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惰性气体位于元素周期表最右侧一栏,它们不喜欢和周围的邻居打交道,甚至连它们自己都是以单原子形式出现的.它们这个家族被称作“惰性气体”,但它们真的懒惰吗?
惰性气体的发现
1868年皮埃尔·让森在观测太阳的色球层时,发现了一条新的黄色谱线,推测太阳中存在一种新物质,命名为“氦”;后来威廉·拉姆齐通过加热钇铀矿找到了氦气.1895年,英国科学家瑞利勋爵和威廉·拉姆齐从空气中分离一种新的元素:氩.科学家由此发现,元素周期表上欠缺了一整类元素.1902年,俄国化学家门捷列夫把它们分类为第0族.后来,拉姆齐继续使用分馏法把液态空气分离成不同的成分,于1898年发现了三种新元素:氪、氖和氙.随着1898年氧气的发现,惰性气体就有了今天的六位成员:氦(He)、氖(Ne)、氩(Ar)、氪(Kr)、氙(Xe)、氡(Rn). 相似文献
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运用辉光放电气体激光器进行大气传输激光通信,是现代先进的通信手段。为配合大专院校、中学中专中技激光通信的教学和科普讲座,我们开发了“CL—2”型Ne—Ne激光通信演示仪。仪器除用于通信演示外,可用来开设He—He激光器静、动态特性和频率特性测试以及激光噪声观测等实验。仪器成本低,可一机多用, 相似文献
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刘春生 《青苹果(高中版)》2009,(2):47-48
元素周期表的最后一纵列包含了氦、氖、氩、氪、氙、氡六种元素,由于这六种元素的单质在通常状况下都是气体,其在自然界中的含量又极少,因而被称为稀有气体元素。又由于这六种元素的原子最外电子层都含有8个电子,已经达到稳定结构,化学性质很稳定,一般情况下不与其他物质发生化学反应,故而又把它们称为惰性气体元素。 相似文献
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一、原子结构知识联系新成果、高科技例1 (2003年全国理科综合高考题)人类探测月球发现,在月球的土壤中含有较丰富的质量数为3的氦,它可以作为未来核聚变的重要原料之一.氦的该种同位素表示为:( ) (A)_3~4He (B)_2~3He (C)_2~4He (D)_3~3He 解析:从题给信息和元素周期表知:氦的质量数为3,质子数为2.由原子符号_Z~AX知,A表示质量数,Z表示质子数,故答案为(B). 二、元素周期表的运用 相似文献
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蔡挥剑 《中学物理教学参考》2005,34(10):59-59
质谱仪产生于20世纪初，英国物理学家阿斯顿为了测定氖的组成及其原子量，参照当时光谱分析的原理，改进了测定阳射线的气体放电装置，设计出一种包括离子源、分析器和收集器的装置，这就是质谱仪．阿斯顿利用它，首先证实了氖存在Ne20和Ne22两种同位素，并测出它们在氖气中的比例为10：1．随后阿斯顿使用质谱仪测定了几乎所有元素的同位素，并因此于1922年获得了诺贝尔化学奖。 相似文献
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我们知道,当测电笔接触交流电的火线或高压直流电时,氖管会发出桔红色辉光。这是因为在外电场激发下,氖管中的氖原子所发生的辉光放电现象。我们在讲授“静电场”时,也多次运用氖管的这一特性做实验,使看不见、摸不着的静电场变得形象、 相似文献
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School disciplines,social representations,and the construction of the didactics of history,geography, and civics 总被引：1，自引：0，他引：1
The author presents a concept of the didactics of history, geography, and civics that seeks to link, through a single dynamic, the civic, political, and social goals of school knowledge with everyday classroom practice and pupils' learning. Two concepts occupy the heart of this construction: those of school disciplines and social representations. The concept of school disciplines addresses the fact that school knowledge is a creation of the school, designed to enable it to achieve the social goals it is assigned. A school discipline is thus a particular combination of goals, content (in the form of shared knowledge), methods, and practices. The concept of social representations is a tool serving to analyze knowledge as theories of the natural and social world, its production, and its reception by the different actors involved. 相似文献
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Yaroslav Senyshyn 《Interchange》1995,26(2):105-126
This paper is a critical evaluation of what is believed by the author to be Kierkegaard's subjective, ambivalent, and arbitrary stereotyping of women. In particular, the paper examines the Kierkegaardian notion of equality, essential feminine characteristics, and finitude. The result is an attempt to apply Kierkegaard's ideas to those issues pertaining to inequality in musical performance; as well, a plea is made for the demystification of the notion of woman as whore or Madonna. 相似文献
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Jamel K. Donnor 《Peabody Journal of Education》2018,93(1):23-37
In this paper, I examine the use of litigation as a strategic tool of resistance for thwarting school desegregation. Utilizing Cowan v. Bolivar County Board of Education as a case study, I argue that, despite losing the constitutional right to racially segregate public schools according to an explicit white supremacist doctrine, whites in Bolivar County, Mississippi, were successful in stemming the impending tide of social change associated with school desegregation through litigation. Litigious resistance not only provided southern whites with a racially moderate epistemology for undermining school desegregation regionally, but their legal challenges to school desegregation also laid the groundwork for non-southern white animus toward all federal education policies that promoted racial inclusion. 相似文献
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借助功能语言学主位和主位推进模式有关理论来分析语篇的衔接、信息分布、连贯、语篇发展以及译者如何利用这些分析结果充分解读翻译源文,在以语篇为翻译单位时,采取何种相应的翻译对策,生成在功能和效果上与之相当的目的语语篇。 相似文献
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William DeGenaro 《Community College Journal of Research & Practice》2013,37(7):529-545
Community college practitioners frequently bemoan negative or stereotypical representations of community college students and community college life in general in the popular media. Saturday Night Live skits and satirical news reports in The Onion enjoy poking fun at community colleges, while mainstream news outlets often fail to challenge stereotypes of community colleges as lacking academic rigor. Those frustrated by these portrayals should know that the press overwhelmingly lauded 2 year colleges during the early decades of the “junior college” movement. Such reporting celebrated the new institutions' missions, and praised their speedy growth as components of public education. In fact, the press often implied that these new campuses reflected an inevitable step in the evolution of American higher education. This paper analyzes media reports about public 2 year colleges (at the time called junior colleges) published during the 1920s and 1930s. The term junior college is used in this historical review since the term was common during the era in question. 相似文献
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ELIYAHU ROSENOW 《Journal of Philosophy of Education》1993,27(2):209-220
ABSTRACT An examination of contemporary publications in the philosophy of education reveals that the authority of the teacher is being eroded. As teachers derive their authority from the democratic state and its compulsory education laws, the undermining of their authority indicates the undermining of the authority of the democratic state and its laws. A comparison between Plato and Dewey from this point of view reveals that this state of affairs is the upshot of the collision between the principle of authority and the principle of liberty, and that this collision constitutes the basic problem of democracy as well as of education for democracy. The challenge to contemporary education is consequently that of exploring ways leading to the rehabilitation of the authority of the teacher. 相似文献
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Becky Francis Louise Archer Julie Moote Jen de Witt Lucy Yeomans 《British Journal of Sociology of Education》2017,38(8):1097-1110
Hyper-femininity and the construction of the ‘girly girl’ label have been documented widely, but there has been less attention to their content (or any distinctions between these constructs). Indeed, it can be argued that the content of femininity remains a controversial and somewhat under-researched topic in feminist scholarship. This is also the case in relation to science, which has been widely characterised as a masculine terrain, but there has been less attention to why femininity is excluded from/by science. This article attempts to unpick some of these issues, with a particular focus on the construct of the ‘girly girl’, in relation to access to science. Drawing on qualitative data from the Economic and Social Research Council-funded ASPIRES 2 project, we analyse the discourses used by young people and parents in discussion of ‘girly girls’ and physics. We show the misogynist and excluding discourses projected onto the ‘girly girl’, and indeed that are used to interpolate femininity more broadly. We found that in discussions of science and (hyper-)femininity, even potentially positive feminine attributes were denigrated. Hyper-femininity was produced as ‘more than lack’: vacuous, but also a risible presence. In reflecting on our findings we consider whether femininity may be more derided in some discursive contexts (e.g. science discourse) than others, and whether femininity can or should be conceived as more than lack. 相似文献
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Maria Develaki 《Science & Education》2008,17(8-9):873-888
In view of the complex problems of this age, the question of the socio-ethical dimension of science acquires particular importance. We approach this matter from a philosophical and sociological standpoint, looking at such focal concerns as the motivation, purposes and methods of scientific activity, the ambivalence of scientific research and the concomitant risks, and the conflict between research freedom and external socio-political intervention. We then point out the impediments to the effectiveness of cross-disciplinary or broader meetings for addressing these complex problems and managing the associated risks, given the difficulty in communication between experts in different fields and non-experts, difficulties that education is challenged to help resolve. We find that the social necessity of informed decision-making on the basis of cross-disciplinary collaboration is reflected in the newer curricula, such as that of Greece, in aims like the acquisition of cross-subject knowledge and skills, and the ability to make decisions on controversial issues involving value conflicts. The interest and the reflections of the science education community in these matters increase its—traditionally limited—contribution to the theoretical debate on education and, by extension, the value of science education in the education system. 相似文献
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In the literature on the situated and distributed nature of cognition, the coordination of spatial organization and the structure of human practices and relations is accepted as a fact. To date, science educators have yet to build on such research. Drawing on an ethnographic study of high school students during an internship in a scientific research laboratory, which we understand as a “perspicuous setting” and a “smart setting,” in which otherwise invisible dimensions of human practices become evident, we analyze the relationship between spatial configurations of the setting and the nature and temporal organization of knowing and learning in science. Our analyses show that spatial aspects of the laboratory projectively organize how participants act and can serve as resources to help the novices to participate in difficult and unfamiliar tasks. First, existing spatial relations projectively organize the language involving interns and lab members. In particular, spatial relations projectively organize where and when pedagogical language should happen; and there are specific discursive mechanisms that produce cohesion in language across different places in the laboratory. Second, the spatial arrangements projectively organize the temporal dimensions of action. These findings allow science educators to think explicitly about organizing “smart contexts” that help learners participate in and learn complex scientific laboratory practices. 相似文献