共查询到20条相似文献,搜索用时 62 毫秒
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物理实验能力是指运用实验理解、验证物理理论观点以及借助物理实验获得新认识的能力,它由实验基本能力、实验迁移能力和实验科研能力构成.本文分析了初中生物理实验能力发展的特点,指出了在初中实验教学中应重点培养第一级和第二级实验能力. 相似文献
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基于计算机仿真技术,以光学干涉实验和滤波实验为研究对象,应用Matlab软件数值模拟了杨氏双缝干涉实验和多光束干涉实验干涉图形和光强分布图,数值模拟了光学滤波实验字母滤波后的频谱图和字母成像图,结果表明,计算机仿真结果能够清晰的表达出实验和理论的效果。研究结果为光学实验的课堂教学提供了参考。 相似文献
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高考物理科的《考试说明》中明确指出,考生应具有理解能力、推理能力、分析综合能力、应用数学工具处理物理问题的能力与实验能力.其中对实验能力的要求是:能独立的完成所列的实验,能明确实验目的,能理解实验原理和方法,能控制实验条件,会使用仪器,会观察、分析实验现象,会记录、处理实验数据,并得出结论,对结论进行分析和评价;能发现问题、提出问题,并制定解决方案;能运用已学过的物理理论、实验方法和实验仪器去处理问题,包括简单的设计性实验. 相似文献
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物理教学中不能不开展实验创新.实际创新的内涵为实验改进、自制教具、实验管理和实验教研;实验创新的意义不仅在于提高实验效果,还兼有培养学生动脑动手能力,提高学生技术和科学素养的广泛迁移功能. 相似文献
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首先针对目前数字化实验教学研究重实践、轻理论的现状,指出了实验教学理论研究的必要性和紧迫性。然后根据DIS实验系统的特点和对实验教学过程的影响,提出了包含5个功能层面的完整实验体系的理论构想和实验流程模式的概念,并重点按照新的理论构想和分析方法,探讨传统实验和数字化实验在流程模式上的明显区别以及对课堂效果的影响,最后对DIS实验未来的发展提出建议。 相似文献
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Microperforated panels (MPPs) can provide wide-band absorption without fibrous and porous materials and are recognized as next-generation absorption materials. Although the fundamental absorbing mechanism of an MPP absorber is Helmholtz-resonance absorption, sound-induced vibration of an MPP itself can affects the absorption characteristics. There have been some studies considering the effects of the sound-induced vibration and there even is a proposal to widen the absorption bandwidth by positively utilizing the vibration of an MPP itself. On the other hand, in a previous study, the relationship between MPP absorbers and panel-type absorbers was investigated with infinite theory. However, the relationship between Helmholtz-resonance absorption and panel-type absorption in finite flexible MPP absorbers has not been clarified. Herein, from the viewpoint of an absorption-characteristics transition with the perforation ratio, the relationship between Helmholtz-resonance absorption and panel-type absorption including the effects of eigen-mode vibrations of the panel is theoretically and experimentally investigated. The analytical model considers a finite flexible MPP supported in a circular duct, and the predicted data for the absorption coefficient under normal incidence is validated by an experiment using an acoustic tube. From this investigation, it is found that panel-type absorption due to eigen-mode vibrations of the panel occurs independently from Helmholtz-resonance absorption, while panel-type absorption due to a mass-spring resonance of a panel and a back cavity has a trade-off relationship with Helmholtz-resonance absorption with respect to the perforation ratio. 相似文献
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原子吸收光谱法测定南瓜吸收铅的研究 总被引:1,自引:0,他引:1
通过原子吸收光普法研究了南瓜对铅的吸收特性,结果表明:南瓜对铅的吸收量随时间的延长而增加,吸收速率随时间的延长而降低;培养液pH7时对铅的吸收量最大;这一结论与南瓜对重金属镉的吸收特性相似。 相似文献
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原子吸收光谱法测定南瓜吸收镉的研究 总被引:5,自引:1,他引:4
利用原子吸收分光光度计对南瓜吸收重金属镉的特性进行了研究.结果表明,随着镉浓度的增加,南瓜对镉的吸收量增大;随着水培时间的延长,南瓜对镉的吸收量增加,水培8 h后吸收量基本趋于饱和;吸收高峰在水培后2 h时出现,而后随时间的延长而逐渐降低.酸性和碱性条件较中性条件下南瓜植株对镉的吸收量均有下降,在pH 3条件下吸收量最小,pH 7条件下吸收量最大. 相似文献
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利用层多重散射法分析了一种含圆柱形谐振散射体黏弹 材料吸声层在钢背衬条件下的低频吸声特性. 该吸声层由包覆软材料的圆柱空腔周期嵌入橡胶材料中构成, 其中, 散射体轴线与吸声层平行. 结果表明, 20 mm厚吸声层在1000–3000 Hz具有良好的吸声性能. 通过综合分析单个散射体的吸收截面、单层周期散射体的声吸收、 结构内部位移场以及耗散功率密度分布, 揭示了该吸声层的低频吸声机理.
关键词:
水声吸声
吸收截面
耗散功率密度 相似文献
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We study the absorption spectrum of a V-type three-level atom when the laser beam interacts only with one of its two transitions. With the presence of vacuum-induced quantum interference, the absorption spectrum shows some new interesting features, which include ultranarrow absorption line, transparency, and a reverse-saturated absorption that is characterized by a larger absorption with increasing laser intensity. 相似文献
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3-羟基黄酮在不同极性和酸碱度溶剂中的光谱研究 总被引:2,自引:0,他引:2
实验观测了3-羟基黄酮(3-HF)在不同极性溶剂中的吸收光谱和荧光光谱,发现在吸收光谱中有3个吸收带,峰值位于300和345 nm的两个吸收带较强,位于415nm处的吸收带较弱.用345 nm作为激发光,观测到两个荧光带,其中峰值位于400 nm的荧光带为3-HF稀醇式构型的发射,随着溶剂极性的增大其强度增强,峰值位于526 nm的荧光带为3-HF互变异构体的发射,随着溶剂极性的增大其强度减弱,这表明溶剂极性阻碍质子转移的发生.用415 nm的光激发样品,在荧光光谱中发现了3个新荧光谱带,峰值分别位于440,471和515 nm,这3个荧光谱带归属至今未见报道.为了指认这3个荧光谱带,分别观测了3-HF在不同酸碱度溶液的荧光光谱及其吸收光谱,通过对这些光谱的分析研究,指认出荧光峰位于440和471 nm的荧光谱带为3-HF的两种阳离子的发射,峰值位于515 nm的荧光谱带为3-HF的阴离子的发射. 相似文献
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利用差分吸收光谱技术(DOAS)研究了去除BTX(大气中芳香烃污染物的主要成分)测量中O2、O3和SO2的干扰吸收. 针对O2的非线性吸收以及特征吸收结构随柱浓度的不同而变化的特点,研究了O2吸收组成成份-各个吸收带的非同步变化,即三个Herzberg吸收带与O2二聚体吸收带间的非同步变化,以及三个Herzberg吸收带之间,O2-O2和O2-N2两种二聚体吸收带之间也存在的非同步变化;结合各个吸收带的来源与特点研究了各个吸收带在O2吸收中的比重,以及对O2吸收在大气谱中校准误差的影响,最后得出最佳去除方法并证明了光程插值去除O2吸收的可能性. 针对大气中含量较高的O3与SO2的吸收,主要研究了吸收谱主要的影响因素-温度效应对于O3和SO2吸收结构去除误差的影响,讨论了用插值方法去除O3吸收结构时应选择的最佳温度条件. 最后,通过对实际大气进行了实际监测,获得了与点式仪器GC的检测结果的较好相关性,并得到了较低的BTX的检测限,验证了该方法的可行性. 相似文献
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Wen J Zhao H Lv L Yuan B Wang G Wen X 《The Journal of the Acoustical Society of America》2011,130(3):1201-1208
Recently, by introducing locally resonant scatterers with spherical shape proposed in phononic crystals into design of underwater sound absorption materials, the low-frequency underwater sound absorption phenomenon induced by the localized resonances is observed. To reveal this absorption mechanism, the effect of the locally resonant mode on underwater sound absorption should be studied. In this paper, the finite element method, which is testified efficiently by comparing the calculation results with those of the layer multiple scattering method, is introduced to investigate the dynamic modes and the corresponding sound absorption of localized resonance. The relationship between the resonance modes described with the displacement contours of one unit cell and the corresponding absorption spectra is discussed in detail, which shows that the localized resonance leads to the absorption peak, and the mode conversion from longitudinal to transverse waves at the second absorption peak is more efficient than that at the first one. Finally, to show the modeling capability of FEM and investigate shape effects of locally resonant scatterers on underwater sound absorption, the absorption properties of viscoelastic materials containing locally resonant scatterers with ellipsoidal shape are discussed. 相似文献