高温超导微带线滤波器的精确设计方法探讨

文中对高温超导微带线滤波器的精确设计方法进行了探讨 ,以 GSM180 0移动通信基站用高温超导带通滤波器为例进行了设计、模拟和优化。滤波器选用平行耦合型发夹式微带线结构 ,中心频率 174 7.5 MHz,通带带宽 75 MHz。模拟结果表明 :该滤波器具有良好的频响特性 ,带内波纹 <0 .1d B,反射损耗 >15 d B,基本符合设计要求     

由交换群决定的Near环

本文讨论了加群上保持零元的映射集合对映射的加法和乘法作成的Ｎｅａｒ环，研究了它的理想特点，并构造了几类特殊的左，右理想．     

中子晕核结构在引起核碎裂中的特殊作用

基于同位旋相关量子分子动力学模型，研究和对比分析了中子晕核¹¹Li和相等质量稳定核¹¹B在相同入射道条件下引起核碎裂反应中的特征. 由于中子晕核松散的晕中子结构和小的分离能与相等质量稳定核相比具有容易碎裂的特征，因此在较低能区这种松散的晕结构有利于碎裂过程的发生，随入射能量升高，这种晕结构效应逐渐消失. 而且这种在碎裂中的中子晕结构作用随靶核质量和碰撞参数的增加而减弱.     

高阶广义KDV方程和KP方程的数值解法

采用一种线性隐格式来解3-阶和5-阶的广义Korteweg-De Vries(KDV)方程,对这种方法做一推广,就能应用到它的二维形式广义Kadomtsew-Petviashvili(KP)方程．这种方法是无条件稳定的,且是无损耗的．数值实验描述了一个线性孤波运动的情形以及两个孤波交互的情形,从结果来看,它们满足孤立子解的两个守恒-动量守恒和能量守恒．     

Enhancement of stimulated Raman scattering of acetone and the generation of three-color laser by using fluorescence dye RB

The enhancement of stimulated Raman scattering (SRS) of acetone (C3H6O) and the generation of threecolor lasers in lasing dye rhodamine B (RB) were reported. The first-order Stokes wave (629.9 nm) of SRS of C3H6O was amplified by 2.83 times than that of pure CsH6O. At the same time, a dye laser of RB at the wavelength from 575 to 598 nm can be generated in a suitable concentration of RB between 3×10-5and 2×10-4 mol/L. Thus the green pump laser, yellow dye laser, and red Stokes wave concurred.     

Time discretization methods in the computation of unsteady flow

对于不同非定常流动问题, 采用合适的时间离散方法,可有效提高数值精度和计算效率. 本文在总结传统时间离散方法的基础上,对近些年发展的非线性频域法、谐波平衡法、经典时间谱方法、时间谱元法、时间有限差分法等进行了系统地总结.根据离散形式的不同,将上述方法分为时域推进法、频域谐波法、时域配点法和混合方法4大类.首先简要介绍了各类方法的数学思想以及研究进展,并重点比较了(准)周期性非定常流动计算中各方法的精度、效率以及适用范围.然后, 对各种时间离散格式的特点进行总结,并就不同的非定常流动问题如何选择合适的时间离散方法给予了建议.最后, 对这些新型时间离散格式在工程中的应用进行了简要介绍,并对其发展方向进行展望.     

Electrocatalytic oxidation of sulfite by acetylferrocene at glassy carbon electrode

The electrochemical oxidation of sulfite catalyzed by acetylferrocene (AFc) at a glassy carbon electrode (GCE) in 0.2 M NaClO₄ aqueous solution has been studied by cyclic voltammetry. Although sulfite itself showed a sluggish electrochemical response at the GCE, the response could be enhanced greatly by using AFc as a mediator, which enables a sensitive determination of the substrate (sulfite). The reaction rate constant for catalytic oxidation was evaluated as (7.02 ± 0.05) × 10⁴ M ^?1 s^?1 by chronoamperometry. Experimental conditions that maximize the current efficiency of the electrocatalytic oxidation, such as the pH and both the catalyst (AFc) and substrate (sulfite) concentrations, were also investigated. The electrochemical kinetics of electrocatalytic oxidation of sulfite by AFc has been studied by cyclic voltammetry. In the presence of 5 × 10^?4 M AFc, the oxidation current is proportional to the sulfite concentration and the calibration plot was linear over the concentration range 2 × 10^?4–2.4 × 10^?3 M . This result can be applied in the determination of real samples. Copyright © 2005 John Wiley & Sons, Ltd.     

一种新的NMR法测定溶液中碱土金属混合物的方法原理(英文)

本文研究了碱土金属离子-锶、钡及钙可以形成在NMR标尺上是稳定配合物的条件。找到了最适合得到这样的配合物的配体-C222穴醚。研究并归属了碱土金属离子以及碱金属-钠、钾及锂配合物在氯仿中的~(13)C NMR谱。检测出了可用于分析自由配体及其与碱土金属配合物的~(13)C NMR信号,还研究了不同比例混合物的碱土金属及碱金属在氯仿中的~(13)C NMR谱,得到了当自由配体过量时在钡、钙及锶每种金属浓度为1×10~(-3)M的谱中可观测到相当于自由配体及每种离子配合的配体的分立信号。这些信号的积分值的精度可以定量地表征金属离子的浓度,所得结果为首次观测到的。它可以作为用~(13)C NMR波谱建立新的无机分析方法。文中并阐明了作溶液中碱土金属混合物NMR测定方法的具体条件,并讨论了将这一方法扩展到包括一系列碱金属在内的更复杂的混合物的可能性。试验在VARIAN XL-200波谱仪上进行。     

Synthesis and Thermal Properties of a Novel Nitrogen-containing Epoxy Resin

A new nitrogen-containing epoxy resin (XT resin) was synthesized from chain extension of xylenephenolformaldehYlde resin (XPF) and triglycidyl isocyanurate (TGIC) in the presence of base catalyst. FT-IR and H-NMR analysis confirmed the chemical structure of XT resin. It was cured with dicyandiamide (DICY) and diaminodiphenyl sulfone (DDS). Dynamic mechanical analysis (DMA) results showed that the introduction of triazine ring provides epoxy polymer with good thermal stability. Furthermore, high char yields at 800℃ in thermogravimetric (TGA)analysis indicated that XT resin had potential flame retardance.