玻尔兹曼熵和克劳修斯熵的关系

由玻尔兹曼熵关系推导出了克劳修斯熵的表达式,论述了玻尔兹曼熵和克劳修斯熵的关系。     

时间门在天线时域远场测试中的应用

文章利用测量系统的快速扫频功能通过逆傅里叶变换获取天线的时域方向图,并利用时间门对环境散射信号进行了处理,返回频域后获取了更加接近理论的方向图;另外,还通过选择不同时间门实现了2个天线方向图的同时测量,并对时间门误差进行了分析。     

对人才流动的探讨

人才的流动并非都是坏事,合理的人才流动既有助于企业形象的塑造和凝聚力的提升,又有助于企业综合竞争力的提高。但人才过频的流动,对企业会产生不利的影响。中国加入WTO后,人才竞争进入白炽化程度,要留住人才,关键要有一套人才合理流动的机制。     

[Bmim]BF4离子液体中丙烯腈-丙烯酸甲酯共聚物的合成及序列结构

以离子液体1-丁基-3-甲基咪唑氟硼酸盐（[Bmim]BR）作为溶剂，采用丙烯腈（AN）、丙烯酸甲酯（MA）作为单体，偶氮二异丁腈（AIBN）作为引发荆进行自由基共聚反应．利用^13C—NMR谱分析了共聚物中各三单元序列组的摩尔分数与单体投料摩尔分数的关系．通过计算得到的三单元序列摩尔分数推算得两单体的竞聚率为rA=0．33，rM=0．89．同时发现，[Bmim]BF4中AN和MA的链增长过程与Bernoulli模型有较大偏离，说明AN和MA在离子液体中的聚合过程中，增长链邻位上的链节对端基的选择性有较大影响，聚合物的各序列增长与反应时阀、单体摩尔分数及单体转化率有较大关系，并计算了受邻位链节影响的丙烯腈及丙烯酸甲酯的竞聚率：rMM=0．73，rAM=1．79，rAA=0．27，rMA=0．64．     

Pt原子百分含量对FePt合金薄膜结构的影响

采用直流磁控溅射在SiO2（0001）基片上制备了不同Pt原子百分含量的FePt合金薄膜,薄膜样品经过650℃热处理1h,得到了L10有序结构．利用X射线衍射对样品的结构进行了分析,结果表明Pt原子百分含量对形成L10有序结构有明显的影响．     

Atom Transfer Radical Polymerization of Acrylonitrile in Ionic Liquids

The controllable molecular weight and polydispersity of polyacrylonitriles(PANs) were synthesized in ionic liquids(ILs) by atom transfer radical polymerization(ATRP) using ethyl-2 bromopropionate(EPN-Br) as initiator and CuBr/pentamethyldiethylenetria-mine(PMDETA) as catalyst.The polydispersity index(PDI) in the ATRP of acrylonitriel(AN) in ILs is lower than 1.3.From the polymerization kinetics,plots of ln([M]0/[M]) with time show a linear dependence at the early stage of polymerization while the deviation ...     

聚丙烯腈-离子液体稀溶液体系特性粘度值的修正

在40℃下测定聚丙烯腈-离子液体（[BMIM]BF4）稀溶液的特性粘度[η]，发现其比浓增比粘度（ηsp／C）与浓度C并不成线性，而是在低于某个浓度时曲线发生向上弯曲，这种现象早在20世纪50年代的很多高分子溶液中得到证实。发生这一情况的原因仅仅是由于高分子链在毛细管表面的吸附效应。利用在朗缪尔等温线基础上建立起来的吸附效应理论，能很好地修正实验中得到的粘度数据。     

从全液压式二板注塑机看机电液一体化

重点介绍了全液压式二板注塑机的结构原理和特点及机电液一体化的发展前景。     

Structure Analysis of Polyacrylonitrile Polymerized in Ionic Liquids

Polyacrylonitriles （PANs） ware synthesized both by atom transfer radical polymerization （ATRP） anti free radical polymerization in ionic liquid 1 - buty - 3 - methylimidazolium chloride （[bmim]Cl）. [bmim]Cl demonstrates to be a preferable solvent for ATRP of acrylonitrile （AN）. The polymerization maintains the usual advantages of ATRP with molecular weight agrees well with theoretical value and low polydispersity （PDI = 1.15）. It is also shown the higher conversion and lower molecular weight dispersion in ionic liquid than in dimethylformamide （DMF）. From FTIR and NMR analysis, it is confirmed that the chemical structures of PANs synthesized in [bmim]Cl were identical with that obtained in DMF. In atom transfer radical polymerization, the methine and cyan carbon atoms in isotactic configuration for PAN produced in [bmim] Cl have a configuration consisting of about 55.5% isotactic diads. It is higher than that obtained in DMF which is 52.2%. So, ionic liquid has effect on the stereostructure of PANs. Further analysis of ^13C NMR spectra indicated that the isotacticity of PAN synthesized by free radical polymerization was lower than that of PAN prepared by ATRP, although both of them were random in stereoregularity. Besides the pentad tacticities of PANs also suggested that the sequence distributions of them all obey Bernoulli statistics.     

生理生化指标证实8℃为白银豆幼苗的临界生长低温

温州白银豆起源于热带美洲,对低温敏感,在浙江地区经常遭受倒春寒.笔者曾借助电导率法基于Arrhenius图预估白银豆幼苗生长临界低温为8℃.检测了白银豆幼苗在8℃低温胁迫下叶绿素和丙二醛的含量、光系统Ⅱ的最大光化学效率(Fv/Fm)、超氧化物歧化酶和过氧化物酶的活性的24 h动态变化.结果表明,8℃作为白银豆幼苗的临界生长低温是合理的.