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51.
This paper examines local influence assessment in generalized autoregressive conditional heteroscesdasticity models with Gaussian and Student-t errors, where influence is examined via the likelihood displacement. The analysis of local influence is discussed under three perturbation schemes: data perturbation, innovative model perturbation and additive model perturbation. For each case, expressions for slope and curvature diagnostics are derived. Monte Carlo experiments are presented to determine the threshold values for locating influential observations. The empirical study of daily returns of the New York Stock Exchange composite index shows that local influence analysis is a useful technique for detecting influential observations; most of the observations detected as influential are associated with historical shocks in the market. Finally, based on this empirical study and the analysis of simulated data, some advice is given on how to use the discussed methodology.  相似文献   
52.
When we are given only a transform such as the moment-generating function of a distribution, it is rare that we can efficiently simulate random variables. Possible approaches such as the inverse transform using numerical inversion of the transform are computationally very expensive. However, the saddlepoint approximation is known to be exact for the Normal, Gamma, and inverse Gaussian distribution and remarkably accurate for a large number of others. We explore the efficient use of the saddlepoint approximation for simulating distributions and provide three examples of the accuracy of these simulations.  相似文献   
53.
Abstract. In this study we are concerned with inference on the correlation parameter ρ of two Brownian motions, when only high‐frequency observations from two one‐dimensional continuous Itô semimartingales, driven by these particular Brownian motions, are available. Estimators for ρ are constructed in two situations: either when both components are observed (at the same time), or when only one component is observed and the other one represents its volatility process and thus has to be estimated from the data as well. In the first case it is shown that our estimator has the same asymptotic behaviour as the standard one for i.i.d. normal observations, whereas a feasible estimator can still be defined in the second framework, but with a slower rate of convergence.  相似文献   
54.
Zero inflation means that the proportion of 0's of a model is greater than the proportion of 0's of the corresponding Poisson model, which is a common phenomenon in count data. To model the zero-inflated characteristic of time series of counts, we propose zero-inflated Poisson and negative binomial INGARCH models, which are useful and flexible generalizations of the Poisson and negative binomial INGARCH models, respectively. The stationarity conditions and the autocorrelation function are given. Based on the EM algorithm, the estimating procedure is simple and easy to be implemented. A simulation study shows that the estimation method is accurate and reliable as long as the sample size is reasonably large. A real data example leads to superior performance of the proposed models compared with other competitive models in the literature.  相似文献   
55.
This paper documents situations where the variance inflation model for outliers has undesirable properties. The model is commonly used to accommodate outliers in a Bayesian analysis of regression and time series models. The alternative approach provided here does not suffer from these undesirable properties but gives inferences similar to those of the variance inflation model when this is appropriate. It can be used with regression, time series, and regression with correlated errors in a unified way, and adheres to the scientific principle that inference should be based on the data after obvious outliers have been discarded. Only one parameter is required for outliers; it is interpretable as the a priori willingness to remove observations from the analysis.  相似文献   
56.
由于金融市场间价格波动溢出效应具有时变性和动态性的特点,采用双变量BEKK模型研究了国内外农产品期货市场间时变波动溢出关系,得出结论:农产品期货的波动均显著地受到自身前期波动的影响,波动具有聚集性和持久性;美国玉米期货与中国玉米期货不存在波动溢出效应,但是美国大豆期货与中国大豆期货、美国豆粕期货与中国豆粕期货之间均存在双向的波动溢出效应。因此,中国大豆期货和豆粕期货在世界农产品期货市场上具有一定的权力,即定价权。  相似文献   
57.
利用修正的GARCH-M模型,检验了中国2005 - 2010年期间人民币-美元汇率和人民币-欧元汇率收益率及波动的周内效应.研究发现,人民币-美元汇率在周二和周四具有显著升值特征,而人民币-欧元汇率在周四则更容易贬值并同时存在波动性的周二效应,仅在人民币-美元汇率收益率与波动之间呈现显著风险与收益的负向关系,反映出风险越高则人民币-美元汇率越容易升值,这可能是由于汇率市场中投资者的自适应预期所导致.  相似文献   
58.
自2006年以来,我国的资产泡沫严重,研究发现资产价格上涨预期是诱发短期国际资本流动冲击的一个重要因素,严重时会产生金融市场危机风险。基于这样的背景,通过引入资产价格波动变量,修正了Flood引入随机风险溢价的KFG理论模型,分析中国短期国际资本流动触发机制,探究资产价格波动对短期国际资本流动的作用机制。并以此为基础分析中国现有宏观政策对短期国际资本流动风险的作用和政策效果,提出减少投机性国际短期资本流动合理化的政策建议。  相似文献   
59.
世纪之交 ,通货紧缩的现实 ,对通货膨胀提出了挑战 ;通货紧缩就是指价格水平的持续下降 ;由于高新科技的迅猛发展对价格水平运动具有两重作用 ,高新科技的迅猛发展并不必然导致劳动生产率的提高和价格水平的降低 ,甚至出现“劳动生产率悖论” ,成为促使价格水平上涨的一个动因 ,所以“技术型通货紧缩”否定不了通货膨胀 ;当前世界各国对付通货紧缩措施的实质都是通货膨胀的政策 ;从对 2 1世纪通货紧缩的展望来看 ,通货紧缩也不否定通货膨胀 ,通货膨胀远未投降 ,它只是披上了新的更加危险的外衣。从全球的经济现实来看 ,促使通货膨胀和价格水平上涨的的结构性因素及微观内生机制依然存在 ,通货膨胀并没有“寿终正寝” ,世纪性的物价上涨并未结束 ,通货膨胀依然是新世纪经济学的主要“敌人” ,人类驾驭和对付通货膨胀的道路仍很漫长。  相似文献   
60.
已实现波动是针对高频金融时间序列的一种全新的波动度量方法,具有不需要模型和计算方便的优点。赋权已实现波动则对已实现波动进行了改进,是另一种更为有效的波动度量方法。本文从定义形式、无偏性、有效性、日历效应等方面对已实现波动和赋权已实现波动加以比较。通过对上海股票市场的实证研究,说明了赋权已实现波动是优于已实现波动的波动估计量。  相似文献   
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