浅谈给水用塑料管材的质量现状

根据塑料管材的质量现状。介绍了给水用硬聚氯乙烯（PVC-U）管材、聚丙烯（PP-R）管材和交联聚乙烯（PE-X）管材在使用中出现的各种质量问题及原N。     

建筑用新型塑料给水管材的综合性能分析

塑料给水管作为新型的化学建材,具有节能、保护生态环境、改善居住环境、减少饮用水二次污染、提高建筑功能与质量、降低建筑自重和方便施工等优点。笔者经过对目前市场上主要的新型塑料管材——高密度聚乙烯(HDPE)管、交联聚乙烯(PE-X)管、无规共聚聚丙烯(PP-R)管和聚丁烯(PB)管等进行性能分析研究、综合经济比较,并提     

采暖方式的重大变革

冷热镀锌钢管的替代产品——交联聚乙烯管材 ,日前已在河北省武邑县德鑫塑料管材有限公司投入批量生产。至此 ,由交联聚乙烯管材为主要材料的地板辐射采暖也变成了现实。在城镇住宅建设中使用冷热镀锌钢管弊端众多 ,国家有关部委已明令禁止。河北省武邑县德鑫塑料管材有限公司不惜重金引进了化学交联聚乙烯管材专利以及国际一流的生产设备 ,生产出了“国家化学建材测试中心”和“中国预防易学环境卫生监测所”鉴定合格的高科技产品。该产品具有耐热、耐压、耐腐蚀、耐老化、不脆裂、不生锈、不结垢、不霉变、无毒、无噪音、热能损失小、使用…     

建筑用新型塑料给水管材的综合性能分析

塑料给水管作为新型的化学建材,具有节能、保护生态环境、改善居住环境、减少饮用水二次污染、提高建筑功能与质量、降低建筑自重和方便施工等优点。笔者经过对目前市场上主要的新型塑料管材—高密度聚乙烯(HDPE)管、交联聚乙烯(PE-X)管、无规共聚聚丙烯(PP-R)管和聚丁烯(PB)管等进行性能分析研究、综合经济比较,并提出先用建议。     

聚乙烯管在北方地区燃气管网中的应用

燃气用管材是城镇燃气工程施工中的重要材料。目前我国城市燃气管网常用管材主要是钢管、球墨铸铁管以及聚乙烯管(PE管)。在80年代中期,聚乙烯管得到国际燃气界的公认后,开始受到国家有关部门的重视。我国从开始开发和试用聚乙烯管到“九五”期间有了较大发展,使用聚乙烯管的城     

浅谈聚乙烯管材在矿区的推广和应用

聚乙烯（PE100）管材在建筑中的设计理论和施工技术等方面取得了很大的发展和完善，并积累了丰富的实践经验，促使聚乙烯管材在建筑给排水管道工程中占据了相当重要的位置，并形成一种势不可挡的发展趋势。PE100管是采用先进的生产工艺和技术，通过热挤塑而成型，具有耐腐蚀．内壁光滑．流动阻力小、强度高、柔韧性好．重量轻、卫生等特点。这里结合本人在矿区的工作实践谈几点体会。     

可溶解聚氨酯交联大分子的成长过程

进行了可控的交联聚合，对不同时间形成的分子拍摄的透射电镜照片显示了可溶解的交联大分子的形成过程中有三个明显的不同阶段．第一个阶段是预聚物分子反应形成比较小的线团，在照片上显示为一个黑点，称为点分子．第二个阶段是点分子通过表面官能团反应形成前交联大分子．第三阶段是前交联大分子反应形成可溶性交联大分子．     

聚乙烯管在给水工程中的应用

本文通过对聚乙烯管的特点进行了分析，并结合给水工程特定的环境和要求，提出了在敷设聚乙烯管时应该从防老化方面、温度方面，刚度保护方面来考虑，使其在给水工程实践中，充分发挥了聚乙烯管材的优越性和弥补了其缺点。     

双螺杆反应器法制备高相对分子质量聚乳酸共聚物的研究

采用熔融缩聚法合成一定相对分子质量的聚乳酸（PLA），然后通过双螺杆反应挤出机与聚已内酯多元醇（PCL）的聚氨酯预聚体进行熔体扩链，制备聚乳酸共聚物。研究了熔体扩链产物的相对分子质量、形态结构、热性能和力学性能。结果表明，双螺杆反应挤出制备聚乳酸共聚物是可行的，熔体扩链后产物的相对分子质量有大幅度提高，产物是热塑性的，并且比釜式反应混合效果好。     

新型PET超韧性工程塑料的制备

此项工作集中于基于回收PFT瓶的高韧性工程塑料的研究。简要介绍了该聚合物合金的加工过程，其主要工艺是通过低温固相挤出和反应挤出制备。借助扩链剂与PET的反应，形成该材料的三维网络结构，同时保留吹瓶加工时的有序结构。研究了该聚合物合金材料的增韧机理，并分析其性能与结构的关系。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

正~~     

Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has