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971.
主要立足于宏观经济系统四个变量之间是否存在格兰杰因果关系的分析,了解这些变量间的制约或促进关系.基于系统的向量自回归(VAR)上的格兰杰因果关系分析,同时结合经济学理论,提出相应的政策建议. 相似文献
972.
973.
974.
多品种随机数学模型的物流配送中心选址问题 总被引:21,自引:6,他引:21
本文对照文[12],提出了一个多品种随机化的模型,并从数学角度对该模型进行了的一些分析,给出了单配送中心选址问题的一个量化的处理方法,当城市商品需求量服从指数分布或者帕累托分布时,我们的计算公式非常简单。 相似文献
975.
基于知识和模糊神经网络的学习型评价系统 总被引:5,自引:1,他引:5
提出一种学习型评价系统的建立方法. 评价功能是基于决策者(专家) 的知识和模糊神经
网络实现的,适用于以语言型变量为主的系统的评价问题. 样本数据集的建立及语言型变量的
描述,是通过挖掘专家知识,建立符合其偏好的隶属函数实现的. 该评价系统可以充分利用以
往的决策案例,通过学习获取决策者的知识和经验,从而得到与决策者的评价结论相同的评价
结果. 相似文献
976.
D. J. Bartholomew 《Journal of the Royal Statistical Society. Series C, Applied statistics》1998,47(1):1-13
The use of the logit–probit model for constructing social measurement scales is explored by using two data sets. The first was specifically designed for scaling and consists of answers by 1490 individuals to five questions on economic self-determination. The second is from the Workplace Industrial Relations Survey and relates to answers to six questions addressed to 1005 firms about innovations. It is shown that although scales can be constructed their precision (reliability) is likely to be low. Further, for examples like these, latent class models may give an equally satisfactory account of the data. 相似文献
977.
Parameter estimation for association and log-linear models is an important aspect of the analysis of cross-classified categorical data. Classically, iterative procedures, including Newton's method and iterative scaling, have typically been used to calculate the maximum likelihood estimates of these parameters. An important special case occurs when the categorical variables are ordinal and this has received a considerable amount of attention for more than 20 years. This is because models for such cases involve the estimation of a parameter that quantifies the linear-by-linear association and is directly linked with the natural logarithm of the common odds ratio. The past five years has seen the development of non-iterative procedures for estimating the linear-by-linear parameter for ordinal log-linear models. Such procedures have been shown to lead to numerically equivalent estimates when compared with iterative, maximum likelihood estimates. Such procedures also enable the researcher to avoid some of the computational difficulties that commonly arise with iterative algorithms. This paper investigates and evaluates the performance of three non-iterative procedures for estimating this parameter by considering 14 contingency tables that have appeared in the statistical and allied literature. The estimation of the standard error of the association parameter is also considered. 相似文献
978.
Gunnar Taraldsen 《Journal of applied statistics》2011,38(5):977-986
The problem of inference based on a rounded random sample from the exponential distribution is treated. The main results are given by an explicit expression for the maximum-likelihood estimator, a confidence interval with a guaranteed level of confidence, and a conjugate class of distributions for Bayesian analysis. These results are exemplified on two concrete examples. The large and increasing body of results on the topic of grouped data has been mostly focused on the effect on the estimators. The methods and results for the derivation of confidence intervals here are hence of some general theoretical value as a model approach for other parametric models. The Bayesian credibility interval recommended in cases with a lack of other prior information follows by letting the prior equal the inverted exponential with a scale equal to one divided by the resolution. It is shown that this corresponds to the standard non-informative prior for the scale in the case of non-rounded data. For cases with the absence of explicit prior information it is argued that the inverted exponential prior with a scale given by the resolution is a reasonable choice for more general digitized scale families also. 相似文献
979.
A multidimensional scaling methodology (STUNMIX) for the analysis of subjects' preference/choice of stimuli that sets out to integrate the previous work in this area into a single framework, as well as to provide a variety of new options and models, is presented. Locations of the stimuli and the ideal points of derived segments of subjects on latent dimensions are estimated simultaneously. The methodology is formulated in the framework of the exponential family of distributions, whereby a wide range of different data types can be analyzed. Possible reparameterizations of stimulus coordinates by stimulus characteristics, as well as of probabilities of segment membership by subject background variables, are permitted. The models are estimated in a maximum likelihood framework. The performance of the models is demonstrated on synthetic data, and robustness is investigated. An empirical application is provided, concerning intentions to buy portable telephones. 相似文献
980.
黄政新 《南京理工大学学报(社会科学版)》2011,24(3):23-33
Bell不等式(1964)提出了定域隐变量理论和量子力学对比的量化标准,导致了首次在实验上区别这两个理论的可能性。自1972年Clauser等人第一个实验以来,至今已完成了几十个实验。占压倒多数的实验的结果同量子力学的预言符合得很好而违反定域隐变量理论的预言。本文第一节首先讨论了这些实验中的某些漏洞,第二和第三节分别概述了1972—1982年所完成的12个实验和1985年至今所完成的31个实验的结果。最后强调地指出,尽管至今还没有一个实验能同时封闭定域性漏洞和检测漏洞,但实验结果是不可逆转的。因此,理论物理学家应当承认当前的物理学基础是分裂的,即量子力学同相对论是矛盾的。 相似文献