首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   16177篇
  免费   664篇
  国内免费   207篇
管理学   2071篇
劳动科学   2篇
民族学   62篇
人才学   3篇
人口学   338篇
丛书文集   795篇
理论方法论   376篇
综合类   7495篇
社会学   585篇
统计学   5321篇
  2024年   20篇
  2023年   115篇
  2022年   209篇
  2021年   242篇
  2020年   353篇
  2019年   458篇
  2018年   519篇
  2017年   669篇
  2016年   545篇
  2015年   567篇
  2014年   904篇
  2013年   2208篇
  2012年   1184篇
  2011年   1037篇
  2010年   845篇
  2009年   845篇
  2008年   917篇
  2007年   888篇
  2006年   826篇
  2005年   695篇
  2004年   575篇
  2003年   496篇
  2002年   434篇
  2001年   383篇
  2000年   244篇
  1999年   192篇
  1998年   100篇
  1997年   103篇
  1996年   77篇
  1995年   66篇
  1994年   51篇
  1993年   49篇
  1992年   42篇
  1991年   49篇
  1990年   33篇
  1989年   21篇
  1988年   24篇
  1987年   9篇
  1986年   8篇
  1985年   13篇
  1984年   9篇
  1983年   9篇
  1982年   5篇
  1981年   1篇
  1980年   1篇
  1979年   4篇
  1978年   2篇
  1977年   1篇
  1975年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
In this article, the Bayesian analysis of the regression model with errors terms generated by a first-order autoregressive model is considered. Our aim is to study the effect of two kinds of contamination of this model via the posterior distribution of the regression parameter.  相似文献   
952.
实践教学是生物技术专业教学活动的重要组成部分,让学生亲身参与科学研究活动,是培养学生创新能力的有效方法.根据生物技术专业的特点并结合科研项目,对实践教学进行了教改研究,提出了将生物技术专业实践教学与科研相结合的创新教学模式.  相似文献   
953.
张雅丽  范秀荣 《西北人口》2009,30(5):77-79,84
文章在借鉴“推-拉”理论的基础上.结合中国的实际情况从推力的角度构建农村劳动力转移的“推力模型”,对中国工业化进程中农村劳动力转移的影响因素进行了解释,并提出相应的对策建议。  相似文献   
954.
Abstract

Logistic regression analysis was used to compare users and non-users of senior centers. Variables assessing linkage to the service system were more significant predictors of senior center utilization than predisposing, enabling, or need variables. More specifically, users of senior centers were older and more likely to live in rural areas. They also had more social contacts, better mental health, and fewer ADL problems. Senior center users were also more aware of specific service agencies, more likely to consult formal resources in making service decisions, and more likely to have used other services.  相似文献   
955.
We analyze a variant of the EGARCH model which captures the variation of the intra-day price. We study the asymptotic behavior of the estimators for the parameters of the model. We also illustrate our theoretical results by empirical studies.  相似文献   
956.
For longitudinal time series data, linear mixed models that contain both random effects across individuals and first-order autoregressive errors within individuals may be appropriate. Some statistical diagnostics based on the models under a proposed elliptical error structure are developed in this work. It is well known that the class of elliptical distributions offers a more flexible framework for modelling since it contains both light- and heavy-tailed distributions. Iterative procedures for the maximum-likelihood estimates of the model parameters are presented. Score tests for the presence of autocorrelation and the homogeneity of autocorrelation coefficients among individuals are constructed. The properties of test statistics are investigated through Monte Carlo simulations. The local influence method for the models is also given. The analysed results of a real data set illustrate the values of the models and diagnostic statistics.  相似文献   
957.
实现主食产业化发展,实行产品的标准化是关键。以豪特林(Hotelling)线形选址模型和塞洛普(Salop)的圆周模型为基础,根据具体情况进行修改后建立一个三阶段的博弈模型讨论主食企业和政府的行为问题。  相似文献   
958.
There are a number of situations in which the experimental data observed are record statistics. In this paper, optimal confidence intervals as well as uniformly most powerful (MP) tests for one-sided alternatives are developed. Since a uniformly MP test for a two-sided alternative does not exist, generalized likelihood ratio and uniformly unbiased and invariant tests are derived for the two parameters of the exponential distribution based on record data. For illustrative purposes, a data set on the times between consecutive telephone calls to a company's switchboard is analysed using the proposed procedures. Finally, some open problems in this direction are pointed out.  相似文献   
959.
This article provides an expository account of the multivariate autoregressive moving average models and proposes an extended sample cross-correlation approach for practical model identification. An iterative model building procedure for applying these models to real data is discussed and demonstrated by analyzing the 5-series U.S. Hog Data.  相似文献   
960.
Over the past decades, various principles for causal effect estimation have been proposed, all differing in terms of how they adjust for measured confounders: either via traditional regression adjustment, by adjusting for the expected exposure given those confounders (e.g., the propensity score), or by inversely weighting each subject's data by the likelihood of the observed exposure, given those confounders. When the exposure is measured with error, this raises the question whether these different estimation strategies might be differently affected and whether one of them is to be preferred for that reason. In this article, we investigate this by comparing inverse probability of treatment weighted (IPTW) estimators and doubly robust estimators for the exposure effect in linear marginal structural mean models (MSM) with G-estimators, propensity score (PS) adjusted estimators and ordinary least squares (OLS) estimators for the exposure effect in linear regression models. We find analytically that these estimators are equally affected when exposure misclassification is independent of the confounders, but not otherwise. Simulation studies reveal similar results for time-varying exposures and when the model of interest includes a logistic link.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号