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D. R. Towill M. R. Lambrecht S. M. Disney J. Dejonckheere 《Journal of Purchasing & Supply Management》2003,9(2):73
Due to the complexity of present day supply chains it is important to select the simplest supply chain scheduling decision support system (DSS) which will determine and place orders satisfactorily. We propose to use a generic design framework, termed the explicit filter methodology, to achieve this objective. In doing so we compare the explicit filter approach to the implicit filter approach utilised in previous OR research the latter focusing on minimising a cost function. Although the eventual results may well be similar with both approaches it is much clearer to the designer, both why and how, an ordering system will reduce the Bullwhip effect via the explicit filter approach. The “explicit filter” approach produces a range of DSS designs corresponding to best practice. These may be “mixed and matched” to generate a number of competitive delivery pipelines to suit the specific business scenario. 相似文献
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曝气生物滤池及其填料作用机理 总被引:1,自引:0,他引:1
介绍了曝气生物滤池及其填料的应用情况和研究进展,对曝气生物滤池反应动力学以及其填料作用机理等方面的研究进展进行了研究,概述了影响曝气生物滤池运行的主要因素,同时提出了今后曝气生物滤池的发展方向。 相似文献
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It is generally acknowledged that the growth rate of output, the seasonal pattern, and the business cycle are best estimated
simultaneously. To achieve this, we develop an unobserved component time series model for seasonally unadjusted US GDP. Our
model incorporates a Markov switching regime to produce periods of expansion and recession, both of which are characterized
by different underlying growth rates. Although both growth rates are time-varying, they are assumed to be cointegrated. The
analysis is Bayesian, which fully accounts for all sources of uncertainty. Comparison with results from a similar model for
seasonally adjusted data indicates that the seasonal adjustment of the data significantly alters several aspects of the full
model.
First Version Received: January 2001/Final Version Received: February 2002
Send offprint requests to: Rob Luginbuhl?Correspondence to: Rob Luginbuhl 相似文献
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A Closer Look at the Relation between GARCH and Stochastic Autoregressive Volatility 总被引:1,自引:0,他引:1
We show that, for three common SARV models, fitting a minimummean square linear filter is equivalent to fitting a GARCH model.This suggests that GARCH models may be useful for filtering,forecasting, and parameter estimation in stochastic volatilitysettings. To investigate, we use simulations to evaluate howthe three SARV models and their associated GARCH filters performunder controlled conditions and then we use daily currency andequity index returns to evaluate how the models perform in arisk management application. Although the GARCH models produceless precise forecasts than the SARV models in the simulations,it is not clear that the performance differences are large enoughto be economically meaningful. Consistent with this view, wefind that the GARCH and SARV models perform comparably in testsof conditional value-at-risk estimates using the actual data. 相似文献
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The construction of an importance density for partially non‐Gaussian state space models is crucial when simulation methods are used for likelihood evaluation, signal extraction, and forecasting. The method of efficient importance sampling is successful in this respect, but we show that it can be implemented in a computationally more efficient manner using standard Kalman filter and smoothing methods. Efficient importance sampling is generally applicable for a wide range of models, but it is typically a custom‐built procedure. For the class of partially non‐Gaussian state space models, we present a general method for efficient importance sampling. Our novel method makes the efficient importance sampling methodology more accessible because it does not require the computation of a (possibly) complicated density kernel that needs to be tracked for each time period. The new method is illustrated for a stochastic volatility model with a Student's t distribution. 相似文献
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在辛体系下利用精细积分对矩形波导纵向排列介质层PBG结构进行了分析,并对滤波器进行了优化设计.采用棱单元对波导的横截面进行离散,然后导向哈密顿体系,运用基于黎卡提微分方程的精细积分求出一段介质层和一段空气层的出口刚度阵,再利用区段合并以对问题求解.在此基础上采用序列线性规划法对模型进行求解,得到了滤波性能最优的设计参数.算例表明本文方法具有精确、高效的优点. 相似文献
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基于改进遗传量子算法的FIR数字滤波器设计 总被引:2,自引:0,他引:2
网上证券交易在各国已经得到广泛应用。由网上证券交易引起的变革对传统的交易方式、交易制度产生不可估量的影响力,直接冲击着证券市场、投资者和券商。本文试图从证券市场和券商的角度来分析网上证券交易给它们带来的影响,从而从更深层次上理解网上证券交易的意义,更好地使用它。 相似文献