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1.
纸质文物保护的新技术介绍 总被引：1，自引：0，他引：1
本文通过对组成纸张的化学成分以及对影响其老化的物理因素和化学因素的分析,得出纸的老化是从泛黄开始的,泛黄是由于纸张氧化生成了发色团,紫外光可使纸张中的纤维素发生降解反应,酸可以使纤维发生水解反应,其中纤维素在酸作用下发生水解反应是纸张老化的根本原因。 相似文献
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薄层色谱分离效果的好坏,很大程度上取决于展层剂的组成和配比,还会受硅胶板的活化度、环境温度、显色剂和点样量手法等因素的影响.本文报道了采用薄层色谱法分析玉米芯降解液中单糖的成分,着重对多种展层剂进行优化研究.研究结果显示以正丁醇∶乙酸乙酯∶水=7∶2∶1为展层剂分离糖的效果较好,本文还显示以苯胺-二苯胺-磷酸为显色剂的糖显色效果较好.同时,用上述优化的方法对不同酸浓度处理的玉米芯降解液进行分析研究,可以准确、清晰、便利地定性检测出玉米芯木聚糖中单糖的组分. 相似文献
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目前,国内对产业集群的识别大都是根据产业集群的定义和特点通过主观判断得出,对产业集群的类别标准也极不统一,有的甚至直接将高新区或者各类开发区作为产业集群,或者,有的人将一些并不存在多少经济联系的企业捆绑在一起,形成所谓产业集群的局面.而且,具体的产业集群的识别方法有两大类,一是定性识别方法,如赫芬达尔指数、区位Gini系数、E-G指数、和区位商法等;二是定量识别方法,而我国学者对集群大部分都只是定性的分析,定量分析却少之又少,如投入产出分析法、主成分分析法等,本文将主要从定量分析的角度出发,选择结合区位商法和基于投入产出的主成分分析法对陕西省的产业集群进行识别和检验. 相似文献
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周宇扬 《中学化学教学参考》2021,(4):73-74
一、成分分析法的内涵成分分析法顾名思义是对某事物所含有的成分进行分析的方法。在化学上成分分析法则是对所遇到的未知物质进行成分的定性及定量分析,由此甚至衍生出了一门新的学科--分析化学。但考场上的成分分析与此是存在差异的。考场上的成分分析是指根据题目设问分析相关未知物质的成分,从而对题目作出正确的回答。成分分析法在近年高考化学非选择题中十分常见且尤为重要。 相似文献
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应用主成分因子分析方法对学生学习成绩进行分析,并对学生的学习状态利用定性资料数量化理论进行了统计分析,从而找出了影响学生学习质量的主要成分与主要因素,达到改进教学、提高教学质量的目的. 相似文献
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徐敏 《廊坊师范学院学报(自然科学版)》2012,12(3):56-58
超声波可以降解弱酸废水,特别是在工业处理废水方面运用效果显著,通过实验可以看出,温度、初始浓度、pH等对象对弱酸影响很大。当温度为摄氏30度,初始浓度为135.15mg/L,且pH值为3,4小时的超声波辐射,对石炭酸废水处理效果最好,结果为5.64%。当加入适当的H2O2时,可以使降解提高到61.60%,可见曝气可以加速石炭酸的降解。 相似文献
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兼语句和主谓词组作宾语句,在形式上相似,很容易混淆。语文试卷上常有要求分辨二者的题目,究竟如何去辨析这两种特殊句式?可以从三个方面(即固定动词定性法、语音停顿法、添移成分法)着手。如下面两例(摘选自90年高考语文试题): 甲、人们发现自己马群里的马在一夜间忽然变多了。乙、他的报告能使听讲的学生了解课 相似文献
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刘金勤 《荆州师范学院学报》2008,(3):89-92
动词配价研究争论的焦点主要集中在俞词宾语、时间和处所成分以及工具成分的定性上。相关语义成分与动词隐现的规律表明动词的配价具有动态性,其根本原因在于动词词义具有非自足性。此外,词义与句法表现的不一致性也是另一重要因素。 相似文献
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对11个烤烟品种接种赤星病病原菌后,定期测定叶片的过氧化物酶(POD)同工酶、多酚氧化酶(PPO)、硝酸还原酶(NR)和抗坏血酸氧化酶活性,观察其变化规律．结果表明,相对抗赤星病强的品种,PPO活性上升;POD同工酶活性变幅大而快,接种初期活性稍有下降,然后增强,其中以阴极端2,4同工酶带增加较快,180 h由弱酶带变为强带;NR活性变化不大;抗坏血酸氧化酶活性提高．相反,抗赤星病弱的品种,PPO活性下降;POD同工酶变化不大,呈下降趋势;NR活性变幅大;抗坏血酸氧化酶在接种初期活性下降,84 h后回升．通过对不同品种的烟株接种赤星病菌后几种酶活性的测定,探察到一些抗病机理,也为进一步寻找筛选抗烟草赤星病的生化指标提供了参考． 相似文献
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用40％达科宁胶悬剂500、750、1000倍液，在常年花生叶斑病发生较重的地块上于花生盛花期，喷施花生茎叶．试验表明，用40％达科宁胶悬剂500-750倍液防治花生叶斑病效果好，促进了花生生长，提高了花生产量。 相似文献
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根据胶原生物矿化的原理和方法,制备不同条件下的明胶生物矿化样品,通过红外光谱分析,发现磷酸钙、氯化镁的存在引起明胶分子中酰胺Ⅰ、Ⅱ、Ⅲ带显著褪化,明胶生物矿化与胶原生物矿化的紫外光谱曲线也有相似之处,表明明胶与钙、镁离子存在配位作用,明胶也可能作为生物矿化的模板材料。 相似文献
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本文认为从情境主义的角度看传统教学,其主要问题是学与教操作体系的封闭性,即学校生活对社会生活,课堂情境对现场情境,个体学习对群体学习的事实性封闭.为使素质教育的理念成为成功的教学现实,应构建开放性的学与教的操作体系,即注重学与教的社会性、现场性和群体性. 相似文献
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This article examines the colonial encounters of gender, race and sexuality in the United States and the Philippines in the early 1900s. It traces the anxieties over US men's moral degeneracy and the representation of Filipinas as libidinal temptations, which mobilised US women's active participation in colonial biopolitics and governmentality. It contends that white women as imperial feminists asserted their principled crusade and superiority over white men and brown women by becoming bearers of racialised heteronormative traditions and feminine respectability and becoming barriers to inter‐racial sexual relations. White women focused on the white male domains of military and government and on the colonial education of brown women. Ultimately, the article supplements the Spivakian claim that “white men are saving brown women from brown men”, which has become the quintessential narrative of colonial justification and redemption, with “white women are saving white men and brown women from each other”. Drawing on government, newspaper and school documents, the article engages feminist discussions on the role of women in empire and education. 相似文献
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This paper focus on defining a research question while conducting action research among third-year students attending a course on Research Literacy at a teacher education college. This paper discusses the process of preparing for and conducting action research among third-year students attending a course on Research Literacy at a teacher education college. The students were asked to conduct an action research on their classroom activities. The aim of this article is to present the process and pinpointing the discomfort of the students in formulating a research question suited to action research thanks to two prerequisite conditions: the ‘safe space’ and the ‘tender spot’. The research findings illustrate that the students had difficulty defining their ‘tender spot’. It was necessary to create a ‘safe space’. Furthermore, the findings show that the ‘tender spot’ issues were associated with disciplinary content far more than with generic lesson management or classroom management issues. The approach discussed here is leading to positive change and it may be that this professional development tool can facilitate the induction of novice teachers everywhere. 相似文献
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Lisa M. Henderson Natassa Tsogka Margaret J. Snowling 《Journal of Research in Special Educational Needs》2013,13(1):57-65
Visual stress (the experience of visual distortions and discomfort during prolonged reading) is frequently identified and alleviated with coloured overlays or lenses. Previous studies have associated visual stress with dyslexia and as a consequence, coloured overlays are widely distributed to children and adults with reading difficulty. However, this practice remains controversial. We investigated whether overlays have advantageous and reliable benefits for reading in undergraduate students with and without dyslexia. Both groups read jumbled text faster with a coloured overlay than without. The dyslexic group did not show greater gains than controls, despite reporting significantly more symptoms of visual stress. However, coloured overlays did not improve reading rate or comprehension of connected text. The improvement in reading speed with an overlay was not reliable and was significantly reduced at retesting for dyslexic students. These results question the value of coloured overlays as a tool for identifying visual stress and as a form of remediation for the reading difficulties associated with dyslexia. 相似文献
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杜华 《遵义师范学院学报》2007,9(6):46-48
城市一直是一个言说不尽的话题。近现代很多作家都以女性为视点塑造、想象城市的现状与个性,以女性来观照城市,书写城市。本文分析了三十年代的新感觉派,到张爱玲、王安忆,到贾平凹,到邱华栋、卫慧等作家笔下的女人与城市。 相似文献
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分析了皎原、胶原/HAP、胶原/CaCl2的红外光谱曲线,发现无论胶原矿化与否,在3300cm-1附近的氨基吸收峰无变化,但形成生物矿化物后,必然引起酰胺Ⅰ、Ⅱ、Ⅲ带的吸收减弱.据此,提出了钙与胶原上的C=0配位形成复合物的观点. 相似文献
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概述了国内天然彩色棉花的研究现状,对彩色棉的应用前景进行了简单分析,说明天然彩色棉的研究在２１世纪将取得更大成果,具有广阔的市场前景。 相似文献