全文获取类型
收费全文 | 4401篇 |
免费 | 161篇 |
国内免费 | 21篇 |
专业分类
管理学 | 169篇 |
民族学 | 9篇 |
人才学 | 1篇 |
人口学 | 38篇 |
丛书文集 | 108篇 |
理论方法论 | 107篇 |
综合类 | 1165篇 |
社会学 | 62篇 |
统计学 | 2924篇 |
出版年
2024年 | 2篇 |
2023年 | 16篇 |
2022年 | 17篇 |
2021年 | 32篇 |
2020年 | 70篇 |
2019年 | 103篇 |
2018年 | 144篇 |
2017年 | 197篇 |
2016年 | 129篇 |
2015年 | 134篇 |
2014年 | 164篇 |
2013年 | 1091篇 |
2012年 | 385篇 |
2011年 | 210篇 |
2010年 | 173篇 |
2009年 | 214篇 |
2008年 | 204篇 |
2007年 | 192篇 |
2006年 | 127篇 |
2005年 | 126篇 |
2004年 | 112篇 |
2003年 | 92篇 |
2002年 | 64篇 |
2001年 | 84篇 |
2000年 | 82篇 |
1999年 | 52篇 |
1998年 | 35篇 |
1997年 | 44篇 |
1996年 | 30篇 |
1995年 | 35篇 |
1994年 | 24篇 |
1993年 | 13篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 11篇 |
1989年 | 6篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 11篇 |
1984年 | 28篇 |
1983年 | 22篇 |
1982年 | 17篇 |
1981年 | 9篇 |
1980年 | 13篇 |
1979年 | 8篇 |
1978年 | 16篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 2篇 |
排序方式: 共有4583条查询结果,搜索用时 385 毫秒
81.
以长期水驱实验为基础,建立了等效水驱砂岩储层孔喉结构变化的三维网络模拟模型,结合三维微粒运移机制和有限差分求解方法,得到了长期水驱砂岩油藏孔喉结构变化规律:(1) 冲刷后喉道半径呈增加趋势,喉道半径变化范围变大,极小喉道半径呈微弱减小趋势;(2) 孔隙网络模型中冲刷半径扩大的孔道分布形式与原始孔隙网络结构密切相关,并非所有的大孔道都串联起来贯穿岩芯孔隙网络的两个端面,但入口端和出口端部分大孔道相互连通,形成端面上的大孔道网络群。网络模拟注水结果结合采油井测试,可为注水剖面的调整提供更加可靠的依据。 相似文献
82.
The Cochran–Mantel–Haenszel tests are a suite of tests that are usually defined as conditional tests, tests that assume all marginal totals are known before sighting the data. Here unconditional analogues of these tests are defined for the more usual situation when the marginal totals are not known before sighting the data. 相似文献
83.
摘要:以胡尖山油田长 6、长 4+5 油藏为例,综合应用地质资料、岩芯分析资料、测井资料以及试油资料,开展了长 6和长 4+5 油藏小层划分和对比、单井相分析,建立测井相识别模式,编制小层沉积相平面展布图,进而分析沉积相演化规律;探讨储层砂体展布以及物性分布规律,从而深入认识研究区的储层特征。在此基础上对储层进行流动单元的划分,然后结合试油资料对胡尖山油田长 6、长 4+5 油藏的储层进行有利区域的预测,为油田待开发区域的合理建产开发提供了理论指导 相似文献
84.
When analyzing a response variable at the presence of both factors and covariates, with potentially correlated responses and violated assumptions of the normal residual or the linear relationship between the response and the covariates, rank-based tests can be an option for inferential procedures instead of the parametric repeated measures analysis of covariance (ANCOVA) models. This article derives a rank-based method for multi-way ANCOVA models with correlated responses. The generalized estimating equations (GEE) technique is employed to construct the proposed rank tests. Asymptotic properties of the proposed tests are derived. Simulation studies confirmed the performance of the proposed tests. 相似文献
85.
Semi-parametric modelling of interval-valued data is of great practical importance, as exampled by applications in economic and financial data analysis. We propose a flexible semi-parametric modelling of interval-valued data by integrating the partial linear regression model based on the Center & Range method, and investigate its estimation procedure. Furthermore, we introduce a test statistic that allows one to decide between a parametric linear model and a semi-parametric model, and approximate its null asymptotic distribution based on wild Bootstrap method to obtain the critical values. Extensive simulation studies are carried out to evaluate the performance of the proposed methodology and the new test. Moreover, several empirical data sets are analysed to document its practical applications. 相似文献
86.
We present influence diagnostics for linear measurement error models with stochastic linear restrictions using the corrected likelihood of Nakamura in 1990. The case deletion and mean shift outlier models are developed to identify outlying and influential observations. We derive a corrected score test statistic for outlier detection based on mean shift outlier models. The analogs of Cook's distance and likelihood distance are proposed to determine influential observations based on case deletion models. A parametric bootstrap procedure is used to obtain empirical distributions of the test statistics and a simulation study has been used to evaluate the performance of the proposed estimators based on the mean squares error criterion and the score test statistic. Finally, a numerical example is given to illustrate the theoretical results. 相似文献
87.
Robust tests for comparing scale parameters, based on deviances—absolute deviations from the median—are examined. Higgins (2004) proposed a permutation test for comparing two treatments based on the ratio of deviances, but the performance of this procedure has not been investigated. A simulation study examines the performance of Higgins’ test relative to other tests of scale utilizing deviances that have been shown in the literature to have good properties. An extension of Higgins’ procedure to three or more treatments is proposed, and a second simulation study compares its performance to other omnibus tests for comparing scale. While no procedure emerged as a preferred choice in every scenario, Higgins’ tests are found to perform well overall with respect to Type I error rate and power. 相似文献
88.
It is well known that the testing of zero variance components is a non-standard problem since the null hypothesis is on the boundary of the parameter space. The usual asymptotic chi-square distribution of the likelihood ratio and score statistics under the null does not necessarily hold because of this null hypothesis. To circumvent this difficulty in balanced linear growth curve models, we introduce an appropriate test statistic and suggest a permutation procedure to approximate its finite-sample distribution. The proposed test alleviates the necessity of any distributional assumptions for the random effects and errors and can easily be applied for testing multiple variance components. Our simulation studies show that the proposed test has Type I error rate close to the nominal level. The power of the proposed test is also compared with the likelihood ratio test in the simulations. An application on data from an orthodontic study is presented and discussed. 相似文献
89.
《Journal of Statistical Computation and Simulation》2012,82(4):339-351
A test statistic proposed by Li (1999) for testing the adequacy of heteroscedastic nonlinear regression models using nonparametric kernel smoothers is applied to testing for linearity in generalized linear models. Simulation results for models with centered gamma and inverse Gaussian errors are presented to illustrate the performance of the resulting test compared with log-likelihood ratio tests for specific parametric alternatives. The test is applied to a data set of coronary heart disease status (Hosmer and Lemeshow, (1990). 相似文献
90.
Yan Zhou 《统计学通讯:理论与方法》2017,46(6):2801-2815
The change-point detection problem is determining whether a change has taken place. Two non parametric methods based on empirical likelihood and the likelihood ratio are proposed for detecting a change-point problem in distributions for independent observations. Numerical studies are carried out to evaluate the performance of the proposed methods. The simulation results demonstrate that the proposed methods are robust, that is, they perform well regardless of whether the observations are from the same distribution family. 相似文献