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   1238篇
  免费   56篇
  国内免费   19篇
管理学   59篇
民族学   7篇
人口学   39篇
丛书文集   90篇
理论方法论   30篇
综合类   490篇
社会学   33篇
统计学   565篇
  2024年   1篇
  2023年   15篇
  2022年   12篇
  2021年   26篇
  2020年   26篇
  2019年   26篇
  2018年   39篇
  2017年   49篇
  2016年   39篇
  2015年   30篇
  2014年   61篇
  2013年   185篇
  2012年   99篇
  2011年   87篇
  2010年   74篇
  2009年   54篇
  2008年   51篇
  2007年   61篇
  2006年   55篇
  2005年   53篇
  2004年   43篇
  2003年   45篇
  2002年   39篇
  2001年   36篇
  2000年   21篇
  1999年   21篇
  1998年   12篇
  1997年   10篇
  1996年   7篇
  1995年   12篇
  1994年   5篇
  1993年   2篇
  1992年   4篇
  1991年   5篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1984年   1篇
  1983年   3篇
  1979年   1篇
排序方式: 共有1313条查询结果,搜索用时 15 毫秒
171.
This article analyses the impact of enforcement of four labour standards (pension system enrolment, minimum wage, maximum weekly working hours and written employment contract) on compliance in Peru, where labour regulations and penalties vary according to firm size. The author uses household survey data to analyse a factor not previously studied – adjustment by firms through downsizing to benefit from lower fines and less stringent regulations. The empirical findings indicate that enforcement efforts have little effect on either the degree of compliance or the size of firms.  相似文献   
172.
Abstract

The paper is concerned with an acceptance sampling problem under destructive inspections for one-shot systems. The systems may fail at random times while they are operating (as the systems are considered to be operating when storage begins), and these failures can only be identified by inspection. Thus, n samples are randomly selected from N one-shot systems for periodic destructive inspection. After storage time T, the N systems are replaced if the number of working systems is less than a pre-specified threshold k. The primary purpose of this study is to determine the optimal number of samples n*, extracted from the N for destructive detection and the optimal acceptance number k*, in the sample under the constraint of the system interval availability, to minimize the expected cost rate. Numerical experiments are studied to investigate the effect of the parameters in sampling inspection on the optimal solutions.  相似文献   
173.
174.
In each study testing the survival experience of one or more populations, one must not only choose an appropriate class of tests, but further an appropriate weight function. As the optimal choice depends on the true shape of the hazard ratio, one is often not capable of getting the best results with respect to a specific dataset. For the univariate case several methods were proposed to conquer this problem. However, most of the interesting datasets contain multivariate observations nowadays. In this work we propose a multivariate version of a method based on multiple constrained censored empirical likelihood where the constraints are formulated as linear functionals of the cumulative hazard functions. By considering the conditional hazards, we take the correlation between the components into account with the goal of obtaining a test that exhibits a high power irrespective of the shape of the hazard ratio under the alternative hypothesis.  相似文献   
175.
The product limit or Kaplan‐Meier (KM) estimator is commonly used to estimate the survival function in the presence of incomplete time to event. Application of this method assumes inherently that the occurrence of an event is known with certainty. However, the clinical diagnosis of an event is often subject to misclassification due to assay error or adjudication error, by which the event is assessed with some uncertainty. In the presence of such errors, the true distribution of the time to first event would not be estimated accurately using the KM method. We develop a method to estimate the true survival distribution by incorporating negative predictive values and positive predictive values, into a KM‐like method of estimation. This allows us to quantify the bias in the KM survival estimates due to the presence of misclassified events in the observed data. We present an unbiased estimator of the true survival function and its variance. Asymptotic properties of the proposed estimators are provided, and these properties are examined through simulations. We demonstrate our methods using data from the Viral Resistance to Antiviral Therapy of Hepatitis C study.  相似文献   
176.
The generalized odds-rate class of regression models for time to event data is indexed by a non-negative constant and assumes thatg(S(t|Z)) = (t) + Zwhere g(s) = log(-1(s-) for > 0, g0(s) = log(- log s), S(t|Z) is the survival function of the time to event for an individual with qx1 covariate vector Z, is a qx1 vector of unknown regression parameters, and (t) is some arbitrary increasing function of t. When =0, this model is equivalent to the proportional hazards model and when =1, this model reduces to the proportional odds model. In the presence of right censoring, we construct estimators for and exp((t)) and show that they are consistent and asymptotically normal. In addition, we show that the estimator for is semiparametric efficient in the sense that it attains the semiparametric variance bound.  相似文献   
177.
为库切赢得诺贝尔文学奖奠定基础的《耻》是一部思想深刻的作品,小说以后种族隔离时代的南非为背景,讲述了白人卢里和露茜父女深陷生存困境的故事。他们的遭遇如实地展现了生活在新南非的白人如何一步步丧失话语权,陷入生存“耻”境,最终难逃历史性悲剧宿命的图景。故事背后隐藏着作者对人性的思索和对个体生命历史宿命的感悟。  相似文献   
178.
基于2000-2014年中国工业企业数据库、中国海关进出口数据库与Baker等编制的经济政策不确定性指数的匹配数据,本文实证研究了目的国经济政策不确定性对中国企业出口生存的影响。研究发现:目的国经济政策不确定性的提高显著增加了企业出口失败的概率;异质性分析发现,非国有企业、非东部地区企业,以及出口到高收入国家的企业受经济政策不确定性的影响更大;进一步分析发现,经济政策不确定性的提高显著促进了企业“出口转内销”,劳动密集型企业和一般贸易企业“出口转内销”的幅度更大。  相似文献   
179.
本文通过分析当前高校党风廉政建设的现状, 阐述了努力做好高校纪检监察工作与促进党风廉政建设的关系, 提出了推进党风廉政建设工作的对策。  相似文献   
180.
In this paper we investigate the asymptotic properties of estimators obtained for the semiparametric additive accelerated life model proposed by Bagdonavicius & Nikulin (1995). This model generalizes the well known additive hazards model of survival analysis and is close to the general transformation model (see Dabrowska & Doksum, 1988). Asymptotic properties of the estimator of the regression parameter and the estimator of the reliability function are given in the case of right censoring for discretized data and a numerical example illustrates these results.  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