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941.
942.
基于DEA和主成分分析的中国城市代谢效率研究 总被引:1,自引:0,他引:1
城市代谢效率测度是城市可持续发展研究的重要方向。该文运用数据包络分析(DEA)和主成分分析法考察了2010年中国31个案例城市的代谢效率特征。研究结果显示,中国城市代谢系统效率的地域分异性显著,尤其是西部城市代谢系统的非DEA有效比例较高。这些非DEA有效城市在非可再生资源要素(钢材、原煤、焦炭等)投入、社会经济产出(人均GDP、城市化率等)、非期望产出(固体废弃物、废水和废气)方面有较大改善空间。 相似文献
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945.
This paper aims a review of the literature related to soil reinforcements to achieve lower soil thermal conductivity (2). The use of various natural and synthetic fibers, polymers, geosynthetics, agricultural waste/materials, and nanoclays is discussed and existing prediction models that have been thought to affect low thermal conductivity are presented. 相似文献
946.
农业文化遗产是世界遗产的重要类型,存在于特有的生态系统和文化系统之中。它是一种活态的遗产,因此,需要在发展中对其进行保护。作为农业文化遗产动态保护的有效途径之一,合理的旅游开发能够兼顾遗产的保护与发展,实现对传统农业生产系统的可持续管理。本文在对目前联合国粮农组织命名的全球重要农业文化遗产和列入联合国教科文组织世界遗产中的农业遗产进行梳理归纳的基础上,辨析此类遗产地旅游的概念范畴,总结了农业文化遗产旅游的研究的主要内容。当前,我国的相关研究主要集中在资源评价与开发、产品设计与市场营销、旅游感知以及旅游开发影响等方面。今后农业文化遗产地旅游研究可以在遗产地旅游利益共享机制、旅游演化机理、旅游的生态环境影响以及研究方法上进一步深入和完善,以启发理论并服务于实践。 相似文献
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948.
A pyrethroid insecticide-degrading bacterium, strain HS-24, was isolated from an offshore seawater environment. The strain, which can degrade cypermethrin(CYP) and deltamethrin(DEL), was identified as Methylophaga sp. The optimal culture and degradation conditions for CYP and DEL by strain HS-24 is pH 7 at 28°C. Under optimum culture conditions, strain HS-24 exhibited a broad degradation concentration range of 100, 200, 400, 600, and 800 mg/L for CYP and DEL. The metabolic intermediates were analyzed by NMR, which provided strong evidence that CYP and DEL removal occurred mainly because of a biological process. The toxicity of the degradation products of strain HS-24 was studied simultaneously by measuring the light output of the luminescence bacterium. This demonstrated that the biodegradation ability of strain HS-24 significantly decreased the toxicity of CYP- and DEL-contaminated aquaculture seawater. Finally, the findings of this paper indicate that strain HS-24 is thus revealed as a biological agent for the remediation of marine aquatic environments. 相似文献
949.
950.
The development of modern agriculture has resulted in much homogenization of the landscape consisting of large patches of farmland,so small remnant non-crop habitats especially linear corridors play an important role in the conservation of species and the maintenance of ecosystem functions.However,little attention has been paid to the effects of corridors structural characteristics on the plant species restricted to such habitats.In this study,we selected three types of corridors including ditch,hedgerow and road,and ana-lyzed their structural characteristics.The plant species presented in these corridors were investigated,and the species diversity,abun-dance and frequency were estimated.Moreover,spatial arrangements of corridors were classified into different types to discuss whether there were significant effects of corridor network on plant distribution.The results show that three types of corridors have different ef-fects on plant species composition and diversity.The one-one combined corridor networks and total network associated by three corri-dors have more complex structural features than each single type of corridor.However,there is no strong correlation between the corri-dor networks with their plant species.We suggest that carrying out a pointed vegetation survey at corridor intersections to further test the relationships between structural features of corridor and plants is necessary. 相似文献