全文获取类型
收费全文 | 564篇 |
免费 | 37篇 |
国内免费 | 3篇 |
专业分类
管理学 | 17篇 |
人口学 | 9篇 |
丛书文集 | 12篇 |
理论方法论 | 5篇 |
综合类 | 97篇 |
社会学 | 15篇 |
统计学 | 449篇 |
出版年
2023年 | 7篇 |
2022年 | 7篇 |
2021年 | 9篇 |
2020年 | 15篇 |
2019年 | 32篇 |
2018年 | 27篇 |
2017年 | 40篇 |
2016年 | 24篇 |
2015年 | 30篇 |
2014年 | 24篇 |
2013年 | 111篇 |
2012年 | 51篇 |
2011年 | 26篇 |
2010年 | 20篇 |
2009年 | 18篇 |
2008年 | 19篇 |
2007年 | 18篇 |
2006年 | 19篇 |
2005年 | 12篇 |
2004年 | 19篇 |
2003年 | 18篇 |
2002年 | 11篇 |
2001年 | 13篇 |
2000年 | 7篇 |
1999年 | 10篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1987年 | 1篇 |
排序方式: 共有604条查询结果,搜索用时 281 毫秒
1.
AbstractThe problem of testing equality of two multivariate normal covariance matrices is considered. Assuming that the incomplete data are of monotone pattern, a quantity similar to the Likelihood Ratio Test Statistic is proposed. A satisfactory approximation to the distribution of the quantity is derived. Hypothesis testing based on the approximate distribution is outlined. The merits of the test are investigated using Monte Carlo simulation. Monte Carlo studies indicate that the test is very satisfactory even for moderately small samples. The proposed methods are illustrated using an example. 相似文献
2.
日本是开展自然辩证法研究比较早的国家之一 ,并在研讨自然辩证法方面形成了许多富有启发性的思想方法。可将其概括为 :自由论争的思想方法、“具体化”的思想方法、发展的思想方法、联盟的思想方法 相似文献
3.
Craig H. Mallinckrodt Christopher J. Kaiser John G. Watkin Michael J. Detke Geert Molenberghs Raymond J. Carroll 《Pharmaceutical statistics》2004,3(3):171-186
The last observation carried forward (LOCF) approach is commonly utilized to handle missing values in the primary analysis of clinical trials. However, recent evidence suggests that likelihood‐based analyses developed under the missing at random (MAR) framework are sensible alternatives. The objective of this study was to assess the Type I error rates from a likelihood‐based MAR approach – mixed‐model repeated measures (MMRM) – compared with LOCF when estimating treatment contrasts for mean change from baseline to endpoint (Δ). Data emulating neuropsychiatric clinical trials were simulated in a 4 × 4 factorial arrangement of scenarios, using four patterns of mean changes over time and four strategies for deleting data to generate subject dropout via an MAR mechanism. In data with no dropout, estimates of Δ and SEΔ from MMRM and LOCF were identical. In data with dropout, the Type I error rates (averaged across all scenarios) for MMRM and LOCF were 5.49% and 16.76%, respectively. In 11 of the 16 scenarios, the Type I error rate from MMRM was at least 1.00% closer to the expected rate of 5.00% than the corresponding rate from LOCF. In no scenario did LOCF yield a Type I error rate that was at least 1.00% closer to the expected rate than the corresponding rate from MMRM. The average estimate of SEΔ from MMRM was greater in data with dropout than in complete data, whereas the average estimate of SEΔ from LOCF was smaller in data with dropout than in complete data, suggesting that standard errors from MMRM better reflected the uncertainty in the data. The results from this investigation support those from previous studies, which found that MMRM provided reasonable control of Type I error even in the presence of MNAR missingness. No universally best approach to analysis of longitudinal data exists. However, likelihood‐based MAR approaches have been shown to perform well in a variety of situations and are a sensible alternative to the LOCF approach. MNAR methods can be used within a sensitivity analysis framework to test the potential presence and impact of MNAR data, thereby assessing robustness of results from an MAR method. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
4.
Amy H. Herring Joseph G. Ibrahim Stuart R. Lipsitz 《Journal of the Royal Statistical Society. Series C, Applied statistics》2004,53(2):293-310
Summary. Non-ignorable missing data, a serious problem in both clinical trials and observational studies, can lead to biased inferences. Quality-of-life measures have become increasingly popular in clinical trials. However, these measures are often incompletely observed, and investigators may suspect that missing quality-of-life data are likely to be non-ignorable. Although several recent references have addressed missing covariates in survival analysis, they all required the assumption that missingness is at random or that all covariates are discrete. We present a method for estimating the parameters in the Cox proportional hazards model when missing covariates may be non-ignorable and continuous or discrete. Our method is useful in reducing the bias and improving efficiency in the presence of missing data. The methodology clearly specifies assumptions about the missing data mechanism and, through sensitivity analysis, helps investigators to understand the potential effect of missing data on study results. 相似文献
5.
Craig H. Mallinckrodt John G. Watkin Geert Molenberghs Raymond J. Carroll 《Pharmaceutical statistics》2004,3(3):161-169
Missing data, and the bias they can cause, are an almost ever‐present concern in clinical trials. The last observation carried forward (LOCF) approach has been frequently utilized to handle missing data in clinical trials, and is often specified in conjunction with analysis of variance (LOCF ANOVA) for the primary analysis. Considerable advances in statistical methodology, and in our ability to implement these methods, have been made in recent years. Likelihood‐based, mixed‐effects model approaches implemented under the missing at random (MAR) framework are now easy to implement, and are commonly used to analyse clinical trial data. Furthermore, such approaches are more robust to the biases from missing data, and provide better control of Type I and Type II errors than LOCF ANOVA. Empirical research and analytic proof have demonstrated that the behaviour of LOCF is uncertain, and in many situations it has not been conservative. Using LOCF as a composite measure of safety, tolerability and efficacy can lead to erroneous conclusions regarding the effectiveness of a drug. This approach also violates the fundamental basis of statistics as it involves testing an outcome that is not a physical parameter of the population, but rather a quantity that can be influenced by investigator behaviour, trial design, etc. Practice should shift away from using LOCF ANOVA as the primary analysis and focus on likelihood‐based, mixed‐effects model approaches developed under the MAR framework, with missing not at random methods used to assess robustness of the primary analysis. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
6.
Jerald F. Lawless 《Revue canadienne de statistique》2004,32(3):327-331
Oiler, Gomez & Calle (2004) give a constant sum condition for processes that generate interval‐censored lifetime data. They show that in models satisfying this condition, it is possible to estimate non‐parametrically the lifetime distribution based on a well‐known simplified likelihood. The author shows that this constant‐sum condition is equivalent to the existence of an observation process that is independent of lifetimes and which gives the same probability distribution for the observed data as the underlying true process. 相似文献
7.
家族企业管理机制创新探析 总被引:5,自引:0,他引:5
改革开放以来 ,我国私营经济获得了长足的发展 ,并为我国经济和社会发展做出了重要贡献 ,成为社会主义市场经济的重要组成部分。但随着市场外在条件和社会经济发展格局的变化 ,作为私营资本形式之一的家族企业 ,其自身的不适应性逐步凸现出来。克服家族式管理的不足 ,转换管理机制和管理方式 ,通过资本市场使家族企业完成由家庭化向专业化、由宗法化向市场化的转变 ,是使其真正做大做强的必由之路 相似文献
8.
Summary The paper deals with missing data and forecasting problems in multivariate time series making use of the Common Components
Dynamic Linear Model (DLMCC), presented in Quintana (1985), and West and Harrison (1989).
Some results are presented and discussed: exploiting the correlation between series, estimated by the DLMCC, the paper shows
as it is possible to update state vector posterior distributions for the unobserved series. This is realized on the base of
the updating of the observed series state vectors, for which the usual Kalman filter equations can be applied.
An application concerning some Italian private consumption series provides an example of the model capabilities. 相似文献
9.
证券投资管理专业人才需求分析与人才规格设计 总被引:1,自引:0,他引:1
课题组 《辽东学院学报(社会科学版)》2004,6(5):72-74
随着经济体制改革的深化,社会经济生活中对投融资的需求日益旺盛,大中型企业转机建制、民营企业谋求发展将更加依赖资本市场,证券业因此成为我国新兴行业,证券人才需求不仅空间巨大,而且呈现明显的层次性,既需要高层次的决策者、管理者,更需要具有较强职业技能的管理、服务第一线的应用性人才。证券投资管理专业应据此确定人才培养目标和人才培养规格。 相似文献
10.
Alan Phillips Alan Ebbutt Lesley France David Morgan Mick Ireson Lesley Struthers Guenter Heimann 《Pharmaceutical statistics》2003,2(4):241-251
The International Conference on Harmonisation guideline ‘Statistical Principles for Clinical Trials’ was adopted by the Committee for Proprietary Medicinal Products (CPMP) in March 1998, and consequently is operational in Europe. Since then more detailed guidance on selected topics has been issued by the CPMP in the form of ‘Points to Consider’ documents. The intent of these was to give guidance particularly to non‐statistical reviewers within regulatory authorities, although of course they also provide a good source of information for pharmaceutical industry statisticians. In addition, the Food and Drug Administration has recently issued a draft guideline on data monitoring committees. In November 2002 a one‐day discussion forum was held in London by Statisticians in the Pharmaceutical Industry (PSI). The aim of the meeting was to discuss how statisticians were responding to some of the issues covered in these new guidelines, and to document consensus views where they existed. The forum was attended by industry, academic and regulatory statisticians. This paper outlines the questions raised, resulting discussions and consensus views reached. It is clear from the guidelines and discussions at the workshop that the statistical analysis strategy must be planned during the design phase of a clinical trial and carefully documented. Once the study is complete the analysis strategy should be thoughtfully executed and the findings reported. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献