电磁学中的电路抽象

首先简要回顾"场"与"路"的基本内容,从基本体系上进行比较并列出二者物理量关系.然后从电磁学中电路抽象角度阐明"场"衍生"路"的建模方法及"第四类"基本无源元件演绎.最后,给出的应用实例——生物组织检测的共振光声光谱.     

物理教学应加强科学本质教育

科学的本质是近年来世界范围内科学教育改革所关注的热点问题之一.理解科学的本质,实际上要回答"科学是什么"、"科学不是什么"、"科学能做什么"和"科学不能做什么"等问题.物理学作为自然科学的基础学科、主导学科和重要学科,充分体现了科学的本质特征.物理教学应加强科学本质的教育,使学生加深对科学本质的认识和理解.     

建设以知识、能力和素质为教学目标的大学物理精品课程

介绍了同济大学基础物理教学在精品课程建设中的成功经验.为贯彻"以学生为本"的基本教学指导思想,教研室的老师们提出了"环境浸润"的教学理念,建立了物理探索实验室和物理教学辅助网.以课堂教学为主渠道,开展多种形式的教学活动,形成了"课内与课外结合"、"理论与实践结合"、"教学与育人结合"的教学模式.通过多年的教学实践,取得了良好的教学效果.学生对物理学产生了兴趣,涌现出了一批具有较高水平的学生论文和作品.学生的综合能力和素质得到了培养.     

新课改中,农村初中物理实验教学存在的问题及对策

物理是以实验为基础的自然科学,所谓物理,就是通过"物"--物理实验引入物理概念,研究物理规律.就是要以"物"喻出"理"的本质,以"物"明了"理"的内涵,以"物"揭示"理"的真谛.因此,物理实验是学生获取知识、进行知识创新的重要手段,是培养学生的学习兴趣、科学态度和提高学生终身学习能力的重要途径.     

近红外光纤探头

提出了近红外光纤探头"视距"模型.通过Monte Carlo模拟和两种不同光学性质的双层模型实验,得到了100 μm探头"视距"的经验公式.提出了三层模型的"视距"定义,给出了"层分辨率"的概念,并通过大鼠大脑的试验得到验证.利用近红外光纤探头"视距",可以区分不同的脑组织,在深脑探测手术中进行导航.探头"视距"提出了一个近红外探头视距研究的普遍方法,对光纤探头的设计有重要意义.     

Acoustic remote sensing of the atmosphere

I.IntroductionBy"remotesensing*ismeantatechniquefordctectingand/ormeasuringthelocation,shapc,featuresandstatcsofanobjcctfarbcyondbyaspecifiedtool.Andby"acousticremotescnsingoftheatmosphcre'isthusmeantthctechniquefordetcctingthcstatesoftheatmos-phercandvariousphenomenainitbysoundwavcsasatoo1farbeyond.Itisintcrcstingtonotethattheword"sound'means"acousticwaves'whenuscdasanoun,andhasthemeaningof"toexamine"or"toprobe'whenusedasatransitiveverb.ThcreIYomonecanscethecloserc1ationshipbetwccn"acoustic…     

“微粒说”对光的折射现象的解释

关于"光的本性",在物理学的发展历史中曾经历过"微粒说"和"波动说"的激烈争论.以牛顿为代表的"微粒说"理论认为:光是微粒;而以惠更斯为代表的"波动说"理论则认为:光是波.在1801年托马斯·杨完成"光的双缝干涉"实验挽救了光的"波动说"理论的颓势之前,在关于"光的本性"的激烈争论中,"微粒说"理论略占上风.     

弹弓效应原理简析

文章用速度变换和矢量图对"弹弓效应"的加速原因做出了较为简洁直观的解释,以关于"弹弓效应"的一个简例.分析"弹弓效应"中的加速条件,得出能使入射物体被加速的偏转角范围.与通常所采用的两体碰撞理论相比较,此方法更能凸显"弹弓效应"的加速机理,且能有效避免冗繁的数学运算.将"弹弓效应"与粒子散射问题对照分析,得出两者之间的可类比性.因而可由散射问题中的散射角关于瞄准距离的公式类比推出"弹弓效应"中偏转角与瞄准距离之间的关系.文章还将"弹弓效应"的思想推广到了一般尺度上的两体问题.     

关于新增栏目“解题思路与技巧”

从本期开始,本刊新增一个栏目:"解题思路与技巧".长期以来,中学物理教学在一些学校,被束缚在"题海战术"之中.试图通过大量做题,来提高学生的"应试"能力,其结果是造成学生负担过重,叫苦连天;而实际的解题能力并没得到应有的提高.如何使广大师生从"题海战术"中解放出来,真正掌握解题的思路及方法.这就是我们开辟"解题思路与技巧"这一栏目的初衷.     

如何上网查阅《光谱实验室》上发表的论文

(你的论文在发表后约1—2个月,上网才能检索到)1.在浏览器的地址栏上输入"核心期刊"。当出现菜单后,点击"核心期刊目录",再点击"中文核心期刊要目总览(2008版)",即可查阅各学科的"核心期刊"。若要查阅《光谱实验室》,请查第4编:自然科学,再查"O6/O7—化学/晶体学",第21号即是。也可以在浏览器的地址栏上输入www.google.cn或www.baidu.com,再输入"核心期刊"后,点击"中     

Influence of Solvent Polarity and Viscosity on Nonradiative Processes in Oligothiophenes with Intramolecular Charge Transfer

By the methods of luminescence, picosecond spectroscopy, and quantumchemical calculations the mechanisms of electron excitation energy deactivation in some oligothiophenes with intramolecular charge transfer depending on the solvent polarity and viscosity have been investigated. While for 2Npiperidino5(2,2dicyanovinyl)thiophene (PDCVT) the main channel of nonradiative deactivation is the transition to a lower intermediate state with a twisted double bond controlled by the medium viscosity, in the case of (E){2[25piperidino2thienyl]6(trifluoridemethyl)4H4pyranylidene}propanedinitryl (PTFDN) fluorescence quenching is initiated by the solvent polarity. For two other oligothiophenes, 2Npiperidino5cyanothiophene (PCT) and 2Npiperidino5cyanoterthiophene (PCTT), differing in the length of the thiophene chain, we have revealed, along with the effective quenching of fluorescence in shortchain PCT (independent of the solvent polarity and viscosity), an increase in the radiation capacity in PCTT with increasing polarity of the solvent. The possible mechanisms of nonradiative deactivation in the investigated oligothiophenes are discussed.     

Resonant enhancement of the formation of hydrogen-helium muonic molecules

Formation of muonic molecules and , where J is rotational quantum number, in electron conversion process is investigated at collision energies between 0.004 eV and 50 eV. Corresponding reaction rates are calculated in adiabatic approximation for the three-body Coulomb problem. Significant enhancement of the rates for and is found near 7 eV and 30 eV, respectively. It is shown that the enhancement is due to resonances present in elastic and scattering at these energies. Acceleration of dμ atoms up to the resonant energy could be realized in triple H-D-³He mixture due to the muon transfer from protium to deuterium. Experimental investigation of nuclear synthesis from molecular state directly formed in the mixture is suggested.     

Near-infrared diode laser spectroscopy of the HCSi radical

The , , and band spectra of HCSi radical were investigated by means of near-infrared diode laser spectroscopy to determine precise molecular constants for the and states. The detailed analysis of the rotationally resolved band spectra, studied for the first time in the present investigation, leads to the precise determination of molecular constants for the state associated with the Renner-Teller interaction. We obtained −0.15126663(53) and 495.00698(30) cm⁻¹ as the Renner-Teller parameter ε and the bending vibrational frequency ω₂, respectively. Based on the molecular constants for the and states, the rotational levels of the state were analyzed to obtain molecular constants and information on upper state perturbations. Using the available spectroscopic data, valence force fields for both the and states were estimated to aid in understanding the vibrational energy levels of the HCSi radical.     

Effect of a periodic magnetic field on phase matching condition in second harmonic generation at interactions of laser-plasma

In this paper, the process of second harmonic generation (SHG) is studied in underdense plasma in the presence of a periodic magnetic field. It is shown that the difference of momentums of photon of second harmonic and two photons of main wave can be provided by momentum of everyone of Fourier components of periodic magnetic field so that momentum of nth Fourier component can be chosen by . It is also proven that the highest efficiency of second harmonic generation will be provided by the first Fourier component of periodic magnetic field . It is revealed that periodic magnetic field can produce longitudinal waves at and as well.     

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介绍了开式微波谐振腔测量系统的工作原理及试验结果,获得了Æ10mm钢球模型在6.65kPa干燥空气中以速度5.44km.s-1飞行时的尾迹电子密度测量结果,并且与国外弹道靶试验数据进行了比较。试验结果表明,该系统能够满足模型尾迹电子密度变化对测量系统响应时间的要求,能很好地反映尾迹电子密度变化细节,电子密度测量范围达到109~1011cm-3。     

Statistics of the One-Dimensional Riemann Walk

The Riemann walk is the lattice version of the Lévy flight. For the one-dimensional Riemann walk of Lévy exponent 0<<2 we study the statistics of the support, i.e., set of visited sites, after t steps. We consider a wide class of support related observables M(t), including the number S(t) of visited sites and the number I(t) of sequences of adjacent visited sites. For t we obtain the asymptotic power laws for the averages, variances, and correlations of these observables. Logarithmic correction factors appear for =2/3 and =1. Bulk and surface observables have different power laws for 1<2. Fluctuations are shown to be universal for 2/3 <2. This means that in the limit t the deviations from average M(t)M(t)–M-0304;(t-0304;) are fully described either by a single M independent stochastic process (when 2/3 <1) or by two such processes, one for the bulk and one for the surface observables (when 1<<2).