能力验证计划中防止数据串通的措施

为保证能力验证结果评价有效、可信、公平,对能力验证计划防止数据串通的措施进行了探讨。从样品设计、样品量发放、检测周期3个方面介绍了防止数据串通的措施,以CNAS PT0017–T029"离子色谱法测定水中Cl~–,SO_4^(2–)及NO_3~–三种阴离子的含量"能力验证计划为例,讨论能力验证计划防止数据串通措施的具体实施方法。结果显示,设计分割水平样品、减少样品发放量、缩短能力验证结果上报周期等几种措施可以有效地防止能力验证数据的串通,为能力验证活动的健康发展提供了参考。     

玩具油漆涂层中有机锡检测能力验证样品研制及应用分析

制备了用于可迁移有机锡检测能力验证的玩具油漆涂层样品,并开展了相关测定能力验证计划,采用迭代法、四分位法和敏感分析法3种不同统计方法对23家实验室数据进行统计分析,并对不满意结果的原因进行了分析。结果表明所研制样品的均匀性和稳定性良好,能满足能力验证要求。不同统计方法对实验室能力评定结果存在差异,但指定值差异很小,而能力评定标准差差异较大,运用卡方检验能选择出更合理的统计方法。     

国际实验室间转基因产品检测能力验证的研究

以转基因大豆为例，介绍开展APLAC T034国际间实验室转基因检测能力验证的项目。对于样品量值(添加值)的设定进行试验，对样品的均匀性和稳定性进行检验，并对参试实验室的测试结果进行系统的评价和分析。影响转基因产品测试结果的关键因素是检测方法、基因组DNA提取的质量、PCR反应体系中模板DNA的加入量．以及是否使用标准物质作为质控对照和使用定量标准物质求出相关系数对定量检测结果进行校正。     

基于课程标准的科学建模能力试题开发与检验研究

科学建模能力测评是化学学科核心素养评价改革的重要组成部分.如何基于课程标准对学生科学建模能力进行试题开发和评价是目前化学教育研究者和一线教师所共同关注的研究议题.以整体效度理论为理论基础,采用结构中心设计原则和证据中心设计原则作为设计方法论,构建了基于课程标准的科学建模能力试题开发框架,并以“电离与离子反应”主题中具体...     

广西污水中汞、砷检测能力验证结果分析

利用能力验证计划,对广西全区检验检测机构的污水中汞、砷分析能力进行对比和评价。采用单因子方差对考核样品进行均匀性检测,对全区144家检验检测机构的检测结果进行四分位稳健统计分析,用Z比分值绘制柱状图直观评定各检测机构的测试结果。污水中汞检测结果合格率为77.0%,砷检测结果合格率为84.8%。广西检验机构的汞、砷总体检测能力较强,少数检测机构的检测能力和水平有待提高。     

水杨酸片溶出度测定测量审核结果分析与常见问题探讨

通过对2015—2020年开展的水杨酸片溶出度测定测量审核工作的回顾和梳理,阐述了水杨酸片溶出度测量审核工作的实施模式,分析了可能影响溶出度测定结果的因素,并就参与实验室存在的问题和相关的改进措施进行了探讨。水杨酸片溶出度测定测量审核是相关实验室提升溶出度测定检测能力的一种有效方法,在加强组织方质量管理体系的改进和建设方面也有积极的促进作用。     

基于滴定分析测定可逆反应的平衡常数*——2021年北京学业水平等级性考试化学卷第16题

以2021年北京学业水平等级性考试化学卷第16题所涉及的“Fe²⁺+Ag⁺Fe³⁺+Ag”体系为例,结合热力学理论分析和滴定分析实验,提出了一种在中学化学阶段可操作的测定化学平衡常数的实验方法,为高中化学平衡常数的概念教学提供重要的例证。     

Neural and vascular variability and the fMRI-BOLD response in normal aging

Neural, vascular and structural variables contributing to the blood oxygen level-dependent (BOLD) signal response variability were investigated in younger and older humans. Twelve younger healthy human subjects (six male and six female; mean age: 24 years; range: 19–27 years) and 12 older healthy subjects (five male and seven female; mean age: 58 years; range: 55–71 years) with no history of head trauma and neurological disease were scanned. Functional magnetic resonance imaging measurements using the BOLD contrast were made when participants performed a motor, cognitive or a breath hold (BH) task. Activation volume and the BOLD response amplitude were estimated for the younger and older at both group and subject levels. Mean activation volume was reduced by 45%, 40% and 38% in the elderly group during the motor, cognitive and BH tasks, respectively, compared to the younger. Reduction in activation volume was substantially higher compared to the reduction in the gray matter volume of 14% in the older compared to the younger. A significantly larger variability in the intersubject BOLD signal change occurred during the motor task, compared to the cognitive task. BH-induced BOLD signal change between subjects was significantly less-variable in the motor task-activated areas in the younger compared to older whereas such a difference between age groups was not observed during the cognitive task. Hemodynamic scaling using the BH signal substantially reduced the BOLD signal variability during the motor task compared to the cognitive task. The results indicate that the origin of the BOLD signal variability between subjects was predominantly vascular during the motor task while being principally a consequence of neural variability during the cognitive task. Thus, in addition to gray matter differences, the type of task performed can have different vascular variability weighting that can influence age-related differences in brain functional response.