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121.
隐孢子虫在水环境中存在水平与灭活技术 总被引:1,自引:0,他引:1
介绍了隐孢子虫的介水传播途径与特点、卵囊在水环境中存在水平及有效灭活隐孢子虫技术。隐孢子虫在水环境中显著存在;以饮用水为媒介成为隐孢子虫病传播和暴发流行的重要途径;采取可靠灭活工艺是控制隐孢子虫进入供水系统最重要的屏障。氯化消毒难以有效地灭活隐孢子虫,臭氧和紫外线可获得较理想的灭活效果。臭氧剂量为5~10(mg/L)·min时,灭活率为1-lg(90%);紫外线辐照剂量在9~11mJ/cm2,灭活率为2-lg(99%)。 相似文献
122.
123.
Modeling the Effect of Population Dynamics on the Impact of Rabbit Hemorrhagic Disease 总被引:1,自引:0,他引:1
CARLOS CALVETE 《Conservation biology》2006,20(4):1232-1241
Abstract: The European wild rabbit ( Oryctolagus cuniculus ) is a staple prey species in Mediterranean ecosystems. The arrival and subsequent spread of rabbit hemorrhagic disease throughout southwestern Europe, however, has caused a decline in rabbit numbers, leading to considerable efforts to enhance wild rabbit populations, especially through habitat management. Because rabbit population dynamics depend on habitat suitability and changes in habitat structure and composition subsequent to habitat management, I evaluated the effects of population dynamics on the long-term impact of rabbit hemorrhagic disease on rabbit populations. I used an age-structured model with varying degrees of population productivity and turnover and different habitat carrying capacities, and I assumed the existence of a unique, highly pathogenic virus. My results suggest that disease impact may be highly dependent on habitat carrying capacity and rabbit population dynamics, and the model provided some insight into the current abundance of wild rabbits in different locations in southwestern Europe. The highest disease impact was estimated for populations located in habitats with low to medium carrying capacity. In contrast, disease impact was lower in high-density populations in habitats with high carrying capacity, corresponding to a lower mean age of rabbit infection and a resulting lower mortality from rabbit hemorrhagic disease. The outcomes of the model suggest that management strategies to help rabbit populations recover should be based on improving habitats to their maximum carrying capacity and increasing rabbit population productivity. In contrast, the use of strategies based on temporary increases in rabbit density, including vaccination campaigns, translocations, and temporal habitat improvements at medium carrying capacities, may increase disease impact, resulting in short-term decreases in rabbit population density. 相似文献
124.
Humic acids, especially FA in fractions, contain more oxygen functional groups. In this experiment, on the basis of confirming the action of humic acids on KBD, what was studied is the biological effects of one of main oxygen functional groups, hydroxy group (-OH). The results indicate that inducing pathologic process of KBD, obviously decrease the GSH-Px activity and induce peroxidation membrane injury of tissue. The SOD activity increase in the tissues caused by oxygen functional groups showed that enhancing of free radical reaction should not be neglected. 相似文献
125.
126.
对虾暴发性流行病的病因及预防对策分析 总被引:6,自引:2,他引:6
本文报告了用电子显微镜对1993年对虾暴发性流行病的病原观察结果,确认带包膜的杆状病毒是造成虾病暴发流行的病原。借鉴东南亚各国养虾的经验教训,分析了这次虾病的流行原因是海水富营养化。并结合作者多年从事对虾病害研究工作的实践,讨论了预防对虾暴发性流行病的对策。 相似文献
127.
A case of prenatally diagnosed non-immune hydrops fetalis, that was later shown to be caused by listeriosis, is presented, and the clinical course, as well as the appropriate diagnostic and therapeutic procedures are described. We conclude, that listeriosis should be excluded, whenever a non-immune hydrops fetalis is associated with septicemia, influenza-like illness and fever of unknown origin. 相似文献
128.
Blood flow across the atrioventricular valves and outflow tracts was measured in 55 normal fetuses and 32 fetuses with haemoglobin (Hb) Bart's disease between 18 and 26 weeks of gestation. The mean velocities remained unchanged in both normal and affected fetuses over the gestations studied. The volume flow across both atrioventricular valves and outflow tracts increased as the gestation advanced in both normal and affected fetuses, but was significantly higher in affected than in normal fetuses. The same magnitude of increased flow was found in both hydropic and non-hydropic fetuses with Hb Bart's disease. These findings suggest that fetuses with severe and long-standing anaemia have a remarkable cardiac compensatory mechanism for the maintenance of tissue oxygenation. In response to anaemia and circulatory loading, the cardiac chambers and outflow tracts enlarge proportionately up to twice the normal values. Because of this response and the operation of the Frank-Starling mechanism, the heart is able to maintain a normal mean velocity of propulsion and the net output is increased to two to three times that in normal fetuses. Hydropic changes in these anaemic fetuses appear unrelated to cardiac failure as cardiac failure is not observed at the time that hydropic changes develop. 相似文献
129.
本研究在着力改善生态环境和调整产业空间布局的背景下,着眼于国民经济行业中高能耗、高污染的污染密集型产业,基于2000—2015年中国30个省区的面板数据,在污染密集型产业识别的基础上,考察了污染密集型产业集聚和环境污染的空间特征,构建了空间面板杜宾模型,并从空间溢出视角,探讨了污染密集型产业集聚的环境效应.研究发现:①污染密集型产业集聚和环境污染均具有显著的空间正相关性;②污染密集型产业集聚和环境污染之间存在显著的倒"U"型曲线关系,对于产业集聚水平较高的山西、宁夏和内蒙古,有望通过空间溢出效应和政策干预发挥减排效应,其他省区集聚水平的提高将会加剧环境污染;③经济发展水平和外商直接投资与环境污染之间均具有显著的正相关关系,而技术创新能力的提高能显著降低污染水平. 相似文献
130.
Dr. Mitchell S. Golbus Thomas J. Simpson Mitsuhiko Koresawa Zvi Appelman Charles E. Alpers 《黑龙江环境通报》1988,8(6):401-404
Two fetuses at risk for glucose-6-phosphatase deficiency had in utero liver biopsies. Analysis of each showed this enzyme activity to be in the normal range and the pregnancies continued. Neither child has any clinical or metabolic evidence of glucose-6-phosphatase deficiency. 相似文献