20种保水剂吸水特性的研究     

汪亚峰  李茂松  卢玉东  宋吉青  李章成  罗春燕  缪驰远 《勤云标准版测试》2005,(1)

保水剂用于防治水土流失成为水土保持学科中一个新的研究领域,但目前在这方面还缺少系统的研究,为避免盲目应用保水剂,选取国内外教20种保水剂,通过试验测定了它们的吸水特性,从而为进行水土流失防治选取更适宜的产品做出了依据。实验结果表明:ABD型保水剂吸水速率从小到大的顺序为:ABD4型相似文献   

流动风险源突发性环境事件环境污染及生态损失价值评估     

陈志凡  向哲涛  耿文才  范礼东  陈凤枝 《安徽农业科学》2015,(33)

结合流动风险源次生的突发环境事件发生及污染与控制过程特征,依据有关法律法规,构建流动风险源次生的突发环境事件环境污染及生态损失价值评估程序与技术指标体系。评估程序包括事件调查、环境污染及生态损失识别、环境污染及生态损失价值评估、结果分析与讨论、编写评估报告5个基本环节;将流动风险源次生的突发环境事件造成的损失分为直接经济损失(包括实物价值损失和处置、修复与管理费)和间接经济损失(包括资源性损失和环境功能损失)两大类,共21小类;针对不同的损失类别,采用不同的价值评估方法。最后,以损失项目核查表与损失价值评估总表的形式表征评估结果。  相似文献   

不同的密度和移栽期对水稻产量构成因素的影响     

崔一龙  朴仁哲  朴哲 《延边大学农学学报》1995,(1)

密度和移栽期的不同处理对水稻株高、叶龄、叶色的影响不大，其差异不明显，但稀植（３０×２６ｃｍ）与较密植（３０×１３ｃｍ）相比有效分蘖终止期向后延迟，最高分蘖期相近，有效分蘖率提高，在有效穗中二次分蘖穗所占的比重增多；茎基部仲长节间缩短变粗，秆壁增厚．折损重大，抗倒伏能力增强，二次枝梗数明显增多，从而引起每穗粒数增多。方差分析结果表明：不同密度间产量差异不显著，但不同移栽期之间产量有显著差异；多重比较结果表明，稀植的情况下５月２８日移栽的比５月２０日、２４日移栽的明显减产．其差异达极显著水平。要达到低耗增效的目的，在采用稀植栽培技术体系的同时，应适时早插为宜。  相似文献   

潜水泵站选型中应注意的事项     

王书丽  王兴荣  周锦宏 《排灌机械》2005,23(5):41-42,47

为了解决由于泵站在设计中泵选型不合理而出现的水泵不能正常运行的问题,从水泵生产厂家的角度,通过具体实例,对泵站设计的各个环节进行分析,得出潜水泵运行时的工况点与潜水泵站设计形式及泵选型有关的结论,分析潜水泵站在选型中应注意的事项,给出了选型方法.  相似文献   

DECADAL MODELLING OF RAINFALL EROSIVITY IN BELGIUM     

N. Diodato  G. Verstraeten  G. Bellocchi 《Land Degradation \u0026amp; Development》2014,25(6):511-519

Hydrological extremes are major weather related disasters, but little is known about their long‐term patterns in the context of environmental change. Better understanding of damaging rainfall (e.g. rainfall‐erosivity events) occurring at different time‐scales has important implications for hydrological and land degradation management. The study of the interdecadal variations may help in understanding some of the consequences of abrupt environmental changes over long time periods. Thus, a decadal‐scale rainfall erosivity model (DREM), comparable with the Revised Universal Soil Loss Equation (RUSLE), was developed based on a parsimonious interpretation of rain aggressiveness (95th percentile of rainfalls). The DREM was parameterised to capture interdecadal erosivity variability at the Ukkel station (Belgium), which has the longest RUSLE‐based rain‐erosivity series in Europe (1898–2007). The DREM performed well against decadal RUSLE data, with a coefficient of determination (R²) of 0·72 and a Nash–Sutcliffe efficiency index of 0·71. The model outperformed three well‐established models used in this study (R² ~ 0·4). For a spatial evaluation of the DREM, a pattern of decadal rainfall erosivity was provided for an area around Ukkel, which includes the western part of Germany bordering Belgium, and was compared with maps from the RUSLE approach for 1961–1990. The 95th percentile of June–September rainfalls proved to be a better predictor of decadal rainfall erosivity than yearly based precipitation amount. These results lay the foundation for estimating decadal erosivity in the surrounding areas of Ukkle as well as for historical reconstructions where detailed hydrological data are unavailable, and assumptions cannot be met, for physically based models. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

高效节能双管荧光灯镇流器的研制     

叶文荪 《安徽农业大学学报》1991,(3)

本文论述了一种新型高效节能双管荧光灯镇流器的结构和原理,推求了该镇流器电参数的估算公式,提供了30W及40W双管荧光灯采用该镇流器和采用两个通用的电感式镇流器时的对比实验数据,结果表明:在荧光灯光输出相同的前提下,采用该镇流器不仅接入电路的功率因数高,可减少输入电流50%;而且可减少输入有功功率,30W及40W双灯节能镇流器,在额定电压下,可减少输入有功分别为7W和5W左右。电路总体可节约有功20%,节约无功80%。  相似文献   

大米淘洗过程中7种矿物元素损失研究     

谢涛  罗艳  李健  班雁华  陈桂銮 《安徽农业科学》2013,(28):11499-11500

[目的]研究稻米淘洗次数与微量元素含量关系,评价大米清洗过程矿物成分损失情况。[方法]根据稻米的淘洗过程,测定不同淘洗次数下大米的各种营养元素含量。[结果]试验得出,各种营养成分在大米中不是均匀分布的,在淘洗过程中,营养成分将不同程度地流失,且淘洗次数越多,损失越大。[结论]大米在淘洗过程中各种营养元素均有不同程度损失,因此改进大米的加工过程,生产和食用清洁米,对于有效保留大米中营养元素具有重要意义。  相似文献   

Comparative Analysis of Runo and Sediment Yield with a Rainfall Simulator After Experimental Fire     

E. Marcos  R. Tarrega  E. Luis-Calabuig 《Arid Land Research and Management》2013,27(3):293-307

Changes produced in runoff and sediment levels before and after fire and during the revegetation process were examined using a rainfall simulator. The area was burned in an experimental fire, reaching temperatures from 35° to 563° C. Then it was revegetated using different species combinations. Fifteen permanent plots were established in the burnt area (4 treatments and a control replicated three times). Simulated rainfall of 15 mm per 5 min was applied in each treatment. No significant differences were found in sediment yield and runoff between treatments, but greatest runoff was observed to occur immediately after the fire. A significant relationship was found between runoff and woody cover, and a decrease in runoff can be observed as cover increases. The relationship between sediment yields and runoff rates was also positive. The low rates observed during rainfall simulation are due to the effect of natural vegetation rather than revegetation treatments. The high organic matter content also had an influence on the low rates of runoff and sediment.  相似文献   

Decomposition of a Native Shrub,Piliostigma reticulatum,Litter in Soils of Semiarid Senegal     

M. Diack  M. Sene  A. N. Badiane  M. Diatta  R. P. Dick 《Arid Land Research and Management》2013,27(3):205-218

Developing effective management strategies that restore degraded soils requires an evaluation of the quality of the litter residues. This study relates the chemical composition of the biomass components to the decomposition rates for Piliostigma reticulatum (DC.) Hochst., a native shrub, under field and laboratory conditions. The rates were determined by mass loss. The changes in the specific surface area of the residue in relation to mass loss ranged from 15 X 10 -5 to 45 X 10 -5 which was similar to crop residues in other studies. At field conditions, P. reticulatum mass loss was higher (80% of the initial mass lost over eight months) than that under controlled conditions (50%). Such fast decomposition of residues offers the potential for farmers to stop burning these residues because high amounts of residues will not likely accumulate and cause interference with tillage and planting operations. Further studies are needed on the role of soil fauna on decomposition, mineralization of nutrients from these residues, and the potential for incorporating residues into the system without burning.  相似文献   

The Biology and Control of the Grasshopper Zonocerus variegatus     

W. W. Page 《国际虫害防治杂志》2013,59(3):270-277

Abstract

The grasshopper Zonocerus variegatus (L.) is recognised as a pest of many crops in West Africa. Evidence that it is becoming an increasing problem in southern Nigeria prompted research into the biology, bionomics and control of this insect. Summaries of the main points in the biology, bionomics and recommended control are given. It is concluded that although a chronic pest it only periodically causes economical damage to cassava and community self help is the best level at which to effect control.  相似文献