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正不饱和度又称缺氢指数,即有机物分子与碳原子数相等的开链烷烃相比较,每减少2个氢原子,则有机物的不饱和度增加1,用Ω表示.单键对不饱和度不产生影响,因此烷烃的不饱和度是0(所有原子均已饱和).即烷烃:Ω=0.以此类推一个双键(烯烃、羰基化合物等)贡献1个不饱和度.一个叁键(炔烃、腈等)贡献2个不饱和度.一个环(如环烷烃)贡献1个不饱和度.环烯烃贡献2个不饱和度.一个苯环贡献4个不饱和度.一个碳 相似文献
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为帮助学生更好地理解和掌握有机物不饱和度知识,有别于通常的方法,从价电子的角度解释并计算有机物的不饱和度,以中学生能理解的知识解释了有机物不饱和度的成因,便于学生在理解的基础上记忆,并简单介绍不饱和度在有机化学中的应用. 相似文献
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张安国 《数理化学习(高中版)》2016,(4):63
本文从不饱和度的内容出发,探讨不饱和度在推断同系物及同分异构体中的妙用.不饱和度是推断有机物可能结构的一种新思维,其优点是推理严谨,可防遗漏,在求较为复杂的分子式及同系物、同分异构体的判断等方面时,若能运用不饱和度将有事半功倍之功效,减轻学生学习负担. 相似文献
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不饱和度即缺氢指数，常用Ω表示．了解有机分子的不饱和度，可以快捷有效地确定有机物的分子式，同时利用不饱和度和有机物的分子式可确定有机物的分子结构． 相似文献
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不饱和度是有机化学中的重要概念,但在高中化学教材中没有涉及,教师在平时的课堂教学中也很少系统地介绍不饱和度．其实,灵活地应用不饱和度可以帮助考生迅速解决有机化学中的一些问题,如推测有机物的结构特点、判断同分异构、进行有机推断等．下面,笔者就不饱和度的概念及其在高中有机化学中的应用向大家做简单介绍． 相似文献
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烃分子每增加一个双键或环状结构，称为一个不饱和度，烃分子每增加一个不饱和度必减少两个氢原子，反之亦然，(不饱和度用Ω表示)。 相似文献
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不饱和度又叫缺氢指数,是有机物分子不饱和程度的量化指标,用希腊字母Ω表示。通过不饱和度,可以在仅知道其中碳原子数的前提下迅速地求出氢原子数,从而确定有机物的分子式;更可在仅知道某有机物分子式的情况下,先求不饱和度,从而推断其分子结构。 相似文献
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毛翰 《华侨大学学报(哲学社会科学版)》2012,(3):102-113
各种艺术都是相通的,相互渗透的。除了"诗中有画,画中有诗",还可以说"诗中有乐,乐中有诗","诗中有舞,舞中有诗","诗中有建筑,建筑中有诗",以及"乐中有画,画中有乐","乐中有舞,舞中有乐","乐中有建筑,建筑中有乐"等。各种艺术的互动和配合,主要发生在想象艺术与听觉艺术、视觉艺术之间,以及听觉艺术与视觉艺术之间。书法地位独特,与其它各种艺术都可能相通互动。 相似文献
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钦州湾表层海水温度盐度及pH值时空变化 总被引：2，自引：0，他引：2
根据2009年春夏秋冬4个季节调查资料,分析钦州湾表层海水温度、盐度及pH值的季节变化和分布特征。结果表明：钦州湾海水平均温度春季20．4℃,夏季30．1℃,秋季16．0℃,冬季14．6℃,变化特征与气温的季节变化相同,空间分布为夏秋季河口区的水温都略高于湾口区,而春冬季则相反。海水平均盐度春季20．067,夏季17．975,秋季23．864,冬季23．660,表现为秋季〉冬季〉春季〉夏季,各季节空间分布总体表现为河口区低,湾口区高的趋势。海水pH平均值春季7．82,夏季8．11,秋季8．01,冬季8．10,全年空间分布高值区均出现在大风江口外海域。钦州湾海水比较适宜大蚝、对虾、文蛤等广温广盐性品种的海水养殖。 相似文献
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迟欣 《天津工程师范学院学报》2014,24(3):57-61
我国现行的学科与专业目录包括1997年版《授予博士、硕士学位和培养研究生的学科、专业目录》、2012年版《高等学校本科专业目录》以及2011年版《学位授予和人才培养学科目录》.美国的学科与专业目录被称为Classification of Instructional Programs（CIP）.美国的学科、专业分类系统无论在编制理念上还是技术上都比较完善和成熟,它给我国行业特色院校英语学科与专业互动机制的建立带来了一定的启示.美国加州大学洛杉矶分校（UCLA）的语言学科的院系设置和课程设置,也为我国行业院校英语学科的建设提供了宝贵经验. 相似文献
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崔立斌 《天津师范大学学报(社会科学版)》2005,16(6):75-78
先秦汉语动词作主语、宾语跟名词作主语、宾语是不同的，先秦汉语动词作主语、宾语有四种不同情形：动词作主语、宾语；动词作主语、宾语后活用为名词；动词作主语、宾语时兼有名词性质；动词跟作主语、宾语的词是不同的单位。因此，先秦汉语动词的活用和兼类就少一些。 相似文献
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This study examined the effects of emotional abuse in childhood, along with physical and sexual abuse, on suicidality in adulthood, and whether and how emotional abuse and depressive symptoms in adulthood mediate the association between the childhood emotional abuse and suicidality. The data were drawn from the 2012 Korean General Social Survey, a nationally representative survey with a multistage area proportional probability sampling method. Random effects regression and the Sobel test were used to analyze the relationships between childhood emotional abuse and suicidality and the mediating effects. Random effects models showed that emotional abuse in childhood was positively associated with suicidality in adulthood, even after controlling for physical and sexual abuse in childhood. Emotional abuse and depressive symptoms in adulthood mediated the association between emotional abuse in childhood and suicidality. Depressive symptoms also mediated between emotional abuse in adulthood and suicidality. These findings suggest that emotional abuse in childhood has indirect harmful effects on suicidality in adulthood. It increases suicidality through higher occurrences of re-victimization and depressive symptoms in adulthood. Practitioners and policy makers should recognize that experiences of emotional abuse in childhood may result in re-victimization in adulthood, which, in turn, lead to suicidality. Early intervention programs to reduce the likelihood of experiencing re-victimization may be critical for people exposed to emotional abuse in childhood. 相似文献
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Gender disparities in science and engineering majors in Chinese universities have received increasing attention from researchers and educators in China in recent years. Using data from a national survey of college students who graduated in 2005, this study documents gender disparities in enrollment and academic performance in science and engineering majors, and explores gender disparities in initial employment experiences of science and engineering graduates. It finds that females lag far behind males in enrollment in science and engineering majors overall. However, females actually are more represented than males in some majors such as mathematics and chemistry though the reverse is true for other science and engineering majors. Also, in science and engineering majors, females perform better than males in both general course grades and in English competency tests. Male science and engineering graduates have a clear advantage over their female counterparts in initial employment after graduation: they have a high employment rate, a higher starting salary, and are more likely to be employed in such jobs as business management and technical specialist. The male advantage in employment rate and starting salary persists even after controlling for other factors. 相似文献
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20世纪90年代我国区域高等教育公平与效率变化的实证研究 总被引：5，自引：0，他引：5
公平和效率是各国高等教育发展中存在的重要问题之一。一般认为公平和效率在理论上和宏观上是可以统一的，并能够得到协调发展和可持续发展。然而，从微观和实践层面上分析却往往会发现存在一种矛盾现象，似乎是一个不可调和的两难问题。我国省(市)高等教育发展的公平与效率就是当前急需关注的一个典型的、具体的问题。通过对反映我国1999年和2000年各省(市)高等教育和经济发展状况的多指标进行聚类、相关等统计分析，考察了我国20世纪90年代高等教育区域公平和效率的发展变化特征，并通过对二者量化关系的揭示，对我国省(市)20世纪90年代高等教育公平与效率问题进行了实证分析和评估，并对我国未来省(市)高等教育的进一步发展提出了相应的对策和建议。 相似文献
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Marguerita McGovern 《Pastoral Care in Education》2013,31(3):235-252
The aim and objective of this study is to examine and compare how schools in Galway, Republic of Ireland and Derry in the North of Ireland (cities located within two independent jurisdictions in Ireland) manage and respond to bereavement. To carry out a survey of schools, the ‘Loss in Schools’ questionnaire is considered the most suitable tool. The questionnaire, which contains 10 questions designed to unearth pertinent issues including the needs and concerns of schools, had previously been administered in studies in Hull. Sixty questionnaires were administered in both Galway and Derry, with a return of 38 and 35, respectively. This study illuminates important aspects of the topic. The schools in both Galway and Derry rate bereavement (and parental separation) as highly important in terms of priorities. In terms of policy, some of the respondents in both study sites report that loss is included in their school's policy documents but not formally included in the curriculum. A designated staff member (who would speak to the pupil experiencing the death of a family member or significant other) is evident in 37% of Derry schools and 23% of Galway schools. Some members of staff in both study sites have attended training in bereavement, although the courses are relatively short term. Schools request assistance from other agencies outside the formal schools arena in times of need. In Galway the psychology services are most commonly consulted, while in Derry the Western Education and Library Board Bereavement Counselling teams and Cruse Bereavement Care are identified as additional resources from which help is sought. This paper outlines recommendations on schools' training needs in the area of child bereavement and the request for support to help further develop and formalise school policies. 相似文献
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Utilizing 2068 individuals in 60 organizations in the U.S. and Italy, this study (a) examines the overall relationship between trust in top management and immediate supervisor and overall estimates of satisfaction and perceived organizational effectiveness, (b) compares the amount of variance in satisfaction and effectiveness that can be explained by trust in top management to the amount of variance explained by trust in immediate supervisor, and (c) clarifies the role of information receiving as a predictor of trust in top management and immediate supervisor. Results of a canonical correlation analysis indicated that the canonical equation explained 49% of the variance in the linear composites (Canonical R = .69, p < .001). Trust in top management was more strongly associated with satisfaction and effectiveness than was trust in immediate supervisor. Tzvo separate multiple regression analyses indicated that after controlling for geographic location of company and type of industry, information received about job and organizational issues uniquely explained 26% of the variance in trust in top management and 13% of the variance in trust in immediate supervisor. 相似文献
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聂长建 《山西大学师范学院学报》2008,7(1):8-13
孔子是哲学大师,亦是语言大师。《论语》的巨大影响,在于其思想之精深,亦在于其语言之魅力。孔子的语言观具有几个特点：一是言行一致,二是名实一致,三是文质一致,四是时中的方法,五是老实的态度。孔子的语言具有多方面的美学特征：一是匀称美,二是气势美,三是弹性美,四是睿智美,五是自然美,六是崇高美,七是刚力美,八是人格美,九是无言美。孔子的语言观极具原创性,进而影响其思想;孔子的语言美颇有吸引力,进而传播其思想。其语言的深邃和美相得益彰,凸显孔子思想的伟大。 相似文献