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121.
Epidemiological survey of 573 families, clinical examination of 2593 persons, and X-ray examination of 1136 persons (in 16 typical endemic villages) were conducted, based on the classification of endemiology for KBD disease areas, i.e, mountain type, loess plateau type, plateau type, and flatlands type. It was revealed that the KBD disease areas exhibited the regular pattern of corming-into-being, development and passing-away and the characteristics of growth and decline. Further, it was found clinically that the disease areas may be divided into 4 types, i.e., recent onset, developing, stable, and historical. This division is simple and easy, practical, scientific, and reliable and can be applied by medical personnel at different levels. 相似文献
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123.
Dry deposition velocity of total suspended particles (TSP) is an effective parameter that describes the speed of atmospheric particulate matter deposit to the natural surface. It is also an important indicator to the capacity of atmosphere self-depuration. However, the spatial and temporal variations in dry deposition velocity of TSP at different urban landscapes and the relationship between dry deposition velocity and the meteorological parameters are subject to large uncertainties. We concurrently investigated this relationship at four different landscapes of Guangzhou, from October to December of 2009. The result of the average dry deposition velocity is (1.49 ± 0.77), (1.44 ± 0.77), (1.13 ± 0.53) and (1.82 ± 0.82) cm/sec for urban commercial landscape, urban forest landscape, urban residential landscape and country landscape, respectively. This spatial variation can be explained by the difference of both particle size composition of TSP and meteorological parameters of sampling sites. Dry deposition velocity of TSP has a positive correlation with wind speed, and a negative correlation with temperature and relative humidity. Wind speed is the strongest factor that affects the magnitude of TSP dry deposition velocity, and the temperature is another considerable strong meteorological factor.We also find out that the relative humidity brings less impact, especially during the dry season. It is thus implied that the current global warming and urban heat island effect may lead to correlative changes in TSP dry deposition velocity, especially in the urban areas. 相似文献
124.
活性半焦用于油田含油污水除油的研究 总被引:3,自引:0,他引:3
以经济廉价的半焦为原料,制备用于处理油田含油污水的吸附剂。采用高温焙烧活化、水蒸气活化、高压水热活化以及硝酸、氢氧化钾活化等方法对半焦进行活化处理,通过静态吸附实验测定除油率来评价活化效果,重点讨论了氢氧化钾活化条件对除油效果的影响。结果表明:KOH与半焦质量比为6∶1,80℃浸渍3 h,550℃焙烧1.5 h时,制备的活性半焦吸附除油效果最好,除油率可以达到75.6%;活性半焦对油的吸附符合Freund lich吸附方程。利用酸碱滴定法对样品表面酸碱官能团进行分析,发现KOH活化后半焦表面碱性亲油官能团明显增多;通过SEM对半焦的微观结构进行分析,发现KOH活化后半焦产生大量有利于吸附的孔结构。 相似文献
125.
大气颗粒物对肺免疫系统有潜在毒性作用,打破免疫系统平衡,大气颗粒物成分中危害首当其冲的是大气细颗粒物(PM_(2.5)),为研究大气细颗粒物引起的机体T淋巴细胞中Th1/Th2免疫失衡方向。本研究通过免疫组化实验方法检测暴露后小鼠肺组织中T淋巴细胞的表达,进一步采用流式细胞术检测大气细颗粒物气管滴注后小鼠肺脏淋巴细胞中Th1/Th2比例。暴露组小鼠肺组织免疫组化研究结果提示浸润细胞区有大量的CD4~+T细胞,中高剂量暴露组小鼠肺组织中淋巴细胞亚群Th1/Th2比例向Th1偏移。大气细颗粒物影响免疫失衡,使T淋巴细胞向Th1漂移。 相似文献
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127.
Abstract Agglomeration of the Yangtze Delta (UAYD), one of the most developed regions of China, has witnessed an increasing prevalence in building ecological cities when the ecological cities are pursued by many modern cities, and great achievements have been made in this regard. It is inevitable, however, that certain problems exist during the construction of ecological city, which include but not limited to non-harmonious development of urban complex ecosystem, and the difficulty in quantifying eco-city construction or incomplete quantification in assessing the construction of present and future eco-city. Based on the analysis on social-economic conditions and regional conditions of the UAYD, this paper attempts to set up an index system of eco-cities combining with local characteristics, and to adopt the indices of eco-city, urban harmony, and eco-city colligate to evaluate the ecological level, urban harmonious development and eco-city construction of cities within the UAYD. Results indicate that among 15 cities in UAYD, Suzhou City ranks the highest in terms of eco-city construction, whereas Nantong ranks relatively lower; sustainable eco-city construction is possible only when cities are developed in every respect of harmony. 相似文献
128.
Effects of grazing and fencing on carbon and nitrogen reserves in plants and soils of alpine meadow in the three headwater resource regions 总被引:1,自引:0,他引:1
Knowledge about carbon and nitrogen in plants and soils and response to fence and graze in alpine ecosystems is still rudimentary because of extremely geographic situation. The purpose of this study was to compare the difference among carbon, nitrogen concentration, and content of unit area and dynamics of above- and below-ground biomass, soil organic carbon and total nitrogen between fencing and grazing alpine meadow. The results showed that total carbon and C: N radio in the aboveground tissue were significantly higher in fenced and ungrazing grassland (FU) than those in free grazing grassland (FG). In addition, the order of total carbon and nitrogen concentration of aboveground tissue of different function groups were not identical between them; The total carbon storage (TCS) per unit of aboveground tissue, roots and 0–30 cm soil layer increased after being fenced for 5 years from free grazing grassland (9255.17 g/m2) to fenced and ungrazing grassland (12637.10 g/m2) by 26.79%. The corresponding total nitrogen storage (TNS) increased by 751.42 g/m2. Furthermore over 95% TCS (TNS) come from 0–30 cm soil layer. However there were no significant differences between fenced and ungrazing grasslands of 10 years and 5 years. Therefore fenced to exclude grazing by Tibetan sheep and yaks was an alternative approach to sequester C to the soil in alpine meadow systems. 相似文献
129.
Wang Xinmin Hou Yanlin & Jie Xiaolei Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing China Department of Resource Environment Henan Agricultural University Zhengzhou China. 《中国人口.资源与环境(英文版)》2004,2(4)
A pot experiment was conducted to investigate the influence of citric and oxalic acids effect on Pb and Zn uptake by corn and winter wheat. The experiment was employed with citric acid (CA) applied at 3 rates (0, 1.5 and 3.0 mmol kg-1 soil), oxalic acid (OA) at 3 rates (0, 1.5 and 3.0mmol kg-1 soil) and citric acid combined with oxalic acid (1.5 mmol citric acid combined with 1.5 mmol oxalic acid kg-1). Two types of soil were chose in the experiment. One was collected from the agricultural soil near a battery-recycling factory in Anhui province, China (site A) and the other was collected from a Pb-Zn mine residues in Hunan province, China (site B). The results showed that soil pH varied with the different treatment of citric and oxalic acids. However, there were no differences in all the treatments. 3.0mmol CA kg-1 soil addition significantly increased the concentrations of the CaCI2-extractable Pb and Zn and other treatments have no significantly increased. The highest shoot concentrations of Pb and Zn 相似文献
130.
搞好综合开发是建设现代化农业的战略措施之一,而要搞好综合开发,必先搞好农业区域开发规划。本文根据涟水地区的自然资源、社会经济条件和市场对农副产品及其制品需求出发,把涟水县域划分为2个开发区域,从分析开发的潜力入手,通过投资和效益的分析,提出了区域近、远期的开发目标、步骤和相应的开发措施。 相似文献