985年 | 19篇 |
| 1984年 | 15篇 |
| 1983年 | 14篇 |
| 1982年 | 15篇 |
| 1981年 | 18篇 |
| 1979年 | 13篇 |
| 1978年 | 21篇 |
| 1977年 | 15篇 |
| 1976年 | 11篇 |
| 1975年 | 17篇 |
| 1968年 | 14篇 |
排序方式： 共有3451条查询结果，搜索用时 0 毫秒
61.
Heitor de Oliveira Duarte Enrique Lopez Droguett Márcio das Chagas Moura Elainne Christine de Souza Gomes Constança Barbosa Verônica Barbosa Moacyr Araújo 《Risk analysis》2014,34(5):831-846
We developed a stochastic model for quantitative risk assessment for the Schistosoma mansoni (SM) parasite, which causes an endemic disease of public concern. The model provides answers in a useful format for public health decisions, uses data and expert opinion, and can be applied to any landscape where the snail Biomphalaria glabrata is the main intermediate host (South and Central America, the Caribbean, and Africa). It incorporates several realistic and case‐specific features: stage‐structured parasite populations, periodic praziquantel (PZQ) drug treatment for humans, density dependence, extreme events (prolonged rainfall), site‐specific sanitation quality, environmental stochasticity, monthly rainfall variation, uncertainty in parameters, and spatial dynamics. We parameterize the model through a real‐world application in the district of Porto de Galinhas (PG), one of the main touristic destinations in Brazil, where previous studies identified four parasite populations within the metapopulation. The results provide a good approximation of the dynamics of the system and are in agreement with our field observations, i.e., the lack of basic infrastructure (sanitation level and health programs) makes PG a suitable habitat for the persistence and growth of a parasite metapopulation. We quantify the risk of SM metapopulation explosion and quasi‐extinction and the time to metapopulation explosion and quasi‐extinction. We evaluate the sensitivity of the results under varying scenarios of future periodic PZQ treatment (based on the Brazilian Ministry of Health's plan) and sanitation quality. We conclude that the plan might be useful to slow SM metapopulation growth but not to control it. Additional investments in better sanitation are necessary. 相似文献
62.
We study distributional properties of generalized order statistics (gos) related by a random shift or scaling scheme in the continuous and discrete case, respectively. In the continuous case, we obtain new characterizations of distributions relating non-neighbouring gos extending some results given in the literature for the neighbouring cases. On the other hand, in the discrete case, we investigate the existence and uniqueness of a discrete parent distribution supported on the integers whose gos are related by a random translation. 相似文献
63.
In the time series literature, recent interest has focused on the so-called subspace methods. These techniques use canonical correlations and linear regressions to estimate the system matrices of an ARMAX model expressed in state space form. In this article, we use subspace methods to forecast two series with the help of some exogenous variables related to them. We compare the results with those obtained using traditional transfer function models and find that the forecasts obtained with both methods are similar. This result is very encouraging because, in contrast to transfer function models, subspace methods can be considered as almost automatic. 相似文献
64.
65.
ABSTRACTThe most important factor in kernel regression is a choice of a bandwidth. Considerable attention has been paid to extension the idea of an iterative method known for a kernel density estimate to kernel regression. Data-driven selectors of the bandwidth for kernel regression are considered. The proposed method is based on an optimally balanced relation between the integrated variance and the integrated square bias. This approach leads to an iterative quadratically convergent process. The analysis of statistical properties shows the rationale of the proposed method. In order to see statistical properties of this method the consistency is determined. The utility of the method is illustrated through a simulation study and real data applications. 相似文献
66.
AbstractWe propose a unified approach for multilevel sample selection models using a generalized result on skew distributions arising from selection. If the underlying distributional assumption is normal, then the resulting density for the outcome is the continuous component of the sample selection density and has links with the closed skew-normal distribution (CSN). The CSN distribution provides a framework which simplifies the derivation of the conditional expectation of the observed data. This generalizes the Heckman’s two-step method to a multilevel sample selection model. Finite-sample performance of the maximum likelihood estimator of this model is studied through a Monte Carlo simulation. 相似文献
67.
AbstractA Marshall–Olkin variant of the Provost type gamma–Weibull probability distribution is being introduced in this paper. Some of its statistical functions and numerical characteristics among others characteristics function, moment generalizing function, central moments of real order are derived in the computational series expansion form and various illustrative special cases are discussed. This density function is utilized to model two real data sets. The new distribution provides a better fit than related distributions as measured by the Anderson–Darling and Cramér–von Mises statistics. The proposed distribution could find applications for instance in the physical and biological sciences, hydrology, medicine, meteorology, engineering, etc. 相似文献
68.
In this article power divergences statistics based on sample quantiles are transformed in order to introduce new goodness-of-fit tests. Quantiles of the distribution of proposed statistics are calculated under uniformity, normality, and exponentiality. Several power comparisons are performed to show that the new tests are generally more powerful than the original ones. 相似文献
69.
J. Armando Domínguez-Molina Graciela González-Farías Rogelio Ramos-Quiroga Arjun K. Gupta 《统计学通讯:理论与方法》2013,42(9):1691-1703
In this article, we introduce the matrix extension of the closed skew-normal distribution and give two constructions for it: a marginal one and another based on hidden truncation. Important basic properties of the distribution are presented such as its closure under linear transformation and moment generating function. We also give distributional results for quadratic forms involving random matrices distributed according to two particular cases of it. Using an additive construction, we derive a submodel which can be employed to describe the compound error structure of a very general multivariate stochastic frontier model. Finally, we consider the skew-elliptical extension of the proposed distribution. 相似文献
70.
ABSTRACT The one-sample Wilcoxon signed rank test was originally designed to test for a specified median, under the assumption that the distribution is symmetric, but it can also serve as a test for symmetry if the median is known. In this article we derive the Wilcoxon statistic as the first component of Pearson's X 2 statistic for independence in a particularly constructed contingency table. The second and third components are new test statistics for symmetry. In the second part of the article, the Wilcoxon test is extended so that symmetry around the median and symmetry in the tails can be examined seperately. A trimming proportion is used to split the observations in the tails from those around the median. We further extend the method so that no arbitrary choice for the trimming proportion has to be made. Finally, the new tests are compared to other tests for symmetry in a simulation study. It is concluded that our tests often have substantially greater powers than most other tests. 相似文献