培养学生熟练运用数学知识解决物理问题,提升学科科学思维,培养学生学科核心素养.利用几何画板、Excel图像功能,从定性角度分析帮助学生理解同种点电荷连线中垂线上电场强度的变化情况,利用数学求导、均值不等式求解电场强度的最大值及位置.

情境类试题作为考查学生核心素养的重要载体,在试题命制和教师教学等方面具有重要研究意义.本文从比利时学者罗日叶的情境类型学分析框架出发,结合物理学科特点,从情境类型学的3个一级维度和9个二级维度对北京、上海、广州、天津和新疆五个地区的中考物理情境试题进行量化对比分析,发现创设的真实情境题型较少,科普开放性问题情境较为缺乏,问题情境的认知要求有待提高等问题,并对中考物理情境试题命制和教学提出相关启示.

Our work investigates the structural stability of a C0.5/(BN)0.5 heterojunction single-walled nanotube by comparing the binding energy. The energy band structure, electronic density of states and regulation relation between band gap and indirect-direct properties and tube diameter and type are systematically studied. Based on existing experimental and theoretical results, dynamic simulated calculating of the stitching process is carried out to explore the feasibility of controllable preparation.

文章研究2020年中国大学生物理学术竞赛的第九题,对磁力搅拌器黏性液体中的搅拌子在旋转磁铁磁场作用下的运动,进行实验探究和理论分析.根据搅拌子和旋转磁铁的相对运动情况,将整个实验过程分为同步、不完全同步和不同步转动的三个阶段,观测和记录了三个阶段的实验现象及其细节,其中第二阶段搅拌子在黏性液体中的悬浮现象作为重点探究内容.由于问题复杂,在理论分析中,首先根据同名磁极相互排斥、异名磁极相互吸引的规律进行简单的讨论,然后根据搅拌子在磁场中的附加能量和磁力矩对实验现象进行详细的解释.为了更加清晰地理解搅拌子的悬浮现象,特别注重形象物理模型的构建和直观物理图像的呈现,将复杂问题简单化.研究内容及其方法在课堂教学实践和科普宣传教育中有一定的参考价值.

By using the first-principles density functional method, the electronic properties of single-walled silicon carbide (SiC) nanotubes were systematically studied, especially the band gap turning by the chiral angle and tube diameter. We propose a new strategy for preparing SiC nanotubes, which can be used to prepare single-walled SiC nanotubes with the expected band gap, named “selective shear suture method”. This research provides a new way to synthesize high-quality materials for nano-scale semiconductors, electrical devices and non-silicon-based chips. In particular, the selective defects in the preparation of single-walled nanotubes by electron beam cutting are theoretically solved. This study also provides useful theoretical guidance for the selective preparation of various single-walled nanotubes.

随着我国航空航天事业从航天大国向航天强国迈进,"万有引力与航天"单元内容几乎成为高考试卷中的必考知识点.本文讨论该考点在2021年高考物理试卷中的四种试题类型,并从物理学科核心素养的角度进行分析和比较,为中学物理"万有引力与航天"的教学提供启示和参考.

利用密度泛函理论(DFT),对氮化硼(BN)管状团簇的几何结构、稳定性和电子性质进行了研究.选取合适的BN结构单元作为结构生长基元,采用逐层生长的方式计算得到有限长度、不同截面尺寸的稳定管状团簇.结构中B-N交替排列,结构组成中的四元环和六元环数目均符合一般表达式.计算结果表明,通过适当组装管状团簇以及碳原子掺杂,可以制备出带隙可调的单壁氮化硼纳米管.

本文以初中物理教材中的"分子动理论"为研究对象,结合新课程标准,从实际教学的角度,对2013年修订的人教版、北师大版、沪科版、粤教沪科版、教科版五种版本义务教育课程标准教材中的相关内容和教材插图进行比较,给出一些教学建议;同时对其微观模型建立的假设条件展开深度分析,以便在教学中帮助学生构建正确的物理图像,启发学生思维,为后续的课程学习打好基础.

气体分子动理论是以气体热现象和热运动为主要研究对象的经典微观统计理论,在揭示气体宏观热学性质和过程的微观本质讨论中用到较多假设条件,但对所提出的假设条件进行合理而详细的解释较少,也存在一些不完备的问题.首先,文章对一般教材中气体分子动理论相关问题中所提出的6个假设进行了修正,新增了2个必要假设条件,并给出增删和修改假设的依据,使假设条件更加科学合理;其次,将假设条件应用于理想气体压强公式的推导过程,通过宏观量与微观量平均值的关系进一步成功印证了微观模型建立的正确性;最后对存在的不严密的科学问题进行了详细的说明和补充,使得假设条件更加严谨、科学,便于学生理解和掌握.

We systematically studied the electronic properties of zigzag boron nitride nanoribbons periodically embedded with four- and eight-membered rings (new ZBNNRs) and the influence of vacancies on the electronic properties. The results reveal that the band gap of the new ZBNNRs is greatly reduced, down to a range of 3.830-3.995 eV, enabling the allotropes to display semiconductor properties and satisfying the requirements of the third-generation semiconductor bandgap width, and can provide high-quality materials for the preparation of third-generation semiconductor nanodevices. Second, although the vacancy has not changed the semiconductor characteristics of the new ZBNNRs, the band-gap bandwidth will be reduced to some extent due to the difference in vacancy position and electronic state.

为推动力学"课程思政"教学的有效开展,文章通过分析力学课程的特点和特殊性,探索力学中蕴含的马克思辩证唯物主义思想、与力学知识相关的中国现代科技、爱国主义教育融入点、中国古代在力学发展进程中的成就四方面挖掘"思政元素",寻找"课程教学"与"思政教育"的结合点,对力学课程教学中的思政教育实践进行了有益的探讨,从而为理工科其他课程实施"课程思政"教学改革实践提供一定的参考.

ABSTRACT In this paper, we present a density-functional theory with a particle swarm optimisation algorithm to research the progress of the ligand effects of the gold (Au) structures and growth process of the [Au1L2]n, [Au2L3]n and [Au3L4]n (n = 1–3, L = SCH3, PH2, P(CH3)2,Cl) nanoclusters. Changing of ligand atoms induces minor changes in the Au and Au-L bond lengths. When L = Cl, with increasing n, the size of the Au cores tends to increase, while when L = PH2, with increasing n, the size of Au cores decreases and the length of the ligand protection increases. We give a detailed comparison of the average binding energy, stability, and aromaticity of these clusters and further explain the diverse role of ligand substitution. The order of stability for each ligand, Cl > PH2> SCH3>P(CH3)2, is determined by the average binding energy and the difference between the atomic energies. In addition, the influence of strong Au-Au interactions will weaken the aromaticity of the structure. New nanoclusters that can be widely applied in other fields, and designed by leveraging the ligand effects of the Au structural evolution characteristics.

一般教材没有对无摩擦准静态过程是可逆过程的原因进行详细的解释,并且通过卡诺循环的特例从宏观角度入手解释电冰箱原理也比较抽象.文章提出一种从微观角度入手分析体积功的方法,分别对这两个问题进行了充分的解释.文章提出的方法比较简单方便、联系实际、容易理解,期望对教学有一定的参考价值.

一般教材中根据绝热过程功与路径无关的性质定义内能,内能这样的定义是有缺陷的,它只能给出同一绝热过程上的状态内能之间的关系,而不能给出不同绝热过程上的状态内能之间的关系.文章根据量热学和热功当量实验的相关结论,在已知热量和功的定义基础上,根据热力学第一定律对内能重新进行定义.

Using density functional theory (DFT), we have studied the structure of a zigzag silicene nanoribbons (SiNRs) with periodically embedded with four- and eight-membered rings, and studied their electronic properties by calculating its band structures and density of states (DOS). The results showed that the zigzag SiNRs have a sp2 hybridization, in addition, the band gap gradually decreased with the increase of the width by layer, and gradually changed from semiconductor properties to metal properties. The existence of vacancy defects increased the band gap and energies, but their positions could not change the structure and the electronic properties.

A new class of carbon nanomaterials composed of alternating four- and eight-membered rings is studied by density functional theory (DFT), including single-walled carbon nanotubes (SWCNTs) double-walled carbon nanotubes (DWCNTs) and triple-walled CNTs (TWCNTs). The analysis of geometrical structure shows that carbon atoms' hybridization in novel carbon tubular clusters (CTCs) and the corresponding carbon nanotubes (CNTs) are both sp(2) hybridization; The thermal properties exhibit the high stability of these new CTCs. The results of energy band and density of state (DOS) indicate that the electronic properties of CNTs are independent of their diameter, number of walls and chirality, exhibit obvious metal properties. (C) 2018 The Authors. Published by Elsevier B.V.

Ligand-protected gold clusters are widely used in biosensors and catalysis. Understanding the structural evolution of these kinds of nanoclusters is important for experimental synthesis. Herein, based on the particle swarm optimisation algorithm and density functional theory method, we use [Au-1(SH)(2)](n), [Au-2(SH)(3)](n), [Au-3(SH)(4)](n) (n=1-3) as basic units to research the structural evolution relationships from building blocks to the final whole structures. Results show that there is a line-ring-core' structural evolution pattern in the growth process of the nanoclusters. The core structures of the ligand-protected gold clusters consist of Au-3, Au-4, Au-6 and Au-7 atoms. The electronics and optics analysis reflects that stability and optical properties gradually enhance with increase in size. These results can be used to understand the initial growth stage and design new ligand-protected nanoclusters. [GRAPHICS] .

Based on experimental results, we obtain five types of single-walled carbon nanotube (SWNT) clusters with different chirality indices and diameters using density functional theory (DFT). We then obtain the corresponding SWNTs by using periodic boundary conditions. Studies of the stability and electronic properties show that the stability of the novel SWNTs is independent of the chirality index and relates only to the tube diameter; larger diameters correspond to more stable SWNTs. The electronic properties all show metallic characteristics independent of the chirality indices and tube diameters, thereby promoting the application of metallic-type SWNTs.

The properties of boron nitride nanotubes composed of four- and eight-membered rings (referred to as four-eight-membered rings BNNTs) were calculated using density functional theory (DFT). The calculated results show that the band gap of the four-eight-membered rings BNNTs is greatly reduced, down to a range of 2.530–3.975 eV. The band gap decreases as the number of walls increases, not only enabling the allotropes to show semiconductor properties but also to fully meet the third-generation semiconductor band gap requirements, furthermore, the band gap decreases significantly with the number of walls increases.

以自由粒子为例,分别从薛定谔方程、时间和空间的平移对称性以及波函数的物理意义3个方面,讨论量子力学中平面简谐波应该是复数形式的.