Nitrogen losses from fertilizers applied to maize, wheat and rice in the North China Plain

Ammonia volatilization, denitrification loss and total nitrogen (N) loss (unaccounted-for N) have been investigated from N fertilizer applied to a calcareous sandy loam fluvo-aquic soil at Fengqiu in the North China Plain. Ammonia volatilization was measured by the micrometeorological mass balance method, denitrification by the acetylene inhibition – soil core incubation technique, and total N loss by ¹⁵N-balance technique. Ammonia loss was an important pathway of N loss from N fertilizer applied to rice (30–39% of the applied N) and maize (11–48%), but less so for wheat (1–20%). The amounts of unaccounted-for fertilizer N were in the order of rice > maize > wheat. Deep placement greatly reduced ammonia volatilization and total N loss. Temperature, wind speed, and solar radiation (particular for rice), and source of N fertilizer also affect extent and pattern of ammonia loss. Denitrification (its major gas products are N₂ and N₂O) usually was not a significant pathway of N loss from N fertilizer applied to maize and wheat. The amount of N₂O emission (N₂O is an intermediate product from both nitrification and denitrification) was comparable to denitrification loss for maize and wheat, and it was not significant in the economy of fertilizer N in agronomical terms, but it is of great concern for the environment.     

风力发电机塔架的涂装

按照设计要求制备用于风力发电机塔架的防腐蚀配套涂料,塔架的筒体内部涂层由环氧树脂聚酰胺富锌底漆和环氧树脂聚酰胺云母氧化铁中涂漆组成,筒体外部涂层由环氧树脂聚酰胺富锌底漆、环氧树脂聚酰胺云母氧化铁中涂漆和丙烯酸脂肪族聚氨酯面漆组成。该涂料体系的防腐涂层可常温固化,厚度达到275μm,防腐蚀寿命可达20年之久,其防腐效果、耐冲击性和耐候性良好。文章同时讨论了涂装工艺过程中易出现的问题及解决办法。     

在线技改工程计成功的关键环节——青海水泥股份公司2000t/d级熟料生产线技改工程设计浅谈

设计阶段控制水泥工程造价的措施包括：推行设计招标竞争的机制：推行以设计为主体的工程项目总承包；推行限额设计，运用价值工程管理优化设计方法，加强设计变更的管理，提高设备国产化率；掌握工程造价及物资采购信息，提高投资估算，概算和设计预算的准确性等等。     

Spatial and temporal variability in methane emissions from rice paddies: Implications for assessing regional methane budgets

Growing concern over anthropogenic global climate change has intensified the need to develop accurate budgets of atmospheric methane and other greenhouse gases. Globally, flooded rice cultivation represents a major source of atmospheric methane that is expected to grow with human population. However, current estimates of global methane flux from rice paddies vary by roughly 50%. Understanding the sources of this large variability is critical for developing management strategies for atmospheric methane. Using data collected each growing season from Texas, USA, rice paddies over a 9-year period we examined the spatial and temporal sources of methane flux variability. Using standard deviation of the mean methane flux as a measured of variability, we found that accounting for rice plant height and grain yield reduced spatial variability from 25.2 to 17.7% of the mean. Temporal variability over the entire 9-year data set was 49% of the mean, 71% of which was explained by variations in average rice plant height and total nitrogen fertilizer application. The magnitude of temporal and spatial variability suggests that reliance on single-field studies for determination of global methane budgets may be questionable.     

银杏萜内酯在反相高效液相色谱中保留行为

以水 -甲醇为流动相和InertsilODS3为固定相 ,系统地研究了银杏萜内酯的反相高效液相色谱上保留行为。研究表明 ,银杏萜内酯容量因子的对数和流动相中甲醇含量呈线形关系 ,其相关系数γ大于 0 .965。     

SiO2粉末浮选除铁研究

进行了石英粉末浮选除铁净化试验，结果表明，用六偏磷酸钠作分散剂及浮选调整剂，胺作捕收剂，可获得较为理想的浮选指标。     

高转速、无稳心搅拌装置介绍

本文介绍了一种特殊的高转速、无稳心搅拌系统，具备简洁、高效、稳定、安全的特点，经使用证明，效果良好，性能可靠，为高速搅拌及无稳心反应釜的应用提供了一条新的设计及运用的途径。     

交联球形壳聚糖树脂制备方法研究

介绍了壳聚糖－乙酸溶液制备交联球形壳聚糖树脂的方法，考察了各种制备因素对产品性能的影响，得到了较为合适的反应条件。产品溶酸性能、吸附性能有较大提高，并且容易再生。     

酯交换法合成碳酸二苯酯研究进展

对碳酸二苯酯合成用催化剂、合成工艺、反应装置等进行了综述。认为国内应加强酯交换法合成碳酸二苯酯的基础研究 ,尽快实现其产业化     

用氨水作溶剂制取溴化锂的工艺研究

本文介绍了用氨水作溶剂制取溴化锂的实验方法和生产工艺。通过正交实验确定了最佳工艺条件。从所用原料的价格和工艺操作角度来看，本文提出的方法优于其它方法。