关于电学基础课程物理量的量纲与单位的讨论

本文从“量”的等式观点出发,阐述了电学基础课程相关物理量的量纲与单位问题,包括将已知量代入方程的方法,导出量纲与导出单位,标准函数的量纲等。特别指出,单位冲激函数的量纲是倒时间量纲,单位阶跃特性s(t)与单位冲激特性h(t)都是响应与激励量值的某种比值,它们都不具有电压或电流的量纲,不是普通意义上的响应。唯此,卷积积分公式的量纲才能平衡。本文目的是激发广大教师在课程教学中努力探索量纲问题的积极性。     

A Novel Heat-resisting Surfactant for the Modification of Alumina Nanoparticles

An casy preparation of controlled alumina nanoparticles by the solution precipitate method has been carried out using dendrimer as surfactant.The effects of the amount and size of surfactant on morphological control of powder have also been discussed.     

聚氧乙烯功能基复合修饰聚氨酯合成及其血液相容性研究（Ⅱ）—聚氨酯—接枝

采用以碘酸基为末端基的聚氧乙烯（PEO）接枝聚醚氨酯和氨基酸反应,将赖氨酸（Lys)和酪氨酸（Tyr)通过PEO为“间隔臂”固定在聚醚氨酯上,制备了氨基酸和PEO复合修饰的聚醚氨酯PEU－g-PEO-SO2Lys和PEU－g-PEO-SO2Tyr。通过血小板粘附试验对材料的体外抗凝血性进行 了初步评价。研究结果表明,采用具有选择性吸附纤溶酶原功能的赖氨酸和PEO复合修聚氨酯,不仅减少了材料表面血小板粘附量,而且减少了材料表面栓的形成量。     

钼钒砷杂多酸有机铵盐的合成及热稳定性研究

合成了4个系列（14种）钼钒砷有机铵盐,用红外光谱、pH电位滴定、DAT－TG对其进行表征,确认其分子式为[RnNH4-N]4[HPA](R=Me、Et、Pr、Bu基;n＝1、2、3、4）;并采用DTA－TG、IR进行系列盐分步切断的热性质研究。发现其稳定性随烷基增大、取代基数目增多而增加;且盐的分解是分步进行的,最终产物为杂多阴离子的组成氧化物。     

PP—g—（GMA—co—St）对PA6—PC共混合的反应增容作用

用红外、扫描电镜、熔体流动速率和力学性能等测试方法,研究了甲基丙烯酸缩水甘油酯（GMA）和苯乙烯（St）多单体熔融接枝聚丙烯PP－g-(GMA-co-St)对PA6－PC共混合的反应增容作用。研究结果表明,在熔融共混过程中,PP－g-(GMA-co-St)中的环氧基与PA6的端氨基及PC的端羟基原位生成的接枝共聚物就有效地降低了共混物相间的界面张力,明显提高了共混物相界面的粘着力。少量的PP－g-(GMA-co-St)就能使PA6和PC的相容性得到显著改善。当PP－g-(GMA-co-St)的质量分数为10％时,共混物分散相的相区尺寸细化到0．2μm,其力学性能也有较大提高。PA6／PC／PP－g-(GMA-co-St)共混物的力学性能均衡,达到了弹性体增韧体系难以达到的效果。即使PP－g-(GMA-co-St)组分含量为20％时,共混物仍能保持较好的力学性能,特别是在共混物地韧性得以提高的同时,其强度和伸长率也提高。     

Nonlinear Optical Properties of Tri—nuclear Transition Metal Clusters M—（μ—S）s—M′（M=Mo,W;M′=Cu,Ag,Au）

The static polarizabilities and the second-order hyperpolarizabilities of a series of tri-nuclear metal cluster models MS4(M′PPh3)2(M′PPh3)(M=Mo,W;M′=Cu,Ag,Au)have been calculated within the first-principle theoretical framework. The model clusters have two fragments of rhombic units and it is the charge ransfer from one of these moieties to the other that is responsible for nonlinear optical property. This kind of electronic delocaization, differentiated from that of planar π-system, is very interesting and is worthy for further investigation.     

CH3I分子束激光裂解产物的分布

The photofragmentation of CH_3I at 249 nm has been investigated by means of our crossed laser-molecular beam apparatus with rotatable supersonic beam source. The measured I~*/I yield ratio is about 4/1. The C—I bond dissociation energy obtained is 56±1 kcal mol~(-1). The vibrational energy distribution of CH_3 fragments has been roughly estimated.     

STUDY ON SYNTHESIS OF SELF CORSS LINKED POLYSTYRENE LATEX MICROSPHERES

Emulsifier-free emulsion polymerization of styrene in the presence of β-hydroxy propyl acrylate was studied.The emulsifier-free self cross linked polystyrene latex microspheres was obtained.Monomer conversion is higher than 90% when [St],[β-HPA],[KPS] is 2.66,0.228,and 5.8×10^-3mol/L respectively under 80℃ for 5h.The mono-dispersed latex particle diameter and colloidal particle concentration were given as D=0.23um,N=3.13×10^13/cm^3 by TEM analyse,The factors of influencing latex stability were discussed.Thecopolymer was characterized by IR and dissolution experiment.The apparent activation energy of polymerization and polymerization rate constant were obtained to be 78.7KJ/mol and 514.4/mol.s respectively.     

CONDUCTIVITY METHOD APPLIED TO THE STUDY OF INTERACTION BETWEEN ADSORBENT AND ADSORBATE I．ADSORPTION OF LOW CONCENYRATION OF FREE ACID BY REGENERABLE CHITIN

The adsorption of low concentration of free acid by regenerable chitin is followed by electric conductance determination.The effect of acid concentratioin,content of functioinal amino groups,and ionic strength on adsorption was discussed.Experimental results indicate that the active centre of regenerable chitin is the free amino groups on ist surface ,and that the rate of adsorption of free acid was found to be affected by two factors:the interaction between the adsorbent and the adsorbate in solution and that between the adsorbate molecules or ions in solution.