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   10775篇
  免费   315篇
  国内免费   2篇
管理学   1511篇
民族学   67篇
人才学   3篇
人口学   968篇
丛书文集   70篇
理论方法论   1102篇
综合类   226篇
社会学   5555篇
统计学   1590篇
  2020年   157篇
  2019年   255篇
  2018年   267篇
  2017年   378篇
  2016年   266篇
  2015年   200篇
  2014年   255篇
  2013年   1753篇
  2012年   357篇
  2011年   343篇
  2010年   277篇
  2009年   266篇
  2008年   254篇
  2007年   296篇
  2006年   265篇
  2005年   268篇
  2004年   248篇
  2003年   183篇
  2002年   217篇
  2001年   277篇
  2000年   232篇
  1999年   214篇
  1998年   171篇
  1997年   159篇
  1996年   158篇
  1995年   144篇
  1994年   152篇
  1993年   151篇
  1992年   151篇
  1991年   149篇
  1990年   154篇
  1989年   148篇
  1988年   134篇
  1987年   150篇
  1986年   118篇
  1985年   147篇
  1984年   156篇
  1983年   142篇
  1982年   123篇
  1981年   90篇
  1980年   112篇
  1979年   113篇
  1978年   103篇
  1977年   87篇
  1976年   88篇
  1975年   100篇
  1974年   96篇
  1973年   69篇
  1972年   61篇
  1971年   54篇
排序方式: 共有10000条查询结果,搜索用时 515 毫秒
341.
Urban Ecosystems - Residential yardscapes are at the forefront of human interaction with nature for those living in urban areas across Europe and North America. In recent years a significant amount...  相似文献   
342.
Journal of Population Research - The extant literature shows that fertility desires are an important indicator for understanding and predicting the future course of fertility; however, little work...  相似文献   
343.
Industrial robots are increasingly used by many manufacturing firms. The number of robot manufacturers has also increased with many of these firms now offering a wide range of models. A potential user is thus faced with many options in both performance and cost. This paper proposes a decision model for the robot selection problem. The proposed model uses robust regression to identify, based on manufacturers' specifications, the robots that are the better performers for a given cost. Robust regression is used because it identifies and is resistant to the effects of outlying observations, key components in the proposed model. The robots selected by the model become candidates for testing to verify manufacturers' specifications. The model is tested on a real data set and an example is presented.  相似文献   
344.
Accuracy of the Pearson-Tukey three-point approximation is measured in units of standard deviation and compared with that of Monte Carlo simulation. Using a variety of well-known distributions, comparisons are made for the mean of a random variable and for common functions of one and two random variables. Comparisons are also made for the mean of an assortment of risk-analysis (Monte Carlo) models drawn from the literature. The results suggest that the Pearson-Tukey approximation is a useful alternative to simulation in risk-analysis situations.  相似文献   
345.
Floro E. Caroleo 《LABOUR》1990,4(1):125-146
Abstract. Recent studies on the causes that bring about the increase in unemployment rates of the Mezzogiorno area and Italy are mainly based upon demographic and social causes. The aim of this study is to verify if they can be also influenced by economic factors. Through a dynamic model with partial adaptive hypothesis, some ways by which demand affects the differences of regional unemployment rates has been tested. In this respect it has been considered whether variations in economic activity can lead to different growth rates of regional production owing to the different industrial structures; whether the employers are influenced by local factors in varying the occupation when the production increases, and finally in which way the regional unemployment rate depends on the excess of desired, over effective, labour demand. Data base are from 1959 to 1976, and the unemployment rate is referred only to unemployed workers that is the better proxy of the unemployment connected with the economic cycle. The results show a slight reactiveness to demand, both in industrial labour demand and supply in the Mezzogiorno.  相似文献   
346.
Empirical Bayes is a versatile approach to “learn from a lot” in two ways: first, from a large number of variables and, second, from a potentially large amount of prior information, for example, stored in public repositories. We review applications of a variety of empirical Bayes methods to several well‐known model‐based prediction methods, including penalized regression, linear discriminant analysis, and Bayesian models with sparse or dense priors. We discuss “formal” empirical Bayes methods that maximize the marginal likelihood but also more informal approaches based on other data summaries. We contrast empirical Bayes to cross‐validation and full Bayes and discuss hybrid approaches. To study the relation between the quality of an empirical Bayes estimator and p, the number of variables, we consider a simple empirical Bayes estimator in a linear model setting. We argue that empirical Bayes is particularly useful when the prior contains multiple parameters, which model a priori information on variables termed “co‐data”. In particular, we present two novel examples that allow for co‐data: first, a Bayesian spike‐and‐slab setting that facilitates inclusion of multiple co‐data sources and types and, second, a hybrid empirical Bayes–full Bayes ridge regression approach for estimation of the posterior predictive interval.  相似文献   
347.
We define the exponentiated power exponential distribution and propose a regression model with different systematic structures based on the new distribution. We show that the new regression model can be applied to dispersion data since it represents a parametric family of models that includes as sub-models some widely-known regression models. It then can be used more effectively in the analysis of real data. We use maximum likelihood estimation and derive the appropriate matrices for assessing local influence on the parameter estimates under different perturbation schemes. Some global-influence measurements are also investigated and simulation studies are performed to evaluate the accuracy of the estimates. We provide an application of the regression model with four systematic structures to nursing activities score data in the Unit of the Medical Clinic of University of São Paulo (USP) Hospital.  相似文献   
348.
In this paper, a comparison between the life distribution of a new unit with that of a used unit in the increasing convex order is made leading to a new class of life distributions which we call “new better than used in convex ordering of second order”. This class includes as subclasses the NBU and the NBUC and is a subclass of the NBUCA class. Preservation properties under convolution, random maxima, mixing and formation of coherent structures are established. Stochastic comparisons of the excess lifetime when the inter-arrival times belong to the NBUC(2) class are developed. Some applications of Poisson shock models and a test of exponentiality against NBUC(2) alternative are presented.  相似文献   
349.
Lifetime Data Analysis - CD4-based multi-state back-calculation methods are key for monitoring the HIV epidemic, providing estimates of HIV incidence and diagnosis rates by disentangling their...  相似文献   
350.
Researchers have theorized about the role of sexual shame as a mechanism through which sexual minority stress manifests into mental health difficulties, such as sexual compulsivity for gay and bisexual men (GBM), and about the resilience-promoting effects of sexual pride. However, no validated measures to date have directly tapped into these constructs rather than using proxies for them, such as internalized homonegativity. We developed the Sexual Shame and Pride Scale (SSPS) and conducted a psychometric evaluation of it using a sample of 260 highly sexually active GBM. The scale had the expected structure in factor analysis and showed evidence of internal consistency and test–retest reliability. Correlational analyses demonstrated the convergent validity of sexual shame and sexual pride with relevant constructs. Regression analyses demonstrated the predictive validity of sexual shame in relation to sexual compulsivity, accounting for unique variability even after adjusting for previously demonstrated etiological factors, and the predictive validity of both shame and pride, which interacted to consistently predict four sexual behavior outcomes. Findings suggest the SSPS is a psychometrically valid and reliable measure that may be useful in future empirical work and highlight preliminary evidence for the role of these constructs in the sexual health of GBM.  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