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介绍了积石峡水电站水位及拦污栅压差测量系统的整体组态方案;论述了集中监测单元,上游及下游数据采集装置的结构特点;给出了现地信息监控策略,码盘SSI通讯特点及双冗余设计方案;提出了系统软件功能模块设计策略。 相似文献
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山东省农业机械管理办公室 《农业装备与车辆工程》2001,(4):3-5
此文介绍了"九五”期间农业机械化发展的基本情况及我省农业机械化发展面临的新形势,指出制定"十五”计划及2015年规划的指导思想. 相似文献
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对建筑消防负荷供配电系统的要求和工程实践进行归纳总结,主要论述了不同建筑的分类及其相应的负荷分级和供电系统方案;变压器、开关室的布置及消防设施要求;消防负荷配电系统要求及典型方案;不同消防设备的配电线路布置及典型方案;消防配电线路的保护配置;消防电缆的选型、爆炸场所敷设布置位置、不同耐火性能的电缆敷设保护及电缆孔洞防火封堵.对消防负荷供配电系统的相关规程要求进行了系统的总结说明. 相似文献
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废膜收获机的研究现状和发展趋势 总被引:9,自引:1,他引:9
阐述了膜覆盖种植技术在全国的使用情况及残膜污染产生各种危害的现状;介绍了废膜污染的各种原因和国内外残膜回收机的研究现状及发展趋势;分析了国内外各种残膜回收机存在的问题及应用情况;并就其发展进行了展望。 相似文献
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介绍了色素辣椒播前品种选择、种子处理、施肥及整地的要求;播种机具的选择、改装及播种方法;田间管理的要点及技术要求。 相似文献
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介绍了4TW-Q型全幅玉米联合收获机主要技术参数、结构原理及特点;总结分析了该机使用的经济效益及社会效益;对该机提出改进建议。 相似文献
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水环境容量价值及其影响因素研究 总被引:1,自引:0,他引:1
为了解决水环境与人类社会经济协调发展的问题,阐述了水环境容量价值的内涵、研究内容与影响因素,认为水环境容量价值主要由天然价值、人工价值和稀缺价值组成,受水环境质量标准、水域特性、流域(区域)水资源量、社会生产力水平、科学技术水平、人类生活水平及人口规模、政策、法规、规划等因素影响,并指出了水环境容量价值的重点研究方向。 相似文献
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Albert N. Halter Stanley F. Miller Richard de Jongh Estrada R. Hugo 《Agricultural Systems》1976,1(2):139-162
This paper shows how systems-simulation can be applied to answer agricultural development type questions. A computer simulation model of the Venezuelan cattle industry is presented, some of the validation efforts are discussed, and results from a number of computer runs are shown in order to illustrate how alternative programmes might affect the transition of the traditional cattle population to a more modern and productive population. Different programmes are shown to accomplish some objectives better than others. No optimisation over all possible development objectives was attempted, as this would depend upon the relative weights attached to the objectives by the decision-makers.It has been the authors' experience that modelling of biological and economic processes provides an important link between observations about the real world (raw data) and decision-makers in an information system designed to provide useful information. The building and operation of the computer model of the Venezuelan cattle population illustrates how a systems-simulation approach can be used in policy formulation. 相似文献
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探究农村人口老龄化对农业全要素生产率的影响作用机理,对当前我国加快推进农业现代化以及积极有效应对人口老龄化具有一定的现实启发作用。基于我国2004—2019年的省级面板数据,借助Malmquist指数法对全国30个省市的农业全要素生产率进行测算,通过中介效应模型,从劳动力供给数量效应、劳动力供给质量效应、技术经验累积效应、技术更新效应以及资本投入效应五个方面,探究农村人口老龄化对农业全要素生产率的影响机理。最后,以东北和西南地区为例,进一步分析该作用机理的地区差异性。可以发现:现阶段,农村人口老龄化对农业全要素生产率的抑制作用要强于促进作用。从全国层面来看,农村人口老龄化通过劳动力供给数量、质量以及资本投入三个方面对农业全要素生产率产生抑制作用,通过技术经验累积以及技术更新对农业全要素生产率产生促进作用。但是根据分区域研究的结果可知,这一检验结果与东北、西南地区的并不完全一致,因此在制定相应的政策时,要因地制宜,通盘考虑各个地区之间的差异性。 相似文献
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草原牧区可持续发展在甘肃国民经济中占有重要地位。本文认为,甘肃草原牧区仍然存在生态脆弱、环境压力增大,区域性贫困突出、自我发展能力弱小,人地关系紧张、可持续发展的良性互动机制尚未形成,社会化服务网络不健全、基地建设经营管理水平低下等诸多问题和难点制约。尽快彻底破解以上难题,必然成为未来较长时期内甘肃草原牧区可持续发展的重要选择。 相似文献
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先锋植物沙棘Ⅱ--克隆行为和根系特化是实现沙棘先锋作用的又一根本因素 总被引:3,自引:3,他引:0
沙棘是根源性根出条型克隆植物,它有克隆习性和克隆行为,它具有有性和无性2种繁殖方式。在田间沙棘林内,株间、片断、斑块间,存在着种群遗传上的多样性。沙棘侧根的特化结构组成了天然生物蓄水库,缓解了在干旱条件下对水分需求的矛盾。因此,作为一种双重生态型植物,解决了肥(N2)、水2个重要的生命及生态因子,是实现先锋植物功能的重要原因。 相似文献
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Greenhouse gas emissions from the Canadian beef industry 总被引:1,自引:0,他引:1
Commodity-specific estimates of the greenhouse gas (GHG) emissions from Canadian agriculture are required in order to identify the most efficient GHG mitigation measures. In this paper, the methodology from the Intergovernmental Panel on Climate Change (IPCC) for estimating bovine GHG emissions, for census years from 1981 to 2001, was applied to the Canadian beef industry. This analysis, which is based on several adaptations of IPCC methodology already done for the Canadian dairy industry, includes the concept of a beef crop complex, the land base that feeds the beef population, and the use of recommendations for livestock feed rations and fertilizer application rates to down-scale the national area totals of each crop, regardless of the use of that crop, to the feed requirements of the Canada’s beef population. It shows how high energy feeds are reducing enteric methane emissions by displacing high roughage diets. It also calculates an emissions intensity indicator based on the total weight of live beef cattle destined for market. While total GHG from Canadian beef production have increased from 25 to 32 Tg of CO2 equiv. between 1981 and 2001, this increase was mainly driven by expansion of the Canadian cattle industry. The emission intensity indicator showed that between 1981 and 2001, the Canadian beef industry GHG emissions per kg of live animal weight produced for market decreased from 16.4 to 10.4 kg of CO2 equiv. 相似文献
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Erna Lpez Gerardo Bocco Manuel Mendoza Alejandro Velzquez J. Rogelio Aguirre-Rivera 《Agricultural Systems》2006,90(1-3):62-78
Demographic changes introduced by migration strongly affect economic activities and may thus trigger land-use changes. Migration has been usually overlooked in land use change modelling, even though it is recognized as a dominant demographic factor that influences land use. This paper analyzes to what extent migration patterns influence land-cover and land-use change at the watershed level. A RS-GIS and statistical approach was used to quantify and analyze both land-cover change and change in population per spatial unit. It was hypothesized that migration should exert a strong effect on land-cover change. The exercise was carried out in the Basin of Lake Cuitzeo, Michoacan, in Central Mexico, an area of high emigration to the USA, albeit showing a net increase in its total population. The expansion of scrubland areas at the expense of rain-fed agricultural land is associated with the abandonment of agricultural land with poor soils. As a consequence, vegetal succession has been promoted and subtropical scrubland increased. 相似文献
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