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1.
中国农药施用与农业经济增长脱钩状态:时空特征与影响因素 总被引:1,自引:0,他引:1
[目的]明确农药施用与农业经济增长关联状态及其影响因素,为实现"控药减害增收"的目标提供借鉴。[方法]基于2005—2015年数据利用脱钩理论和对数平均分解指数法分解进行分析。[结果]中国农业经济增长伴生大量农药施用,仅少数省域表现出农药施用和农业经济增长扩张绝对脱钩的理想状态,东北西北部分省域农业经济增长则以更大幅度的农药投入增长为代价。中西部地区劳动力规模和技术进步效应是推动农药施用与农业经济增长脱钩的因素;东部地区种植规模变化、劳动力规模和技术进步因素均是推动农药施用和农业经济增长脱钩的因素;东北地区仅劳动力规模效应成为推动脱钩的力量。[结论]推动农药施用与农业经济增长脱钩需要强化农业科技的创新与普及,完善农业生产过程中的技术支撑,推动农业病虫害监测预警,加大对环境友好型低污染农药和肥料的推广度;构建农户施药的多重约束机制,完善农业病虫灾害保险减少农户对生产过程的风险感知,发挥农业合作社对农户施药行为的规制作用,完善产品分级认证和安全准入制度;通过农地合理流转和农业机械化等方式集约利用农业生产资源;因地制宜推动农药施用与农业经济增长脱钩,结合区域资源优势和农业发展阶段有针对性地设计对策措施。 相似文献
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《Socio》2018
The aim of the paper is to identify which among the aspects that relate to the composition of the student body, school (district) size, management practices and the school principals' own characteristics are associated with the performance of Italian students at grade 8, measured through standardised test scores in reading and mathematics. The analysis makes use of a student-level efficiency model, and several school level variables are included as explanators for efficiency scores. The results show that, especially for reading, the most influential variables relate to the composition of the student body, while the students' performance in mathematics is partly correlated with the management practices adopted by the school principal/head teacher. Schools and schooling can only explain a minor part of the variance in achievement scores, however, and the characteristics of the students themselves play the most significant role. 相似文献
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The paper investigates the relationship between fund performance and fund characteristics of North American private equity (PE) funds, by analyzing the interactions of fund size, fund sequence, and past fund performance on traditional fund return measures. The empirical evidence is based on both linear and polynomial regressions, on a sample of 345 venture capital (VC) and 411 buyout (BO) funds with vintage year over the period 1995–2010. We document a concave relationship between fund size and performance, persistence in PE performance, as well as a convex relationship between fund sequence and performance. We suggest both the optimal fund size and the optimal fund sequence number. Economic implications for investors and general partners are discussed as well. 相似文献
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Mintak Han 《The Service Industries Journal》2019,39(5-6):361-384
Among many techniques for generating new service ideas, morphological analysis has been used due to the advantage of decomposing the system into dimensions and shapes and bringing creative results in the process of recombining them. However, with the rise of smart service systems, the determination of dimensions and shapes has become a critical problem, particularly as both their structure and components become complex. This research focuses on a data-driven approach by incorporating mobile app service documents to increase objectivity and diversity in the construction of a morphology matrix. To this end, firstly, the novelty-quality map is developed to identify innovative data based on quantitative indicators. Secondly, morphological analysis is employed along with experts’ judgment in order to generate new smart service concepts. Finally, the feasibility and effectiveness of the proposed approach are shown based on a comparative analysis with conventional approaches and real services through a case study of smart home. 相似文献
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Using the data in Chinese stock market, we measure the individual stock sentiment beta, which is defined as the sensitivity of individual stock returns to the individual stock sentiment changes. We demonstrate that stocks in the highest individual stock sentiment beta portfolio have significantly higher excess returns, CAPM alpha, Fama-French three-factor alpha and Fama-French five-factor alpha. Besides, we find that the high individual stock sentiment beta stocks are smaller, younger, more volatile stocks with higher price and higher market beta. After controlling for firm characteristic, the returns of High-Low individual stock sentiment beta portfolios are still significantly positive. Moreover, we show the effect of the individual stock sentiment beta on stock returns is positive and significant in different stock markets, in different sample periods, and in bull and bear market. Besides, the results of the Bayes-Stein individual stock sentiment beta are still stable. 相似文献
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为了更好地将人眼视觉感知特性应用于视频压缩系统,从而去除视频的视觉冗余成分,在利用像素域的恰可察失真(Just Noticeable Distortion,JND)阈值的基础上,结合JND阈值的空间相关性与图像块类型,提出了一种改进的残差滤波算法。该算法首先在像素域计算出每个像素的JND阈值,然后在变换单元(Transform Unit,TU)中挖掘每个像素JND阈值与其周围邻近像素JND阈值之间的空间相关性,再利用索贝儿(Sobel)边缘检测算子将TU分成不同类型的图像块,并且计算出对应的复杂度因子,最后结合上述像素JND阈值的空间相关性和TU复杂度因子对TU残差进行滤波。提出的算法模型可以嵌入到高效率视频编码(High Efficiency Video Coding,HEVC)框架。实验结果表明,在全I帧配置下,提出的算法与标准算法HM16.0相比,在人眼主观感知质量基本一致的情况下,平均可节省16.1%的码率。 相似文献
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作为推动国民经济增长和促进社会稳定的基础力量,中小企业在市场中扮演着最活跃的经济主体。与大企业相比,中小企业有其鲜明的成长特征,从动态演进视角选取体量规模、生命周期、要素需求三个维度,系统探讨了中小企业的差异化特征。结论显示:体量规模特征反映在个体与群体以及经济板块之间;生命周期特征体现在死亡陷阱和空间格局演变上;要素需求特征会根据阶段创新内容的不同做出适时调整。 相似文献