全文获取类型
收费全文 | 4462篇 |
免费 | 377篇 |
国内免费 | 55篇 |
专业分类
财政金融 | 306篇 |
工业经济 | 164篇 |
计划管理 | 904篇 |
经济学 | 1222篇 |
综合类 | 248篇 |
运输经济 | 40篇 |
旅游经济 | 111篇 |
贸易经济 | 540篇 |
农业经济 | 940篇 |
经济概况 | 419篇 |
出版年
2024年 | 56篇 |
2023年 | 157篇 |
2022年 | 183篇 |
2021年 | 208篇 |
2020年 | 298篇 |
2019年 | 245篇 |
2018年 | 184篇 |
2017年 | 236篇 |
2016年 | 195篇 |
2015年 | 202篇 |
2014年 | 244篇 |
2013年 | 386篇 |
2012年 | 322篇 |
2011年 | 316篇 |
2010年 | 227篇 |
2009年 | 183篇 |
2008年 | 212篇 |
2007年 | 205篇 |
2006年 | 171篇 |
2005年 | 149篇 |
2004年 | 102篇 |
2003年 | 74篇 |
2002年 | 66篇 |
2001年 | 42篇 |
2000年 | 40篇 |
1999年 | 24篇 |
1998年 | 29篇 |
1997年 | 34篇 |
1996年 | 17篇 |
1995年 | 17篇 |
1994年 | 9篇 |
1993年 | 11篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 2篇 |
排序方式: 共有4894条查询结果,搜索用时 328 毫秒
101.
This is a review article that unifies several important examples using constrained optimisation techniques. The basic tools are three simple mathematical optimisation results subject to certain constraints. Applications include calibration, benchmarking in small area estimation and imputation. A final illustration is constrained optimisation under a general divergence loss. 相似文献
102.
重叠滤波多音(O-FMT)是针对滤波多音(FMT)系统频谱利用率低的缺点而根据超奈奎斯特(FTN)概念引入子载波重叠得到的方案。鉴于O-FMT系统在频偏环境下的性能缺陷,理论分析了频偏对系统信号各部分的影响,比较了O-FMT与正交频分复用(OFDM)系统的抗频偏性能。针对频偏性能优化问题,提出了基于最佳线性无偏估计(BLUE)的改进盲估计算法,设计了基于频域滤波器系数的内嵌结构进行频偏补偿。仿真实验表明,O-FMT相比OFDM具有更好的抗频偏能力,改进的盲估计算法估计值精度更高,抗干扰、抗衰落能力更强,设计的频偏补偿结构可以使系统获得更好的性能。 相似文献
103.
针对某老式卫星返回时雷达跟踪数据曾发生的测量异常及质量较差等情况,为解决此类数据在返回弹道及落点计算中出现的实际困难以及给出应对措施,基于工程实际情况给出了三种不同建模类型下的弹道计算方法——当前统计解耦扩展卡尔曼滤波(EKF)、动力学建模无迹卡尔曼滤波(UKF)、多项式滑窗最小二乘估计算法,并应用该次质量较差的实际观测数据进行了算法应用效果分析与落点计算情况对比,对计算中的经验及教训进行了总结。研究结果表明,所给出的三种算法在面对较差质量数据时性能差异较大,在工程实际应用中可考虑将多种算法互为参考。研究结果及其经验教训对卫星返回弹道及落点的实时估计的工程实施有一定的参考价值。 相似文献
105.
IAN DEW‐BECKER 《Journal of Money, Credit and Banking》2014,46(5):837-888
New Keynesian model in which households have Epstein–Zin preferences with time‐varying risk aversion and the central bank has a time‐varying inflation target can match the dynamics of nominal bond prices in the U.S. economy well. The model generates a large steady‐state term spread and its fitting errors for bond yields are comparable to those obtained from a nonstructural three‐factor model, and one‐third smaller than in models with a constant inflation target or risk aversion. Including data on interest rates has large effects on variance decompositions, making investment technology shocks much less important than found in other recent papers. 相似文献
106.
Hind El Makrini 《Journal of Strategic Marketing》2017,25(7):530-546
Purpose: To help increase understanding of the export performance, we investigate the influence of firm size, research and development (R&D), advertising expenditures and network relationships, and develop a conceptual model to increase export intensity. Design/methodology/approach: The research involved a four-year longitudinal study of export performance of 168 exporting SMEs in Morocco (672 observations). The two-stage least square estimation (G2SLS) was used to test the hypotheses. Findings: The findings of the two-stage least square estimation (G2SLS) suggest that export sales and domestic sales are interdependent and influence each other. R&D expenditures and network affiliation have positive and significant impact on export sales, while advertising expenditure has a negative and significant influence on export sales. Research limitations/implications: Readers should use caution in generalizing the findings unless verified in other developing contexts. Practical implications: The findings of this study are useful for managers and export policy makers in developing countries. A proper understanding of the predictors of export performance may help them encourage the growth and diversification of exports that is so vital for developing countries. Originality/value: Export performance is a key element in the field of international marketing. Unfortunately, the literature exhibits a lack of empirical studies in developing countries, particularly in Maghreb regions. The empirical testing of the theoretical model in a developing economy is a significant contribution to fill the needed gap in the literature toward generalizing findings. 相似文献
107.
108.
To identify the relevant product markets for Swedish pharmaceuticals, a spatial econometrics approach is employed. First, we calculate Moran's Is for different market definitions and then we use a spatial Durbin model to determine the effect of price changes on quantity sold of own and competing products. As expected, the results show that competition is strongest between close substitutes; however, the relevant product markets for Swedish pharmaceuticals extend beyond close substitutes down to products included in the same class on the four‐digit level of the Anatomic Therapeutic Chemical system as defined by the World Health Organization. The spatial regression model further indicates that increases in the price of a product significantly lower quantity sold of that product and in the same time increase the quantity sold of competing products. For close substitutes (products belonging to the same class on the seven‐digit level of the Anatomic Therapeutic Chemical system), as well as for products that, without being close substitutes, belong to the same therapeutic/pharmacological/chemical subgroup (the same class on the five‐digit level of the Anatomic Therapeutic Chemical system), increased competition is also visible after 1 July 2009 when the latest policy changes with regards to pharmaceuticals have been implemented in Sweden. 相似文献
109.
Bahadır Yüzbaşı Mohammad Arashi S. Ejaz Ahmed 《Revue internationale de statistique》2020,88(1):229-251
In this study, we suggest pretest and shrinkage methods based on the generalised ridge regression estimation that is suitable for both multicollinear and high-dimensional problems. We review and develop theoretical results for some of the shrinkage estimators. The relative performance of the shrinkage estimators to some penalty methods is compared and assessed by both simulation and real-data analysis. We show that the suggested methods can be accounted as good competitors to regularisation techniques, by means of a mean squared error of estimation and prediction error. A thorough comparison of pretest and shrinkage estimators based on the maximum likelihood method to the penalty methods. In this paper, we extend the comparison outlined in his work using the least squares method for the generalised ridge regression. 相似文献
110.
《Review of Income and Wealth》2018,64(3):703-730
This paper contributes to the growing literature on spatial prices in large heterogeneous countries. While the literatures on spatial variation and temporal movement in prices have grown in parallel, this study marks a departure by providing a unified treatment and proposing a comprehensive framework that allows both approaches. The proposed model is based on twin extensions of the household version of the “country product dummy model” by allowing for a dynamic stochastic specification and interdependence of spatial prices of geographically adjacent regions. Tests of temporal stability and regional independence of the estimated spatial prices are proposed and applied in this paper. The paper shows that the introduction of an autoregressive error process of order one, AR(1), improves the efficiency of the estimates of parameters, urban‐rural and temporal price indices under certain conditions. The Indian application points to a rich potential for using the proposed framework in cross country comparisons such as the International Comparison Program (ICP) exercises. 相似文献