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水资源是关系农村社会经济发展、农民增收的重要因素。本文从协调政府与农民关于增效与增收的目标出发,以2017年中国环渤海设施蔬菜主产地蔬菜专业村357个蔬菜种植户调研数据为例,运用联立方程组模型及条件混合过程（CMP）、倾向得分匹配方法（PSM）与工具变量分位数（IVQR）方法,对滴灌技术推广的约束因素与增效增收能力进行分析,探索促进中国农业可持续发展的路径。研究结果表明：①水资源稀缺程度较高的蔬菜主产地,种植年限较短,但家庭资本充裕且对节水知识了解程度越高的蔬菜种植户更倾向于采用滴灌技术;②滴灌技术具有明显的增效增收作用,蔬菜种植户采用滴灌技术后,每吨灌溉水产出可增加17.16 kg蔬菜,增收45.90 元,具有推广的长效动力;③滴灌技术的产出与经济效应存在“马太效应”,对于生产条件好的农户而言,滴灌技术的产出与经济效应更加明显;④技术供给层面的灌溉制度设计不健全、设备工程设计与质量较差、培训与售后服务不足,农户技术应用层面的专业知识与技术缺乏、与现代农业对接能力弱,以及政府层面的补贴不够科学、到位是影响农户滴灌技术采用积极性的重要因素,需要加以注意,此外,灌溉水价的适当提高,将有助于加快田间节水技术的推广。 相似文献
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CMP JDO Hibernate的比较 总被引：2，自引：0，他引：2
袁兆英 《淮南师范学院学报》2006,8(3):33-34
文章是对java领域中影响较大的三种O/RMapping技术进行了比较,并通过实际的性能测试,通过直观,有说服力的数据来对三者进行比较。 相似文献
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Based on the remote sensing （RS） and geographic information system （GIS） analysis of the Landsat multispectral scanner （MSS） and thematic mapper （TM） satellite images of 1983, 1993, and 2005, the present research examined the effectiveness of the urban construction boundaries （UCBs） in containing urban growth within the 6th Ring Road of Beijing Municipality. Three indicators on boundary control were proposed, through which the effectiveness of boundary containment, land inventory sufficiency and illegal adjacent development to the UCBs were explored. The results suggested that, first, the UCBs were limited in effectiveness in containing urban growth; second, the area encompassed by the UCBs might not be designed large enough to accommodate new development. The frustration of the urban growth control through the UCBs mainly resulted from the lack of a transparent system for urban land use planning and control to provide sufficient information, the limitation of the traditional land use prediction method to consider contingencies, and the absence of a mechanism to monitor and adjust the UCBs to respond just in time to urban change. 相似文献
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采用比较指令和一个定时器实现交通灯控制,与采用顺序控制指令和多个定时器实现交通灯控制相比,设计程序简单且直观清晰． 相似文献
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Wei XK Ding QB Zhang L Guo YL Ou L Wang CL 《Journal of Zhejiang University. Science. B》2008,9(7):520-526
Nucleoside phosphorylases (NPases) were found to be induced in Enterobacter aerogenes DGO-04, and cytidine and cytidine 5'-monophosphate (CMP) were the best inducers. Five mmol/L to fifteen mmol/L cytidine or CMP could distinctly increase the activities of purine nucleoside phosphorylase (PNPase), uridine phosphorylase (UPase) and thymidine phosphorylase (TPase) when they were added into medium from 0 to 8 h. In the process of enzymatic synthesis of adenine arabinoside from adenine and uracil arabinoside with wet cells ofEnterobacter aerogenes DCJO-04 induced by cytidine or CMP, the reaction time could be shortened from 36 to 6 h. After enzymatic reaction the activity of NPase in the cells induced remained higher than that in the cells uninduced. 相似文献
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农地规模经营是实现现代农业的主要路径之一,探究劳动力老龄化与家庭农地转出决策,对促进小农户与现代农业的有机衔接有着重要意义。基于改进的家庭生命周期模型和中国家庭金融调查数据,从家庭层面实证检验了家庭劳动力老龄化对农地流转的影响及其家庭结构的异质性。结果发现：①中国现在还存有近1/3的农村家庭有老年人参与劳动,随着老龄化人口占比越来越高,以老年人为农业生产主体的小农户未来也可能长期存在;②劳动力老龄化对农地转出决策具有抑制作用。相比其他家庭类型,有老年劳动力的家庭转出农地的可能性降低了约5%;③不同家庭内部结构下,劳动力老龄化对家庭农地转出决策的抑制作用存在差异,抑制作用大小表现为负担期Ⅰ>赡养期Ⅰ>空巢期Ⅰ。本文认为,对于高龄的老年劳动力,需进一步建立健全农村社会保障制度,促进这部分农户通过以转代耕的方式把农地转出至农业生产效率更高的经营主体;对于低龄的老年劳动力,需配合较为完善的农业社会化服务以实现提升农业生产效率与农地养老的双重目标。 相似文献
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