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31.
基于经济时空的中国林业产业发展路径 总被引:1,自引:0,他引:1
经济时间和经济空间是研究产业变迁的两个重要维度,就林业产业时空特性而言,中国林业产业的发展面临着时空分离和时空压缩的困境。在经济全球化进程中,林业产业要适应现代科技变革和产业变迁,必须寻求新的发展路径:实现林业产业的时空转换,拓宽林业产业的市场时空;提高林业产业技术,促进林业产业的时空延伸;优化林业产业布局,提高林业产业的时空效益。 相似文献
32.
BAYESIAN SUBSET SELECTION AND MODEL AVERAGING USING A CENTRED AND DISPERSED PRIOR FOR THE ERROR VARIANCE 总被引:1,自引:0,他引:1
Edward Cripps Robert Kohn David Nott 《Australian & New Zealand Journal of Statistics》2006,48(2):237-252
This article proposes a new data‐based prior distribution for the error variance in a Gaussian linear regression model, when the model is used for Bayesian variable selection and model averaging. For a given subset of variables in the model, this prior has a mode that is an unbiased estimator of the error variance but is suitably dispersed to make it uninformative relative to the marginal likelihood. The advantage of this empirical Bayes prior for the error variance is that it is centred and dispersed sensibly and avoids the arbitrary specification of hyperparameters. The performance of the new prior is compared to that of a prior proposed previously in the literature using several simulated examples and two loss functions. For each example our paper also reports results for the model that orthogonalizes the predictor variables before performing subset selection. A real example is also investigated. The empirical results suggest that for both the simulated and real data, the performance of the estimators based on the prior proposed in our article compares favourably with that of a prior used previously in the literature. 相似文献
33.
贾岛出家及还俗的时间地点问题是贾岛生平仕历研究的一个重要问题。通过对现有史料记载以及贾岛等人诗文的考证分析,可知贾岛贞元九年(793)在北岳恒山出家为僧,时年15岁。后曾住洛阳石楼及嵩山一带。贞元十七年(801)在石楼与韩愈初次相识。元和六年(811)春在洛阳又遇到时任河南县令的韩愈,同年秋跟随韩愈赴长安准备应进士举,但并未马上还俗。冬十一月返回家乡范阳,处理僧俗事务。至迟于次年即元和七年(812)春还俗并参加进士考试,时年34岁。 相似文献
34.
朱其兆 《长春理工大学学报(高教版)》2005,(3)
介绍了序批式活性污泥法(Sequencing Batch Reactor,简称SBR)工艺的产生、发展和特点以及目前脱氮除磷研究的主要进展。 相似文献
35.
36.
Discrete time modelling of disease incidence time series by using Markov chain Monte Carlo methods 总被引:1,自引:0,他引:1
Alexander Morton Bärbel F. Finkenstädt 《Journal of the Royal Statistical Society. Series C, Applied statistics》2005,54(3):575-594
Summary. A stochastic discrete time version of the susceptible–infected–recovered model for infectious diseases is developed. Disease is transmitted within and between communities when infected and susceptible individuals interact. Markov chain Monte Carlo methods are used to make inference about these unobserved populations and the unknown parameters of interest. The algorithm is designed specifically for modelling time series of reported measles cases although it can be adapted for other infectious diseases with permanent immunity. The application to observed measles incidence series motivates extensions to incorporate age structure as well as spatial epidemic coupling between communities. 相似文献
37.
Cathy W. S. Chen F. C. Liu Mike K. P. So 《Australian & New Zealand Journal of Statistics》2008,50(1):29-51
To capture mean and variance asymmetries and time‐varying volatility in financial time series, we generalize the threshold stochastic volatility (THSV) model and incorporate a heavy‐tailed error distribution. Unlike existing stochastic volatility models, this model simultaneously accounts for uncertainty in the unobserved threshold value and in the time‐delay parameter. Self‐exciting and exogenous threshold variables are considered to investigate the impact of a number of market news variables on volatility changes. Adopting a Bayesian approach, we use Markov chain Monte Carlo methods to estimate all unknown parameters and latent variables. A simulation experiment demonstrates good estimation performance for reasonable sample sizes. In a study of two international financial market indices, we consider two variants of the generalized THSV model, with US market news as the threshold variable. Finally, we compare models using Bayesian forecasting in a value‐at‐risk (VaR) study. The results show that our proposed model can generate more accurate VaR forecasts than can standard models. 相似文献
38.
劳动价值理论是经济学的基本理论。经济学价值论的使命是说明商品交换价值的决定和运动规律。新经济时代正在到来,人类生产方式也正在发生广泛而深刻的变化,价值决定理论也将随着现实经济的发展而发展。在知识经济时代,商品同样有一个客观的交换基础——劳动时间,但所有商品的价值已不完全由社会必要劳动时间确定,特别是知识产品的价值量是由个别劳动时间确定的。 相似文献
39.
裴秀娟 《河北理工大学学报(社会科学版)》2003,3(Z1):121-122
研究了基础釉的成分、蓄光粉的加入量、釉层厚度和烧成温度制度等因素对蓄光陶瓷发光性能的影响以及各种制品最佳工艺技术路线的确定. 相似文献
40.
An important characteristic of high-tech industries is decreasing component prices over time. In the personal computer industry, some component prices decline at a rate of 1% per week. This paper develops an inventory model for products experiencing continuous decrease in unit price. We develop an accurate closed-form approximate solution to the model. Our results indicate that declining prices lead to substantial decrease in the optimal cycle time and much frequent ordering. This explains the heavy emphasis on just-in-time inventory management practiced by successful companies in high-tech industries. While previous models attributed the success of just-in-time policies to reduced holding cost and improved quality, under declining prices a substantial source of savings becomes lower costs of raw materials which is significant part of cost in these industries. We illustrate the results of the model with a numerical example and perform sensitivity analysis. 相似文献