镧系元素冠醚配合物K稳的计算

通过镧系元素电子结构及冠醚的具体分析，运用无机电力学的原理，通过作图、分析、计算的方法给出镧系元素冠醚配合物的K稳与Ln^3 的有效核Z^*及半径r的关系。     

稀土发光材料简介

引言稀土元素(Rare Earth)是指元素周期表中ⅢB族的镧系元素(从原子序数57的镧(La)到原子序数71的镥(Lu)),以及与镧系元素结构相似,关系密切的钪(Sc)和钇(Y),共17种元素。1794年芬兰人加多林(J.Gadolin)从硅铍钇矿(又称加多林矿)中成功分离出第一种钇组稀土混合氧化物——钇土。之后百余年,人们相继发现了铈(1803年),镧(1839     

神奇的稀土

神奇的稀土“稀土”是“稀土元素”的简称。它们位于元素周期表的第Ⅲ副族，包括钪、钇和镧系元素共１７种金属元素。稀土的名称是从１８世纪沿用下来的，当时认为提取这类元素的矿物甚为稀少，加上技术水平的限制，只能以类似碱土的形式提取出来，故被命名为稀土。实际上...     

科技知识

我国稀土储量居世界第一位“稀土”这个名字是历史上遗留下来的,意思是“稀少的土”。其实稀土不是土,而是金属。稀土金属是指元素周期表中ⅢB族中第57至71号15个镧系元素,加上钇和钪。我国稀土金属储量居世界第一位,生产能力居第二,仅决于美国。     

稀土及其应用

稀土及其应用谭冬寒钪、钇和镧系元素统称为稀土元素，常用“ＲＥ”或“ＴＲ”表示。这是从１８世纪末沿用下来的错误名称，事实上它们既不是土，也不稀有。如铈比锡、钇比铅、铥比银和汞都多，它们在地壳中的含量为０．０１７５６％。稀土元素在现代工业中的用量虽远不及...     

用质子共振谱法测定双环〔3,3,1〕壬二烯的结构和异构体的组成

通过气液色谱的分析以及应用银——镧系元素位移试剂的自旋共振谱来研究双环〔3,3,1〕壬二烯同分异构体组成的测定。3,7——二甲烯基双环〔3,3,1〕壬烷与吸附在作为骨架的镍上的氢气在发生氢化作用的过程中没有呈现出立体专一性,首先表现出异构化过程,然后才是氢化作用。双环〔3,3,1〕壬二烯及其衍生物对于研究许多有机反应的机理是一种方便的模型     

汞的“惰性”及其盐类的分子式

汞是位于周期表中第六周期镧系元素后dS区内的ⅡB族元素。它的电子层结构是1S~22S~22P~63S~23P~63d~(10)4S~24P~64d~(10)4f~(14)5S~25P~65d~(10)6S~2(简写为2 8 18 32 18 2)。这种电子层结构确是一种饱和的封闭式结构。这正是汞单质特性之一的“惰性”表现的结构基础。对于这个问题该怎样来认识呢?     

稀土元素的发现和应用

随着现代科学技术的飞速发展,稀土元素日益显示出它的重要作用,特别是在新材料的研制和应用中,它已经扮演了重要的角色。稀土元素是一个多成员的大家族。它由元素周期表中ⅢB族的钪(Sc)、钇(Y)和镧系元素组成,共17个成员,且都是金属元素。这些元素之所以能形成一个大家族,主要是因为它们的性质十分相似,且在自然界中,易于共生而难以分离。也正因为如此,17种稀土元素的一一发现,在历史上经历了一个漫长的过程。     

中国的稀土

1.稀土的定义稀土就是化学元素周期表中镧系元素——镧(La)、铈(Ce)、镨(P)r、钕(Nd)、钷(Pm)、钐(Sm)、铕(Eu)、钆(Gd)、铽(Tb)、镝(Dy)、钬(Ho)、铒(Er)、铥(Tm)、镱(Yb)、镥(Lu),以及与镧系15个元素密切相关的两个元素——钪(Sc)和钇(Y)共17种元素,称为稀土元素(RareEart)h,简称稀土(RE或R,其氧化物称REO)。稀土元素是从18世     

闻一多诗作诗论及杂文与人格的方正和圆满

作为学者的闻一多在针对其研究对象进行分析时,总是将其文和其人相结合.其实,作为人们研究对象的闻一多,其诗作、诗论与杂文等,也都是其方正人格的表现.闻一多凡事追求完美和极致,由于其人格建立在高洁的基石上,因此,他之由绅士转变为斗士,就不是政治家的政治表现,而是坚持正义、寻求真理的知识分子行为.所以,其方正人格的"绝唱"又使其诗作诗论乃至杂文的品位得到彰显.闻一多虽然失去了宝贵生命,但正因为他有"道",所以无论其诗作、诗论还是人格,都能获得圆满和永生.     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…     

库克斯顿城堡

城堡, 是欧洲典型的建筑之一, 每个城堡都有一个美丽的传说或是一段历史。从本期开始, 我们将推出“城堡之旅”, 带各位读者去浏览、观赏欧洲各地的城堡, 开始一段文化与历史的旅途!     

The Reader Response Approach to Teaching of English Literature

During interview with English majors, it was found that a majority of students expressed disappointment with their experience of English literature classes. Students' dislike of learning English literature appears to be the major problem of teaching English literature in China. Reader response approach is a good way to solve this problem. In this paper, I explain the rationale behind the reader response approach, such as its origin, definition, features, assumptions, and strategies. Then I illustrate how reader response approach works as a teaching strategy by presenting several teaching models. At last I evaluate its usefuiness for teachers and present the advantages of reader response approach in Chinese context.