986 resultados para Ações (Finanças)


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本文介绍土壤中多元素的ICP-AES分析方法。文中详细叙述了操作步骤,并给出了分析的精密度、准确度、检出限的数据及与其它分析方法的比较、讨论了干扰元素的影响及其消除的措施。

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选用硝酸和过氧化氢作为消解剂,采用微波技术消解蛹虫草样品,用电感耦合等离子体发射光谱(ICP-AES)法同时测定其中K、P、Ca、Mg、Cu、Fe、Zn、Mn共8种微量元素的含量。进行微波消解条件的优化选择及分析线性、精密度和回收率等实验,建立同时测定蛹虫草中多种微量元素的微波消解-ICP-AES方法。本方法所测元素的标准曲线均有良好的线性关系,以猪肉粉国家标准物质GBW08522为对照进行验证,其回收率为91%~106%,相对标准偏差(RSD)<3.0%;该法加标回收率为90%~108%,RSD<3.0%,具有较好的准确度和精密度,是一种快速、准确而高效的分析方法。测定结果表明,蛹虫草富含有K、P、Mg、Ca、Zn元素。

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本文介绍了植物及其它生物试样中多元素的电感耦合等离子体(ICP)光谱的分析方法。介绍了植物样品的处理方法及给出了分析的精密度、准确度、检出限和变异系数。并和美国的标样及国内标准样品的比较。讨论了干扰元素的影响及其消除干扰的措施。

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结合密钥扩展算法和划分子集的方法,提出7轮AES-192的不可能差分分析方法.首先估算猜测初始轮的错误密钥的最小概率;然后计算所需的明密文对的数量并选择明密文对,计算密文对的差分,猜测特殊的密钥字节对其进行不可能差分攻击.该攻击需要278选择明文,记忆存储空间为2129分组,以及约2155的7轮AES-192加密.与目前现有的结果相比,该攻击需要更少的选择明文数和较低的时间复杂度.

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Major, minor and trace elemental contents in northeast China soybeans were determined by using inductively, coupled plasma atomic emission spectrometry (ICP-AES). Three different sample digestion methods including two wet digestions, HNO3-HClO4 and HNO3-H2SO4 and a dry ash method were compared. Owing to the high oil content in soybeans, long time is needed and access acid should be added, with mixed acid digestion methods, which may result in higher sample blank. Therefore, the dry ask method would be more proper for the pre-treatment of soybean samples. Potassium and phosphorus are major elements in soybeans, so the effect of potassium and phosphorus on the other elements was investigated. Results showed that the potassium and phosphorus did not affect the determination. of other trace elements. There are not significant differences in trace elemental contents for the eleven northeast China soybeans.

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The inductively coupled plasma atomic emission, spectrometry (ICP-AES) and its signal characteristics were discussed using modem spectral estimation technique. The power spectra density (PSD) was calculated using the auto-regression (AR) model of modem spectra estimation. The Levinson-Durbin recursion method was used to estimate the model parameters which were used for the PSD computation. The results obtained with actual ICP-AES spectra and measurements showed that the spectral estimation technique was helpful for the better understanding about spectral composition and signal characteristics.

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本文对电感耦合等离子体原子发射光谱分析 (ICP AES)中电荷注入检测器 (CID)得到的二维光谱的频率特性作了研究。测量光谱经过傅里叶变换得到其光谱的频域分布。结果表明 ,测量光谱在频域中的信号可被分为两部分 :即低频信号和高频信号。前者代表有用的分析信号而后者代表背景和噪声。然而 ,不能采用简单滤除高频信号的方法来去除噪声 ,因为这样虽然高频信号没有明显改变但会使背景变形。

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An information system for inductively coupled plasma atomic emission spectrometry (TCP-BES) in MS Windows environment was developed based on the previous work in the laboratory. The system contains the data of about 28 000 spectral lines and a function of ICP spectral simulation,so it would be very helpful for line selection. The system also contains the Kalman filter and factor analysis programmes written with MS Visual Basic(version 4.0), which can be used for spectral interference correction and peak position optimization. A large amount of real spectral scanning data of rare earth elements were included in the system for user's references. All these characteristics made the system more useful and practical.

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本文将反向传播人工神经网络(BP-ANN)用于ICP-AES中重叠光谱干扰的校正。利用模拟的Ce413.380nm和Pr413.361nm光谱对神经网络的训练方式、输入值范围、噪声影响等作了较详细的讨论。

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本文采用Voigt线形函数对ICP-AES中谱线重叠和结构背景的干扰作了模拟。结果表明,模拟的光谱与实测的光谱基本一致,因而利用模拟光谱对话线选择具有一定的指导意义。

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本工作以Kalman滤波技术为光谱干扰校正方法,选择典型的光谱干扰为例,系统研究了波长定位误差影响滤波结果准确性的规律性,提出了改善波长定位精度的途径。对于谱线重叠干扰的校正,波长定位精度一般应优于0.1pm;利用新息序列零均白噪音特性建立指示函数优化扫描光谱峰位,大大提高了波长定位精度,保证了滤波结果的准确性。

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本文采用国产WP-2L型平面光栅摄谱仪配置国产GP3.5D型ICP光源进行了彩色电视荧光级氧化钇中14个稀土杂质元素分析方法的研究。样品溶液以不去溶方式引入ICP。当样品溶液中Y2O3的浓度为20mg/ml时,测定下限分别为铕、镱和0.00020%,镧、铈、钛、钆、镝、钬、铒和铥0.00050%,镨、钐和铽0.0010%。相对标准偏差为3.2~9.8%。

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本文提出了用ICP-AES法直接对海洋沉积物标准样品中多元素同时分析。ICP-AES法具有灵敏度高,测量精度好,线性范围宽等优点[I-4]。在此文中对样品前处理做了方法的研究。选用了多元素同时测定,空白值低、省时的溶解方法。相对标准偏差为0.03-6.9%,同时对GSD-9标准样进行了分析,结果与标准样值相符。

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本文研究了用ICP-AES法,不必化学分离,一次同时测定混合稀土铜合金名14种稀土和非稀土元素,获得满意结果。