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1.
张喜英 《周口师范高等专科学校学报》2000,17(2):103-104
普通热过滤和减压热抽滤，都是防止低温时溶质析出，消除其它杂质的固淮分离方法，普通热过滤是采用的铜质夹套仪器，这种仪器，体积大，加热时间长，易堵塞漏斗颈，实验不能继续进行，而减压热抽滤，虽然速度快，但需要仪器多，操作麻烦，溶质易在吸滤瓶内结晶，系统误差大，产品相应减少，故进行了基本操作改进，把夹套热过滤器的保温性和减压热抽滤器的速度快、吸的干的特点，加以综合利用，设计了一套热抽滤器装置，通过实验效果 相似文献
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化学实验中,为加速过滤,使沉淀抽吸干燥,采用减压过滤的方法进行抽滤(图1)。 但是,用此法进行抽滤,不但需用多种实验仪器设备,同时还浪费大量的水。为此,笔 者设计实验装置(直接在吸滤 瓶上连接一橡皮吸气球,此球 可用血压计手压球代替),见 图2～3。 相似文献
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减压过滤用橡胶板相接密封的方法湖南吉首大学化学系（４１６０００）张克梅减压过滤，此法可加速过滤，并使沉淀抽吸得较干燥。在安装抽滤装置时，为了使布氏漏斗与吸滤瓶相接密封，必须配上一个大、小合适的橡皮塞，橡皮塞插入吸滤瓶内的部分不得超过塞子高度的１／２。... 相似文献
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巧用贮气装置进行抽滤湖南省武冈市第四中学（４２２４１１）张礼斌笔者用湖北省武穴师范天平厂生产的Ｊ２６２３型贮气装置和抽滤瓶连接成功地进行了抽滤，效果较好，大大减少了过滤时间．特别适用于设有抽滤设备又想节省演示过滤实验时间的农村中学．一．装置结构（见附... 相似文献
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在化学实验中,常常有些实验需要鼓气和抽气,鼓气常用皮老虎;抽气常用吸耳球或抽滤器．皮老虎是塑料或皮革制成的,容易老化,漏气;用抽滤器抽气效果也不是太好．本人制作的简易气泵,具有吹气和抽气两种功能,很好地解决了这个问题．一．原理利用儿童饮料瓶受压挤后能... 相似文献
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热分析实验中仪器的气密性好坏是影响测试结果客观性和准确性的重要因素之一,但在实际测试中却往往被忽视.研究了草酸钙和石墨在高纯氮气、空气、不同氧含量的氮气下的差热曲线和热重曲线的特点和差异,提出差热类仪器及差热-热重联用仪的草酸钙检漏法、热重类仪器的石墨检漏法,是简便易行、准确有效的方法. 相似文献
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《中学化学教学参考》2000,(7)
一、实验内容1.产品的合成:碘在酸性条件下被氯酸钾氧化成ＫＩＯ3 ＨＩＯ3,溶液经氢氧化钾中和后,与氯化钙发生复分解反应生成碘酸钙。2.产品的分析:用间接碘量法测定。二、主要仪器、试剂及材料1.主要仪器圆底烧瓶 100ｍＬ1只磁力搅拌器1台电子继电器1台结晶皿(水浴缸)1只漏斗1只吸滤瓶1只量筒 100ｍＬ1只 10ｍＬ2只表面皿1只球形冷凝管(带磨口塞)1支电接点温度计(导电表)1支电加热器(300Ｗ)1只温度计(100℃)1支布氏漏斗和抽滤瓶(带橡皮塞)1套烧杯 600ｍＬ1只 500ｍＬ1只 150ｍＬ2只 100ｍＬ1只移… 相似文献
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知识基础:2002年4月中国化学会修订的《全国高中学生化学竞赛大纲》就奥赛实验提出了下列基本要求：有机制备与有机合成的基本操作。电子天平。配制溶液、加热、冷却、沉淀、结晶、重结晶、过滤(包括抽滤)、洗涤、蒸发浓缩、常压蒸馏与回流、倾析、分液、搅拌、干燥。通过中间过程检测(如pH、温度、颜色等)对实验条件进行控制，产率和转化率的计算。实验安全与事故紧急处置的知识与操作。废弃物处置。仪器洗涤和干燥。 相似文献
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唐拾元 《中小学实验与装备》2000,(2)
九年制义务教育初中化学课本 ,安排了一些关于压强、温度变化的实验 ,为了使学生便于观察 ,笔者经过反复实验后 ,设计了下列装置如图1所示 ,收到了较好的效果。1 测量变温1 1 在大试管中注入少量水 ,Ｕ型管中注入品红溶液 ,用橡胶管连接好。1 2 用滴管沿试管内壁慢慢滴入浓硫酸 ,并用玻璃棒不断搅拌 ,同时打开弹簧夹。现象 :Ｕ型管右端迅速上升 ,左端下图 1降 ,停止实验后 ,左右水柱慢慢恢复相等。2 测量变压2 1 在吸滤瓶中放入少量固体氢氧化钠 ,Ｕ管中注入品红溶液。用橡胶管连接好 ,并用弹簧夹夹紧。2 2 用导气管向吸滤瓶中吹入… 相似文献
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The present study utilized both classroom- and student-level observation methods to investigate the relations among first grade students’ (N = 533) problem behaviors and their classroom instructional experiences. Additionally, the role of teachers’ (N = 57) warm demander characteristic, a combination of warmth and responsiveness and classroom control and demand, was considered. Multilevel modeling revealed a positive association between problem behaviors and student time in both teacher-facilitated small-group instruction and off-task, and to less time in types of instruction where students were expected to manage themselves. Interaction effects further indicated that the positive association between problem behaviors and time in teacher-facilitated, small-group instruction only existed when students with more problem behaviors were in classrooms with teachers who were high or average in warm demander characteristic, whereas the opposite pattern existed for students of teachers low in warm demander characteristic. In addition, students of teachers who were high in warm demander characteristic spent less time in disruption/waiting (a main effect), and for these students a positive association between problem behaviors and students’ time in disruption/waiting existed (an interaction effect). Implications for policy, practice, and future research are discussed. 相似文献
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传统中值滤波对所有像素采用同一的处理方法,导致图像细节信息丢失严重。依据噪声分布特征,设计了基于集内离散度的噪声检测器,并结合自适应中值滤波,实现有针对性的噪声过滤,减少非噪声信息丢失。实验证明,该算法具有较高的消除脉冲噪声和保留细节信息能力。 相似文献
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融入社会聚焦市场--关于"电脑绘画"课程的教学模式探析 总被引：2，自引：0，他引：2
电脑绘画给广大美术爱好者和专业美术设计人员提供了一个全新的绘画和设计天地,深受大家的喜爱."电脑绘画"课程教学有其自己的性质与特点,在实施教学之前要分析社会与考察商业市场,在教学过程中要针对这些特点构建"电脑绘画"课程的教学模式并选择恰当的教学方法. 相似文献
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段守新 《海南师范大学学报(社会科学版)》2011,24(4):97-101
在新世纪第一个十年的视野中观察2010年的短篇小说创作,数量上保持了稳产态势。从创作的情感态度、艺术风格、题材选择以及修辞意蕴上分别体现了＂温情补偿＂与＂理性反思＂的对举、＂散文气质＂与＂寓言品格＂的异趣、＂城市经验＂与＂乡村追忆＂的消长、＂文体自觉＂对＂话语施暴＂的矫正等特点。 相似文献
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庐山植物区系的特征和植被的分布 总被引：1，自引：0，他引：1
樊忠良 《黄冈师范学院学报》1994,(1)
本文通过对庐山植物区系成分的分析，指出庐山植物区系特征是：以亚热带植物成分为主，还有热带和温带植物成分的亚热带低山植被，具有古热带和冷北极两大植物区系成分的相互渗透、相互交融的一种过渡性自然景观．在植被分布上，明显地反映出亚热带低山植被的垂直地带性分布规律． 相似文献
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语言模型具有很好的可理解性特征,但在多数情况下,其精确性是难满足要求的。利用改进型微粒群算法优化输入变量的语言值及对应的正交模糊集参数,再应用Wang方法以形成语言模型,在保持可理解性的情况下,获得较精确的语言模型。改进型微粒群算法采用惯性权重自适应动态调整策略,结果显示该改进算法在语言模型过程中更容易获得全局最优解,学习效率和优化性能明显提高。 相似文献
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The Consistency and Concomitants of Inhibition: Some of the Children, All of the Time 总被引：6，自引：1，他引：6
Kenneth H. Rubin Paul D. Hastings Shannon L. Stewart Heather A. Henderson Xinyin Chen 《Child development》1997,68(3):467-483
Toddlers displaying extremely inhibited behavior may be at risk for becoming socially withdrawn. However, behavioral inhibition may be a multifaceted characteristic, and its concurrent relation to toddler wariness with peers has not been examined. In this study, 108 toddlers (54 females) and their mothers were observed in novel situations involving unfamiliar settings, adults, and peers. Vagal tone, temperament, separation-reunion behavior, and maternal oversolicitousness also were assessed. There was little consistency of inhibited behavior across the 3 situations. Consistently inhibited toddlers had fearful temperaments, showed distress following maternal separation, and had mothers who were warm and controlling but unresponsive to children's cues during interaction. Toddlers with highly fearful temperaments and highly oversolicitous mothers were the most inhibited across contexts. 相似文献
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燃烧器附近结焦和炉膛内的大量结焦、积灰,常使空气动力工况遭到破坏,使炉膛出口温度升高,引起对流受热面壁温升高,破坏锅炉水循环,限制锅炉出力,降低锅炉的效率。本文针对电站锅炉燃烧器的特点,从燃料特性、锅炉设计及运行等方面分析造成结焦的原因,提出了防止结焦的措施。 相似文献
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We proposed that an individual's characteristic style of interaction will predict his or her problem-solving behavior and family problem-solving effectiveness. We test this hypothesis for mothers, fathers, and adolescent boys and girls ( M age = 12.7 years) in 431 rural families using both warm and hostile interaction styles. One set of videotape coders observed a general family discussion and measured interaction style. A year later, another, independent set of coders observed a family problem-solving task. Family members reported family problem-solving effectiveness immediately following the problem-solving task. The results indicated that a hostile interaction style directly predicted destructive problem-solving behavior and indirectly predicted family problem-solving effectiveness. A warm interaction style related directly to constructive problem-solving behavior and indirectly to family problem-solving effectiveness. 相似文献
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Philip E. Vernon 《Educational research; a review for teachers and all concerned with progress in education》2013,55(3):184-193
Sixth‐form students who had expressed varying degrees of commitment to entering teaching as a career reported on their knowledge of the teaching profession, their expectations for teacher training and on their own educational experiences. By the time they had entered the sixth form most had developed quite sophisticated views about the profession and about their own potential to become effective teachers. A warm and approachable personality was seen as the most important characteristic of the good primary teacher, while for the secondary teacher, subject matter competence was emphasized. Students planning to enter teaching saw themselves, already, as warm and approachable, but felt that their training would have a great effect on their general level of competence, and indeed on their confidence. At their chosen college of education, they anticipated too much ‘educational theory’ and not enough on ‘methods of teaching’ or teaching practice. Most students who planned to teach had had a reasonable amount of prior experience in one of a wide range of teaching settings. This appeared to have had a beneficial effect, especially for those enrolled in formal work experience programmes. 相似文献