厂商动态

厂商动态３Ｃｏｍ公司与Ｓｉｅｍｅｎｓ公司携手合作３Ｃｏｍ公司和Ｓｉｅｍｅｎｓ公司于近日宣布，两家公司已结成战略联盟，以适应集成电话数据网络市场日新月异的发展．两家公司将首先保证Ｓｉｅｍｅｎｓ公司的Ｈｉｃｏｍ电信系统与３Ｃｏｍ公司的企业数据网络系统可以...     

气凝胶──一种结构可控的新型功能材料

气凝胶是一种结构可控的新型轻质纳米多孔性非晶固态材料，具有许多特殊性质，因而蕴藏着广阔的应用前景。本文综述了气凝胶材料的制备方法、结构控制原理、性质和各种可能的应用。     

从供应商受益角度研究国际供应链合作关系

首先指出从供应商受益角度对国际供应链合作关系进行研究的重要意义，接着对国际供应链合作关系的起源及其概念界定进行了综合分析；其次对国际供应链战略伙伴关系下的供应商受益进行了相关研究结论的综合，并对我国供应商参与国际供应链合作的实际受益进行分析，然后将两者进行了比较，最后综合全文探讨得出本文研究的结论。     

蒸发式冷凝器管束中强制对流空气CFD模拟

运用FLUENT软件对圆管、椭圆管及交变曲面波纹管管束中强制对流空气热力过程进行了模拟,模拟数据经过Tecplot.10处理后直观地表征了3种管型管束中空气的速度场、压力场及温度场。结果表明,交变曲面波纹管在提高流体湍动程度及强化传热温差方面优于其它两种管型。     

第二套常减压装置低温热回收技术的应用

常减压装置低温余热较多.利用较少,造成热量损失。利用初顶油气、稳定石脑油等低温余热加热除盐水建立热水站,在节汽、节电等方面取得了较好的效果。     

Extended-spectrum beta-lactamase-producing Klebsiella pneumoniae strains causing nosocomial outbreaks of infection in the United Kingdom

Representative isolates from 10 distinct extended-spectrum beta-lactamase-producing strains of Klebsiella pneumoniae that caused hospital outbreaks in the United Kingdom from 1991 to 1994 were examined for relationships between their enzymes and plasmids. The beta-lactamases were identified by a combination of isoelectric focusing and gene sequencing. SHV-2 beta-lactamase was produced by isolates from four outbreaks, SHV-5 was involved in three, and SHV-4, TEM-15, and TEM-26 were involved in one outbreak each. All of the extended-spectrum beta-lactamases were encoded by self-transmissible plasmids, with sizes ranging from about 70 to 160 kb. No similarities between the restriction digest patterns of the extended-spectrum beta-lactamase-encoding plasmids were detected, except to some extent between those that produced TEM-15 and TEM-26. Thus, outbreaks of hospital infection with these organisms in the United Kingdom from 1991 to 1994 involved distinct organisms and resistance plasmids and appeared to be unrelated.     

Synthesis and triplex forming properties of an acyclic N7-glycosylated guanine nucleoside

A chiral acyclic nucleoside, one in which the ribose carbohydrate has been replaced with a glycerol-based linker, is prepared by glycosylating guanine at the N7-nitrogen. The stereochemically pure derivative is converted to a DMT-protected phosphoramidite for incorporation into DNA sequences. Sequence containing the acyclic N7-dG nucleoside are capable of forming DNA triplexes in which it is likely that the N1-H and N2-amino groups of the N7-dG are involved in recognition of the guanine base in G-C base pairs.     

气体动压轴承动态参数测定原理

将气体动压轴压简化为转化气膜系统后，针对其动力特点，给出气膜在微幅振动下动压轴承的实用数学模型和测定动态参数的方法，并进行了测量误差的修正。     

石化行业自动化控制仪表常见故障分析及其处理

介绍化工生产过程中仪表故障及其处理措施。