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151.
The study summarizes the results of a long-term research on the factors influencing the structure of ungulate communities in the southern Russian Far East and Middle Urals. The effect of these factors in communities of the southern Far East is largely complicated by interspecific relationships between ungulates. The role of such relationships in the Middle Urals is less apparent, and the territorial distribution of ungulates is largely determined by anthropogenic transformation of habitats.  相似文献   
152.
The zoonotic transmission of hepatitis E, caused by the hepatitis E virus (HEV), is an emerging issue. HEV appears common in pigs (although infected pigs do not show clinical signs), and evidence suggests that a number of hepatitis E cases have been associated with the consumption of undercooked pork meat and products. Little information is available on whether cooking can eliminate HEV, since there is currently no robust method for measuring its infectivity. HEV infectivity can be clearly demonstrated by monitoring for signs of infection (e.g., shedding of virus) in an animal model. However, this approach has several disadvantages, such as lack of reproducibility and unsuitability for performing large numbers of tests, high costs, and not least ethical considerations. Growth in cell culture can unambiguously show that a virus is infectious and has the potential for replication, without the disadvantages of using animals. Large numbers of tests can also be performed, which can make the results more amenable to statistical interpretation. However, no HEV cell culture system has been shown to be applicable to all HEV strains, none has been standardized, and few studies have demonstrated their use for measurement of HEV infectivity in food samples. Nonetheless, cell culture remains the most promising approach, and the main recommendation of this review is that there should be an extensive research effort to develop and validate a cell culture-based method for assessing HEV infectivity in pork products. Systems comprising promising cell lines and HEV strains which can grow well in cell culture should be tested to select an assay for effective and reliable measurement of HEV infectivity over a wide range of virus concentrations. The assay should then be harnessed to a procedure which can extract HEV from pork products, to produce a method suitable for further use. The method can then be used to determine the effect of heat or other elimination processes on HEV in pork meat and products, or to assess whether HEV detected in any surveyed foodstuffs is infectious and therefore poses a risk to public health.  相似文献   
153.
Synthetic wastewaters are widely used in many fields of wastewater research and operational management. However, few comparative studies have been conducted on the large number of published formulations. Eleven synthetic formulations simulating municipal wastewaters were selected based on their frequency of use, relative complexity, ease of formulation and cost and compared to two real municipal wastewaters. Synthetic wastewaters vary significantly in their compositions and characteristics, especially in terms of alkalinity, BOD K 1, SOUR, BODU, COD/BOD and C/N/P ratio, although they are portrayed as ‘typical’ in terms of characteristics and suitability for use. The pH, alkalinity and the presence of Ca and Mg should be considered in combination with the diluent used. Where the diluent is tap water, then the presence of treatment chemicals should also be considered. The effects of the micronutrients present are also an important factor. The study found that no single formulation is appropriate for all situations. Both the Syntho and Synthes formulations attempt to simulate real wastewater, whereas other formulations primarily act as readily biodegradable vectors for toxicity analyses, characterisation studies and treatment process evaluations. The criteria for choosing a particular synthetic wastewater very much depend on its intended application and require careful selection.  相似文献   
154.
Allowable sound pressure levels for industrial, commercial and residential sources of noise are typically governed by state and/or local noise regulations. This paper presents a six-step methodology which was successfully applied by a supermarket in Massachusetts to secure state permission to build and operate a new 52,000 square foot store. This multiple step process included baseline noise monitoring, obtaining reference sound levels of the proposed rooftop refrigeration equipment, predicting future sound levels, and recommending soundlevel mitigation techniques. Post-construction monitoring at the store verified that actual worst-case sound levels agreed with predicted values.  相似文献   
155.
156.
为了防止煤的自燃,采用双氧水氧化升温实验,对灵石肥煤在不同阻化剂下的阻化效果进行了研究。利用阻化时间变化率判定阻化效果。结果表明,添加氧化铝厂赤泥作为协效物质的协效阻化剂有效抑制了煤样的氧化升温,提高了阻化效果,阻化时间变化率达50.78%,为灵石肥煤最佳新型协效阻化剂。新型阻化剂原料廉价易得、反应条件温和、制备过程简单、环境友好,且实现了尾矿废渣的综合利用。  相似文献   
157.
158.
北京市畜禽养殖业氨排放的分布特征   总被引:4,自引:0,他引:4  
氨是形成可吸入颗粒物(PM2.5)的重要前体,采用国外排放因子的平均值作为排放因子,研究了北京市畜禽养殖业氨排放的分布特征。2012年北京畜禽养殖业产生的氨为4.43万t。顺义区排放量最多,占总排放量的20.4%;朝阳区仅养殖少量奶牛,海淀区养殖量少,门头沟区为北京生态涵养发展区,上述几个区氨排放量较低。顺义区排放强度最大,为8.9 t/km2,其后依次为大兴区、平谷区、密云县,而朝阳区、门头沟区、丰台区、海淀区排放强度较小,北京市平均氨排放强度为2.70 t/km2。肉鸡养殖是氨排放的最大贡献源,占总排放量的37.8%,养猪业次之,占37.3%。研究结果可为北京市氨及大气污染防治,尤其是霾天气治理提供科学依据。  相似文献   
159.
Trends of changes in the successional status of northern taiga forests exposed to technogenic pollution in the Kola Peninsula are discussed. Main studies of digression in spruce and pine forests are characterized on the basis of the dynamics of species composition of phytocenoses and chemical composition of atmospheric fallout, soils, and dominant plants.  相似文献   
160.
Fluctuations in the abundance of insular groups of sea otters on the Commander Archipelago are analyzed with regard to changes in meteorological conditions. The main factors responsible for the abrupt decline of the Bering Sea group between 2002 and 2004 are discussed. A statistically significant correlation has been revealed between fluctuations of sea otter abundance and the cycles of solar activity in the period since 1992. Changes in the age and sex structure of the insular groups of sea otters are evaluated.  相似文献   
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