溢洪道高速水流边壁蚀损分析与防护

就防洪、泄洪的工具溢洪道的建设、蚀损、防护方面措施做了简要介绍。     

Estimation of associative nitrogen fixation in relation to water regime and plant nutrition in a long-term pot experiment with rice (Oryza sativa L.)

Summary The contribution of associative N₂ fixation to the N nutrition of lowland rice was estimated in a long-term pot experiment with ten consecutive crops of rice. The experiment comprised two N and two K levels with wet (WF) and dry fallow (DF) between the cropping seasons. Growth of N₂-fixing cyanobacteria was prevented. Greatest yields were obtained in the high NK fertilizer treatment, but with continuation of the experiment yields responsed more to DF than to WF. Nitrogenase activity, however, was favoured by WF. Higher K application increased and higher N application decreased nitrogenase activity. Under WF treatments the organic C and total N contents of the soil remained unchanged during the experimental period, but alternate drying and flooding in DF treatments caused a decline. Lower N fertilizer rates in the second five-crop period did not affect yields, but increased the ratio of N removed to N applied. For the ten-crop period the estimated N balance was positive in the low-N and negative in the high-N treatments. N balances were also established separately for both the first and the second halves of the ten-crop period. In the first period N losses were higher, and the N balance was mostly negative. In the second period only high-N combined with low-K fertilization resulted in a negative N balance. DF favoured N losses in the first but not in the second period. The highest N gain in the second period was found in the DF treatment with low-N and high-K application. In this treatment, nearly one-quarter of the N taken up by the above-ground parts of the plants could be ascribed to associative N₂ fixation. In the corresponding treatment with the higher N level and a 49% higher yield, the contribution of fixed N declined to less than 5%. When harvested straw contained more than 10 mg N g^–1, the N balance was mostly negative, while at N contents less than 10 mg N g^–1, the N balance was generally positive.     

Use of tween 20 as a substrate for assay of lipase activity in soils

Abstract

A method for assaying the soil lipase activity is described. It involves the titrimetric estimation of the amount of lauric acid released by the lipase activity when the soil is incubated with Tween 20 in the presence of toluene at 30°C for 18 h under agitation. The method is simple and precise and incubation without agitation is also possible. The method has been applied to six different kinds of soils. The lipase activity in the cultivated soils ranged from 22.5 to 75.5 mmol min^?1 g^?1 of dried soil. The K _m value for Tween 20 was 1.8 × 10^?4 m. The optimum pH was approximately 7.5. The hydrolysis of liveen 20 in soil was inhibited by glycerol which was the essential moiety of glyceride. The inhibition by glycerol was found to be competitive. These results indicate that Tween 20 is a potential substrate for the assay of the glyceride hydrolytic activity in soils.     

Intensive beach management as an improved sea turtle conservation strategy in Mexico

We evaluate the role of intensive beach management, meaning intense patrolling and nest reburial to a central hatchery, as a strategy for improving the success of sea turtle conservation at nesting sites in Mexico. We report the results of an experimental program at Playa Cuixmala, Jalisco, western Mexico. Sea turtle conservation efforts in Mexico have, in general, poor results because of lack of funds, which leads to insufficient beach protection and severe negative effects of nest removal on hatching success and sex ratios. Alternative strategies are needed to optimize limited resources. We predicted that intensive beach management, which included intense patrolling and careful nest reburial, could be an effective way to maximize nest survival and hatchling release under limited financial and human resources. The results of our 9-year study were very positive. Survival rate increased several fold during the study period. Hatching success and sex ratios were not significantly different between in-situ and removed nests. Survival in removed nests was, however, much higher that in-situ nests, because of predation and beach erosion. In total, the small (3 km length) Playa Cuixmala became the second most productive sea turtle nesting beach in the region because of these concentrated efforts. Intense beach management can be an important technique for sea turtle conservation, and can be properly applied to small beaches or the most productive sections of large beaches.     

关于渝北区宝圣湖长效管理机制及城市湖库保护措施的探讨

通过对渝北区宝圣湖整治措施、整治效果及存在的问题进行分析,结合城市湖库污染成因,探讨了宝圣湖水环境保护长效管理机制及城市湖库环境保护措施,为城市湖库及其他地表水的保护提供依据。     

Toxicological effects of TiO2 and ZnO nanoparticles in soil on earthworm Eisenia fetida

Nanoparticles (NPs) of TiO₂ and ZnO are receiving increasing attention due to their widespread applications. To evaluate their toxicities to the earthworm Eisenia fetida (Savigny, 1826) in soil, artificial soil systems containing distilled water, 0.1, 0.5, 1.0 or 5.0 g kg⁻¹ of NPs were prepared and earthworms were exposed for 7 days. Contents of Zn and Ti in earthworm, activities of antioxidant enzymes, DNA damage to earthworm, activity of cellulase and damage to mitochondria of gut cells were investigated after acute toxicity test. The results from response of the antioxidant system combined with DNA damage endpoint (comet assay) indicated that TiO₂ and ZnO NPs could induce significant damage to earthworms when doses were greater than 1.0 g kg⁻¹. We found that Ti and Zn, especially Zn, were bioaccumulated, and that mitochondria were damaged at the highest dose in soil (5.0 g kg⁻¹). The activity of cellulase was significantly inhibited when organisms were exposed to 5.0 g kg⁻¹ of ZnO NPs. Our study demonstrates that both TiO₂ and ZnO NPs exert harmful effects to E. fetida when their levels are higher than 1.0 g kg⁻¹ in soil and that toxicity of ZnO NPs was higher than TiO₂.     

防护林体系空间配置优化系统的研究与应用

该文分析了防护林体系空间配置研究现状中存在的问题,以智能优化防护林体系空间配置为思想,结合计算机技术和层次分析法,根据信息系统的理论,在Microsoft.net平台下研究并实现了防护林体系空间配置优化系统。该系统结合层次分析法的基本步骤,以向导的方式,提示用户按照设定的步骤,并结合应用区域的实际情况和专家经验,完成防护林体系空间配置的优化。为进一步验证系统的功能,应用该系统对华北土石山区半城子流域的防护林体系空间配置进行了优化,结果表明,该系统具有功能设计合理、界面友好、操作简便等显著特点,并具有较好的应用价值。该系统为防护林体系空间配置研究向智能化、高效化方向迈进奠定了基础      

站库仪表监测系统的防雷及过电压保护

概述了输油泵站和库区防雷设施及过电压保护的现状和特点,分析了目前输油泵站和库区仪表微机监测系统的防雷及过电压保护存在的缺陷,提出了适用于电力系统、建筑防雷和各种电子设施的综合防护原则。针对输油泵站和库区仪表监测系统微电子设备的特点,提出了应采取的防护措施。     

雏鸡感染巨型艾美耳球虫后细胞免疫的研究

通过用地塞米松处理鸡和用特异性抗原刺激因子的微量全淋巴细胞转化试验（ＬＰＡ）,研究雏鸡抗Ｅｉｍｅｒｉａｍａｘｉｍａ再感染中细胞免疫现象。结果表明,地塞米松处理可损伤鸡抗Ｅ．ｍａｘｉｍａ再感染的免疫力,这提示了ＣＤ８＋Ｔ细胞,γ－ＩＦＮ及ＩＬ－２等在抗．Ｅｍａｘｉｍａ再感染中的作用,利用Ｅ．ｍａｘｉｍａ卵囊抗原作刺激因子的微量全血ＬＰＡ结果表明,其刺激指数值与鸡抗Ｅ．ｍａｉｘｉｍａ再感染抵抗力有关。     

Contracting for Migration for the Reason of Zoological Environment

Migration for the reason of zoological environment is the measure for solving the crisis of zoological environment. Nowadays, governments play the chief role in the Migration for the reason of zoological environment, but the migration themselves do not have the freedom to decide whether migrate or not. Because the activity of migration is related to the restraint of economy, culture, law, etc. It is the object of migration that protect the zoological environment and improve the welfare of habitant, which must be concerned when constructing the systems of migration. This paper proves the possibility of contracting for migration based on the methodology of the cost-income analysis. On the other hand, it also argues for changing the mode of migration from that controlled by governments to being decided by habitant themselves.