与“探究型学习模式”结伴而行

新一轮的高中物理课程改革正在如火如荼地进行,围绕着创新意识与实践能力的培养,转变学习方式、注重探究型学习成了课程改革的重中之重."探究型学习"已经成为三维目标体系中"过程与方法"目标达成的核心载体.这种理念要求教学朝着自主学习、合作学习、探究型学习的方向发展;其中一个重要而具体的内容就是改变被动的接受式学习方式,倡导主动参与的探究型学习模式.     

浅析物理开放题的编制

《物理课程标准》明确提出物理课程的基本理念为“注重学生发展，改变学科本位；从生活走向物理，从物理走向社会；注重学科探究，提倡学习方式多样化；建构新的评价体系．”物理开放题由于自身的一些独有特点而能够在实际教学中充分体现物理课程的基本理念．近年来，物理开放题作为一种新的题型越来越受到人们的青睐．     

物理探究学习的课堂评价探析

把物理探究学习融入物理课程与教学实践之中已成为当今物理教育改革发展的一个重要特征．1996年美国《国家科学教育标准》把科学探究列入其“科学内容标准”之首；2000年英国颁布的国家课程把科学探究作为科学课程的四个目标的首要目标；2003年3月31日我国教育部颁布的《普通高中物理课程标准（实验）》所倡导的课程理念中明确指出“科学学习要以探究为核心．探究既是科学学习的目的，又是科学学习的方式”．“物理课程的核心理念是培养学生的科学素养”．“发展学生的科学素养又离不开科学的学习过程．科学的核心是探究，教育的重要目标是促进学生的发展，物理课程应当体现这两者的结合，突出物理探究学习方式”．而物理探究学习的课堂评价在学生物理探究学习过程中起着至关重要的作用．     

物理教学实施探究式学习的三个原则

新课程标准明确指出：“高中物理课程应促进学生自主学习，让学生积极参与、乐于探究、勇于实验、勤于思考．通过多样化的教学方式，帮助学生学习物理知识与技能，培养其科学探究能力，使其逐步形成科学态度与科学精神．”因此，物理教学中探究式学习应着力于学生学习方式的改善，让学生体验科学探究过程，了解科学研究方法，增强创新意识和实践能力；激励学生在教学过程中主动学习和探究精神，调动学生学习的主动性、积极性，促进其个性全面健康地发展和情感、态度、价值观的自我体现．但目前的教学中，仍存在一定的认识误区和实践中的错误倾向．笔者根据对探究式学习的理解和实践认为物理教学的本质是科学的学习，而科学探究是科学学习的核心．可以说，中学物理教学的最终目标应是在学习物理知识的过程中，初步培养学生建立科学探究的意识和能力．为了达到这个目标，应在平时教学中引导学生进行探究式学习．在教学中实施探究式学习还应注意三个原则．     

探究性学习在声速测量实验课中的运用

为了进一步提高大学物理实验课堂教学的质量,根据探究性学习的特点,构建声速测量实验课的实验教学过程,采用创建探究方向、拓展探究方向和加大探究自由度及激励机制,从而提高了大学物理实验课堂教学的自主性、实践性、开放性和激励性。     

以问题为载体,培养学生的科学探究能力——"伏安法测电阻"探究教学设计

1 设计思想 “探究学习方式特别强调问题在学习活动中的重要性．一方面强调通过问题来进行学习，把问题看作是学习的动力、起点和贯穿于学习过程的主线；另一方面通过学习来生成问题，把学习过程看成是发现问题、提出问题、分析问题和解决问题的过程．”物理教师应该是科学问题的开发者．有必要对一些探究的物理问题创设一些情境，让学生在观察和体验中有所发现，有所联想，萌发出科学问题；或者创设一些任务，让学生在完成任务中运用科学思维，自己提炼出应探究的科学问题．启发学生提出科学问题是非常重要的，这正如爱因斯坦所说的：“提出一个问题往往比解决一个问题更重要．因为解决问题也许是一个数学上或实验上的技能而已，而提出新问题，新的可能性，从新的角度去看待旧的问题，却需要有创造性的想象力，而且标志着科学的真正进步．”在“伏安法测电阻”的教学活动中，笔者以问题为载体，激活学生思维，培养学生的科学探究能力，取得了良好的教学效果．     

WebQuest——网络探究学习

1 WebQuest简介 所谓WebQuest,就是利用互联网资源,引导学生对某个或某类问题(课题)进行学习、探究.这种学习方式是1995年美国圣地亚哥州立大学教育技术系的伯尼·道奇博士和汤姆·马奇创建的.     

动量定理的探究式教学

高中物理新课标对物理教学改革的指导思想：一是教法要朝探究式教学方向变革；二是课教学要改变学生的学习方式，积极倡导探究性的学习方式．宗旨是培养学生的探究能力，提高学生的科学素养，我们应努力，     

课外自主以趣导行

新课程强调要使学生适应终身学习的要求，具有终身学习的基础知识、基本技能和方法；倡导学生主动参与，乐于探究，勤于动手；培养学生搜集和处理问题的能力，获取新知识的能力，分析和解决问题的能力．要让学生具备这些能力，仅靠课堂45分钟是不够的，而需要教师指导学生在课外开展自主学习，使课堂教学目标的完成在课外得到有力补充．     

发展研究型基础物理实验教学的理念与实践

随着高校科研的快速发展,传统实验教学模式面临新的挑战.北京大学基础物理实验教学中心坚持科研引领实验教学的理念,立足于基础物理实验课教学,结合科学研究,探索研究型教学的实验课程模式,创建了基础与创新协同发展的基础物理实验课程教学新体系.在实验过程中,鼓励学生自主探究,通过查阅资料,设计方案,完成实验和交流成果,培养学生的...     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.