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231.
厌氧发酵技术能较好地实现城市生活垃圾的资源化、无害化和减量化,是目前垃圾处理技术一个新的重要发展方向,而国内尚无运行的厌氧发酵处理厂。针对国外厌氧发酵技术的应用情况和发展趋势,侧重于从工程应用方面总结已建厌氧发酵处理厂的发酵技术,为我国厌氧发酵处理厂的建设和运行提供一定的技术支持。 相似文献
232.
电化学法处理苯酚模拟废水的研究 总被引:2,自引:0,他引:2
电化学法处理废水中有机污染物,具有效率高、操作简便、与环境兼容等优点,是一种很有潜力的高级氧化技术。实验是以废旧一号干电池中的碳棒作电极,用烧杯作电解池,在室温下,通过改变支持电解质(Na2SO4)浓度、负载电压、pH值和苯酚初始浓度等影响因素,对苯酚模拟废水进行电化学处理,利用高效液相色谱仪对其处理效果进行了分析研究,结果表明:支持电解质(Na2SO4)浓度为20.0g/L、负载电压为5.5V、pH值为8.0是处理苯酚模拟废水的最佳条件。最后对苯酚的降解机理进行了初步探讨。 相似文献
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236.
基于WRF模式,利用发生在远距离“天鹅”台风作用下的西南低涡暴雨个例,通过修改台风动力风场,分析了不同数值试验中西南低涡降水系统对台风系统的响应。结果表明:在“天鹅”台风作用下,增强了水汽和不稳定能量的输送,导致了长时间强降水的发生;不同的台风动力风场作用下,西南低涡的移动路径具有明显的不同,降水也具有明显的区域性局地差异;在增强(减弱)台风倒槽动力风场环流作用下,低涡系统中心偏西(东)偏北(南),相应地,低空急流输送带偏东(西),进而导致中低层水汽和不稳定能量输送偏东(西),以及中低层辐合带空间位置偏东(西),进而对区域性降水空间位置产生影响,导致了降水区域局地性差异,表明远距离台风对西南低涡环流系统具有重要影响 相似文献
237.
Urban and rural dual structure in Western China is obvious.The economic development of the central cities is relatively quick while that of the rural areas is lagging behind.The speeding up of urbanization contributes to the intensively uncoordinated development of urban and rural areas.Besides,the eco-fragile environment,shortage of available water resources,adverse geographic location,and relatively backward social economy restrict the development of urbanization in Western China.However,Western China also has the advantages of backwardness.This paper analyzes the present situation and development trend of urbanization in Western China.The results show that Western China has basically formed a development pattern with"industry promotes agriculture and urban leads to village".Therefore,combined with the present situation of Western China,this paper describes and analyzes the opportunities and challenges that may appear in the process of urbanization in Western China,puts forward the development pattern in which urban and rural areas can gain mutual support and co-development,and provides related recommendations. 相似文献
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The concept of evolvability is controversial. To some, it is simply a measure of the standing genetic variation in a population
and can be captured by the narrow-sense heritability (h2). To others, evolvability refers to the capacity to generate heritable phenotypic variation. Many scientists, including Darwin,
have argued that environmental variation can generate heritable phenotypic variation. However, their theories have been difficult
to test. Recent theory on the evolution of sex and recombination provides a much simpler framework for evaluating evolvability.
It shows that modifiers of recombination can increase in prevalence whenever low fitness individuals produce proportionately
more recombinant offspring. Because recombination can generate heritable variation, stress-induced recombination might be
a plausible mechanism of evolvability if populations exhibit a negative relationship between fitness and recombination. Here
we use the fruit fly, Drosophila melanogaster, to test for this relationship. We exposed females to mating stress, heat shock or cold shock and measured the temporary
changes that occurred in reproductive output and the rate of chromosomal recombination. We found that each stress treatment
increased the rate of recombination and that heat shock, but not mating stress or cold shock, generated a negative relationship
between reproductive output and recombination rate. The negative relationship was absent in the low-stress controls, which
suggests that fitness and recombination may only be associated under stressful conditions. Taken together, these findings
suggest that stress-induced recombination might be a mechanism of evolvability. 相似文献
240.
Yong MinXiaogang Jin Jie Chang Changhui PengBaojing Gu Ying GeYang Zhong 《Ecological modelling》2011,222(17):3277-3284
Indirect effects are assumed to be the major causes of the complexity and stability of ecological networks. The complexity of urban-rural complexes (URCs) could also be attributed to the indirect effects associated with human activities. No studies, however, have quantified the strength of indirect effects in relation to urban biogeochemistry. A network environ analysis (NEA) was used for this study to investigate and compare indirect effects in relation to the nitrogen (N) cycling networks of 22 natural ecosystems and five URCs. Results show that indirect effects were proven to be weak for URC N cycling networks (accounting for only ∼2% of the overall effects measured in natural ecosystems). The weak indirect effects found provide a counterexample for the hypothesis that indirect effects are in fact the dominant components of biogeochemical networks. It also implies that human activity in itself does not always raise the complexity of ecological processes as previously suggested. Weak indirect effects also lead to perturbation fragility for URC N cycles (where the decay rate is greater in comparison to natural ecosystems by a factor of 13). In order to improve the robustness and efficiency of URC biogeochemical cycling, a knockout analysis was carried out. By comparing results after removing single interactions between natural ecosystems and URCs it was found that the loss of indirect effects require cooperative strategies to optimize N cycling networks within URCs. 相似文献