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   91818篇
  免费   1982篇
  国内免费   18篇
管理学   12335篇
民族学   556篇
人才学   25篇
人口学   7001篇
丛书文集   603篇
理论方法论   9438篇
综合类   2678篇
社会学   42393篇
统计学   18789篇
  2023年   511篇
  2021年   574篇
  2020年   1520篇
  2019年   2204篇
  2018年   2090篇
  2017年   3177篇
  2016年   2376篇
  2015年   2056篇
  2014年   2648篇
  2013年   18914篇
  2012年   2444篇
  2011年   2251篇
  2010年   2064篇
  2009年   2238篇
  2008年   2143篇
  2007年   1960篇
  2006年   2188篇
  2005年   2353篇
  2004年   2169篇
  2003年   1884篇
  2002年   1996篇
  2001年   2002篇
  2000年   1771篇
  1999年   1691篇
  1998年   1498篇
  1997年   1334篇
  1996年   1299篇
  1995年   1323篇
  1994年   1297篇
  1993年   1275篇
  1992年   1262篇
  1991年   1201篇
  1990年   1175篇
  1989年   1024篇
  1988年   1122篇
  1987年   989篇
  1986年   888篇
  1985年   1063篇
  1984年   1120篇
  1983年   1001篇
  1982年   935篇
  1981年   860篇
  1980年   802篇
  1979年   861篇
  1978年   758篇
  1977年   682篇
  1976年   649篇
  1975年   631篇
  1974年   516篇
  1973年   433篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
291.
292.
The authors review the trends in the use of computers in the delivery and support of career guidance and counseling identified at the symposium International Perspectives on Career Development. The papers presented emphasized that 20th‐century computer‐based systems continue to be used, mainly delivered via the World Wide Web. These systems are enhanced through audio, video, graphics, strategies to provide needs assessment, and support by cybercounselors or expert system design. The papers also revealed a new trend: the use of elegant Web sites to store and search immense libraries of resources needed by professionals and clients and to facilitate communication and collaboration among professionals in cyberspace. Concerns, issues, and resources related to many areas, including the readiness of clients to use computer‐based systems, were also raised; existing sources of guidelines are noted.  相似文献   
293.
Generalized additive models for location, scale and shape   总被引:10,自引:0,他引:10  
Summary.  A general class of statistical models for a univariate response variable is presented which we call the generalized additive model for location, scale and shape (GAMLSS). The model assumes independent observations of the response variable y given the parameters, the explanatory variables and the values of the random effects. The distribution for the response variable in the GAMLSS can be selected from a very general family of distributions including highly skew or kurtotic continuous and discrete distributions. The systematic part of the model is expanded to allow modelling not only of the mean (or location) but also of the other parameters of the distribution of y , as parametric and/or additive nonparametric (smooth) functions of explanatory variables and/or random-effects terms. Maximum (penalized) likelihood estimation is used to fit the (non)parametric models. A Newton–Raphson or Fisher scoring algorithm is used to maximize the (penalized) likelihood. The additive terms in the model are fitted by using a backfitting algorithm. Censored data are easily incorporated into the framework. Five data sets from different fields of application are analysed to emphasize the generality of the GAMLSS class of models.  相似文献   
294.
295.
296.
297.
A growing literature examines the empirical relationship between the joint reproductive preferences of marital partners and reproductive outcomes in Africa. Less explored is how spousal power in decision making may be influenced by lineage type. Using pooled data from Ghana, we investigate how lineage affects gendered reproductive decision outcomes and find some evidence that matrilineal women are more able than nonmatrilineal women to translate their reproductive preferences into action consistent with their goals.  相似文献   
298.
用Ostwald粘度计测定液体粘度系数的实验是医学院校物理实验课普遍开设的基本实验之一,这套装置为本实验室自行设计制作,并在本实验室使用.此装置具有实验结果误差小,操作方便,不易损坏仪器,取料容易,观测视角广阔,体积狭小,结构简单紧凑等特点,文中具体介绍了粘度计保护盒的制作、安装及整套实验装置的使用方法.  相似文献   
299.
Longitudinal data often contain missing observations, and it is in general difficult to justify particular missing data mechanisms, whether random or not, that may be hard to distinguish. The authors describe a likelihood‐based approach to estimating both the mean response and association parameters for longitudinal binary data with drop‐outs. They specify marginal and dependence structures as regression models which link the responses to the covariates. They illustrate their approach using a data set from the Waterloo Smoking Prevention Project They also report the results of simulation studies carried out to assess the performance of their technique under various circumstances.  相似文献   
300.
Summary.  A stochastic discrete time version of the susceptible–infected–recovered model for infectious diseases is developed. Disease is transmitted within and between communities when infected and susceptible individuals interact. Markov chain Monte Carlo methods are used to make inference about these unobserved populations and the unknown parameters of interest. The algorithm is designed specifically for modelling time series of reported measles cases although it can be adapted for other infectious diseases with permanent immunity. The application to observed measles incidence series motivates extensions to incorporate age structure as well as spatial epidemic coupling between communities.  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