悬浮液进样一火焰原子吸收光谱法测定中草药中的锰     

薛元英  林培喜  陈静  唐永 《茂名学院学报》2001,11(4):10-12

将悬浮液进样－火焰原子吸收光谱法应用于中草药中锰的测定，建立了中草药中锰的快速分析新方法，将样品粉碎，磨细悬浮于琼脂胶体中，直接喷入空气－乙炔，火焰，以空白溶液为参比，用氘灯扣除背景吸收，用标准曲线法测定了泽泻中的锰，测定结果与消化法一致，两种方法的相对误差小于3．6％，RSD小于1．8％,t检验表明两种方法之间无显著性差异，方法简便，快速，准确。  相似文献   

Using Flint,Michigan, lead data in introductory statistics     

Travis Loux  Andrew K. Gibson 《Teaching Statistics》2019,41(3):85-88

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“马尔可夫链蒙特卡洛”(MCMC)方法在估计IRT模型参数中的应用   总被引：2，自引：0，他引：2  

王权 《考试研究》2006,(4)

本文介绍和阐述怎样运用“马尔可夫链蒙特卡洛”(MCMC)技术,并结合Bayes方法来估计IRT的模型参数。首先简要地概述了MCMC方法估计模型参数的基本原理;其次介绍MCMC方法估计模型参数的一般方法,涉及Gibbs抽样、取舍抽样、Metropolis-Hastings算法等概念和方法;最后以IRT的“二参数逻辑斯蒂”(2PL)模型为例,重点介绍了用“Gibbs范围内的M-H算法”估计项目参数(β1jβ2j)的算法过程。结束本文时还解说了MCMC方法的特点。阅读本文需具有随机过程、Markov链、Bayes方法等概率论的基本知识。  相似文献   

多小波子空间采样定理     

陈俊丽  卢恩博  黄炳 《上海大学学报(英文版)》2007,11(6):570-575

Unlike scalar wavelets,multiscaling functions can be orthogonal,regular and symmetrical,and have compact support and high order of approximation simultaneously.For this reason,even if multiscaling functions are not cardinal, they still hold for perfect A/D and D/A.We generalize the Walter's sampling theorem to multiwavelet subspaces based on reproducing kernel Hilbert space.The reconstruction function can be expressed by multiwavelet function using the Zak transform.The general case of irregular sampling is also discussed and the irregular sampling theorem for multiwavelet subspaces established.Examples are presented.  相似文献   

丽水市城区居民环境意识调查分析与评价研究     

吕耀平  求渊 《浙江教育学院学报》2004,(3):35-40

采用滚雪球抽样,对丽水市城区居民共500人进行了调查,分析了居民环境意识状况,发现环境意识水平与受教育水平、经济水平以及职业密切相关.  相似文献   

An activity‐based learning third‐level course on survey sampling     

Gabrielle E. Kelly 《Educational studies》2010,36(4):461-464

This paper describes a novel method for the delivery of an introductory module on survey sampling at a third‐level institution. As part of the module, students undertake a practical survey that is of interest not only to themselves but also to university administrators and other module coordinators. Unlike many data collection activities used in class, these data have intrinsic value. This module is shown to produce students with a high level of expertise in survey sampling. It also fosters in students wider generic capacities, such as information, communication and problem‐solving skills and teamwork and leadership skills that prepare them for further study and employment. The emphasis on activity‐based learning has led to increased student participation, improved examination results as well as enhanced student satisfaction with the module.  相似文献   

The Effect of Sampling-Time Variation on Latent Growth Curve Models     

Matt L. Miller  Emilio Ferrer 《Structural equation modeling》2017,24(6):831-854

Longitudinal data are often collected in waves in which a participant’s data can be collected at different times within each wave, resulting in sampling-time variation that is unaccounted for when waves are treated as single time points. Little research has been reported on the effects of this temporal imprecision on longitudinal growth-curve modeling. This article describes the results of a simulation study into the effect of sampling-time variation on parameter estimation, model fit, and model comparison with an empirical validation of the model fit and comparison results.  相似文献   

Children with Down Syndrome Sharing Past Personal Event Narratives with Their Teacher Aides: A Pilot Study     

Anne K. van Bysterveldt  Marleen F. Westerveld 《International Journal of Disability, Development & Education》2017,64(3):249-269

Personal narrative ability is crucial for social–emotional well-being and classroom participation. This study investigated the ability of 10 school-age participants with Down syndrome to share past personal experiences with their teacher aides in their school environment. To participate, children were required to speak in short sentences and be largely intelligible to unfamiliar listeners. Personal narratives were elicited using photo prompts, comprising a set of the child’s own photographs and a standard set of photographs and accompanying verbal prompts, utilising a clinical language sampling protocol. Personal narratives were analysed on quality, syntactic complexity, verbal fluency and intelligibility. Examiner behaviour was evaluated for measures of syntactic complexity, mean turn length in utterances and number of utterances. Results indicated significant difficulties in producing quality personal narratives in both photo conditions. Examiner behaviour was negatively correlated to the participants’ spoken language performance. Clinical implications are highlighted.  相似文献   

全站仪坐标放样内外一体化的探索     

夏广岭 《北京工业职业技术学院学报》2007,6(2):49-51

为了减小目前常用坐标放样方法中手工输入全站仪数据对作业精度和速度的影响,利用CASS、SV300等数字测图软件相应功能提取各设计点的坐标值,把这些设计数据与控制点数据合并成一个数据文件后,将此数据文件通过数据线传输到全站仪内存文件中,现场利用全站仪自带的坐标放样软件,快速准确地进行放样,从而实现了坐标放样的内外一体化.  相似文献   

电力系统频率保护频率的计算改进方案研究     

王野  姜万东  凌锋  迟玉国 《丽水学院学报》2015,(2):41-47

目前,市场上电力系统频率保护装置频率的计算主要分为软件法和硬件法两种。基于软件测频算法存在计算误差较大及计算数据窗长度高达160 ms的情况,以及硬件频率测量法由于谐波的影响存在频率计算误差较大的问题,提出采用数字滤波器结合三点采样频率算法的频率计算方案。该计算方案具有计算频率的数据窗较短,频率计算误差小,且受谐波影响小的优点。该频率计算方案可在中压保护、频率电压控制和快切中使用,可大大提高保护和自动装置的技术指标。  相似文献