全文获取类型
收费全文 | 24438篇 |
免费 | 415篇 |
国内免费 | 3篇 |
专业分类
管理学 | 3474篇 |
民族学 | 205篇 |
人才学 | 4篇 |
人口学 | 3546篇 |
丛书文集 | 98篇 |
理论方法论 | 1944篇 |
综合类 | 543篇 |
社会学 | 11808篇 |
统计学 | 3234篇 |
出版年
2021年 | 64篇 |
2020年 | 205篇 |
2019年 | 326篇 |
2018年 | 1953篇 |
2017年 | 2100篇 |
2016年 | 1385篇 |
2015年 | 300篇 |
2014年 | 365篇 |
2013年 | 2428篇 |
2012年 | 772篇 |
2011年 | 1548篇 |
2010年 | 1376篇 |
2009年 | 1125篇 |
2008年 | 1166篇 |
2007年 | 1360篇 |
2006年 | 373篇 |
2005年 | 594篇 |
2004年 | 601篇 |
2003年 | 498篇 |
2002年 | 415篇 |
2001年 | 357篇 |
2000年 | 302篇 |
1999年 | 285篇 |
1998年 | 228篇 |
1997年 | 225篇 |
1996年 | 257篇 |
1995年 | 192篇 |
1994年 | 210篇 |
1993年 | 200篇 |
1992年 | 203篇 |
1991年 | 201篇 |
1990年 | 201篇 |
1989年 | 188篇 |
1988年 | 180篇 |
1987年 | 186篇 |
1986年 | 146篇 |
1985年 | 173篇 |
1984年 | 200篇 |
1983年 | 185篇 |
1982年 | 162篇 |
1981年 | 135篇 |
1980年 | 142篇 |
1979年 | 139篇 |
1978年 | 132篇 |
1977年 | 119篇 |
1976年 | 118篇 |
1975年 | 116篇 |
1974年 | 106篇 |
1973年 | 93篇 |
1972年 | 66篇 |
排序方式: 共有10000条查询结果,搜索用时 375 毫秒
81.
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
82.
Point processes are the stochastic models most suitable for describing physical phenomena that appear at irregularly spaced
times, such as the earthquakes. These processes are uniquely characterized by their conditional intensity, that is, by the
probability that an event will occur in the infinitesimal interval (t, t+Δt), given the history of the process up tot. The seismic phenomenon displays different behaviours on different time and size scales; in particular, the occurrence of
destructive shocks over some centuries in a seismogenic region may be explained by the elastic rebound theory. This theory
has inspired the so-called stress release models: their conditional intensity translates the idea that an earthquake produces
a sudden decrease in the amount of strain accumulated gradually over time along a fault, and the subsequent event occurs when
the stress exceeds the strength of the medium. This study has a double objective: the formulation of these models in the Bayesian
framework, and the assignment to each event of a mark, that is its magnitude, modelled through a distribution that depends
at timet on the stress level accumulated up to that instant. The resulting parameter space is constrained and dependent on the data,
complicating Bayesian computation and analysis. We have resorted to Monte Carlo methods to solve these problems. 相似文献
83.
Christian P. Robert Xiao-Li Meng Jesper Møller Jeffrey S Rosenthal C Jennison M. A Hurn F Al-Awadhi Peter McCullagh Christophe Andrieu Arnaud Doucet Petros Dellaportas Ioulia Papageorgiou Ricardo S Ehlers Elena A Erosheva Stephen E Fienberg Jonathan J Forster Roger C Gill Nial Friel Peter Green David Hastie R King Hans R Künsch N. A. Lazar C Osinski 《Journal of the Royal Statistical Society. Series B, Statistical methodology》2003,65(1):39-55
84.
Michael S. Rendall Ryan Admiraal Alessandra DeRose Paola DiGiulio Mark S. Handcock Filomena Racioppi 《Statistical Methods and Applications》2008,17(4):519-539
In non-experimental research, data on the same population process may be collected simultaneously by more than one instrument.
For example, in the present application, two sample surveys and a population birth registration system all collect observations
on first births by age and year, while the two surveys additionally collect information on women’s education. To make maximum
use of the three data sources, the survey data are pooled and the population data introduced as constraints in a logistic
regression equation. Reductions in standard errors about the age and birth-cohort parameters of the regression equation in
the order of three-quarters are obtained by introducing the population data as constraints. A halving of the standard errors
about the education parameters is achieved by pooling observations from the larger survey dataset with those from the smaller
survey. The percentage reduction in the standard errors through imposing population constraints is independent of the total
survey sample size. 相似文献
85.
86.
87.
88.
Banks winners in tournaments are difficult to recognize 总被引:1,自引:0,他引:1
Gerhard J. Woeginger 《Social Choice and Welfare》2003,20(3):523-528
Given a tournament T, a Banks winner of T is the top vertex of any maximal (with respect to inclusion) transitive subtournament of T. In this technical note, we show that the problem of deciding whether some fixed vertex v is a Banks winner for T is NP-complete.
Received: 22 February 2002/Accepted: 20 June 2002
Supported by the START program Y43-MAT of the Austrian Ministry of Science.
I would like to thank two thank the referees for a careful reading of the paper, for helpful remarks, and for many suggestions
how to improve the presentation. 相似文献
89.
S. Vansteelandt E. Goetghebeur 《Journal of the Royal Statistical Society. Series B, Statistical methodology》2003,65(4):817-835
Summary. We estimate cause–effect relationships in empirical research where exposures are not completely controlled, as in observational studies or with patient non-compliance and self-selected treatment switches in randomized clinical trials. Additive and multiplicative structural mean models have proved useful for this but suffer from the classical limitations of linear and log-linear models when accommodating binary data. We propose the generalized structural mean model to overcome these limitations. This is a semiparametric two-stage model which extends the structural mean model to handle non-linear average exposure effects. The first-stage structural model describes the causal effect of received exposure by contrasting the means of observed and potential exposure-free outcomes in exposed subsets of the population. For identification of the structural parameters, a second stage 'nuisance' model is introduced. This takes the form of a classical association model for expected outcomes given observed exposure. Under the model, we derive estimating equations which yield consistent, asymptotically normal and efficient estimators of the structural effects. We examine their robustness to model misspecification and construct robust estimators in the absence of any exposure effect. The double-logistic structural mean model is developed in more detail to estimate the effect of observed exposure on the success of treatment in a randomized controlled blood pressure reduction trial with self-selected non-compliance. 相似文献
90.