抗磁离子与氨基酸络合的NMR研究

用NMR测T₁法研究了Fe³⁺存在条件下,抗磁离子Zn²⁺、Cd²⁺、与丙氨酸的络合情况。顺磁离子使配体碳原子的纵向弛豫时间T₁明显缩短。加入抗磁离子后,由于配体竞争并将Fe³⁺置换下来,而大大加长T₁时间,根据弛豫时间的变化便可判断几种抗磁离子的相对络合能力。本文引入一个物理参数来表征抗磁离子的络合能力。     

New generalized computations of quasi-planar waveguides characteristics

An efficient hybrid field solution to the general multilayer substrates transmission line problems with full shielded and half open cross-sectional geometry is presented by using the waveguide modes coupling and decoupling procedure in the spectral domain. Modal transverse transmission lines corresponding to the LSE and LSM modes are taken into account so that the Green's elements for the edge conditions can be derived by a simple iterative method. In this paper, we analyze not only the propagation constants and characteristic impedances but also the available transmission power capacity and power distribution of most commonly used structures. Normalized eigenmode power levels characterizing the propagation features are computed.     

Formation of CNx thin films by reactive pulsed laser deposition assisted by electron cyclotron resonance microwave discharge

Amorphous carbon nitride thin films were synthesized by pulsed laser deposition combined with electron cyclotron resonance (ECR) microwave discharge in nitrogen gas. The ECR discharge supplies active nitrogen species in the deposition environment and to the growing film surface, enhancing the film growth in complex processes accompanied by chemical reaction. The synthesized films were characterized by Rutherford backscattering spectroscopy (RBS), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and Raman spectroscopy. The films were determined to consist purely of carbon and nitrogen with a nitrogen concentration of 42%, and have a thickness of 550 nm over which carbon and nitrogen are well distributed. Structural characterizations based on XPS, FTIR and Raman analysis showed that these films appear to contain several bonding configurations between carbon and nitrogen with a small amount of C≡N bonds compared with other bonding states. Received: 31 August 2000 / Accepted: 12 December 2000 / Published online: 23 May 2001     

Point-splitting regularization for gauge theories: Quantum electrodynamics

As a method of regularization, point splitting has played an essential role in the recent theoretical determination of the masses of the Higgs boson and the top quark. It is the purpose of this paper to put this pointsplitting regularization on a firm basis. The result turns out to be extremely simple: replace the usual vertex factor-ieγ ^µ in quantum electrodynamics by $$ - ie(\gamma _\mu - \frac{{\not p}}{{p \cdot \delta }}\delta _\mu ),$$ wherep is the momentum of the photon line, andδ ^µ is the distance for point splitting. No additional vertices are needed.     

盐酸川芎嗪的荧光光谱研究及应用

在 p H6— 10的水溶液中 ,盐酸川芎嗪产生稳定的荧光。最佳激发波长与发射波长分别为 2 95nm和335nm,当盐酸川芎嗪浓度为 5.0× 10 -6— 5.0× 10 -5mol/ L时 ,荧光强度与浓度有良好的线性关系。据此建立了荧光光度法直接测定盐酸川芎嗪注射液中盐酸川芎嗪含量的方法 ,该方法的相对标准偏差为3.51% ,检出下限为 1.0× 10 -6mol/ L。     

克尔效应导致的鬼像位置移动

在近轴条件下,利用矩阵光学的方法研究了高功率高斯光束通过不同光学元件时,克尔效应导致的介质折射率的变化对鬼像位置的影响.计算了单个双凸透镜,单个双凹透镜以及4F系统中反射光线形成的低阶鬼像的位置移动,并将鬼像位置移动的规律表示为入射光束束腰和峰值光强的函数.     

混合纤芯光子晶体光纤超平坦色散的研究

利用平面波展开法,系统地研究了一种具有混合纤芯结构的光子晶体光纤的色散特性. 数值计算结果表明,通过优化结构参量,这种新型结构的光子晶体光纤在通信窗口1.55 μm 附近可以获得带宽超过800 nm的超平坦色散区域（色散曲线的变化范围不超过 ±0.6 ps·km－1·nm－1）.