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121.
Serfling and Xiao [A contribution to multivariate L-moments, L-comoment matrices. J Multivariate Anal. 2007;98:1765–1781] extended the L-moment theory to the multivariate setting. In the present paper, we focus on the two-dimensional random vectors to establish a link between the bivariate L-moments (BLM) and the underlying bivariate copula functions. This connection provides a new estimate of dependence parameters of bivariate statistical data. Extensive simulation study is carried out to compare estimators based on the BLM, the maximum likelihood, the minimum distance and a rank approximate Z-estimation. The obtained results show that, when the sample size increases, BLM-based estimation performs better as far as the bias and computation time are concerned. Moreover, the root-mean-squared error is quite reasonable and less sensitive in general to outliers than those of the above cited methods. Further, the proposed BLM method is an easy-to-use tool for the estimation of multiparameter copula models. A generalization of the BLM estimation method to the multivariate case is discussed. 相似文献
122.
《Scandinavian Journal of Statistics》2018,45(3):590-617
We consider the local estimation of the stable tail dependence function when a random covariate is observed together with the variables of main interest. Our estimator is a weighted version of the empirical estimator adapted to the covariate framework. We provide the main asymptotic properties of our estimator, when properly normalized, in particular the convergence of the empirical process towards a tight centred Gaussian process. The finite sample performance of our estimator is illustrated on a small simulation study and on a dataset of air pollution measurements. 相似文献
123.
This study examines how a research intermediary can successfully manage collaboration among research partners, while mitigating resource dependence in multi-partner programs. For that purpose, two fundamentally different strategies are explored: tertius gaudens and tertius iungens. Previous literature has not addressed the possibility that the effective deployment of tertius broker strategies may be contingent on multiple factors. Using a qualitative in-depth case study, we contribute to the literature by showing that the effective development of the tertius broker strategies in our study context is contingent on partner type, business integration and product readiness. 相似文献
124.
A frequency domain bootstrap (FDB) is a common technique to apply Efron’s independent and identically distributed resampling technique (Efron, 1979) to periodogram ordinates – especially normalized periodogram ordinates – by using spectral density estimates. The FDB method is applicable to several classes of statistics, such as estimators of the normalized spectral mean, the autocorrelation (but not autocovariance), the normalized spectral density function, and Whittle parameters. While this FDB method has been extensively studied with respect to short-range dependent time processes, there is a dearth of research on its use with long-range dependent time processes. Therefore, we propose an FDB methodology for ratio statistics under long-range dependence, using semi- and nonparametric spectral density estimates as a normalizing factor. It is shown that the FDB approximation allows for valid distribution estimation for a broad class of stationary, long-range (or short-range) dependent linear processes, without any stringent assumptions on the distribution of the underlying process. The results of a large simulation study show that the FDB approximation using a semi- or nonparametric spectral density estimator is often robust for various values of a long-memory parameter reflecting magnitude of dependence. We apply the proposed procedure to two data examples. 相似文献
125.
Taoufik Bouezmarni Sébastien Bellegem Yassir Rabhi 《Revue canadienne de statistique》2020,48(3):582-595
In this article we introduce a nonparametric estimator of the spectral density by smoothing the periodogram using beta kernel density. The estimator is proved to be bounded for short memory data and diverges at the origin for long memory data. The convergence in probability of the relative error and Monte Carlo simulations show that the proposed estimator automatically adapts to the long- and the short-range dependency of the process. A cross-validation procedure is studied in order to select the nuisance parameter of the estimator. Illustrations on historical as well as most recent returns and absolute returns of the S&P500 index show the performance of the beta kernel estimator. The Canadian Journal of Statistics 48: 582–595; 2020 © 2020 Statistical Society of Canada 相似文献
126.
We consider the competing-risks problem without making any assumption concerning the independence of the risks. Maximum-likelihood estimates of the cause-specific hazard rates are obtained under the condition that their ratio is monotone. We also consider the likelihood-ratio test for testing the proportionality of two cause-specific hazard rates against the alternative that the ratio of these two hazard rates is monotonic. This testing problem is equivalent to testing independence against likelihood-ratio dependence of the time to failure and the cause of failure in the competing-risks setup. We allow for random censoring on the right. The asymptotic null distribution of the test statistic is obtained and is found to be of the chi-bar-square type. The problem is extended to the case of more than two risks. A numerical example is given to illustrate the procedure. 相似文献
127.
吴伟东 《北京理工大学学报(社会科学版)》2017,19(2):142-149
为促进科学立法,揭示在实践中影响着劳动法律行动结果的因素,利用上海、深圳、天津等10个城市的问卷调查数据,以《劳动合同法》中关于劳动合同签订的文本规定为切入点,从交换理论的视角出发进行了Logistic回归模型分析,发现劳动关系中的资源依赖格局,会影响行为主体在劳动法律干预下的行为选择与演化,从而影响劳动法律文本的行动结果。社会关系及其在法律干预下的发展规律,是法律调节社会关系的客观现实和经验基础。要有效地实现法律在国家治理中的重要职能,亟需进一步推进经验层面的实证研究。 相似文献
128.
论文从S&P 500指数期权数据中提取出波动率偏斜与风险中性偏度指标, 采用Logistic模型研究了波动率偏斜/风险中性偏度是否对未来真实的市场尾部风险具有预测力。结果发现, 波动率偏斜/风险中性偏度仅含有未来市场尾部风险的一定信息, 但并不能准确预测未来市场尾部风险发生的状态。相反, 波动率偏斜/风险中性偏度与投资者情绪指标显著相关。 相似文献
129.
We consider a class of long-range-dependent Gaussian processes defined in a semiparametric framework. We propose a new estimator of the long-range dependence parameter, based on the integration of the periodogram in two windows. We show that it is asymptotically Gaussian and calculate the rate of convergence. We optimise parameters defining the window function for the minimum mean-square-error criterion. In a Monte-Carlo study, we compare the proposed estimator with previously studied estimators. 相似文献
130.
Vadim Teverovsky Murad S. Taqqu Walter Willinger 《Journal of statistical planning and inference》1999,80(1-2):211-227
We report on an empirical investigation of the modified rescaled adjusted range or R/S statistic that was proposed by Lo, 1991. Econometrica 59, 1279–1313, as a test for long-range dependence with good robustness properties under ‘extra’ short-range dependence. In contrast to the classical R/S statistic that uses the standard deviation S to normalize the rescaled range R, Lo's modified R/S-statistic Vq is normalized by a modified standard deviation Sq which takes into account the covariances of the first q lags, so as to discount the influence of the short-range dependence structure that might be present in the data. Depending on the value of the resulting test-statistic Vq, the null hypothesis of no long-range dependence is either rejected or accepted. By performing Monte-Carlo simulations with ‘truly’ long-range- and short-range dependent time series, we study the behavior of Vq, as a function of q, and uncover a number of serious drawbacks to using Lo's method in practice. For example, we show that as the truncation lag q increases, the test statistic Vq has a strong bias toward accepting the null hypothesis (i.e., no long-range dependence), even in ideal situations of ‘purely’ long-range dependent data. 相似文献