全文获取类型
收费全文 | 19323篇 |
免费 | 526篇 |
国内免费 | 1篇 |
专业分类
管理学 | 2799篇 |
民族学 | 70篇 |
人才学 | 1篇 |
人口学 | 1903篇 |
丛书文集 | 78篇 |
教育普及 | 2篇 |
理论方法论 | 1737篇 |
现状及发展 | 1篇 |
综合类 | 258篇 |
社会学 | 9456篇 |
统计学 | 3545篇 |
出版年
2021年 | 112篇 |
2020年 | 281篇 |
2019年 | 377篇 |
2018年 | 443篇 |
2017年 | 609篇 |
2016年 | 478篇 |
2015年 | 349篇 |
2014年 | 461篇 |
2013年 | 3033篇 |
2012年 | 631篇 |
2011年 | 621篇 |
2010年 | 450篇 |
2009年 | 378篇 |
2008年 | 450篇 |
2007年 | 472篇 |
2006年 | 460篇 |
2005年 | 448篇 |
2004年 | 414篇 |
2003年 | 379篇 |
2002年 | 417篇 |
2001年 | 522篇 |
2000年 | 532篇 |
1999年 | 463篇 |
1998年 | 345篇 |
1997年 | 317篇 |
1996年 | 328篇 |
1995年 | 306篇 |
1994年 | 286篇 |
1993年 | 291篇 |
1992年 | 347篇 |
1991年 | 318篇 |
1990年 | 286篇 |
1989年 | 291篇 |
1988年 | 293篇 |
1987年 | 252篇 |
1986年 | 245篇 |
1985年 | 279篇 |
1984年 | 272篇 |
1983年 | 251篇 |
1982年 | 219篇 |
1981年 | 185篇 |
1980年 | 169篇 |
1979年 | 196篇 |
1978年 | 179篇 |
1977年 | 160篇 |
1976年 | 136篇 |
1975年 | 158篇 |
1974年 | 120篇 |
1973年 | 116篇 |
1972年 | 95篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
791.
B. J. Gajewski R. Lee M. Bott U. Piamjariyakul R. L. Taunton 《Journal of applied statistics》2009,36(9):933-944
Data envelopment analysis (DEA) is a deterministic econometric model for calculating efficiency by using data from an observed set of decision-making units (DMUs). We propose a method for calculating the distribution of efficiency scores. Our framework relies on estimating data from an unobserved set of DMUs. The model provides posterior predictive data for the unobserved DMUs to augment the frontier in the DEA that provides a posterior predictive distribution for the efficiency scores. We explore the method on a multiple-input and multiple-output DEA model. The data for the example are from a comprehensive examination of how nursing homes complete a standardized mandatory assessment of residents. 相似文献
792.
Studying the right tail of a distribution, one can classify the distributions into three classes based on the extreme value index γ. The class γ>0 corresponds to Pareto-type or heavy tailed distributions, while γ<0 indicates that the underlying distribution has a finite endpoint. The Weibull-type distributions form an important subgroup within the Gumbel class with γ=0. The tail behaviour can then be specified using the Weibull tail index. Classical estimators of this index show severe bias. In this paper we present a new estimation approach based on the mean excess function, which exhibits improved bias and mean squared error. The asserted properties are supported by simulation experiments and asymptotic results. Illustrations with real life data sets are provided. 相似文献
793.
In response surface methodology, one is usually interested in estimating the optimal conditions based on a small number of experimental runs which are designed to optimally sample the experimental space. Typically, regression models are constructed from the experimental data and interrogated in order to provide a point estimate of the independent variable settings predicted to optimize the response. Unfortunately, these point estimates are rarely accompanied with uncertainty intervals. Though classical frequentist confidence intervals can be constructed for unconstrained quadratic models, higher order, constrained or nonlinear models are often encountered in practice. Existing techniques for constructing uncertainty estimates in such situations have not been implemented widely, due in part to the need to set adjustable parameters or because of limited or difficult applicability to constrained or nonlinear problems. To address these limitations a Bayesian method of determining credible intervals for response surface optima was developed. The approach shows good coverage probabilities on two test problems, is straightforward to implement and is readily applicable to the kind of constrained and/or nonlinear problems that frequently appear in practice. 相似文献
794.
Julian P. T. Higgins Simon G. Thompson David J. Spiegelhalter 《Journal of the Royal Statistical Society. Series A, (Statistics in Society)》2009,172(1):137-159
Summary. Meta-analysis in the presence of unexplained heterogeneity is frequently undertaken by using a random-effects model, in which the effects underlying different studies are assumed to be drawn from a normal distribution. Here we discuss the justification and interpretation of such models, by addressing in turn the aims of estimation, prediction and hypothesis testing. A particular issue that we consider is the distinction between inference on the mean of the random-effects distribution and inference on the whole distribution. We suggest that random-effects meta-analyses as currently conducted often fail to provide the key results, and we investigate the extent to which distribution-free, classical and Bayesian approaches can provide satisfactory methods. We conclude that the Bayesian approach has the advantage of naturally allowing for full uncertainty, especially for prediction. However, it is not without problems, including computational intensity and sensitivity to a priori judgements. We propose a simple prediction interval for classical meta-analysis and offer extensions to standard practice of Bayesian meta-analysis, making use of an example of studies of 'set shifting' ability in people with eating disorders. 相似文献
795.
Carroll KJ 《Pharmaceutical statistics》2006,5(4):283-293
In oncology, it may not always be possible to evaluate the efficacy of new medicines in placebo-controlled trials. Furthermore, while some newer, biologically targeted anti-cancer treatments may be expected to deliver therapeutic benefit in terms of better tolerability or improved symptom control, they may not always be expected to provide increased efficacy relative to existing therapies. This naturally leads to the use of active-control, non-inferiority trials to evaluate such treatments. In recent evaluations of anti-cancer treatments, the non-inferiority margin has often been defined in terms of demonstrating that at least 50% of the active control effect has been retained by the new drug using methods such as those described by Rothmann et al., Statistics in Medicine 2003; 22:239-264 and Wang and Hung Controlled Clinical Trials 2003; 24:147-155. However, this approach can lead to prohibitively large clinical trials and results in a tendency to dichotomize trial outcome as either 'success' or 'failure' and thus oversimplifies interpretation. With relatively modest modification, these methods can be used to define a stepwise approach to design and analysis. In the first design step, the trial is sized to show indirectly that the new drug would have beaten placebo; in the second analysis step, the probability that the new drug is superior to placebo is assessed and, if sufficiently high in the third and final step, the relative efficacy of the new drug to control is assessed on a continuum of effect retention via an 'effect retention likelihood plot'. This stepwise approach is likely to provide a more complete assessment of relative efficacy so that the value of new treatments can be better judged. 相似文献
796.
Bringing together women and family in quality perspective bring about interesting discussions in this paper. By integrating
previous studies and considering expert opinions, we determinate the variables and dimensions with respect to women’s existence
regarding their roles both in the family and at work. Many activities carried out by women represent the consumer aspects
of their role. Women undertake these activities to fulfill their needs, which can be classified in the order of preference
using Maslow’s Hierarchy of Need. Women success can be measured based on their ability to perform their roles successfully.
We identify women’s performance by using quality approach of Personal Quality Maintenance (PQM), which is widely applied in
many organizations in order to maintain the service delivery, which meets the customer satisfaction. The effort to enhance
women’s satisfaction for their success in playing the multirole in the family and at work is our main consideration. This
study may contribute a new point of view regarding for the women’s welfare and existence. 相似文献
797.
798.
Population Research and Policy Review - 相似文献
799.
Employment and earnings of foreign-born scientists and engineers 总被引:1,自引:1,他引:0
Espenshade Thomas J. Usdansky Margaret L. Chung Chang Y. 《Population research and policy review》2001,20(1-2):81-105
Population Research and Policy Review - 相似文献
800.
This paper examines a wide variety of forms, and full histories, of family structure to test existing theories of family
influences and identify needs for new theories. The focus is on links between childhood family structure and both completed
schooling and risk of a nonmarital birth. Using a 27-year span of panel (PSID) data for U.S. children, we find that: (a) change
is stressful, (b) timing during childhood is relevant, (c) adults other than parents are important, and (d) two more recently
studied family structures (mother-with-grandparent(s) and mother-with-stepfather) do not fit the molds of existing theories.
The findings suggest that new theories should consider allocation of resources and reasons people group into family structures.
Received: 11 September 1998/Accepted: 27 March 2000 相似文献