发挥实验在物理教学中的作用

实验是物理教学的重要组成部分,然而随着现代教育技术的发展,多媒体技术的应用,越来越多的教师选择多媒体课件演示代替物理演示实验,实验题目代替学生实验,有的学校物理实验设备陈旧,有的几乎不开物理实验课,长此以往学生对物理学习几乎没什么兴趣,学生的动手能力和创新能力也难以提高．     

原子吸收光谱法测定污水处理后污泥中的Hg、As、Pb、Cd和Cr

采用火焰原子吸收光谱法测定了污水处理后污泥中的重金属离子,测定结果(mg/kg)为:Hg 0.91、As 2.71、Pb 2.99、Cd 0.52、Cr 647.8.相对标准偏差分别为:1.8％、2.0％、1.6％、1.1％、0.9％.     

关注概念生成过程,培养数学抽象思维——以人教版教材“平面直角坐标系”为例

数学抽象作为数学学科核心素养之一,是指通过对数量关系与空间形式的抽象,得到数学研究对象的素养.主要包括:从数量与数量关系、图形与图形关系中抽象出数学概念及概念之间的关系,从事物的具体背景中抽象出一般规律和结构,并用数学语言予以表征.抽象有时是指"抽象的产物(结果)",有时是指"抽象的过程"或"抽象的方法".     

变量代换和几类四次多项式微分方程的通解

研究了几类四次多项式微分方程,利用变量代换法得到了方程的通解的充分性条件.     

一种合成马来内酰胺衍生物的新方法

报道了一种合成马来酰亚胺衍生物的新方法。以顺丁烯二酸酐为起始原料，经开环酰胺化、脱水关环两步反应合成了15个目标化合物，其结构经¹H NMR确证。     

化学检测实验室内部质量控制方法及结果评价探讨

质量是企业发展之本,关系消费者的切身利益。在日益激烈的市场竞争中,企业愈发意识到质量管理的重要意义。质量控制是质量管理的一个重要组成部分,GB/T 19000-2016[1]对质量控制的定义是"质量管理的一部分,致力于满足提供质量要求"。对于化学检测实验室,保证检测结果有效性是最重要的质量要求之一。     

Dynamically Tunable and High-Contrast Graphene-Based Terahertz Electro-Optic Modulator

We propose and discuss terahertz(THz) electro-optic modulator induced by periodically patterned graphene microcavity. Due to the joint effect of graphene plasmon resonances and Fabry-Perot(F-P) oscillations, plasmon-induced transparency(PIT) effect is achieved and the operation frequency can be dynamically tuned by graphene Fermi energies and structural parameters. The results reveal that modulation depth(MD) larger than 80% is obtained across a wide frequency range from 4.2 THz to 9.4 THz, and the largest MD and Q factor reaches 95% and 15.8, respectively. In addition, operation frequency range and MD can also be tuned by optimizing the structure parameters. This investigation promises the development of high-performance widely tunable THz modulator in chip integrated photonic circuits.     

船舶辐射噪声解调谱相位耦合特性与应用

研究了船舶辐射噪声解调谱谐波线谱的相位特性,通过对实际船舶辐射噪声数据分析,指出船舶辐射噪声解调谱线谱中轴频线谱相位和部分谐波线谱相位之和,与叶频线谱相位的差值为零或为一常数,即存在相位耦合关系。给出了频率具有耦合关系、相位差为非零常数谐波信号的高阶累量,并对这种谐波信号的高阶谱进行了仿真计算。研究了船舶辐射噪声解调谱线谱相位耦合特性的利用方法,通过对部分典型弱调制噪声信号高阶谱分析,指出利用相位耦合关系可以提高弱解调谱船舶目标的螺旋桨参数特征提取能力。      

Betweenness-based algorithm for a partition scale-free graph

Many real-world networks are found to be scale-free. However, graph partition technology, as a technology capable of parallel computing, performs poorly when scale-free graphs are provided. The reason for this is that traditional partitioning algorithms are designed for random networks and regular networks, rather than for scale-free networks. Multilevel graph-partitioning algorithms are currently considered to be the state of the art and are used extensively. In this paper, we analyse the reasons why traditional multilevel graph-partitioning algorithms perform poorly and present a new multilevel graph-partitioning paradigm, top down partitioning, which derives its name from the comparison with the traditional bottom-up partitioning. A new multilevel partitioning algorithm, named betweenness-based partitioning algorithm, is also presented as an implementation of top-down partitioning paradigm. An experimental evaluation of seven different real-world scale-free networks shows that the betweenness-based partitioning algorithm significantly outperforms the existing state-of-the-art approaches.     

水热法制备BiFeO_3粉体的相变研究

本文以Fe(NO_3)_3·9H_2O 和Bi(NO_3)_3·5H_2O为反应原料,以KOH为矿化剂, 利用水热方法在矿化剂浓度4.5 mol/L至12.0 mol/L区域内制备出钙钛矿结构的BiFeO_3粉体材料.经过XRD慢扫(扫描速率为0.008°/s)及peakfit软件模拟分析得知,在KOH浓度由4.5～12.0 mol/L转变的过程中,产物的物相由三方相BiFeO_3向六方相BiFeO_3的转变.同时BiFeO_3铁电性能研究也证实了以上相变的存在.