转化高新技术促进烟气脱硫技术发展

文章综述了国内烟气脱硫技术及设备发展的历程和现状，分析了引进国外全套烟气脱硫技术装置对国内用户所造成的巨大经济压力，提出走转化高新技术发展国内烟气脱硫技术的道路，介绍了国内外脱硫技术与国内技术相结合，在天津市重点工程项目上实施的实例。     

感应电动势与参照系的相对关系

本文从电磁场变换入手,举例说明感应电动势的大小及区分感生、动生电动势与参照系有关.     

腐殖质对二氧化锰引起的五氯酚转化反应的影响

研究了在二氧化锰催化引起的五氯酚的转化反应中,腐殖质前身化合物的加入对五氯酚去除率的影响,并以p-coumaricacid为代表研究了体系pH值、反应时间、二氧化锰的质量浓度以及腐殖质前生物的浓度和分子结构对去除率的影响。结果表明,反应的最佳pH值范围是4～4.70,去除率在80%左右。五氯酚在24h内去除速率较快,去除率达到75%左右;反应到168h,去除速率趋于0,去除率达到80%左右。相同条件下,无p-coumaricacid的对照体系中,对应的反应时间内去除率仅分别为20%和25%左右。五氯酚的去除率还随二氧化锰质量浓度和p-coumaricacid浓度的增加而增大。当二氧化锰的质量浓度由0增加到100g·L-1时,去除率由0增大为95%;而当p-coumaricacid的浓度由0增加到1mmol·L-1时,去除率由25%增大到100%左右。此外,不同腐殖质前身物的分子结构和浓度对去除率分别起到了提高、不明显改变和降低的作用。     

双氰胺对不同形态氮在红壤中转化的影响

采用室内好气培养方法，研究了碳酸氢铵、尿素在红壤中的转化，加入硝化抑制剂(双氰胺)对尿素、碳酸氢铵的水解速率、硝化速率的影响，以及硝化抑制剂用量问题。结果表明，无论加入DCD与否，大部分尿素在4d内水解，各处理硝态氮质量分数于35d内出现峰值，铵态氮质量分数变化趋势基本相似，尿素态氮和铵态氮的形态差异主要存在于培养4d内。双氰胺的加入明显提高了相应处理的铵态氮质量分数，降低了硝态氮的质量分数；硝化抑制剂对高质量分数(≥50％)铵态氮、尿素态氮处理的抑制效果优于低质量分数(≤50％)处理。至培养结束时中壤土中仍存在较高质量分数的铵态氮，故铵的硝化时间、尿素水解产生铵的硝化时间有待进一步研究。     

铜绿假单孢菌AS1.860对紫杉醇的微生物转化

从32株微生物中筛选出对紫杉醇1具有转化能力的4个菌株，并从中挑选出铜绿假单孢菌AS1．860进行放大实验，投入100mg紫杉醇，分离出3个产物，并通过核磁共振谱鉴定了结构，分别为baccatin Ⅲ2、baccatin V3和10—去乙酰baccatin Ⅲ4，其中2和3也是人体代谢的产物。     

Copper distribution in chemical soil fractions and relationships with maize crop yield

Agricultural practices can lead to copper accumulation in soils and at high concentration it can become toxic for plants. One common toxic effect of copper on plants is a decrease of crop yield. Here, we studied 1) the crop yield of maize grown on plots of a soil intentionally enriched with copper sulphate and 2) the possible relationship between the copper concentration in chemical soil fractions and the maize crop yield. Anthropogenic copper is mainly bound to manganese oxides, to iron oxides and to the organic matter. Maize (Zea maize L.) was grown on outdoor experimental plots. The crop yield was evaluated for three development stages: the 6–10 leaf stage, the female flowering stage and the maturity stage, 2, 4 and 6 years after the soil copper enrichment. Strong crop yield reductions, proving a toxic effect of copper on maize growth were noted 2 years after the copper input at the maturity stage and 4 years after the copper input at the 6–10 leaf stage. Variations in maize crop yield are described with linear multiple regression equations including the variable copper content in soil, and other variables when needed such as soil pH, soil organic carbon level and the climatic variables, the precipitation rate and the ambient temperature. The crop yield study at the 6–10 leaf stage and at the female flowering stage does not provide significant regression equations, while the crop yield study at the maturity stage does. Request variables for the models are the total copper content or the copper bound to the organic matter and the meteorological data. Electronic Publication     

Farmland size,chemical fertilizers,and irrigation management effects on maize and wheat yield in Mexico

ABSTRACT

Farmland size is a key factor in debates over agricultural land use, food security, agrochemical pollution, and the future of smallholder systems. This paper examines relationships between farmland size, chemical fertilizers and irrigation management, and maize and wheat yield in Mexico. We used agricultural census data to estimate the mean farmland areas and crop yields of 5.5 million farms and nine million agricultural plots in 2,455 Mexican municipalities. We also derived indices of socio-environmental and management factors to examine relationships with yield. Using multiple regression models, we found that although mean farmland area positively relates to maize and wheat yield, the relationships depend critically on the management contexts of chemical fertilizers and irrigation, which vary widely across farm size gradients. Smallholder yield gaps were associated with deficits in irrigation, rather than chemical inputs. Findings highlight the growing need for expanded irrigation access and/or water management assistance for smaller farms.     

陕西省农业旱灾系统及农业旱灾灾情模型研究

为试图解决当前有关干旱（旱灾）指标的片面性,本文提出了农业旱灾系统（ＡＤＳ）,并设计了描述农业旱灾灾情的模型：Ｅ＝ｋ＊Ｍ＊Ｈ＊Ａ。农业旱灾系统由气象干旱（Ｍ）、水利抗旱（Ｈ）、农业承旱（Ａ）及农业旱灾灾情（Ｅ）等四个要素组成。每一要素均由若干区域性指标进行刻划。在分析陕西省农业旱灾特点的同时,建立了陕西省农业旱灾系统的框架,并利用各种资料分析了陕西省农业旱灾灾情。分析结果表明,由该模型计算的陕西省各县级单位的农业旱灾灾情和几十年来的实际资料是相吻合的,模型是可靠的。而且,通过模型和实际情况的对比,能够为研究农业旱灾灾情形成机制提供更好的佐证。     

Fish Community Structure as a Measure of Degradation and Rehabilitation of Riparian Systems in an Agricultural Drainage Basin

/ Assessing the health of ecological components of agroecosystems may be accomplished by examining changes in the drainage basin, which serves as an integrator of the agroecosystem landscape. In this study we examined fish communities in terms of an array of indicators of structure and related these to changes in riparian vegetation and agricultural practice. Evidence suggests management practices designed to foster healthier environments by, for example, reestablishing riparian vegetation were associated with positive impacts on the integrity of the fish community. At the same time, continued intensification of agricultural practices in parts of the drainage basin in recent years likely has had an off-setting influence in overall improvements in agroecosystem health. Assessments of changes in the structure of the fish associations provide the balance sheet by which the counteracting influences can be aggregated and assessed.KEY WORDS: Fish community structure; Riparian system; Agricultural drainage basin     

危机管理体制构建与政府职能转变--后非典时期对于突发公共灾害处置的思考

本文以公共卫生危机和社会突发事件为个案,以政府面对这些危机所面临的挑战和取得的经验为研究对象,分析公共危机产生的原因和基本特征,提出了面对公共危机时应建立政府危机管理的预警系统,建立快速反应机制,动员社会参与危机救治,加强信息流通,加强公共危机的法制化建设.