防结块工业硝酸钾新工艺的应用研究

1万t防结块工业硝酸钾的生产装置选用硝酸镁与氯化钾为原料,采用新研究开发的复分解循环反应法生产硝酸钾新工艺,副产品为六水氯化镁,六水氯化镁含少量硝酸钾,故称之为氮钾镁肥。简要介绍了生产装置的工艺原理流程、主要设备选型、产品质量、主要经济技术数据、"三废"防治等。本生产投资少,成本低,产品附加值高。     

厌氧氨氧化工艺的高效应用

厌氧氨氧化菌,俗称"红菌",通过生物化学反应,它们可以将污水中所含有的氨氮转化为氮气,以达到去除氨氮的作用,是污水处理领域很重要的微生物,该技术可以说是废水处理领域脱氮的巅峰技术。具有耗能小、占地小、运行成本低等优势,但是厌氧氨氧化菌的培养以及工艺稳定受温度、pH、溶解氧、悬浮物、有机污染物浓度等诸多因素影响,影响其运行稳定性。基于此,文章将重点分析在温度、pH和溶解氧在最佳范围时,将MBR、臭氧催化氧化技术联合用于厌氧氨氧化工艺的前处理技术,实现液体和悬浮物固体的分离,再进行厌氧氨氧化脱氮处理,结果表明,增加该前处理技术后能够有效提升厌氧氨氧化菌活性,提高厌氧氨氧化的运行稳定性。     

带自适应Lasso罚的科技人才流动多水平模型研究

随着高水平科技人才竞争日益激烈,科技人才流动受到全球政治、经济、文化和地理等诸多因素的影响。对于不同的经济体,筛选不同水平下影响科技人才流动的关键因素,并估计出这些因素的影响程度,成为颇具价值的研究课题。在真实数据中,由于变量数量众多、数据存在缺失、不同经济体影响因素差异较大,现有模型面临诸多挑战。本文通过利用带自适应Lasso罚的分位数回归,构建缺失数据插补后的科技人才流动模型,以刻画不同分位数水平下全球各经济体科技人才流动的重要影响因素,以期为政府及相关部门提供决策参考。     

Estimating shadow price for symbiotic nitrogen and technical efficiency for legume‐based conservation agriculture in Malawi

Determining the value of legumes as soil fertility amendments can be challenging, yet this information is required to guide public policy and to incentivise prescribed land‐management practices such as conservation agriculture. We use a directional input distance function (DIDF) to estimate shadow prices for symbiotic nitrogen and the technical efficiency for mixed maize‐legume production systems in Malawi. The shadow prices reflect the trade‐off between fertiliser nitrogen and symbiotic nitrogen required to achieve a given quantity of output. Our results reveal considerable technical inefficiency in the production system. The estimated shadow prices vary across farms and are, on average, higher than the reference price for commercial nitrogen. The results suggest that it would be beneficial to redesign the current price‐support programs that subsidise chemical fertilisers and indirectly crowd‐out organic soil amendments such as legumes.     

苹果中6种有机磷农药残留检测的影响因素分析

基于NY/T 761—2008方法,考察了提取溶剂、氮吹终点、基质效应、提取方式和浓缩方式5个因素对苹果中敌敌畏、乐果、甲基对硫磷、毒死蜱、杀扑磷及三唑磷检测结果的影响.其中,氮吹终点的判断是影响检测结果的关键因素,氮吹过度会造成有机磷农药损失,氮吹不完全则造成检测结果远大于实际含量.氮吹不完全情况下,氯化钠是造成基质...     

华北平原小麦—玉米轮作对奶牛粪肥的消纳能力研究

奶牛粪便富含植物营养物质,制作粪肥还田对提高土壤养分、改善土壤质量、提高作物产量以及解决牛场环境污染均具有重要的意义。文章设计了空白(CK)、习惯施肥(NPK)和不同粪肥量M30、M60、M120、M240处理,开展不同施肥模式对小麦玉米产量、土壤肥力及硝态氮残留等方面的研究。研究结果表明,连续施用两年粪肥后,粪肥施用量较高的M120、M240处理小麦玉米籽粒产量、秸秆产量、土壤全氮和速效钾含量均高于NPK处理;施用粪肥均提高土壤有机质和速效磷的含量。施用粪肥与常规施肥相比,在0~200cm的土壤剖面上NO~-_3-N分布特征完全不同,施用粪肥各处理土壤NO~-_3-N除在耕层含量较高外,耕层以下含量均较低,且差异较小。0~200cm土壤剖面NO~-_3-N累积量随着粪肥的增加而增加,6月份0~200cm粪肥各处理NO~-_3-N累积量均低于NPK处理,10月份NO~-_3-N累积量M240处理高于NPK处理,表现出过量施用粪肥造成NO~-_3-N大量累积。     

Marketing strategy in emerging markets: a conceptual framework

Citing difference between emerging and developed markets, scholars highlight need for different approaches to marketing in emerging markets. In this paper, we argue that while there are some unique characteristics of emerging markets, all countries within emerging markets do not have similar levels of product penetration and consumption. As a result, it is wrong to assume that emerging markets are untapped and under-served across the product categories. To a list of characteristics identified as unique to emerging markets, we add large population as an important characteristic and discuss its strategic implications. We develop a conceptual framework that factors in combined effect of varying degrees of product penetration & consumption levels with large population of emerging market countries. The conceptual framework identifies four strategic alternatives for marketing in emerging markets. Instead of recommending any generic marketing strategy, we propose that marketers need to choose an appropriate mix of strategies aimed at primary and selective demand creation in emerging markets.     

Social Structural Inquiries,Part 1, Qualitative and Quantitative Theories

A tightened linkage between theory and data would enhance cumulative sociological knowledge. Toward that end this article selectivity reviews and develops social structural theories – theories that explain data. To reestablish that qualitative as well as quantitative theories can be structural, it presents examples that are organized by the qualitative versus quantitative division and the level of analysis – micro, meso, macro, and the world. Boudon’s structural schematics cover all of the examples, suggesting a basic perspective that can refocus much of the diversity of current sociology.     

The Use of Organic vs. Chemical Fertilizer with a Mineral Losses Tax: The Case of Dutch Arable Farmers

The paper focuses on farm-level nitrogen fertilization strategies of Dutch arable farmers for analyzing the substitution of organic fertilizers (manure) with chemical fertilizers. The model developed investigates the impact of the major parameters affecting the inferiority of manure compared with chemical fertilizers, including the low availability and non-uniformity of the nitrogen in manure, and the low level and high non-uniformity of plant-available nitrogen supplied via manure. The sensitivity of the optimal fertilization decisions and its associated environmental impact to product price, manure cost, and environmental tax is also examined. The theoretical analysis is applied to a representative Dutch grower of ware potatoes in the northern part of the Netherlands. The results suggest that in the absence of a subsidy the representative farmer will prefer to apply nitrogen only via chemical fertilizers.     

谈高职英语教学中的分层教学

为使不同层次的学生英语学习都有实实在在的提高和收获,要时机选择慎重,考虑学生的心理承受力, 英语分层教学值得提倡。