A capacitance servo control plunger for accurate lifetime measurement

The recoil distance Doppler shift method has been widely used in the study of nuclear structure to determine the level lifetime and absolute transition probabilities.A capacitance servo control plunger based on this method has been successfully developed by the Nuclear Structure Group of the China Institute of Atomic Energy.Three microscopes were employed to check the parallelism and can therefore guarantee a delicate measurement of the distance between the target and the stopper.This new plunger made a successful performance in the test experiment and the measured lifetime of the 2~+→0~+ transition in ~(78)Kr is in agreement with the previous value.     

加强实验知识的迁移引导学生思维的拓展

从多个方面阐述了如何在实验复习教学中,有意识地进行适当的知识迁移,以引导学生思维的拓展, 培养学生的创新思维能力.     

2009年高考物理选择题的解法示例

在高考物理试卷题型中,选择题主要考查对物理现象、物理概念、物理规律的认识、判断、理解和应用等;具有覆盖面广、知识容量大、题目新颖、灵活多变、客观性强等优点;不仅能考查学生对基础知识的掌握,还能考查学生的思维敏捷性,是高考中物理广泛采用的一种题型.     

基于TPACK理论的高中物理课堂教学设计与思考——以“探究加速度与力、质量的关系”为例

TPACK是指教师在教学过程中将学科知识、教学知识和技术知识深度融合,从而把学科知识有效地内化为学生的知识,TPACK水平越高,表明教师利用技术手段进行教学的能力越高.基于TPACK理论的教学设计是指教师在具体的教学情境中,恰当选择教学方式、技术手段,构建以生为本的生本课堂,帮助学生理解掌握学习内容,达到提高学生学习兴趣、提升教育教学质量的目的.笔者根据TPACK理论以"探究加速度与力、质量的关系"为例进行教学设计,以期为高中物理教师的课堂教学提供借鉴.     

New high spin level scheme of 87Sr

High spin states of the odd-A ⁸⁷Sr were populated by the fusion-evaporation reaction ⁸²Se(⁹Be, 4n) ⁸⁷Sr at a beam energy of 46 MeV. Excited levels of ⁸⁷Sr have been extended up to an excitation energy of 7.4 MeV at spin 31/2ħ. The coupling of a g_9/2 neutron hole to the yrast states of the ⁸⁸Sr core can account for the low-lying states in ⁸⁷Sr. The structure of the higher spin states is discussed by analogy with those of the neighboring odd-A N=49 isotones and possible configurations are proposed.     

从投掷问题到概率论的创立

点数问题的解决是概率论创立的标志.该问题最终由帕斯卡和费马圆满解决,正是这些新思想奠定了概率论基础.惠更斯的<论赌博中的计算>第一次把概率论建立在公理、命题和问题上而构成较完整的理论体系.     

半平面中调和函数的积分表示

In this article, we consider the integral representation of harmonic functions. Using a property of the modified Poisson kernel in a half plane, we prove that a harmonic function u（z） in a half plane with its positive part u^＋（z） = max{u（z）, 0} satisfying a slowly growing condition can be represented by its integral of a measure on the boundary of the half plan.     

硼对HZSM-5分子筛酸性和择形性的影响

用不同含量的硼对HZSM-5分子筛进行改性,研究硼对HZSM-5酸性和对甲苯甲醇烷基化制对二甲苯反应的影响.通过XRD, SEM, N_2物理吸脱附, NH_3-TPD和Py-IR对催化剂进行表征,结果表明硼改性的催化剂仅有弱酸位,随着硼含量增加,弱酸位酸量和B/L增加,并且硼改性后在HZSM-5分子筛中产生新的弱B酸位.弱酸位有利于抑制二甲苯异构化反应和二甲苯进一步烷基化反应,提高对二甲苯选择性.实验结果表明随着弱酸酸量的增加,对二甲苯选择性增加,甲苯转化率减小.与HZSM-5相比, 1.7%B/HZSM-5催化剂弱酸酸量增加了226%,因此在1.7%B/HZSM-5催化剂上获得98.57%的对二甲苯选择性.     

以实验探究为主线 促进教学目标落实

以“ 电容器的电容”公开课为例, 谈谈如何以实验探究为主线设计教学过程, 从而达到促进教学目标有 效落实的目的