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排序方式: 共有1616条查询结果,搜索用时 93 毫秒
661.
难降解废水生物处理中的共代谢作用   总被引:2,自引:0,他引:2  
综述了共代谢作用的机理、特点及研究现状,展望了共代谢在废水生物处理中的应用前景。  相似文献   
662.
B—82细菌的筛选及降解甲胺磷的实验研究   总被引:9,自引:0,他引:9  
从受甲胺磷长期污染的土壤中采取土样,经驯化富集后筛选到一株能高效降解甲胺磷的细菌B-82菌株,经初步鉴定,为施氏假单胞菌(Pseudomonas stutzeri)。菌株B-82能以甲胺磷为为施氏假单胞菌氮和磷源进行生长并将其降解为无机磷,此菌能耐受0.5%的甲胺磷。  相似文献   
663.
钟成华 《重庆环境科学》2002,24(4):47-48,51
河流水质规划中常常要用水质数学模型来模拟水体的水质、刻划岸边污染带、对水质进行预测,并结合其它模型对污染物排放进行总量控制,以及对污染方案进行水质验证。由于水质数学模型的单向性(即数据只能从输入流向输出),在实际工作中当需要逆计算时(如计算水环境容量等)往往采取试算法,工作量较大。本文介绍的影响系数矩阵法可以方便快捷地完成上述各项工作。此法在中英国际合作项目“长江、嘉陵江水污染控制规划研究”中已采用,效果较好。  相似文献   
664.
基于对型材挤压特点的详尽分析 ,提出了铝型材挤压模CAD/CAE/CAM系统功能模型并确定了基于UG和ANSYS平台的系统集成方案 ,对关键软件模块进行二次开发 ,在此基础上对平模挤压折角、槽型材和分流组合模挤压扁管型材进行了分析。  相似文献   
665.
对沈阳市农田(水田、旱田、菜田)土壤中农药残留调查表明,禾大壮、丁草胺、敌百虫、辛硫磷、阿特拉津、乐果、氧化乐果、溴氰菊酯、1605残留量测定结果均低于检出限。六六六残留几何平均水平为0.011mg/kg.DDT为0.039mg/kg;旱田、水田六六六异构体的残留主要是β-BHC,DDT异构体的残留主要是p,p'-DDE.  相似文献   
666.
Greenhouse gas(GHG) emissions from oil and gas systems are an important component of the GHG emission inventory. To assess the carbon emissions from oilfield-produced water under atmospheric conditions correctly, in situ detection and simulation experiments were developed to study the natural release of GHG into the atmosphere in the Shengli Oilfield,the second largest oilfield in China. The results showed that methane(CH4) and carbon dioxide(CO2) were the primary gases released naturally from the oilfield-produced water.The atmospheric temperature and release time played important roles in determining the CH4 and CO2emissions under atmospheric conditions. Higher temperatures enhanced the carbon emissions. The emissions of both CH4 and CO2from oilfield-produced water were highest at 27°C and lowest at 3°C. The bulk of CH4 and CO2was released from the oilfield-produced water during the first release period, 0–2 hr, for each temperature, with a maximum average emission rate of 0.415 g CH4/(m3·hr) and 3.934 g CO2/(m3·hr), respectively. Then the carbon emissions at other time periods gradually decreased with the extension of time. The higher solubility of CO2 in water than CH4 results in a higher emission rate of CH4 than CO2over the same release duration. The simulation proved that oilfield-produced water is one of the potential emission sources that should be given great attention in oil and gas systems.  相似文献   
667.
Experimental design and response surface methodology(RSM) were used to optimize the modification of conditions for glass surface grafting with acrylamide(AM) monomer for preparation of a glass fiber reinforced poly(vinylidene fluoride)(PVDF) composite membrane(GFRP-CM). The factors considered for experimental design were the UV(ultraviolet)-irradiation time, the concentrations of the initiator and solvent, and the kinds and concentrations of the silane coupling agent. The optimum operating conditions determined were UV-irradiation time of 25 min, an initiator concentration of 0–0.25 wt.%,solvent of N-Dimethylacetamide(DMAC), and silane coupling agent KH570 with a concentration of 7 wt.%. The obtained optimal parameters were located in the valid region and the experimental confirmation tests conducted showed good accordance between predicted and experimental values. Under these optimal conditions, the water absorption of the grafted modified glass fiber was improved from 13.6% to 23%; the tensile strength was enhanced and the peeling strength of the glass fiber reinforced PVDF composite membrane was improved by 23.7% and 32.6% with an AM concentration at 1 wt.% and 2 wt.%. The surface composition and microstructure of AM grafted glass fiber were studied via several techniques including Field Emission Scanning Electron Microscopy(FESEM), Fourier transform infrared spectroscopy-attenuated total reflectance(FTIR-ATR) and energy dispersive X-ray spectroscopy(EDX). The analysis of the EDX and FTIR-ATR results confirmed that the AM was grafted to the glass fiber successfully by detecting and proving the existence of nitrogen atoms in the GFRP-CM.  相似文献   
668.
秸秆还田对双季稻产量及氮磷径流损失的影响   总被引:3,自引:0,他引:3       下载免费PDF全文
为探索减少稻田氮磷流失的有效耕作措施,以南方典型黄壤双季稻田为研究对象,采用田间长期定位观测试验,研究了连续7 a(2008—2014年)秸秆还田(RFS)替代38.7%的N、40.8%的P2O5和42.7%的K2O晚稻化肥投入与常规化肥(RF)处理对双季稻产量、地表径流中ρ(TN)、ρ(NH4+-N)、ρ(NO3--N)、ρ(TP)、ρ(DP)(DP为溶解态总磷)的影响.结果表明:与常规化肥处理相比,秸秆还田处理不仅可从源头上减少晚稻化肥投入,还可降低稻田径流液中氮、磷养分含量,分别使TN和TP流失量减少12.6%、9.7%;氮流失主要以DIN(可溶性无机氮)为主,DIN/TN(DIN输出量在TN输出量中所占比例)为66.2%~70.8%;磷流失主要以DP(可溶性磷酸盐)为主,DP/TP(DP输出量在TP输出量中所占比例)为60.1%~65.9%;秸秆还田处理下早稻较常规化肥处理有增产趋势,增幅为4.5%~10.1%,晚稻有减产风险,但减产差异不显著,平均减幅为6.3%.因此,秸秆长期还田是一种秸秆资源有效利用和节肥增效减失的耕作方式.   相似文献   
669.
火电行业"十三五"主要大气污染物减排潜力情景分析研究   总被引:3,自引:0,他引:3  
火电行业是总量减排的重点行业,也是主要大气污染物削减量的首要贡献者,其主要大气污染物排放量的削减抵消了其他行业的排放增长,为"十二五"全国减排任务的完成做出了重大贡献.本研究在火电行业主要大气污染物排放控制现状分析的基础上,结合火电行业技术政策措施要求,对火电行业"十三五"新增排放量进行了预测,并设置基于技术可行、排放标准以及超低排放三套减排情景,测算"十三五"减排潜力,评估火电行业"十三五"减排空间,对全国及各省火电行业减排形势提出了相应的意见和建议.  相似文献   
670.
This paper develops a new crop mapping method through combined utilization of both time and frequency information based on wavelet variance and Jeffries–Matusita (JM) distance (CIWJ for short). A two-dimensional wavelet spectrum was obtained from datasets of daily continuous vegetation indices through a continuous wavelet transform using the Mexican hat and the Morlet mother wavelets. The time-average wavelet variance (TAWV) and the scale-average wavelet variance (SAWV) were then calculated based on the wavelet spectrum of the Mexican hat and the Morlet wavelet, respectively. The class separability based on the JM distance was evaluated to discriminate the proper period or scale range applied. Finally, a procedure for criteria quantification was developed using the TAWV and SAWV as the major metrics, and the similarity between unclassified pixels and established land use/cover types was calculated. The proposed CIWJ method was applied to the middle Hexi Corridor in northwest China using 250-m 8-day composite moderate-resolution imaging spectroradiometer (MODIS) enhanced vegetation index (EVI) time series datasets in 2012. The CIWJ method was shown to be efficient in crop field mapping, with an overall accuracy of 83.6 % and kappa coefficient of 0.7009, assessed with 30 m Chinese Environmental Disaster Reduction Satellite (HJ-1)-derived data. Compared with methods utilizing information on either frequency or time, the CIWJ method demonstrates tremendous potential for efficient crop mapping and for further applications. This method could be applied to either coarse or high spatial resolution images for agricultural crop identification, as well as other more general or specific land use classifications.  相似文献   
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