二灰碎石基层沥青路面横向裂缝问题的初步探讨

本文针对二灰碎石基层沥青路面横向裂缝的原因,并提出了二灰碎石基层沥青路面横向裂缝的特点。     

二灰碎石半刚性基层沥青路面横裂缝起因的探讨

本文针对在施工中混凝土路面出现的干缩裂缝、横向断板及纵向断板产生的原因进行分析,并提出了相应的预防措施。     

空心板板缝开裂的原因及预防措施

本文较为详细地论述了预制楼板裂缝产生的原因;预防预制楼板开裂的有效措施以及裂缝出现后的有效补救方法。     

用丝束电极研究亚硝酸钠对低碳钢缝隙腐蚀的影响

在5％NaCl溶液和5％NaCl＋5％NaNO2溶液中，采用丝束电极技术测量了低砖、钢缝隙内、外的自腐蚀电位和电化学阻抗谱，研究了亚硝酸钠对低碳钢缝隙腐蚀的影响．结果表明，在5％NaCl溶液中，缝隙内的碳钢为阳极、缝隙外为阴极；随浸泡时间增加，腐蚀不均匀性增加．加入5％NaNO2后，缝隙内外的腐蚀电位都正移，电位差减小，碳钢的腐蚀速度显著降低．亚硝酸钠使碳钢表面形成致密氧化膜，有效抑制了碳钢的缝隙腐蚀．     

电偶腐蚀和缝隙腐蚀的发生及预防

主要介绍了电偶腐蚀和缝隙腐蚀的定义、发生原理、常见形式及相应的预防措施。     

金沙江干热河谷元谋强侵蚀区土壤裂隙形成与侵蚀机制

根据金沙江干热河谷元谋地区红土层非常发育的裂隙现象,对该地区典型区土壤裂隙形成的环境和土壤剖面进行了调查,并采样进行相关土壤理化性质测定、粘土矿物X-射线衍射分析以及土壤微形态研究。结果表明:(1)该区旱季丰富的土壤裂隙形成与该区主要分布的第四系古红土层(QS)和第四系元谋组的黄棕色土层(QY)等红土母质特性有密切关系;(2)由于土壤裂隙非常发育,成为了边坡崩塌和直接产生重力侵蚀的成因,加剧了土壤侵蚀过程,导致了土柱和土林等强侵蚀景观形成。研究表明,土壤裂隙是金沙江干热河谷元谋地区强烈侵蚀和水土流失所特有的成因。     

Synthetic Pyrethroid Insecticides: Some Studies with Locusts

Abstract

Laboratory studies were carried out to determine the course of poisoning and toxicity of some synthetic pyrethroid insecticides (bioresmethrin, cismethrin, cypermethrin, deltamethrin, fenpropathrin, fenvalerate and permethrin) against the desert locust. From doses in excess of the LD₉₉ all the insecticides were quick acting; from doses of about the LD₉₉ or less the insects are rapidly knocked down or show symptoms of poisoning, but may recover. The symptoms which follow treatment by the various insecticides are described. Although these insecticides are all highly toxic to locusts there are many other insecticides which are similarly toxic, can be sprayed at high concentrations and are much cheaper.     

Detection and Monitoring of Larger Grain Borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae)

Methods for detecting and for monitoring Prostephanus truncatus(Horn) are crucial components in phyto- sanitary control, research programmes and pest management against this beetle. P. truncatus is unusual in that its populations are distributed widely between natural habitats and stores holding maize grain and dried cassava roots, which necessitates a similarly wide range of sampling methodologies. This review considers successful and unsuccessful approaches to sampling the pest populations in both stores and the natural environment and concludes with a consideration of how monitoring could contribute to integrated pest management for P. truncatus.     

分析水泥混凝土路面早期裂缝的原因及其预防措施

水泥混凝土路面早期裂缝产生的原因有:在设计时路面强度设计不够.选材时材料质量不过关,施工中没有严格按规程施工。预防措施是:设计时要充分考虑路面强度,材料质量要好,配比要精确,施工时避免高温下工作,加强潮湿养护。     

论述混凝土裂缝形成的原因及防治措施

论述混凝土在施工中裂缝产生的几个重要因素。分析和总结裂缝产生的原因，强调了施工中所采用的几种防治措施。