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室内空气中甲醛检测方法的比较研究 总被引：1，自引：0，他引：1
本文利用国家标准“酚试剂分光光度法”的化学法和4160—19．99m型甲醛分析仪的仪器法对室内空气中的甲醛进行了样品检测的对比实验,结果表明,利用两种方法测定样品所得到的结果无显著性差异,而且使用甲醛分析仪在现场检测快捷方便,有利于开展室内环境甲醛的检测和普查工作。 相似文献
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分别用火焰原子吸收法和1,10-菲啰啉分光光度法测定铬铁废液中铁的总量.绘制了两种方法的标准曲线,测定了空白值、加标回收率和标准样品.两种方法的空白值都比较稳定,相关性以及斜率等数值都很接近,它们的准确度都比较好,相对标准偏差分别为1.2%和2.6%.两者的平均回收率分别为108%和94%,基本符合实验要求.因此,两种方法的测定结果都在真值允许范围内,它们的标准曲线,精密度和准确性都比较好.两种方法的结果通过t检验,无显著性差异.两者都适用于低浓度的铁溶液,但分光光度法灵敏度稍高. 相似文献
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《佳木斯教育学院学报》2016,(5)
本文对原子吸收法测定样品中铜的含量进行探究,利用标准曲线法作为定量分析方法,在仪器推荐的浓度范围内,制备含待测元素的对照样品溶液6份,浓度依次递增。用原子吸收分光光度计测量出不同浓度下样品溶液的吸光度,绘制出浓度吸光度标准曲线。探究所测样品吸光度下含铜的浓度。 相似文献
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微波消解-电感耦合等离子体质谱法测定食品中总磷含量 总被引：1，自引：0，他引：1
目的:建立一种测定食品中总磷含量的微波消解-电感耦合等离子体质谱(ICP-MS)方法,为检验工作提供更加快捷,精准的方法。方法:样品中加入HNO3和H2O2进行微波消解,以Sc为内标元素,用电感耦合等离子体-质谱仪进行测定。结果:总磷含量在0~10mg/L范围内有良好的线性关系,相关系数为0.9997;对两种实际样品的平均加标回收率范围分别为95.31%~101.48%和97.51%~103.74%;对同一种样品进行精密度测定,相对标准偏差为0.1%;本法最低检出限为0.032mg/L。采集5种样品用国标法与本法作比对实验,经统计学检验P=0.1170.05,表明两种方法无显著性差异。结论:所建立的ICP-MS方法准确度高,重现性好、操作简便、大大减少了样品前处理时间,适用于各类食品中总磷含量的测定。 相似文献
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用吸量管和药用针头自制微型滴定管对葡萄糖注射液中葡萄糖含量的测定实验进行微型化的设计与研究。并对微型滴定法与常量滴定法的平行测定结果进行比较。F检验、t检验结果均在允许范围内,相对偏差均小于2．0％,结果两种测定方法无显著性差异。 相似文献
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研制了一个磷铁国家标准样品,研制过程包括选料、加工、均检及定值均严格按照GB／T15000《标准样品工作导则》和YB／T082《冶金产品分析用标准样品技术规范》的要求进行。该标准样品经化学成分的粒度检验、均匀性检验及近一年的稳定性监测,显示均匀性和稳定性良好;定值了碳、硫、磷、硅、锰、镍、铬和钛等九个特性量值,由九个实验室采用不同原理、准确可靠的分析方法进行定值分析,保证每个元素都采用两种或两种以上的定值分析方法,确定的标准值准确、可靠,并对定值参数进行了不确定度的评估。 相似文献
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李鹏志 《石家庄职业技术学院学报》2013,(6):19-21
在铸铁生产中,炉前检测铁水化学成分主要有仪器检测和经验检测两种方法.其中,仪器检测有直读光谱仪测定法和热分析法;经验检测主要指铸造企业凭经验或借助三角试块白口宽度来预测铸铁牌号或成分的方法.分析了如何使用这两种检测方法对铁水进行炉前检测. 相似文献
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In view of the lack of instruments for measuring biology teachers' pedagogical content knowledge (PCK), this article reports on a study about the development of PCK items for measuring teachers' knowledge of pupils' errors and ways for dealing with them. This study investigated 9th and 10th grade German pupils' (n?=?461) drawings in an achievement test about the knee-jerk in biology, which were analysed by using the inductive qualitative analysis of their content. The empirical data were used for the development of the items in the PCK test. The validation of the items was determined with think-aloud interviews of German secondary school teachers (n?=?5). If the item was determined, the reliability was tested by the results of German secondary school biology teachers (n?=?65) who took the PCK test. The results indicated that these items are satisfactorily reliable (Cronbach's alpha values ranged from 0.60 to 0.65). We suggest a larger sample size and American biology teachers be used in our further studies. The findings of this study about teachers' professional knowledge from the PCK test could provide new information about the influence of teachers' knowledge on their pupils' understanding of biology and their possible errors in learning biology. 相似文献
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John Jerrim Luis Alejandro Lopez-Agudo Oscar David Marcenaro-Gutierrez 《British Educational Research Journal》2022,48(3):420-445
In this paper we investigate the link between the language in which pupils take the Programme for International Student Assessment (PISA) test and the scores they achieve in this assessment, focusing upon the case of Wales. Using five rounds of PISA data and an instrumental variable approach, we show how pupils who took the test in Welsh score around 0.3 standard deviations (30 PISA test points) lower in reading, mathematics and science than their peers who took the test in English. This finding is robust to different model specifications and statistical approaches. We argue that this may indicate that the academic performance of teenagers in Wales may be underestimated in PISA – particularly amongst those who take this test in Welsh. 相似文献
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王保军 《唐山师范学院学报》2005,27(6):92-93
信度与效度是衡量心理测验质量的重要指标。增加测验长度是提高测验信度和效度的重要方法之一。由于各学者对效度的代表符号规定不一，导致对于说明测验长度与测验效度关系的公式及其计算结果难于理解和解释。根据经典测量理论对代表测验长度与测验效度关系的公式进行分析和讨论，提出测验效度与长度关系的表达公式。 相似文献
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研究间异质性检验是合并各独立研究效应量的前提条件.利用Stata软件不仅可制作森林图和Galbraith星状图进行定性分析,而且可以计算Q、I2和H统计量进行定量分析.综合使用两种分析方法能够实现对异质性的准确判断. 相似文献
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This paper draws on results of a research project InterActive Education: Teaching and Learning in the Information Age (see www.interactiveeducation.ac.uk). The overall aim of the project was to examine ways in which new technologies can be used in educational settings to enhance learning. Research was carried out across a range of school subjects: English, history, geography, mathematics, modern foreign languages, music and science. Within this paper we report on the work of two teachers within the same primary school who devised an initiative to support the development of composition skills of children aged 10 and 11, using Dance eJay software. We explore the ways in which collaborations took place between the pupils, arguing that eJay provides a rich mediational tool where creative outcomes are negotiated. We suggest that the computer workstation provides the mediational means by which all pupils – whether or not they possess formal instrumental skills – can be creative, working within a musical style in which they are culturally located. Furthermore, we propose that the teacher is central to the creative–collaborative process and suggest implications for teachers when planning for creative, collaborative work in the classroom using music software such as eJay. 相似文献
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普通话水平测试具有“语音标准的模糊性、成绩评定的主观性、测评方式的个别性”特点，这不可避免地导致测评误差。因此为缩小测评误差，提高测试质量，我们必须深层次地分析导致误差的原因，探讨缩小误差的有效途径。 相似文献
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ZHAO Qifeng 《中国考试》2008,(6)
构想效度(construct validity)一直是效度研究的核心问题,本文对中国汉语水平考试(HSK[高等])和实用汉语水平认定考试(C.TEST)的构想效度进行了探讨。文章首先梳理了这两种考试的构想模型,并初步提出了操作性定义。研究样本为550名同时参加了这两种考试的考生,我们使用因素分析法对所得数据进行分析。结果显示,目前我们只能有把握地说,这两种考试都测到了考生的"阅读理解"能力,对其他能力的检验本文还不能给出明确的结论。 相似文献