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1.
周传升 《中学物理教学参考》2001,(3):59-60
地球是个巨大的磁体 ,它周围空间存在的磁场叫地磁场 .经过长时间的研究 ,人们已基本掌握了地磁场的一些性质及变化规律 ,但至今仍有很多问题没有搞清楚 .1.地磁起源之谜人类很早就提出了地磁场的起源问题 ,为解释这个问题 ,历史上曾先后提出过许多观点 .最早提出地磁学说的是 16世纪英国科学家吉尔伯特 ,他认为在地球内部存在着一个巨大的永久磁铁 ,这个永久磁铁的南极在地球地理北极附近 ,北极在地理南极附近 ,这一理论叫永磁体假说 .通过观测地磁场的分布 ,地球内部确实存在着一个象永磁体那样的场 .这一学说 ,当时被人们接受了 .然而 ,… 相似文献
2.
范公瑾 《数理化学习(高中版)》2014,(10):34-34
信息链接：地磁场是地球物理学的基本问题之一,地磁场产生的原因尚无定论,普遍认为是由地核内液态铁的流动引起的,还有一种假说应用“磁现象的电本质”来做解释,认为地核在6000K的高温和360万个大气压的环境中会有大量的电子逃逸出来,地幔间会形成负电层,地球自转造成地幔负电层旋转产生环形电流,地磁场由此而生． 相似文献
3.
地球是个巨大的磁体 ,它周围空间存在的磁场叫地磁场 .地磁场的强度并不大 ,在地面附近的磁感应强度大约只有 5× 1 0 - 5T ,而一般的永久磁体附近的磁感应强度可达 0 .4～ 0 .7T .经过长期的研究 ,人们已基本掌握了地磁场的一些性质、变化规律及对地球上各种生物的影响等 ,但至今地磁场仍有很多问题尚无定论 .1 地磁场的起源人类很早就提出了地磁场的起源问题 ,为解释这个问题 ,历史上曾先后提出过许多观点 .目前 ,较为成熟的是磁流体发电机学说 .1 945年 ,物理学家埃尔萨塞根据磁流体发电机的原理 ,认为当液态的外地核在最初的微弱磁场… 相似文献
4.
<正> "假说—演绎法"是在观察和分析的基础上提出问题以后,通过推理和想象提出解释问题的假说,根据假说进行演绎推理,再通过实验检验演绎推理的结论。如果实验结果与预期结论相符,就证明假说是正确的,反之,则证明假说是错误的。可见,演绎推理是一种必然性推理。当前最流行的"假说—演绎法"模型是:某项研究从解决一个问题开始,通过逻辑推理或想象,导出一个假说,由此推演出必然的、可观察的待检验陈述,如果这些陈述被证明是正确的,就得出被确证的结论。 相似文献
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一些疑难问题的解答,用已有的方法难以得到令人满意的解释,倘若大胆猜想,提出探讨性的假想解释,就产生了假说。只要假说成立,问题便圆满解决。这样的思维方法,称之为假说方法。假说方法是依据科学原理和一定的事实材料,对未知事物的因果性和规律性作出科学解释的方法。应用假说方法证明一类与自然数n有关的不等式,不仅简明,而且有规律可循。 相似文献
6.
20世纪初,西方学者开始关注奥斯曼帝国的起源问题,维特克的"加齐起源说"是对此问题的经典回应,在学界被视为圭臬。自20世纪40年代以来,学界对"加齐起源说"的质疑不断,但仅有两位学者提出了新的解释模式,分别是美国学者希思·沃德·洛里提出的"劫掠同盟假说",鲁迪·保罗·林德纳教授的文化人类学"部落-国家理论"解释模式。两种不同的叙事范式,仅能反映奥斯曼早期国家形成的某一维度。与通常认为的不同,基督徒与比提尼亚当地居民对奥斯曼早期国家的形成起到了推动作用。 相似文献
7.
语言的起源问题一直以来是困扰人类的一个难以破解的谜,很多关于语言起源的假说应运而生。而随着科技的发展和人类对语言的认识不断深化,对于语言的假说则更注重科学性,论证更加具体,立论越发谨慎小心,趋向于不直接做出结论。本文着重论述当代几种有影响力的假说及其论证,如语言起源的一源论,这些论证为语言起源问题的研究带来了一些生机。 相似文献
8.
语言的起源问题一直以来是困扰人类的一个难以破解的谜,很多关于语言起源的假说应运而生.而随着科技的发展和人类对语言的认识不断深化,对于语言的假说则更注重科学性,论证更加具体,立论越发谨慎小心,趋向于不直接做出结论.本文着重论述当代几种有影响力的假说及其论证,如语言起源的一源论,这些论证为语言起源问题的研究带来了一些生机. 相似文献
9.
解育洁 《山西大学师范学院学报》2008,(4):112-114
萨丕尔—沃尔夫假说是20世纪语言学界一个影响颇大又很有争议的理论。其主要论述了语言、思维、文化之间的关系。我们可以运用该假说解释“一叶知秋”本义的地域性和文化内涵,进而对该假说产生新的认识：第一,该假说可以从语言产生和语言应用两个角度来理解文化对语言产生的反作用和语言对思维的构建作用;第二,该假说也可以用于解释同一种语言的方言中存在的文化差异现象。 相似文献
10.
地磁场是考纲明确的考点内容 ,在近几年的高考试题中屡有出现。因其与生产、生活实际、现代科学技术应用和近代物理知识紧密相关 ,故深得命题者的青睐 ,在学习或复习中应引起高度重视。下面本文就从几个方面对地磁场进行阐述以飨读者。1 地磁场的起源说地球是一个磁体 ,地球周围空间有磁场分布 ,这就是地磁场 ,如图 1所示 ,地磁的北极大致在地理南极附近 ,地磁南极约在地理北极附近。地磁场的水平分量总是从地球南极指向地球北极 ,而竖直分量则南北相反 ,南半球垂直地面向上 ,北半球垂直地面向下。以上特点已得公允 ,但就其起源问题一直争… 相似文献
11.
本文在地磁场逆转的力学模拟模型的基础上提出了一个带分路的多盘发电机模型,并用它的解来模拟地磁逆转的变化规律,获得了较为满意的结果. 相似文献
12.
＂地磁日变观测与日变规律研究＂是针对地球物理学专业学生设立的专题研究性实验项目,旨在使学生通过实际观测了解地球磁场存在的短期平静变化规律,深入认识日变观测在地磁勘探中的重要性及其影响因素,增强学生实际动手能力,培养学生在实践中发现问题、分析与解决问题的综合研究能力。 相似文献
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14.
磁暴期间,导电网络(如电力系统、管道和电话电缆)中会感应出电压。用计算穿过环路的变化垂直磁场或者计算由沿环路变化的水平磁场来得到地面水平环路感应出的电压,这两种方法是等效的,都应用了麦克斯韦方程组,但是它们的等效很难形象化地给予解释。考虑到磁场的发散特性,穿过水平环路的垂直磁场如何相关到环路外围的水平磁场(由于地面线电流),用磁扰动的例子来说明两种方法在计算导电网络中感应电压上是等效的。 相似文献
15.
Robert A. Bell 《Communication quarterly》2013,61(4):358-373
This field study investigates associations among loneliness, career success, and communication competence in an effort to account for the finding of Bell, Roloff, Van Camp, and Karol (1990) that individuals who occupy low positions in organizational hierarchies may be more prone to loneliness. Subjects were 182 employees at a state government agency. Each subject's level in the organization was assessed by assigning him or her to one of five ordinal categories, ranging from Clerical (Level 1) to Director (Level 5). In addition, the Revised UCLA Loneliness Scale and a measure of communication competence were completed. Hypothesis 1, which predicted a negative relationship between organizational level and loneliness, was supported for male subjects only. The second hypothesis, which anticipated a positive correlation between organizational level and communication competence, was again supported only for males. The third prediction that loneliness would be inversely related to competence received strong support for both sexes. The final hypothesis predicted that the inverse relationship between level and loneliness expected in Hypothesis 1 would become positive when controlling for baseline differences in communication competence between higher‐and lower‐positioned employees. No evidence was found that greater communication competence among employees at higher organizational levels masked a real tendency for career success to be accompanied by more loneliness. These results are discussed in terms of gender differences in the interface of work life and personal relationships. 相似文献
16.
John Charles 《Quest (Human Kinetics)》2013,65(3):267-277
The focus of the Thirty-Second Dudley Allen Sargent Lecture is the role of values in kinesiology. As the options of what we can do in our personal and professional lives increase due to such forces as advancing technologies and globalization, the more vexing and pressing question is frequently: What should we do? With deference to the impact of Dudley Allen Sargent on the shaping of our field and with reference to his values as a case study, I will consider innovative curricular approaches to values in action for tomorrow's world. 相似文献
17.
A national survey of 131 park and zoo educators' teaching beliefs was conducted in 14 parks and zoos in the US in 1996 by The Ohio State University Extension. The survey included two primary instruments. The Van Tilburg/Heimlich Teaching Beliefs Scale and a self‐report time on task and importance of task related to teaching methods and techniques. A third series of questions explored teaching purposes. The Van Tilburg/Heimlich Teaching Beliefs Scale is a psychometric instrument containing two parallel Thurston equal‐appearing interval scales. Outcomes are graphed into a two by two matrix using the concepts of ‘sensitivity’ and ‘inclusion’. Developed with a theoretical base of adult education, these scales apply well to nonformal environmental educators. An operational hypothesis for the study, which was corroborated by the data, was that a preponderance of respondents would self‐identify their beliefs to be those of ‘Enabler’ – low control, high inclusion. The application of beliefs to practice, however, might suggest otherwise. 相似文献
18.
黄春晖 《宁德师专学报(自然科学版)》2011,23(1):75-78
介绍固体物理课程的分子晶体中范德瓦尔斯相互作用.概述有关范氏相互作用的研究动态,范氏力的产生根源,推导范氏相互作用势,例举范氏相互作用的具体应用.旨在强调这一领域研究的重要性,精心组织教学内容,激发学生的兴趣. 相似文献
19.
Chellachamy Manoharan Kasinathan Veeramuthu Ramdoss Venkatachalapathy Ramasamy Ilango 《浙江大学学报(A卷英文版)》2008,9(7):988-993
This study investigates the magnetic mineralogy and paleointensity values of a collection of archaeological artifacts （pottery）. The actual magnetic carriers and their domain states present in the archaeological pottery were obtained using the low field susceptibility, thermomagnetic curves and acquisition of isothermal remanence. The magnetic mineralogy of all the samples was dominated by ferrimagnetic mineral （magnetite/magnetite with low titanium content）, which was suitable for paleointensity measurements. The geomagnetic paleointensity value obtained by subjecting them to modified Thellier and Thellier method, is found to be （48.81±0.15） μT. 相似文献
20.
《欧洲教育》2013,45(1):63-70
Secretary of State Van Leijenhorst, in consensus of opinion with Minister Deetman, decided to cut the national budget for educational research by one-third from Dfls. 21 million to Dfls. 14 million by 1st January 1984 (see Table of Conversion). This budget is controlled by the Foundation for Educational Research (SVO [Stichting voor Onderzoek van het Onderwijs]), which also co-ordinates most of the educational research conducted in The Netherlands. Requests for research projects can be made by workers in the field of education, organizations, or the Minister. The drastic cut means that previous agreements with Van Leijenhorst's predecessor Hermes are totally swept aside. This fatal operation has filled the Board of Directors of SVO, the National Foundation for Educational Research, with both perplexity and rage. The Board has accused the Secretary of political breach of promise. These and other facts are mentioned in a communiqué that the Board and Committee of SVO have just distributed, compelled by the fast-growing stream of rumors. The communiqué is made public at a time when the internal debate between the Secretary of State and the Minister of Education and Science has not been rounded off yet. 相似文献