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161.
对城乡自然生态关系的认识   总被引:1,自引:0,他引:1  
针对目前对城乡之间自然生态关系缺乏准确的研究现状,首次提出建立城乡自然生态关系概念的观点,认为在城市化和城市规划研究中应加强对城乡资源关系、资源利用关系、组成要素关系和要素感知关系等方面的研究,提出应充分认识利用这种关系。  相似文献   
162.
本文立足于防灾科技学院现有的文化环境,进一步明确了学院办学特色,探讨了如何从硬件、课程、科研、队伍、活动建设和学校精神培育等不同层面构建具有防灾减灾特色的学校文化体系的方法.  相似文献   
163.
The principles of hydrocarbon exploration and production provide well-established and tested principles and technologies to investigate storage of fluids in the subsurface. CO2 can be stored in the subsurface using settings of: (A) thick permeable coal seams; (B) depleted oil and gas fields; (C) saline aquifers of regional extent, with an overlying seal. The North Sea Sleipner project shows that CO2 can be injected into the pore space of deep geological aquifers deeper than 800 m at 1 Mt/yr, using established technology. Suitable sediment sequences of saline aquifers exist in all hydrocarbon-producing areas, are volumetrically much larger than exploited oil and gas fields, and hold the potential to easily store all worldwide CO2 emissions until 2050. Geological principles are established to assess entire continents for candidate sites of CO2 storage. This shows that opportunity may be widespread, but needs more specific local investigations. Onshore sub-Saharan Africa is considered the most problematic region – but even here there are potentially viable sediment sequences. No demonstration projects currently exist for CO2 capture and storage using small-scale onshore facilities. A simple estimate, assuming CO2 value of $20 per ton, suggests that single boreholes onshore may be viable over 20 years with supply rates of 100,000 ton CO2 per year. In principle, atmospheric CO2 could be captured by cultivated biomass, and co-fired in existing power stations. Or energy crops could be grown, CO2 to be used, and stored deep below ground, in a country distant from an original fossil-fuel CO2 emission site.  相似文献   
164.
基于UG平台构建三维铝型材挤压模具CAD系统   总被引:1,自引:0,他引:1  
在UG平台上 ,建立了三维铝型材挤压模具CAD系统 ,可以方便地设计出参数化的铝型材挤压平面模和导流模。系统的设计采用了面向对象的技术 ,具体的程序实现则利用了UGOPEN/API接口和UGOPEN/GRIP语言  相似文献   
165.
Acriticalanalysisofenvironmentalevolutionintheloess-plateauareaLuZhongchen(ResearchCenterforEco-EnvironmentalSciences.Chinese...  相似文献   
166.
经济发展方式的转变是我国化解资源环境约束、提高经济发展质量和效益、实现可持续发展的必由之路,而循环经济正是转变经济发展方式的有效途径。但实践中,有些地方政府和企业在用循环经济变革传统发展方式方面还存在种种误区,以致于严重偏离了循环经济的真正目标。通过对循环经济的目的、思路、实践、思想等内容的阐释,帮助人们准确把握循环经济要义,为积极推进经济发展方式转变提供参考。  相似文献   
167.
广东丰溪自然保护区昆虫多样性初步研究   总被引:1,自引:0,他引:1  
通过对广东大埔丰溪自然保护区设置30个样地调查采集昆虫标本,并将所采集的标本进行区系分析和物种多样性分析,结果表明:丰溪自然保护区作为南亚热带向中亚热带过渡地带,其昆虫区系以东洋区成分占绝对优势;昆虫物种多样性指数在1.7491~2.7728之间,阔叶林下昆虫物种多样性指数平均数要高于竹林.  相似文献   
168.
Livestock production and the use of synthetic fertilizer are responsible for about half of the global emission of NH3. Depending on the animal category between 10 and 36% of the N in animal excreta is lost as NH3. The current annual NH3 emission in developing countries of 15 million ton N accounts for of the global emission from animal excreta. In addition, 7.2 million tons NH3N of synthetic N fertilizers are lost as NH3 in developing countries. This is 80% of the global NH3 emission from synthetic fertilizer's use. Along with human population increase and economic growth, livestock production in developing countries may even increase by a factor of 3 between now and 2025. The net result of rapid increase of livestock production combined with higher efficiency is an increase in NH3 emissions of only 60% from 15 to 24 million tons NH3N between 1990 and 2025 in developing countries. Livestock production is an important consumer of feedstuffs, mainly cereals, thereby inducing additional demand for synthetic fertilizers. Despite the projected major increase of synthetic fertilizer use from 42 to 106 million ton N between 1990 and 2025, the NH3 loss in developing countries may decrease if a shift towards other fertilizer types, that are less vulnerable to NH3 volatilization, is realized. According to the scenario, the total emission of NH3 associated with food production in developing countries will increase from 22 to 30 million ton N yr−1 between 1990 and 2025. Although the NH3 emission increases more slowly than food production, in particular, animal production may show geographic concentration in certain regions, which may lead to high local emission densities and associated environmental problems.  相似文献   
169.
Community‐based water supply (CBWS) is an example of how a community manages common pool resources (CPR). This results in an alternative approach to solve water supply problems in developing countries by enhancing community participation in managing water supply. This research evaluates the sustainability of five CBWS projects in Cikarang, Indonesia by using Ostrom's design principles, with additional sustainability factors found in the Sustainable Development Goal (SDG) on drinking water and groundwater sustainability. Quinn et al. (2007) criteria were used in the analysis, and the results show that the management of four CBWS institutions were absent and one CBWS institution was weak. With regards to the SDG's drinking water target, the CBWS institutions were unable to comply with safe water standards, and in terms of groundwater sustainability, efforts to monitor and sustain groundwater tables were absent. Results from this research suggest that more focus must be placed on water quality and groundwater sustainability for CBWS projects.  相似文献   
170.
本文概述了当前在研型号可靠性增长试验的现状和存在问题,并提出了改进措施的建议。  相似文献   
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