核磁共振成像一维空间编码教学实验

利用梯度磁场实现检测信号的空间编码,是核磁共振成像(MRI)的关键技术.本文采用ccc系列样品将二维问题简化为一维,使用超小型教学用核磁共振成像仪进行了一维空间编码实验研究,并对实验过程及实验结果进行了计算模拟和分析.     

闭曲面上C0流有伪轨跟踪性质的条件

给出了闭曲面上奇点孤立的C⁰流有伪轨跟踪性质的充分必要条件     

Synthesis of ZnAl2O4/α-Al2O3 complex substrates and growth of GaN films

With the solid phase reaction between pulsed-laser-deposited (PLD) ZnOfilm and α-Al2O3 substrate, ZnAl2O4/α-Al2O3 complex substrates were synthesized. X-ray diffraction (XRD) spectra show that as the reaction proceeds, ZnAl2O4 changes from the initial (111)-oriented single crystal to poly-crystal, and then to inadequate (111) orientation. Corresponding scanning electron microscope (SEM)images indicate that the surface morphology of ZnAl2O4 transforms from uniform islands to stick structures, and then to bulgy-line structures. In addition, XRDspectra present that ZnAl2O4 prepared at low temperature is unstable at the environment of higher temperature. On the as-obtained ZnAl2O4/α-Al2O3 substrates, GaN films were grown without any nitride buffer using light-radiation heating low-pressure MOCVD (LRH-LP-MOCVD). XRD spectra indicate that GaN film on this kind of complex substrate changes from c-axis single crystal to poly-crystal as ZnAl2O4 layer is thickened. For the single crystal GaN, its full width at half maximum (FWHM) of X-ray rocking curve is 0.4°. Results indicate that islands on thin ZnAl2O4 layer can promote nucleation at initial stage of GaN growth, which leadsto the (0001)-oriented GaN film.     

25MeV／u^6He十^9Be破裂反应的α碎片发射

测量了在25MeV／u^6He轰击^9Be靶的破裂反应产生的α碎片双微分截面及角分布，并在Ser—ber模型的框架下计算了在破裂反应中衍射破裂与擦去过程的贡献，并对结果进行了讨论．结果表明基于包含衍射破裂和擦去过程的Serber模型可以对^6He的直接反应进行较好地描述，擦去过程的贡献远大于衍射破裂的贡献．相对于^6Li而言，^6He较大的去2n微分截面源于它的弱束缚特性。     

连续树映射非游荡集的拓扑结构

本文研究树（即不含有圈的一维紧致连通的分支流形）上连续自映射的非游荡集的拓扑结构．证明了孤立的周期点都是孤立的非游荡点；具有无限轨道的非游荡点集的聚点都是周期点集的二阶聚点，以及ω－极限集的导集等于周期点集的导集和非游荡集的二阶导集等于周期点集的二阶导集．     

Modulation Frequency Multiplexed Tunable Diode Laser Spectroscopy System for Simultaneous CO, CO2 Measurements

A modulation frequency multiplexed dual diode-laser system is developed for simultaneous detection of the two most common fire gas products CO and CO2. Simultaneous detection is achieved by modulating each laser at different frequencies, demodulating the signal by a pair of lock-in amplifiers for each gas. Laser beams are combined and detected by one detector after passing through an identical optical path. The experimental results show little performance degradation associated with modulation frequency multiplexing, and no cross-talk between the two multiplexed detection channels is measured.     

高斯光束照射下的圆盘夫琅禾费衍射

推导了高斯光束照射圆孔或圆盘的衍射场普遍表达式，计算了半波带数接近于零的情况下上述衍射场的数据，进而分析了圆盘衍射场在艾里斑中增加一个暗环的原因。     

实施概念图教学对学生物理学习影响的实证研究

概念图教学作为一种教学策略，在国外有着广泛的研究和应用．国内也有不少文献对此进行了介绍．概念图教学在物理教学中的实验研究，在一定程度上证实了概念图教学对学生的物理学习有影响，概念图教学优于传统的物理教学．     

用复印量探测中学数学主要刊物

中学数学杂志在我国千姿百态、繁花似锦的期刊之林中是一株新秀。它主要登载我国数学研究工作者、广大中学数学教育工作者撰写的中学数学教育科研论文,教学经验、体会、解题思维和方法等文章。它提倡不同观点的自由讨论,文章具有一定独特的创见和特色,反映出一定时期我国中学数学教育思想和中学数学教学研究的最新水平和成果。     

化学计量检定管理信息系统

介绍了一种以计算机关系型数据库作为开发平台研制开发的，应用于化学计量检定工作管理的管理信息系统。该系统能方便、快捷地检索、统计、汇总和打印下属工厂的信息及各计计器具的受检情况。