生活中的电学现象

电与人们的生活息息相关，引导学生利用所学过的物理知识分析生活中的电学现象，不仅能培养其观察能力，还能激发学习的兴趣，提高应用能力．下面是几个与生活实际相联系的电学问题．     

从"物理现象"入手提高学生解决实际问题的能力一例

物理学是一门研究物质、能量及其相互作用的科学，它注重对物质世界普遍而基本的规律的探索，与生活实际、实验有很密切地联系．同时，物理学科又是比较抽象的，它的许多基本概念、基本规律是理想化的、理论性非常强的。使学生具备应用物理知识解释生活中的现象、解决生产和生活中的实际问题的能力，是中学物理教学和高考所要考察的重要目标之一。     

剖析生活现象 探究自然规律

昭平地处亚热带，降雨量较多，雨后，落叶紧贴地面，很难清扫，其原因是什么呢?为此，我们决定成立研究性学习小组，同心协力来探究这一物理现象。     

气压保温瓶和高压锅中的物理知识

气压保温瓶和高压锅的设计制造原理主要依据了压强等物理知识．以它们为载体的物理问题既能让学生知道其中的物理知识，又能使学生从中锻炼解决实际问题的能力，真正领悟到物理课程的价值，更重要的是使学生掌握了认识事物的一般规律．     

几个奇妙趣味现象的演示

物理演示实验是物理课教学的一个重要环节，也是每一个物理教师的良好助手，它有利于学生掌握课程的基本内容，也有助于培养学生探索自然规律的兴趣和能力，从而引导学生透过物理现象，去追求新的规律，获得新的知识。因此，国内外的物理教学都把演示实验作为教学的组成部分．     

自主 合作 为物理实验插上生活的翅膀

物理学“寓”理于“物”,而世间的万物又呈现于生活并服务生活．所以在教学中尽可能从学生的生活实际出发,在课堂上为学生展现丰富多彩的物理现象和活生生的物理情景,加强学生对日常生活的感性认识,学会用心观察生活,以使学生对物理课的学习产生浓厚的兴趣．     

物理教学中如何转变学生头脑中的错误概念

物理概念是物理知识体系中重要的组成部分，是用浓缩了的形式表现大量知识的手段，是科学抽象的直接产物，它反映自然界各种丰富多彩复杂的物理现象中最基本的质的规律性．物理概念掌握不好，会直接影响物理规律的掌握，直接影响对物理世界的认识．因此，在物理教学中，重视学生对基本物理概念的理解，已成为物理教师和研究者的共识．本文以建构主义学习理论为指导，分析了学生头脑中错误概念形成的途径，阐述了教师如何制造“冲突”来转变学生头脑中错误概念．     

切勿让物理教学徘徊在生活之外——对2012年高考浙江理综卷两道物理题评析有感

以2012年高考浙江理综卷两道物理题为例进行评析,并结合笔者平时的教学,提出如何提高学生运用物理知识解决生活中实际问题能力的几点意见.     

把物理课堂延伸到生活中

物理与我们的生活息息相关,生活中许多神奇的现象都能用物理知识来解释．初中生对神奇的自然界充满好奇,当他们刚接触物理时会被千变化的物理现象所吸引,从而产生强烈的求知欲．因此,我们的物理课堂一定要延伸到生活当中,让学生从生活中发现物理,并把物理知识应用到生活中．     

物理练习有效设计及其策略

1 引言 物理练习是实际物理问题、物理现象的科学简化、科学抽象和理想化的模型,它借助于文字语言把物理情境和想要思考的问题展现给学生,使学生在比较短的时间内迅速而有效地学会运用物理知识,并在应用中形成技能,而技能的形成又为进一步顺利掌握知识和运用知识创造条件．     

一种核四极共振探测系统中天线探头的设计方法

针对基于核四极共振技术的爆炸物探测系统实际要求提出一种抑制振铃拖尾的天线设计方法. 该天线探头由高Q值调谐电路、阻抗匹配电路以及振铃拖尾抑制电路组成. 电路仿真结果表明,所设计的天线探头可以有效地抑制振铃拖尾,缩短天线的恢复时间,大大提高探测系统的可靠性.     

激光等离子体无源电探针探测及光谱诊断的比较分析

提出一种利用无源电探针探测激光焊接光致等离子体的方法。采用光电同步采集系统对激光焊接光致等离子体进行研究,利用无源电探针和光纤式光谱仪探测光致等离子体,利用等离子鞘层理论分析电信号,并运用相对光强法计算出光致等离子体的电子温度,比较同步光电信号分析结果。将不涂覆表面物质以及表面分别涂覆KF和TiO₂三种情况下的计算结果进行对比,对影响结果准确性的因素进行分析。研究结果表明通过无源探针法计算等离子体温度与光谱信号计算结果基本吻合,准确度受等离子体离子质量的影响。无源电探针法能够反映激光焊接光致等离子体内温度变化,具有较好的实时性,可以作为激光等离子体监测手段。     

The New Fluorescent Membrane Probe Ahba: A Comparative Study with the Largely Used Laurdan

Lipid bilayers have been largely used as model systems for biological membranes. Hence, their structures, and alterations caused on them by biological active molecules, have been the subject of many studies. Accordingly, fluorescent probes incorporated into lipid bilayers have been extensively used for characterizing lipid bilayer fluidity and/or polarity. However, for the proper analysis of the alterations undergone by a membrane, a comprehensive knowledge of the fluorescent properties of the probe is fundamental. Therefore, the present work compares fluorescent properties of a relative new fluorescent membrane probe, 2-amino-N-hexadecyl-benzamide (Ahba), with the largely used probe 6-dodecanoyl-N,N-dimethyl-2-naphthylamine (Laurdan), using both static and time resolved fluorescence. Both Ahba and Laurdan have the fluorescent moiety close to the bilayer surface; Ahba has a rather small fluorescent moiety, which was shown to be very sensitive to the bilayer surface pH. The main goal was to point out the fluorescent properties of each probe that are most sensitive to structural alterations on a lipid bilayer. The two probes were incorporated into bilayers of the well-studied zwitterionic lipid dimyristoyl phosphatidylcholine (DMPC), which exhibits a gel-fluid transition around 23 °C. The system was monitored between 5 and 50 °C, hence allowing the study of the two different lipid structures, the gel and fluid bilayer phases, and the transition between them. As it is known, the fluorescent emission spectrum of Laurdan is highly sensitive to the bilayer gel-fluid transition, whereas the Ahba fluorescence spectrum was found to be insensitive to changes in bilayer structure and polarity, which are known to happen at the gel-fluid transition. However, both probes monitor the bilayer gel-fluid transition through fluorescence anisotropy measurements. With time-resolved fluorescence, it was possible to show that bilayer structural variations can be monitored by Laurdan excited state lifetimes changes, whereas Ahba lifetimes were found to be insensitive to bilayer structural modifications. Through anisotropy time decay measurements, both probes could monitor structural bilayer changes, but the limiting anisotropy was found to be a better parameter than the rotational correlation time. It is interesting to have in mind that the relatively small fluorophore of Ahba (o-Abz) could possibly be bound to a phospholipid hydrocarbon chain, not disturbing much the bilayer packing and being a sensitive probe for the bilayer core.     

Conductivity of ionic crystals when they are irradiated by picosecond electron beams

This paper discusses the pulsed electron conductivity σ of KCl, KBr, and NaCl crystals when they are excited by an electron beam (0.2 MeV, 50 ps) with current densities in the interval j=(30–10⁴) A/cm². It is shown that the lifetime of the electrons in the conduction band is τ≪100 ps. To explain the experimental σ(j) dependences, a model is proposed that includes electron capture by structural defects and stable radiation defects at low excitation densities and electron capture predominantly by unstable radiation defects generated by the excitation pulse at high excitation densities. Fiz. Tverd. Tela (St. Petersburg) 41, 1200–1203 (July 1999)     

Evaluation of Stability and Sensitivity of Cell Fluorescent Labels When Used for Cell Migration

The directed migration of mammalian cells is a foundation of development and growth. A variety of processes such as tissue development, wound healing, pathogen recognition/destruction as well as cancer metastasis are the result of regulated or dysregulated cell migration. While the ability to measure a cell’s propensity to migrate has clinical relevance in several settings, no universal protocol has been established to measure cell migration. A variety of techniques are currently used to measure migration including manual counting, flow cytometry or Coulter counting, microfluidic devices, computerized spectroscopic methods, or the use of various tracking dyes interfaced with fluorescent or non-fluorescent plate readers. In order to expedite the measurement of migration, we compared several common cytoplasmic and lipophilic cell tracking dyes to determine the best dye for determining migration of rare population of cells. CellVue® Burgundy was found to be superior over calcein AM, Cell Tracker Green CMFDA (chloromethyl fluorescein diacetate), Vybrant CFDA (carboxy fluorescein diacetate succinimidyl ester) in its retention within cells, superior to CellVue® NIR 815, PKH67, and CM DiI with regard to signal to noise ratio, and superior to PKH26 with regard to instrument versatility.     

Penetration of an Electric Field into Conductive Media

The penetration of an electric field into a conductor with conduction electrons in a nondegenerate state is investigated. It is shown that the screening of an electric field is much more efficient in a nonlinear mode than in a linear mode.     

近红外光谱预处理中几种小波消噪方法的分析

以菜籽油的一阶导数近红外光谱为研究对象,探讨小波变换在近红外光谱信号消噪方面的应用,分别采用九点平滑法、小波分解与重构法、非线性小波软阈值法和小波变换模极大值法对导数光谱进行消噪处理并对消噪效果进行比较分析。结果表明,小波变换模极大值光谱消噪法得到了较高的信噪比,小波软阈值法次之,其余两种方法消噪效果较差。小波变换模极大值法有效的保留了光谱的有用信息,为近红外光谱的分析精度和模型的稳健性奠定了良好的基础。     

吖啶橙二聚体作为荧光探针测定牛血清白蛋白

以吖啶橙在十二烷基硫酸钠介质中生成的二聚体作为荧光探针,讨论了其与牛血清白蛋白相互作用的情况.实验表明,蛋白质的加入可使低荧光的吖啶橙二聚体荧光恢复,且其荧光增强的程度与体系中蛋白质的加入量在一定浓度范围内呈线性关系.在优化实验条件下,线性范围为0.8-34 mg/L,检出限为0.126 mg/L.     

Electric field-induced unzipping of hydrogenated carbon nanotubes into graphene nanoribbons

We have investigated the electric field effect on horseshoe-shape carbon nanotubes (CNTs) resulting from hydrogen adsorption on the single-wall armchair (n,n)CNTs with 6 ≤ n ≤ 16 by using the density functional theory calculations. The horseshoe-shape CNT is completely unzipped into a graphene nanoribbon upon applying a critical electric field, which decreases with increasing CNT diameter, thus enabling one to select a nanoribbon width. A simple model based on the tensile force exerted on the tube walls by the applied electric field was introduced to understand the CNT-diameter dependence of the critical field.