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排序方式: 共有277条查询结果,搜索用时 31 毫秒
191.
C. D. Papaspyrides J. G. Poulakis P. C. Varelides 《Resources, Conservation and Recycling》1994,12(3-4)
A dissolution/reprecipitation process has been developed for recycling low density polyethylene. In this paper model experiments on virgin material, either in the form of pellets or film for greenhouses, are presented. It is proposed dissolution of the plastic in an appropriate solvent, reprecipitation by means of non-solvents, washing of the material obtained and drying. The solvent mixtures involved are separated by distillation for further reuse. Toluene/acetone proved to be the most satisfactory solvent/non-solvent system. The recycled material was evaluated in terms of the following properties: melt flow index (MFI), crystallinity, mechanical performance in tensile mode and grain size analysis. 相似文献
192.
一株高耐铜菌株的分离及特性的研究 总被引:7,自引:0,他引:7
为探索去除电镀废水中铜的处理方法 ,更有效地治理含铜废水造成的环境污染。本文采用梯度浓度驯化的方法 ,从自然界筛选了高耐铜的微生物。经鉴定该菌为枝孢霉属 (Cladosporiumsp .) ,它能耐受铜离子的最高浓度为 72 0mg L ,该菌在摇床培养过程中能成菌丝球 ,其最适生长温度为 2 5°C ,最适 pH 5 .0 ,培养时间为 72h ,摇床转速为 15 0r min。用碱进行预处理可提高菌株的吸附量 ,经 0 .2NNaOH预处理过的菌丝球对含 2 0mg L的铜离子进行吸附实验 ,其吸附量可达15 .64mg L。 相似文献
193.
为查明有机污染物的种类,取死鱼水经GDX-501树脂富集后,用气相色谱/质量选择检测器分析。检出水中82种污染物。 相似文献
194.
Fishing and Farming at Lake Chad: Overcapitalisation, Opportunities and Fisheries Management 总被引:1,自引:0,他引:1
Marie-Thérèse Sarch 《Journal of environmental management》1996,48(4):305-320
Overcapitalisation is one way in which fishing is said to exert a negative externality on the wider economy. Resources invested in fishing could be invested more productively in other sectors of the economy. The logical solution is the shift of resources, in particular scarce capital, from fishing to more profitable sectors. This paper examines the rural economy at Lake Chad and the implications from the results of a socio-economic survey of fishing households for potential fisheries management measures, in particular those which would limit or reduce the level of resources invested in the Lake's fishery. Survey results demonstrate a close link between the farming and fishing activities of many households and suggest that the integration of fishing and farming necessitate consideration of the inter-sectoral impacts of potential fisheries management measures. 相似文献
195.
Daojun Zhang Ziran M Baodong Wang Tao Zhu Duan Weng Xiaodong Wu Hongyan Wang Ge Li Jiali Zhou 《环境科学学报(英文版)》2020,32(2):145-154
A series of vanadium based catalysts(VxMn(4-x)Mo3Ce3/Ti) with different vanadium(x wt.%) and manganese((4-x) wt.%) contents have been prepared by the wet impregnation method and investigated for selective catalytic reduction(SCR) of NO_x by NH_3 in the presence of 8 vol.% H_2O and 500 ppm V SO_2.The physicochemical characteristics of the catalysts were thoroughly characterized.The SCR of NO_x by NH_3(NH_3-SCR) activity, especially the low-temperature activity, significantly increased with increasing V_2O_5 content in the catalyst until the V_2O_5 content reached 1.5 wt.%, which corresponds well with the redox properties of the catalyst.All of the metal oxides were well dispersed and strongly interacted with each other on the catalyst surface.V mainly exists in the V~(5+)state in the catalysts.The strong synergistic effect between the vanadium and cerium species led to formation of more Ce~(3+)species, and that between the vanadium and manganese species contributed to formation of more manganese species with low valences.All of the catalysts exhibited strong acidity, while the redox properties determined the NH_3-SCR activity, especially the low-temperature activity.H_2O and SO_2 had severe inhibiting effects on the activity of V1.5Mn2.5Mo3Ce3/Ti.However, good H_2O and SO_2 resistance and high NO_x conversion by V1.5Mn2.5Mo3Ce3/Ti could be achieved in the presence of SO_2 and almost no decline was observed in a long-term test at 275℃ for 168 hr in the presence of SO_2 and H_2O, which can be attributed to the sulfate species formed on the catalyst surface. 相似文献
196.
Lin Zhu Zhaoping Zhong Jianming Xue Yueyang Xu Chunhua Wang Lixia Wang 《环境科学学报(英文版)》2018,30(3):306-316
Niobium oxide as the promoter was doped in the V/WTi catalyst for the selective catalytic reduction(SCR)of NO.The results showed that the addition of Nb_2O_5could improve the SCR activity at low temperatures and the 6 wt.%additive was an appropriate dosage.The enhanced reaction activity of adsorbed ammonia species and the improved dispersion of vanadium oxide might be the reasons for the elevation of SCR activity at low temperatures.The resistances to SO_2of 3V6Nb/WTi catalyst at different temperatures were investigated.FTIR spectrum and TG-FTIR result indicated that the deposition of ammonium sulfate species was the main deactivation reason at low temperatures,which still exhibited the reactivity with NO above 200°C on the catalyst surface.There was a synergistic effect among NH_3,H_2O and SO_2that NH_3and H_2O both accelerated the catalyst deactivation in the presence of SO_2at 175°C.The thermal treatment at 400°C could regenerate the deactivated catalyst and get SCR activity recovered.The particle and monolith catalysts both kept stable NO_xconversion at 225°C with high concentration of H_2O and SO_2during the long time tests. 相似文献
197.
A series of H-SAPO-34 zeolites were synthesized by a hydrothermal method in fluoride media. The as-synthesized H-SAPO-34 zeolites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 physisorption, temperature-programmed desorption of NH3 (NH3-TPD) and nuclear magnetic resonance (NMR) measurements. The results showed that a certain concentration of F− anions promoted the nucleation and crystallization of H-SAPO-34. The H-SAPO-34 synthesized in the fluoride media showed high crystallinity, uniform particle size distribution, large specific surface area and pore volume, and enhanced acidity. Therefore, Cu/SAPO-34 based on the fluoride-assisted zeolite showed a broadened temperature window for the selective catalytic reduction of NO by NH3 (NH3-SCR) reaction due to the enhanced acidity of the zeolite and the improved dispersion of copper species. 相似文献
198.
Amer Obeidi Keith W. Hipel D. Marc Kilgour 《Journal of the American Water Resources Association》2006,42(6):1629-1645
Abstract: A systematic technique is proposed for assisting in the design and implementation of policy and addressing the need to minimize or resolve disputes that may arise in the enforcement of regulations. The Graph Model for Conflict Resolution is a methodology that facilitates the modeling and analysis of interactive multiple participant-multiple objective decision problems. In the problems considered here, decision makers and policy planners engaged in capacity building typically have different viewpoints over appropriate ways of developing options and enforcing policy choices. Incompatible understandings of resource potentials and limits, and disparities in utilization of these resources, exasperate stakeholders and make the capacity building process counterproductive and even conducive to conflict. A systematic conflict resolution technique is invaluable to policy makers and practitioners in defusing confrontations and reaching out for consensus among participants. In support of current approaches to policy planning and regulation, the Graph Model provides accurate predictions and strategic insights into shortand long-term opportunities in multiple participant-multiple objective decision situations. A conflict among the government of Canada, the Mi'kmaq First Nation, and commercial fishermen over the sharing of a natural resource in New Brunswick, Canada, is used to illustrate the advantages of this technique in practical problems. 相似文献
199.
Qiuzhun Chen Xiang Zhang Bing Li Shengli Niu Gaiju Zhao Dong Wang Yue Peng Junhua Li Chunmei Lu John Crittenden 《Frontiers of Environmental Science & Engineering》2021,15(5):92
200.
Joshua K. Abbott James E. Wilen 《Journal of Environmental Economics and Management》2009,58(3):300-314
Recreational fisheries are increasingly important in fisheries management; for some species, recreational take rivals or exceeds the amount harvested by commercial fishermen. Most recreational fisheries are regulated with gear restrictions, bag limits, and time/area closures, but there is increasing interest in the market-based solutions employed in commercial fisheries — this despite the lack of an adequate bioeconomic theory of the joint commercial/recreational aspects of many recreational fisheries. This paper integrates a detailed production specification with traditional bioeconomic tools in order to better understand the implications of rationalization schemes targeted at the charter sector. While confirming some of the qualitative conclusions of the commercial fisheries literature on open access and regulated open access our model also generates rich and novel predictions with respect to input choices, the number of vessels and congestion externalities. We devise a system of instruments that generate efficient outcomes and extensively discuss issues associated with their real-world implementation. 相似文献