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   3456篇
  免费   102篇
  国内免费   19篇
管理学   168篇
民族学   19篇
人才学   1篇
人口学   78篇
丛书文集   149篇
理论方法论   66篇
综合类   1187篇
社会学   248篇
统计学   1661篇
  2024年   2篇
  2023年   14篇
  2022年   13篇
  2021年   24篇
  2020年   60篇
  2019年   91篇
  2018年   114篇
  2017年   161篇
  2016年   81篇
  2015年   83篇
  2014年   156篇
  2013年   767篇
  2012年   250篇
  2011年   152篇
  2010年   185篇
  2009年   144篇
  2008年   150篇
  2007年   170篇
  2006年   161篇
  2005年   131篇
  2004年   122篇
  2003年   93篇
  2002年   86篇
  2001年   74篇
  2000年   55篇
  1999年   37篇
  1998年   28篇
  1997年   30篇
  1996年   30篇
  1995年   21篇
  1994年   11篇
  1993年   16篇
  1992年   10篇
  1991年   10篇
  1990年   6篇
  1989年   8篇
  1988年   8篇
  1987年   1篇
  1986年   2篇
  1985年   4篇
  1984年   2篇
  1983年   3篇
  1982年   1篇
  1981年   2篇
  1980年   3篇
  1979年   3篇
  1978年   2篇
排序方式: 共有3577条查询结果,搜索用时 958 毫秒
1.
Abstract

The economic mobility of individuals and households is of fundamental interest. While many measures of economic mobility exist, reliance on transition matrices remains pervasive due to simplicity and ease of interpretation. However, estimation of transition matrices is complicated by the well-acknowledged problem of measurement error in self-reported and even administrative data. Existing methods of addressing measurement error are complex, rely on numerous strong assumptions, and often require data from more than two periods. In this article, we investigate what can be learned about economic mobility as measured via transition matrices while formally accounting for measurement error in a reasonably transparent manner. To do so, we develop a nonparametric partial identification approach to bound transition probabilities under various assumptions on the measurement error and mobility processes. This approach is applied to panel data from the United States to explore short-run mobility before and after the Great Recession.  相似文献   
2.
Abstract

The mean estimators with ratio depend on multiple auxiliary variables and unknown parameters in a finite population setting. We propose a new generalized approach with matrices for modeling the mutivariate mean estimators with two auxiliary variables. Our approach brings naturally a graphical analysis for comparing mean estimators.  相似文献   
3.
This article shows the influence of being a refugee from Latin America or a nonrefugee immigrant from southern Europe or Finland on self-reported illness, controlling for social factors and lifestyle. The study population consisted of 338 Latin American refugees, a random sample of 396 Finnish and 161 southern European immigrants and 996 age-, sex- and education-matched Swedish controls. The data were analysed unmatched with logistic regression (multivariate analysis) in main effect models. The strongest independent risk indicator for long-term illness was being a Latin American refugee (estimated odds ratio (OR)=2.96, 95% confidence interval (CI)=2.19–3.82). There was a significant association between being a Latin American refugee and period prevalence, ill health and unsatisfied need for care. Being a southern European or Finnish immigrant was a risk indicator of ill health but was not associated with the other dependent factors. Not feeling secure in daily life was a strong risk indicator for long-term illness and ill health (estimated OR=1.89, 95% CI=1.26–2.76 and OR=3.04, 95% CI= 1.97–4.48) respectively). Being a Latin American refugee was equal in importance to traditional risk factors such as overweight and not taking regular exercise for long-term illness and ill health.  相似文献   
4.
依法行政是依法治国的主要任务和关键所在。通过对恩施自治州的行政执法状况进行调查,结果表明:恩施自治州的行政执法在总体上是好的,但也存在诸多问题。  相似文献   
5.
通过深入分析非英语专业大学生英语作文中出现的内容、篇章结构、语言表达等方面的非语法错误,提出了写前阶段构思、审题技巧训练及寓写作于精读课教学等相应的纠错策略。  相似文献   
6.
Olive Oil Consumption in Greece: A Microeconometric Analysis   总被引:2,自引:1,他引:1  
In this paper, the factors affecting at-home demand for three types of oils and fats in Greece, with emphasis on olive oil, are investigated using the linear approximation of the Almost Ideal Demand System and family budget survey data. To overcome the econometric problem created with the existence of zero expenditure, a generalization of the two-stage Heckman procedure is employed. In order to investigate the role of self-consumption, two different samples were used. The first includes all households; the second excludes those that acquire olive oil only from own production. According to the results, there are important differences in the first stage of the decision process between the two samples. Unlike the first stage, the second stage of the decision process found no important differences between the results for the two samples.  相似文献   
7.
分析了影响数控火焰切割机加工精度的主要因素,利用开放式数控系统的软件开放性,提出了采用IGCAQBP学习算法的神经网络方法来对包括金属热变形、机械传动误差等非线性因素在内的多种因素造成的加工误差进行误差补偿,设计了嵌入开放式数控系统中的神经网络误差补偿器,给出了实用的补偿器使用方法,并对误差补偿功能进行了扩展,仿真结果和实际应用表明该方法稳定有效。  相似文献   
8.
当代陶行知研究的基本特点是以生活教育为中心,从理论研究走向实践探索,加强了国内与国外的联系,呈现出一种历史研究与现实借鉴、理论探讨与实践总结有机结合、互补共进的新局面。建国后,人们一直在争论的几个基本理论问题,到20世纪90年代已不再是人们的关注热点。现在学术界展开热烈讨论的问题主要有生活教育理论、创造教育思想、陶行知与中外文化教育、陶行知教育思想与当代中国教育的改革和发展等。  相似文献   
9.
针对串联型稳压器,设计了一种应用于串联型稳压器具有自建基准的新型误差放大电路。该电路具有构思巧妙,结构优化,易于集成及较高的开环增益,共模抑制比及交流特性的优点。通过验证,实测数据与仿真结果基本一致。  相似文献   
10.
Summary For technological applications it can be useful to identify some simple physical mechanisms, which, on the basis of the available knowledge of the production process, may suggest the most appropriate approach to statistical control of the random quantities of interest. For this purpose the notion of rupture point is introduced firstly. A rupture point is characterized bym randomly arising out of control states, assumed to be mutually exclusive and stochastically independent. Shewhart's control charts seem to represent the natural statistical tool for controlling a rupture point; however it is shown that they are fully justified only when the hazard rates attached to the causes of failure are constant. Otherwise, typically in the presence of time increasing hazard rates, Shewhart's control charts should be completed by a preventive intervention rule (preventive maintenance). In the second place, the notion of dynamic instability point is introduced, which is specifically characterized by assuming that the random quantity of interest is ruled by a stochastic differential equation with constant coefficients. By discretization, developed according to a possibly new approach, it is shown that the former model reduces to an equation error model, which is among the simplest used in adaptive control, and thus particularly easy to deal with in regard to parameter estimation and the definition of the optimum control rule.  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