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51.
煤烟型大气污染解决方法   总被引:3,自引:0,他引:3  
重点介绍了新型燃煤工艺——水平火焰无烟工业炉及其特点,并提出排烟尾气处理的资源化方案。  相似文献   
52.
Forty-two open neural tube defects (NTDs) were identified in our series of 7440 amniocenteses tested between 11 and 15 weeks of gestation. Using a cut-off of ≥2.0 MOM, the detection rate for open NTDs was 95 per cent; 100 per cent each for anencephaly and spina bifida; and 78 per cent for encephalocele. Two encephaloceles had AFP levels less than 2.0 MOM and negative AChEs. Thirty-four (81 per cent) of these NTDs were tested between 13 and 15 weeks and 8 (19 per cent) before 13 weeks. There were 0.6 per cent false positives by AFP (excluding serious abnormalities and fetal death) and 0.1 per cent after AChE. The likelihood of an open NTD after an elevated AFP (≥2.0 MOM) was 24 and 77 per cent for any serious abnormality. These results, when combined with an earlier study, indicate that amniotic fluid AFP appears to be as sensitive a test for open NTDs between 13 and 15 weeks as between 16 and 20 weeks. Additional experience is necessary to determine this before 13 weeks.  相似文献   
53.
We have investigated the ability of high-resolution proton NMR spectroscopy to provide a biochemical constituent screening of human amniotic fluid (AF). Proton NMR spectra were obtained at 300 MHz on AF from patients undergoing amniocentesis in the mid-trimester. Only AF from normal pregnancies (normal fetal karyotype, normal a-fetoprotein levels, normal birth outcome) was used in this study. The AF supernatant was lyophilized and resuspended in deuterated water containing 0.1 mm phosphate buffer and 6.02 mm disodium maleate. Identification of low molecular weight compounds was confirmed by two-dimensional NMR spectra (primarily correlated spectroscopy, or COSY) and standard addition techniques. A broad profile of compounds were ‘NMR visible’ in a single proton spectrum, including creatinine, glucose, organic acids (acetate, citrate, and lactate) and several amino acids (alanine, histidine, leucine, phenylalanine, tyrosine and valine). The proton spectrum was unaffected by prior freezing/thawing of AF samples. We were able to quantify compounds by comparison with an added concentration standard (maleate) at concentrations as low as 30 μm. Good agreement with literature values based on other analytical techniques was obtained.  相似文献   
54.
张玉春  许积年 《环境工程》1995,13(4):37-39,30
用TOC总有机碳测定仪来鉴定污水和生活用水处理效果及污染指标是它的一项实际应用,而本义介绍的用来测定CO2则是一项开创性的工作。作者在对进口的TOC仪使用的基础上研究了测定气体中总碳、总有机碳尤其是CO2问题,取得了较好的结果并应用到实际测定中。  相似文献   
55.
在磁场中活性炭吸附有机物的研究   总被引:7,自引:0,他引:7  
将磁化技术引入吸附过程中,考察了磁场处理对活性炭吸附苯、硝基苯、苯甲酸、氯苯和苯酚的影响.结果表明,预磁处理能使非极性物质苯和极性较小的氯苯、苯酚在活性炭上的吸附容量减小,而使极性较大的苯甲酸和有NO2基团的硝基苯的吸附容量增大.增大磁场强度能加强苯和苯甲酸的磁处理效果。  相似文献   
56.
在进行矿井水中油类分析时,用正己烷作为萃取剂,以工作曲线代替标准曲线,从而使油平均回收率增加到96%以上。并在正己烷用量、水样预处理等测试参数选择上做了条件试验。  相似文献   
57.
Using a case study of the Lake Abitibi Model Forest (LAMF), this study aims to assess the temporal and spatial variability in carbon storage during 1990–2000, and to present a comprehensive estimation of the carbon budget for LAMF's ecosystems. As well, it provided the information needed by local forest managers to develop ecological and carbon-based indicators and monitor the sustainability of forest ecosystems. Temporal and spatial carbon dynamics were simulated at the landscape level using ecosystem model TRIPLEX1.0 and Geographical Information System (GIS). The simulated net primary productivity (NPP) and carbon storage in forest biomass and soil were compared with field data and results from other studies for Canada's boreal forests. The results show that simulated NPP ranged from 3.26 to 3.34 tC ha−1 yr−1 in the 1990s and was consistent with the range measured during the Boreal Ecosystem-Atmosphere Studies (BOREAS) in central Canada. Modeled NPP was also compared with the estimation from remote sensing data. The density of total above-and belowground biomass was 125.3, 111.8, and 106.5 tC ha−1 for black spruce, trembling aspen, and jack pine in the LAMF ecosystem, respectively. The total carbon density of forested land was estimated at 154.4 tC ha−1 with the proportion of 4:6 for total biomass and soil. The analysis of net carbon balance of ecosystem suggested that the LAMF forest ecosystem was acting as a carbon sink with an allowable harvest in the 1990s.  相似文献   
58.
有机气溶胶的来源与形成研究现状   总被引:8,自引:3,他引:8  
谢绍东  于淼  姜明 《环境科学学报》2006,26(12):1933-1939
介绍了有机气溶胶来源与形成的研究现状,从有机气溶胶的化学组成特征、一次有机气溶胶的来源和二次有机气溶胶的形成机制论述其研究进展.一次有机气溶胶主要来源于烹调油烟、机动车排放、生物质燃烧、工业或民用燃油锅炉释放出的有机物,还有道路扬尘、沥青、刹车尘、轮胎屑、室外香烟烟雾、以及高等植物蜡、细菌活动和草本植物等.大气中的半挥发性有机物可通过物理和化学吸附形成二次有机气溶胶,一些挥发性有机物可通过气相化学反应转化为低挥发性的物质并形成二次有机气溶胶,其主要前体物是芳香族化合物,如苯、甲苯、二甲苯,以及烯烃、烷烃、环烷烃、萜烯和生物排放的非饱和氧化物.  相似文献   
59.
我国现行的供水和水处理方式制约着城市直饮水和中水深度处理回用的应用和发展 ,根据城市实际建立分质供水与中水回用相结合的供水体系 ,将成为解决这一问题的有效途径  相似文献   
60.
Focus on eco-friendly processing techniques makes vegetable tanning a viable option in leather processing and establishes the subsequent need for the more efficient methods of extraction in tannin manufacture. Application of ultrasound has been tried in the extraction of tannins from myrobalan nuts in order to improve the extraction efficiency, to perform the extraction under milder process conditions and to reduce the process time. The influence of process parameters such as ultrasonic output power, time and temperature has been studied. Scale-up trials and the use of ultrasound in pulse mode have also been attempted. The results show that a three- to fivefold improvement is possible with ultrasonic output from 20 to 100 W. Extraction efficiency has been calculated from the maximum extractable materials from myrobalan nuts. Extraction efficiency is found to be 90% for ultrasound, 100 W without external heating as compared to 77% for control process at 70 °C for 4 h. Therefore, ultrasound could be employed even dispensing with provision for temperature controls. The use of ultrasound in pulse mode offered 70% extraction efficiency of continuous mode. Scale-up trials indicate that there exists an optimum ultrasonic output power depending on the amount of nuts used, to achieve better extraction efficiency. The effectiveness of ultrasonically extracted tannin solution has also been tested in the tanning process for its applicability. The degree of tanning efficacy has been assessed by shrinkage temperature measurement. The results indicate that ultrasonically extracted tannin solution is suitable for tanning process. Therefore, application of ultrasound in tannin extract manufacture is a viable option with added advantages.  相似文献   
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