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都市农业生态可持续发展评价体系研究 总被引：1，自引：0，他引：1
本研究构建都市农业生态可持续发展评价体系,形成涵盖农业资源集约程度、农业废弃物综合利用率、以及农业节能降耗水平等3个维度的一级指标,筛选出农药施用强度、化肥施用强度、种植业废弃物综合利用率、畜禽养殖废弃物综合利用率、以及单位能耗创造的农林牧渔增加值等5项二级指标。基于评价模型,本研究运用极值法和离差法测算了2016年35个大中城市都市农业生态可持续发展的综合评价指数,并对各城市的分类评价情况加以比较,对都市农业实现绿色发展提出四项政策建议。研究结果表明:(1)大中城市粮食与蔬菜年秸秆量与畜禽粪便年排放量均占全国比重10%左右;(2)大中城市秸杆综合利用率、畜禽养殖粪污资源化利用率分别比全国平均水平高3.83%和16.16%;(3)我国2016年都市农业生态可持续综合指数为52,贵阳、西安、哈尔滨名列前茅,而上海、北京等城市排名较低;(4)大中城市农业废弃物综合利用率总体较高,但农业资源集约度不高,特别是化肥施用量强度约为全国平均水平的两倍,且西宁、长春和银川等城市的农业节能降耗水平尚需提升。 相似文献
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以广东梅县农业系统为研究对象,以种植业与畜牧业之间的资源综合利用为核心约束,构建农业结构优化模型、购买能值节约估算模型、货币能值增益估算模型,对农业系统资源综合利用效果进行能值评价。结果表明：2004—2008年,种养间资源综合利用能明显改变梅县的农业结构,年均货币能值增加(2.15E+21)sej,年均能值交换率从2.57增为4.42,年均环境负载率由0.62降为0.17,年均可持续发展指数从9.27增为43.52。梅县农业资源综合利用既能降低环境负载率,又能提高能值交换率,促进农业可持续发展。 相似文献
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以资源综合利用、资源减量投入、生态保护能力、绿色供给能力和经济效益水平5个维度构建陕西省农业绿色发展水平指标评价体系,选取2012—2021年农业数据,运用熵值法对陕西省农业绿色发展水平进行评价.结果表明,陕西省近10年来农业绿色发展水平总体呈上升趋势;绿色供给能力、经济效益水平和生态保护能力对其绿色发展贡献较大;资源... 相似文献
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农业部规划设计研究院农副产品加工研究所 《农业工程技术:农产品加工》2010,(4):26-27
农业是我国的基础产业,也是弱质产业.我国农业自然资源紧缺,保障供给压力大,决定了必须把依靠农业科技进步提高资源利用水平和效率放在重要地位;我国农产品深加工产品少,综合利用水平低,产业链条短,附加值低,决定了必须加强技术推广体系建设,增强农业公共服务能力. 相似文献
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图书馆随书附盘的创新管理模式 总被引：2，自引：0，他引：2
沈萍 《农业图书情报学刊》2008,20(11)
随书附盘作为电子附件已成为图书发行的重要组成部分,面对数量日益增多的随书附盘,要根据馆情找到行之有效的管理办法,以提高其利用率. 相似文献
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Madnick SE 《Science (New York, N.Y.)》1977,195(4283):1191-1199
Demands for more effective information management, coupled with advances in computer hardware and software technology, have resulted in the emergence of the information utility concept, whereby computers specialized for information storage and processing serve as information nodes. The information nodes, which may be interconnected, can provide information management services to both conventional and personal computers. In this article the key hardware and software components of classical information systems are described to provide background on the requirements for an information utility. Four approaches to the development of specialized information nodes, drawing on various advances in technology, are presented: (i) firmware enhancement, (ii) intelligent controllers, (iii) minicomputer back-end processors, and (iv) highly modular database machines. The benefits of these advances will be systems that are more efficient, reliable, and easy to use. 相似文献
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Analyses of the economics of solar collection in the firm- and shifting-peak cases (that is, with off-peak electricity indefinitely available or with a flat load curve) indicate that, for many important applications, solar energy systems that interface with electric utilities can be justified only in terms of the value of the off-peak utility fuels that they displace. In regions where off-peak electricity costs are low, the most economically efficient solar energy systems will be those that use electricity as the auxiliary energy source. This implies extremely low break-even costs for a number of important solar energy applications. In regions where the cost of off-peak electricity is higher than that of competing energy forms, the most economical solar energy systems will utilize auxiliary fuels other than electricity. The general conclusion is that conventional electric utility systems and most solar energy systems represent a poor technological match. The basic problem is that both technologies are very capital intensive. The electric utility, because of the high fixed costs of generation, transmission, and distribution capacity, represents a poor backup for solar energy systems. On the other hand, the solar collection system, because it represents pure, high-cost capital and because of its outage problems, cannot be considered as a part-load source of auxiliary energy for the electric utility system. 相似文献
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Aromatic molecules are key constituents of many pharmaceuticals, electronic materials, and commodity plastics. The utility of these molecules directly reflects the identity and pattern of substituents on the aromatic ring. Here, we report a palladium(II) catalyst system, incorporating an unconventional ortho-dimethylaminopyridine ligand, for the conversion of substituted cyclohexanones to the corresponding phenols. The reaction proceeds via successive dehydrogenation of two saturated carbon-carbon bonds of the six-membered ring and uses molecular oxygen as the hydrogen acceptor. This reactivity demonstrates a versatile and efficient strategy for the synthesis of substituted aromatic molecules with fundamentally different selectivity constraints from the numerous known synthetic methods that rely on substitution of a preexisting aromatic ring. 相似文献
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陕北丘陵区农田蒸散规律及对土壤水环境的影响与防治对策 总被引：3，自引：1，他引：3
为了探讨陕北黄土高原农田土壤蒸散规律及水分环境现状,提高土壤水分利用效率,采用TDR法测定了土壤水分,对陕北峁状丘陵区旱梯田裸露地、作物地以及农田覆盖地土壤水分进行系统监测,并结合野外自动气象哨资料,分析了该区农田土壤水分蒸散规律。结果表明,裸露地周年存在两个蒸发高峰期,年蒸发量占降水量的74.4%;土地空闲期对恢复土壤水分亏缺贡献很大;地面采取部分覆盖(地膜覆盖,覆盖率60%)有利于土壤水分环境的恢复与保护,而采取全覆盖(组合覆盖和秸秆覆盖,覆盖率100%)有利于土壤水分的高效利用。在此基础上提出了提高该区土壤水分利用率的有效技术途径:采取双料沟垄组合覆盖技术最大限度地抑制裸露地表的无效蒸发,草粮轮作、避免耕地荒芜提高土壤水分利用率。 相似文献
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Detection of Genetic Diversity in Synthetic Hexaploid Wheats Using Microsatellite Markers 总被引：1，自引：0，他引：1
Ninety-five synthetic hexaploid wheats (2n = 6x = 42, AABBDD) were analyzed using 45 microsatellite markers to investigate the potential genetic diversity in wheat breeding programs. A total of 326 alleles were detected by these microsatellite primer pairs, with an average of 6.65 alleles per locus. The polymorphic information content (PIC), Simpson index (SI), and genetic similarity (GS) coefficient showed that the D genome is of the highest genetic diversity among the A, B, and D genomes in the synthetic hexaploid wheats. The results also indicated that the synthetic hexaploid wheat is an efficient way to enrich wheat genetic backgrounds, especially to use the genetic variations of the D genome from Aegilops squarrosa for wheat improvement. The UPGMA dendogram, based on a similarity matrix by a simple matching coefficient algorithm, delineated the above accessions into 5 major clusters and was in accordance with the available pedigree information. The results demonstrated the utility of microsatellite markers in detecting DNA polymorphism and estimating genetic diversity. 相似文献
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采用土地经济学研究方法,从土地利用结构、土地利用程度和土地利用效益3个方面,对阜平县2003年土地资源利用状况进行了对比分析.结果表明:近20a来,阜平县林业生产有较大发展,土地利用结构日趋合理,与其土地自然性状和林业县定位基本相符,但居民点及工矿用地增长较快,新开垦耕地多数利用方式不尽合理;土地利用程度有较大提高,荒山开发利用及林业建设成效明显,森林覆盖率26.26%,但森林资源区域分布不均匀,保持水土与调节生态和气候的作用依然有限;土地利用的总体效益有一定提高,但单位效益指标较低,需进一步改善生产条件、增加科技投入,提高土地资源利用效益. 相似文献
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森林资源资产价值的综合评估方法 总被引：1，自引：0，他引：1
陈瑶 《东北林业大学学报》2009,37(6)
针对目前森林资源资产价值评估中偏重经济价值的问题,提出了基于森林资源3种效益价值综合评估的方法,并指出森林资源资产综合评估的基本思路.,在结合森林资源资产评估的特点之上,给出了综合评估的评估模型,提出了各效益价值权重确定的方法,构建了森林资源资产各效益评价的方法集,阐明了综合评估方法的工作流程. 相似文献
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通过分析云计算环境中资源分配和用户任务请求的过程，提出了云计算环境中的用户效用函数，并引入风险对云计算服务和资源由于被非授权访问造成的损失进行量化，得出了基于风险的用户期望效用函数.最后，通过仿真实验论证了任务执行数与用户需求，时间，费用和用户效用之间的关系.从仿真实验可以看出，用户的一次提交的任务数存在一个理想值，在这个理想值附近，其用户效用最好. 相似文献