全文获取类型
收费全文 | 7456篇 |
免费 | 197篇 |
国内免费 | 76篇 |
专业分类
管理学 | 640篇 |
民族学 | 29篇 |
人才学 | 4篇 |
人口学 | 66篇 |
丛书文集 | 607篇 |
理论方法论 | 126篇 |
综合类 | 4846篇 |
社会学 | 151篇 |
统计学 | 1260篇 |
出版年
2024年 | 16篇 |
2023年 | 36篇 |
2022年 | 49篇 |
2021年 | 52篇 |
2020年 | 79篇 |
2019年 | 132篇 |
2018年 | 142篇 |
2017年 | 204篇 |
2016年 | 174篇 |
2015年 | 215篇 |
2014年 | 357篇 |
2013年 | 681篇 |
2012年 | 465篇 |
2011年 | 407篇 |
2010年 | 379篇 |
2009年 | 382篇 |
2008年 | 430篇 |
2007年 | 502篇 |
2006年 | 516篇 |
2005年 | 433篇 |
2004年 | 391篇 |
2003年 | 353篇 |
2002年 | 296篇 |
2001年 | 280篇 |
2000年 | 178篇 |
1999年 | 86篇 |
1998年 | 79篇 |
1997年 | 63篇 |
1996年 | 46篇 |
1995年 | 56篇 |
1994年 | 53篇 |
1993年 | 42篇 |
1992年 | 33篇 |
1991年 | 23篇 |
1990年 | 20篇 |
1989年 | 31篇 |
1988年 | 19篇 |
1987年 | 12篇 |
1986年 | 6篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有7729条查询结果,搜索用时 261 毫秒
211.
Designing and integrating composite networks for monitoring multivariate gaussian pollution fields 总被引:2,自引:0,他引:2
J. V. Zidek W. Sun & N. D. Le 《Journal of the Royal Statistical Society. Series C, Applied statistics》2000,49(1):63-79
Networks of ambient monitoring stations are used to monitor environmental pollution fields such as those for acid rain and air pollution. Such stations provide regular measurements of pollutant concentrations. The networks are established for a variety of purposes at various times so often several stations measuring different subsets of pollutant concentrations can be found in compact geographical regions. The problem of statistically combining these disparate information sources into a single 'network' then arises. Capitalizing on the efficiencies so achieved can then lead to the secondary problem of extending this network. The subject of this paper is a set of 31 air pollution monitoring stations in southern Ontario. Each of these regularly measures a particular subset of ionic sulphate, sulphite, nitrite and ozone. However, this subset varies from station to station. For example only two stations measure all four. Some measure just one. We describe a Bayesian framework for integrating the measurements of these stations to yield a spatial predictive distribution for unmonitored sites and unmeasured concentrations at existing stations. Furthermore we show how this network can be extended by using an entropy maximization criterion. The methods assume that the multivariate response field being measured has a joint Gaussian distribution conditional on its mean and covariance function. A conjugate prior is used for these parameters, some of its hyperparameters being fitted empirically. 相似文献
212.
The exponentially weighted moving average (EWMA) chart is often designed assuming the process parameters are known. In practice, the parameters are rarely known and need to be estimated from Phase I samples. Different Phase I samples are used when practitioners construct their own control chart's limits, which leads to the “Phase I between-practitioners” variability in the in-control average run length (ARL) of control charts. The standard deviation of the ARL (SDARL) is a good alternative to quantify this variability in control charts. Based on the SDARL metric, the performance of the EWMA median chart with estimated parameters is investigated in this paper. Some recommendations are given based on the SDARL metric. The results show that the EWMA median chart requires a much larger amount of Phase I data in order to reduce the variation in the in-control ARL up to a reasonable level. Due to the limitation of the amount of the Phase I data, the suggested EWMA median chart is designed with the bootstrap method which provides a good balance between the in-control and out-of-control ARL values. 相似文献
213.
Jorge Quiroz Richard Montes Heliang Shi Satrajit Roychoudhury 《Pharmaceutical statistics》2019,18(3):316-328
Assessment of analytical similarity of tier 1 quality attributes is based on a set of hypotheses that tests the mean difference of reference and test products against a margin adjusted for standard deviation of the reference product. Thus, proper assessment of the biosimilarity hypothesis requires statistical tests that account for the uncertainty associated with the estimations of the mean differences and the standard deviation of the reference product. Recently, a linear reformulation of the biosimilarity hypothesis has been proposed, which facilitates development and implementation of statistical tests. These statistical tests account for the uncertainty in the estimation process of all the unknown parameters. In this paper, we survey methods for constructing confidence intervals for testing the linearized reformulation of the biosimilarity hypothesis and also compare the performance of the methods. We discuss test procedures using confidence intervals to make possible comparison among recently developed methods as well as other previously developed methods that have not been applied for demonstrating analytical similarity. A computer simulation study was conducted to compare the performance of the methods based on the ability to maintain the test size and power, as well as computational complexity. We demonstrate the methods using two example applications. At the end, we make recommendations concerning the use of the methods. 相似文献
214.
Yunquan Song Yanji Zhu Xiuli Wang Lu Lin 《Journal of Statistical Computation and Simulation》2019,89(17):3196-3212
Nonresponse is a very common phenomenon in survey sampling. Nonignorable nonresponse – that is, a response mechanism that depends on the values of the variable having nonresponse – is the most difficult type of nonresponse to handle. This article develops a robust estimation approach to estimating equations (EEs) by incorporating the modelling of nonignorably missing data, the generalized method of moments (GMM) method and the imputation of EEs via the observed data rather than the imputed missing values when some responses are subject to nonignorably missingness. Based on a particular semiparametric logistic model for nonignorable missing response, this paper proposes the modified EEs to calculate the conditional expectation under nonignorably missing data. We can apply the GMM to infer the parameters. The advantage of our method is that it replaces the non-parametric kernel-smoothing with a parametric sampling importance resampling (SIR) procedure to avoid nonparametric kernel-smoothing problems with high dimensional covariates. The proposed method is shown to be more robust than some current approaches by the simulations. 相似文献
215.
Cathy W. S. Chen Hong Than-Thi Mike K. P. So 《Journal of Statistical Computation and Simulation》2019,89(2):191-210
This paper proposes a new hysteretic vector autoregressive (HVAR) model in which the regime switching may be delayed when the hysteresis variable lies in a hysteresis zone. We integrate an adapted multivariate Student-t distribution from amending the scale mixtures of normal distributions. This HVAR model allows for a higher degree of flexibility in the degrees of freedom for each time series. We use the proposed model to test for a causal relationship between any two target time series. Using posterior odds ratios, we overcome the limitations of the classical approach to multiple testing. Both simulated and real examples herein help illustrate the suggested methods. We apply the proposed HVAR model to investigate the causal relationship between the quarterly growth rates of gross domestic product of United Kingdom and United States. Moreover, we check the pairwise lagged dependence of daily PM2.5 levels in three districts of Taipei. 相似文献
216.
A smoothed bootstrap method is presented for the purpose of bandwidth selection in nonparametric hazard rate estimation for iid data. In this context, two new bootstrap bandwidth selectors are established based on the exact expression of the bootstrap version of the mean integrated squared error of some approximations of the kernel hazard rate estimator. This is very useful since Monte Carlo approximation is no longer needed for the implementation of the two bootstrap selectors. A simulation study is carried out in order to show the empirical performance of the new bootstrap bandwidths and to compare them with other existing selectors. The methods are illustrated by applying them to a diabetes data set. 相似文献
217.
218.
在需求分布规律变化情况下,报童在进行订货决策时会因为错误判断需求分布规律而导致期望库存成本增加。为了解决这一问题,本文集成传统历史需求信息和非传统需求信息以正确地认知需求分布规律,在此基础上决策订货量。假设需求服从均值不同、方差相同的两种类型的正态分布,每一种正态分布的概率已知。利用信号检测理论构建基于历史需求信息与需求分布概率的报童最优订货策略,并与只基于需求分布概率的直觉规则订货策略进行对比。结果表明:只要排除需求分布概率很大或很小两种极端情况,最优订货策略比直觉规则订货策略在控制期望库存成本方面的作用更明显,即利用历史需求信息可以有效修正报童对实际需求分布的检测结果,从而提高实际订货决策的准确性。研究结果对传统历史需求信息和非传统需求信息的集成以及需求信息交换等有一定的管理学启示和应用价值。 相似文献
219.
Marcie Fisher-Borne Andre Brown 《Journal of Ethnic & Cultural Diversity in Social Work》2018,27(2):157-175
This article describes an exploratory qualitative case study using a research method novel to social work known as Photovoice. This case study of the Photovoice process assesses its value as a community-based participatory research (CBPR) method with marginalized communities within social work research. Photovoice was used to engage young Black men as researchers into their own lived experience. Through a photographic and group participatory project, participants discussed how intersections of race, gender, and sexuality affect their lives and health. While this methodology has proliferated within public health literature, little research exists within social work. Photovoice represents a research well-aligned with core social work values of empowerment and social justice. This method offers our profession a participatory, action-oriented tool to inform practice and policy and does so in the voices of communities who often go unheard. 相似文献
220.
Judite Leite Hugo S. Gomes Andreia de Castro-Rodrigues Rui Abrunhosa Gonçalves 《Journal of Child Custody》2018,15(2):116-135
In Portugal, there is a gap regarding psychological tests validated for forensic contexts, particularly those related to child custody issues. The Parent–Child Relationship Inventory (PCRI) is one of the most used instruments in child custody contexts. This study aimed to analyze the psychometric properties of PCRI in a Portuguese forensic sample. PCRI factorial structure and psychometric properties were analyzed in a sample of 144 parents involved in child custody assessments. The questionnaire showed good internal consistency, except for the parental support, autonomy, and role orientation scales. It also showed good discriminant capacity. The confirmatory factor analysis did not replicate the 7-factor model proposed by Gerard. The results were discussed based on the use of PCRI in the context of child custody assessment. 相似文献