Simulation of Rate Retardation in RAFT Polymerization of Styrene with Low RAFT-Initiator Ratio

Controlledradicalpolymerizationhasrapidlypro gressedsinceitsintroduction,andseveralnewmeth odshavebeendevisedforitspractice.Thesenewtechniquesincludeiniferterpolymerization,radical polymerizationwith2,2,6,6tetramethyl1piperidiny loxyl(TEMPO),atomtransferradicalpolymerization(ATRP)andreversibleadditionfragmentationchain transfer(RAFT)polymerization[1—4].Inallcasescontrolledradicalpolymerizationprocessescanbeachievedbyintroducingareversiblereactionbetween livinganddormantspecies.Especially…     

关于入学率与平均预期受教育年限的思考

探讨平均预期受教育年限、平均受教育年限与入学率的关系。平均预期受教育年限完全取决于教育发展程度，可以由衡量教育普及程度的入学率测算。我国的平均预期受教育年限不到11年，提高平均预期受教育年限有一定的空间。探讨提高我国平均预期受教育年限的几种方案。     

Effect of flushing on the detachment of biofilms attached to the walls of metal pipes in water distribution systems

Biofilm detachment caused by flushing can result in secondary contamination in drinking water distribution systems (DWDSs). To evaluate the impact of flushing on biofilm detachment, actual water supply pipes including ductile cast iron pipes (DCIPs), gray cast iron pipes (GCIPs), and stainless steel compound pipes (SSCPs) were used in this study. Real-time quantitative polymerase chain reaction and 454 pyrosequencing were used to quantify bacteria and analyse microbial community composition, respectively. The results showed that the pipe material greatly influences the resistance of a biofilm to flushing. Biofilms attached to DCIPs were able to resist quite strong flushing, while those attached to GCIPs and SSCPs were sensitive to flushing. Both flush-resistant and flush-sensitive bacteria were present in all the biofilms, but their frequency differed among the different metal pipes. Thus, the resistance to flushing of bacteria is related not only to the nature of the bacteria, but also to the pipe material. Although flushing can remove some of the biofilm and may be a good way to clean the DWDS, the shear stress needed to remove the biofilm differs among different pipe types. The results of this study provide technical support for the management and operation of DWDS.     

《经济数学基础》试题评价分析

本文对1999年1月、1999年3月、2000年1月及2000年7月考试的《经济数学基础》四份试题进行了统计，总结了考试要点，并作评价与分析，对今后的教学提出一些建议。     

Wave protection effect of periodic row of bottom-hinged flap-type wave energy converters

A flap-type wave energy converter (WEC) is combined with a nearshore breakwater to expand the application of WECs both economically and environmentally. Based on the linear potential theory, an eigenfunction expansion solution is developed for a periodic row of bottom-hinged flap-type WECs exposed to normal waves. Additionally, the viscous effect is considered using the ship rolling solution method with a viscous damping term included in the equation of motion, and the viscous damping expression is also described. The proposed solution is verified by comparison with published literatures. The results including the wave energy conversion efficiency, the reflected and transmitted proportion of the incident wave energy are presented for a range of wave periods and geometric ratios. It is demonstrated that better wave protection effects can be attained with smaller gaps between the WECs, where the transmitted proportion of the incident wave energy is lower. An optimal geometric ratio thus exists for a given wave power absorption and a specific wave period.     

Jordan域边界的拟等距扩张

本文证明了Ｊｏｒｄａｎ域的边界上的拟等距映照在一定条件下可以扩张为Ｄ上的拟等距映照，该结果是Ｆ．Ｗ．Ｇｅｈｒｉｎｇ的对应的平面结果的空间拓广．     

信息技术在集成供应链管理中的应用

信息技术高速发展,供应链与供应链之间的竞争日益激烈。集成供应链管理能较好地满足竞争与发展的需要。本文论述了信息技术如何在集成供应链管理中发挥应有的作用,实现供应链节点企业的“多赢”局面。     

关于重构我国农村义务教育财政体制的思考

我国农村义务教育财政面临着政府教育经费投入不足、学校财政经费严重短缺、教育财政资源分布不均衡等问题。这些问题是由于地方政府农村义务教育财权和事权不统一、财政转移支付制度不完善和地方政府财政预算约束力软化等原因造成的。重构我国农村义务教育财政体制应采取以下策略：建立“分地区、分级负责”的农村义务教育财政管理制度,建立以“地市级财政收支缺口”为标准的农村义务教育一般转移支付制度,建立系统的农村义务教育经费预算、监督和审计制度。     

Study on a 5.0 W/80 K single stage Stirling type pulse tube cryocooler

A single stage Stifling pulse tube cryocooler was designed based on REGEN 3.2 and fabricated for testing. The experimental results show that the cooler can provide a cooling capacity of 5.0 W at 79.1 K, and produce a no-load temperature of 57.0 K, operating with an average pressure of 2.50 MPa and a frequency of 60 Hz, performance results that are very close to the calculated values. The cryocooler can be cooled from room temperature to 80 K in 8.5 min. The fast cooldown time is a result of the small regenerator.     

师生深度共读名著的策略摭探

师生共读名著活动,不仅能让学生真正读懂名著,还能提升学生的认知水平,让名著所蕴含的精髓成为学生成长道路上宝贵的精神食粮。教师可采取以下策略开展师生深度共读名著活动:在正文阅读前进行整体审视,确保阅读时间和阅读环境恰当适宜,利用有效方式引导学生交流,通过情境创设分析名著,阅读结束后引导学生反思。