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61.
E. Floriani R. Lima R. Vilela Mendes 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(2):295-302
In this paper, we examine the effects of the
gravitational field on the dynamical evolution of the cavity-field
entropy and the creation of the Schr?dinger-cat state in the
Jaynes-Cummings model. We consider a moving two-level atom
interacting with a single mode quantized cavity-field in the
presence of a classical homogeneous gravitational field. Based on
an
su(2) algebra, as the dynamical symmetry group of the model, we derive the reduced density operator of the cavity-field
which includes the effects of the atomic motion and the gravitational field. Also, we obtain the exact solution and the approximate
solution for the system-state vector, and examine the atomic dynamics. By considering the temporal evolution of the
cavity-field entropy as well as the dynamics of the Q-function of the cavity-field we study the effects of the gravitational
field on the generation of the Schr?dinger-cat states of the cavity-field by using the Q-function,
field entropy and approximate solution for the system-state vector. The results show that the
gravitational field destroys the generation of the Schr?dinger-cat state of the cavity-field. 相似文献
62.
S. Kar Y. K. Ho 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(2):157-165
We have investigated the bound states and resonance states of
plasma-embedded tdμ and ddμ molecular ions using accurate
correlated basis functions. The plasma effect has been taken care of by
considering the Debye shielding approach of plasma modeling which admits a
variety of plasma conditions. The density of resonance states are calculated
using the stabilization method. The ground and excited states energies, and
the S-wave resonance energies of tdμ and ddμ molecular ions
immersed in plasmas are reported for various shielding parameters, along
with the 1S and 2S threshold energies of the tμ and dμ atoms. 相似文献
63.
化学三重表征研究一直深受国内外学者的重视,目前,初级表征的研究已有一定的理论基础,但是,次级表征(即不同表征水平之间的转化)的研究仍是研究的弱点和难点。纸笔检测、口语报告研究方法都存在一定的局限。为了从信息加工过程研究三重表征间转化的基本特点,采用眼动分析法对12名初三学生进行3×3两因素混合实验。结果显示:(1)在初三上册期末,学优生基本可以进行三重表征之间的直接转化;(2)学中生符号表征较强且依赖于符号表征,表现出“双通道协同加工”现象,符号—宏观、微观转化水平较强,宏观—微观、符号和微观—符号、宏观转化水平较弱;(3)学困生普遍缺乏三重表征的思维和意识,三重表征间的转化水平较低,相比较而言,符号-宏观、微观表征转化稍强于宏观-微观、符号表征转化和微观-符号、宏观表征转化。 相似文献
64.
基于绿色化学对社会可持续发展的重要性,提出科学教育中“绿色应用”素养的理论框架,结合高中生化学学习特征开发测评工具,实施测量,分析处理测试数据,探查了高中生“绿色应用”素养的行为水平。研究发现,高中生“绿色应用”素养水平与其学科能力水平具有较好的一致性,不存在性别差异。测评结果为绿色化学实践提供借鉴和启发,以促进学生“绿色应用”素养的提升。 相似文献
65.
66.
Crisólogo Dolores-Flores Martha Iris Rivera-López Javier García-García 《International Journal of Mathematical Education in Science & Technology》2019,50(3):369-389
This paper reports the results of a research exploring the mathematical connections of pre-university students while they solving tasks which involving rates of change. We assume mathematical connections as a cognitive process through which a person finds real relationships between two or more ideas, concepts, definitions, theorems, procedures, representations or meanings or with other disciplines or the real-world. Four tasks were proposed to the 33 pre-university students that participated in this research; the central concept of the first task is the slope, the last three tasks contain concepts like velocity, speed and acceleration. Task-based interviews were conducted to collect data and later analysed with thematic analysis. Results showed most of the students made mathematical connections of the procedural type, the mathematical connections of the common features type are made in smaller quantities and the mathematical connection of the generalization type is scarcely made. Furthermore, students considered slope as a concept disconnected from velocity, speed and acceleration. 相似文献
67.
68.
Mathematical definitions are an important mathematical construct which has been noted as a challenging topic for both teachers and students. This study provides an analysis of the form and content of a set of 308 definitions of quadrilateral types provided by 44 novice pre-service elementary teachers (NPSTs) who had not yet studied geometry or definitions on the college level. Analysis of definition structure including necessary, sufficient, and minimal conditions, as well as hierarchical and partitional structure, provides insight into what NPSTs may think about the form of mathematical definitions in general. Analysis of the properties used in definitions of each shape type and the frequency of those properties reveals the shape types with which NPSTs are most and least familiar. These results are presented alongside possible applications and implications for instruction. 相似文献
69.
以本校全体初三年级学生为研究对象,并将其分成实验组与对照组;通过集体备课设计完成的微课被上传至线上供实验组学生自学使用;经过2个月的实践,对学生的自学化学能力进行调查、比较与分析。结果表明,借助微课进行自学能提高学生的自学化学能力;在性别差异上,女生自学化学能力依旧好于男生,男生自学化学能力获得明显进步,实践效果好于女生;在学业水平差异上,学困生自学化学能力提升幅度最大,中等生次之,而优等生自学化学能力提升幅度最小。基于以上研究结论及实践中获得的经验,提出下列建议:建构具有中学化学学科特色的“微课链”;搭建学生反馈和教师交流的平台;构建家校联合体监督学生自学过程。 相似文献
70.
阐述了研究生参与大型仪器管理的必要性、运行机制及实施环节,建立了"统一管理,专人负责,用管结合,开放使用"的管理模式.实践证明,这一措施的实施对规范大型仪器管理、提高仪器利用率以及实验室科研项目顺利进行起到了积极促进作用. 相似文献