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991.
992.
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
993.
A gamma regression model with an exponential link function for the means Is considered. Moment properties of the deviance statistics based on maximum likelihood and weighted least squares fits are used to define modified deviance statistics which provide alternative global goodness of fit tests. The null distribution properties of the deviances and modified deviances are compared with those of the approximating chi-square distribution and It is shown that the use of the modified deviances gives much better control over the significance levels of the tests. 相似文献
994.
Kaatje Els Bollaerts Winy Messens Laurent Delhalle Marc Aerts Yves Van der Stede Jeroen Dewulf Sophie Quoilin Dominiek Maes Koen Mintiens Koen Grijspeerdt 《Risk analysis》2009,29(6):820-840
A quantitative microbial risk assessment (QMRA) according to the Codex Alimentarius Principles is conducted to evaluate the risk of human salmonellosis through household consumption of fresh minced pork meat in Belgium. The quantitative exposure assessment is carried out by building a modular risk model, called the METZOON-model, which covers the pork production from farm to fork. In the METZOON-model, the food production pathway is split up in six consecutive modules: (1) primary production, (2) transport and lairage, (3) slaughterhouse, (4) postprocessing, (5) distribution and storage, and (6) preparation and consumption. All the modules are developed to resemble as closely as possible the Belgian situation, making use of the available national data. Several statistical refinements and improved modeling techniques are proposed. The model produces highly realistic results. The baseline predicted number of annual salmonellosis cases is 20,513 ( SD 9061.45). The risk is estimated higher for the susceptible population (estimate 4.713 × 10−5 ; SD 1.466 × 10−5 ) compared to the normal population (estimate 7.704 × 10−6 ; SD 5.414 × 10−6 ) and is mainly due to undercooking and to a smaller extent to cross-contamination in the kitchen via cook's hands. 相似文献
995.
Radostaw Kala 《统计学通讯:理论与方法》2013,42(9):849-873
The paper gives a self-contained account of minimum dispersion linear unbiased estimation of the expectation vector in a linear model with the dispersion matrix belonging to some, rather arbitrary, set of nonnegative definite matrices. The approach to linear estimation in general linear models recommended here is a direct generalization of some ideas and results presented by Rao (1973, 19 74) for the case of a general Gauss-Markov model A new insight into the nature of some estimation problems originaly arising in the context of a general Gauss-Markov model as well as the correspondence of results known in the literature to those obtained in the present paper for general linear models are also given. As preliminary results the theory of projectors defined by Rao (1973) is extended. 相似文献
996.
Optimality of experimental designs for spatially correlated observations is investigated.come two dimensional correlation structures are discussed and an attempt has been made to find optimal or nearly optimal design for each sitution.The solution lend to designs similar to that used for repeated measurements.The relative efficiency of the proposed designs in comparison to randomized latin square designs is tabulated for some cases. 相似文献
997.
D. R. Cox Michelle Jackson Shiwei Lu 《Journal of the Royal Statistical Society. Series A, (Statistics in Society)》2009,172(2):483-493
Summary. Square contingency tables with matching ordinal rows and columns arise in particular as empirical transition matrices and the paper considers these in the context of social class and income mobility tables. Such tables relate the socio-economic position of parents to the socio-economic position of their child in adulthood. The level of association between parental and child socio-economic position is taken as a measure of mobility. Several approaches to analysis are described and illustrated by UK data in which interest focuses on comparisons of social class and income mobility tables that are derived from the same individuals. Account is taken of the use of the same individuals in the two tables. Additionally comparisons over time are considered. 相似文献
998.
F. Chang 《统计学通讯:模拟与计算》2013,42(5):1104-1114
Optimal designs for estimating the parameters and also the optimum factor combinations in multiresponse experiments have been considered by various authors. However, till date, in mixture experiments optimum designs have been studied only in the single response case. In this article, attempt has been made to investigate optimum designs for estimating optimum mixing proportions in a multiresponse mixture experiment. 相似文献
999.
郭文娟 《山西农业大学学报(社会科学版)》2013,(11):1151-1156
老龄事业是全面建设小康社会和实现中华民族伟大复兴中国梦的重要方面,未富先老、未备先老、抚养比高是我国农村进入老龄化社会的主要矛盾,而养老模式的合理建构是应对老龄化的突破口,引发学界高度关注。基于中文社会科学引文索引(CSSCI)20002013年期刊文章,分析和梳理学界对养老模式有价值的探讨,从而为顶层政策设计和地方发挥裁量权提供理论和现实依据。由一元向多元发展是我国养老模式的必然趋势。家庭养老、社区居家养老、社会养老以及多层次的养老是养老相关主要模式。现有研究视角涉及多个学科,以发展何种养老模式为重点和养老模式如何组合是学者研究探讨的重点。未来养老保障基本围绕家庭养老为主体、社区居家为依托展开,而社会化养老是必然趋势。在养老模式的具体层面、统筹层面、价值层面、制度文化建设等方面有进一步拓展的空间。 相似文献
1000.
If a specific biological mechanism could be determined by which a carcinogen increases lung cancer risk, how might this knowledge be used to improve risk assessment? To explore this issue, we assume (perhaps incorrectly) that arsenic in cigarette smoke increases lung cancer risk by hypermethylating the promoter region of gene p16INK4a, leading to a more rapid entry of altered (initiated) cells into a clonal expansion phase. The potential impact on lung cancer of removing arsenic is then quantified using a three‐stage version of a multistage clonal expansion (MSCE) model. This refines the usual two‐stage clonal expansion (TSCE) model of carcinogenesis by resolving its intermediate or “initiated” cell compartment into two subcompartments, representing experimentally observed “patch” and “field” cells. This refinement allows p16 methylation effects to be represented as speeding transitions of cells from the patch state to the clonally expanding field state. Given these assumptions, removing arsenic might greatly reduce the number of nonsmall cell lung cancer cells (NSCLCs) produced in smokers, by up to two‐thirds, depending on the fraction (between 0 and 1) of the smoking‐induced increase in the patch‐to‐field transition rate prevented if arsenic were removed. At present, this fraction is unknown (and could be as low as zero), but the possibility that it could be high (close to 1) cannot be ruled out without further data. 相似文献