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   19789篇
  免费   399篇
  国内免费   1篇
管理学   2606篇
民族学   111篇
人口学   1746篇
丛书文集   74篇
教育普及   1篇
理论方法论   1762篇
综合类   186篇
社会学   9937篇
统计学   3766篇
  2023年   131篇
  2022年   91篇
  2021年   133篇
  2020年   348篇
  2019年   515篇
  2018年   609篇
  2017年   790篇
  2016年   610篇
  2015年   407篇
  2014年   571篇
  2013年   3519篇
  2012年   731篇
  2011年   682篇
  2010年   500篇
  2009年   406篇
  2008年   536篇
  2007年   486篇
  2006年   527篇
  2005年   410篇
  2004年   418篇
  2003年   354篇
  2002年   369篇
  2001年   471篇
  2000年   419篇
  1999年   405篇
  1998年   312篇
  1997年   263篇
  1996年   281篇
  1995年   289篇
  1994年   247篇
  1993年   257篇
  1992年   299篇
  1991年   297篇
  1990年   289篇
  1989年   255篇
  1988年   239篇
  1987年   203篇
  1986年   229篇
  1985年   250篇
  1984年   218篇
  1983年   192篇
  1982年   160篇
  1981年   130篇
  1980年   155篇
  1979年   171篇
  1978年   134篇
  1977年   115篇
  1976年   88篇
  1975年   93篇
  1974年   93篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
371.
The aim of this paper is to summarize literature relevant to the professional organization and to present a contemporary analysis of the archetype concept in this field. In order to understand recent and ongoing changes in professional organizations, the paper begins with a review of how the professional archetype evolved from the 1960s to 1990. Then, with examples from contemporary accounting, health care and law organizations, it considers the processes by which an institutionalized archetype can change. Forces for change – such as deregulation, competition, technology and globalization – can challenge the interpretive scheme and eventually delegitimize the existing archetype. At the same time, significant environmental changes can override isomorphic pressures and de‐institutionalize the long‐accepted structures. Thus we herald the emergence a new professional archetype – or perhaps several competing archetypes. Finally, the paper reviews the evolving field of professional organization as a whole, and understands the extant archetypes. A typology of professional organizations is proposed that currently seems to have three clusters of organizations – possibly three competing archetypes – namely, the traditional professional partnership, the specialized ‘Star’ form and the corporate global professional network, or GPN.  相似文献   
372.
回想你上次面临新的领导机遇时,出现了什么情况?不管你是受命领导团队、部门还是整个企业,你很可能通过谈判争取该职位的薪水和待遇,比如:头衔、假期及奖金,但你是否争取过在该职位上取得成功的条件呢?  相似文献   
373.
The paper presents a general method of designing constant-factor approximation algorithms for some discrete optimization problems with assignment-type constraints. The core of the method is a simple deterministic procedure of rounding of linear relaxations (referred to as pipage rounding). With the help of the method we design approximation algorithms with better performance guarantees for some well-known problems including MAXIMUM COVERAGE, MAX CUT with given sizes of parts and some of their generalizations.  相似文献   
374.
The paper proposes a joint mixture model to model non-ignorable drop-out in longitudinal cohort studies of mental health outcomes. The model combines a (non)-linear growth curve model for the time-dependent outcomes and a discrete-time survival model for the drop-out with random effects shared by the two sub-models. The mixture part of the model takes into account population heterogeneity by accounting for latent subgroups of the shared effects that may lead to different patterns for the growth and the drop-out tendency. A simulation study shows that the joint mixture model provides greater precision in estimating the average slope and covariance matrix of random effects. We illustrate its benefits with data from a longitudinal cohort study that characterizes depression symptoms over time yet is hindered by non-trivial participant drop-out.KEYWORDS: Latent growth curve, MNAR drop-out, survival analysis, finite mixture model, mental health  相似文献   
375.
Researchers in statistical shape analysis often analyze outlines of objects. Even though these contours are infinite-dimensional in theory, they must be discretized in practice. When discretizing, it is important to reduce the number of sampling points considerably to reduce computational costs, but to not use too few points so as to result in too much approximation error. Unfortunately, determining the minimum number of points needed to achieve sufficiently approximate the contours is computationally expensive. In this paper, we fit regression models to predict these lower bounds using characteristics of the contours that are computationally cheap as predictor variables. However, least squares regression is inadequate for this task because it treats overestimation and underestimation equally, but underestimation of lower bounds is far more serious. Instead, to fit the models, we use the LINEX loss function, which allows us to penalize underestimation at an exponential rate while penalizing overestimation only linearly. We present a novel approach to select the shape parameter of the loss function and tools for analyzing how well the model fits the data. Through validation methods, we show that the LINEX models work well for reducing the underestimation for the lower bounds.  相似文献   
376.
In this article, we first propose the modified Hannan–Rissanen Method for estimating the parameters of autoregressive moving average (ARMA) process with symmetric stable noise and symmetric stable generalized autoregressive conditional heteroskedastic (GARCH) noise. Next, we propose the modified empirical characteristic function method for the estimation of GARCH parameters with symmetric stable noise. Further, we show the efficiency, accuracy and simplicity of our methods with Monte-Carlo simulation. Finally, we apply our proposed methods to model the financial data.  相似文献   
377.
本文介绍了蒙古尔部族的组成、形成和发展,并对其族长、土司的特点和承继作了详尽的描述。本文介绍了蒙古尔部族的组成、形成和发展,并对其族长、土司的特点和承继作了详尽的描述。  相似文献   
378.
本文对蒙古尔部族的组成、形成和发展作了介绍,其中对族长、土司的特点和承继作了详尽的描述。  相似文献   
379.
This paper is an assessment of the impact of child support enforcement and welfare policies on nonmarital teenage childbearing and motherhood. We derive four hypotheses about the effects of policies on nonmarital teenage childbearing and motherhood. We propose that teenage motherhood and school enrollment are joint decisions for teenage girls. Based on individual trajectories during ages 12–19, our analysis uses an event history model for nonmarital teenage childbearing and a dynamic model of motherhood that is jointly determined with school enrollment. We find some evidence that child support policies indirectly reduce teen motherhood by increasing the probability of school enrollment, which, in turn, reduces the probability of teen motherhood. This finding suggests that welfare offices may wish to place greater weight on outreach programs that inform more teenagers of the existence of strong child support enforcement measures. Such programs might reduce nonmarital teen motherhood further and thus reduce the need for welfare support and child support enforcement in the long run.
Lingxin HaoEmail:
  相似文献   
380.
A heteroscedastic regression based on the odd log-logistic Marshall–Olkin normal (OLLMON) distribution is defined by extending previous models. Some structural properties of this distribution are presented. The estimation of the parameters is addressed by maximum likelihood. For different parameter settings, sample sizes and some scenarios, various simulations investigate the performance of the heteroscedastic OLLMON regression. We use residual analysis to detect influential observations and to check the model assumptions. The new regression explains the mass loss of different wood species in civil construction in Brazil.  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