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用HF/3-21G解析梯度方法研究H_2CCC:的氢氢键插入和加成反应机理,结果表明,H2CCC:的H—H插入为直接插入,取端端(end-on)接近方式;H_2加成经两步完成.第一步是2+2加成,因对称性禁阻取三中心过渡态,四中心作用发生在反应的后期,第二步是CH_3CHC:的1,2氢重排.预言气相中H—H插入容易发生,势垒值约为45 kJ/mol. 相似文献
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电荷注入检测器—端视等离子体原子发射光谱中分析动态范围 总被引:2,自引:0,他引:2
实验研究了电荷注入检测器-端视电感耦合等离子体光谱中分析动态范围,测量了AL,B、Be,Cd,Cu,Co,Fe,Li,Sr,V,K,Sr等12个元素的不同光谱级次的44条分析工作曲线。结果表明,分析范围为4-5个数量级,无明显自吸收,Lomakin公式的自吸收系数b=1,说明在CID-AVICP光谱中有较宽的分析动态范围 。 相似文献
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微波等离子体炬耦合方式的研究 总被引:7,自引:0,他引:7
采用气动雾化连续进样、端视观测法,考察了微波等离子体炬原子发射光谱法中等离子体Ar线的背景发射以及Al,Mg,V等元素的信号发射强度随天线耦合连接点位置的不同而发生的变化.结果表明,当天线位于炬管顶端,即天线距离活塞3λ/4和λ/4时均能获得较好的等离子体,λ/4略好,信号发射强度和信背也较大,只是精密度略差一些.初步探讨了MPT炬管的电磁场结构. 相似文献
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《Surface and interface analysis : SIA》2004,36(7):666-667
ISO Technical Report 19319:2003 contains information on the determination of lateral resolution, analysis area and sample area viewed by the analyser in surface analyses by Auger electron spectroscopy and x‐ray photoelectron spectroscopy. This article provides a brief summary of this information. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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端视ICP-AES法测定钕铁硼永磁材料中常量及微量元素 总被引:2,自引:0,他引:2
报道了用高灵敏度的电感耦合等离子体原子发射光谱法(ICP-AES)直接测定钕铁硼永磁材料中常量、少量及微量元素:Nd、Fe、Co、B、La、Ce、Pr、Dy、Gd、Sm、Al、Mn、Ca、Mg、Ga和Si的分析方法。选择了合适的分析线,研究了基体元素Nd、Fe、Co对被测杂质元素分析线的光谱干扰,采用基体匹配与背景扣除法进行校正。各被测元素的检出限为0.5~30μg/L,回收率为92~110%,相对标准偏差小于7%。本法已用于钕铁硼产品的快速检验,并获得了满意的结果。 相似文献
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揭示了带形上随机环境中随机游动的内蕴分枝结构一带移民的多物种分枝过程.利用内蕴分枝结构,可精确表达游动的首次击中时.给出了内蕴分枝结构的如下两个应用:(1)计算出首次击中时的均值,给出游动大数定律速度的显示表达,(2)得到从粒子角度看环境的马氏链不变测度的密度函数的显示表达,进而可用另一种"站在粒子看环境"的方法直接证明游动的大数定律. 相似文献
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The effects and benefits of N2 addition to the central channel of the ICP through the nebulizer gas used in ICP OES with axial view configuration were investigated in the present study. The N2 flow rate, nebulizer gas flow rate, RF power and sample uptake rate were evaluated and compared for two sample introduction systems (pneumatic nebulization/aerosol desolvation and conventional pneumatic nebulization). It was observed that N2 did not affect solution nebulization and aerosol transport but affects the ICP characteristics. The higher thermal conductivity of N2 (in comparison with Ar) changes energy distribution in the ICP, observed by monitoring the signals of Ar emission lines and sodium emission. The ratio Mg(II)-280.270 nm/Mg(I)-285.213 nm was utilized as a diagnostic tool for plasma robustness. The addition of N2 (20 mL min−1) increased plasma robustness significantly and mitigated effects caused by Na, K and Ca. For 40 spectral lines evaluated, it was observed that the emission signals of ionic spectral lines were in general more affected by N2 than those of atomic spectral lines. Detection limits, precision, sensitivity and linearity of calibration curves obtained using N2-Ar-ICP were almost similar to those obtained using Ar-ICP. The analysis of 5 different reference materials revealed that accuracy was not degraded by adding N2 to the Ar-ICP. 相似文献
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Julio C. J. Silva Daniele M. Santos Solange Cadore Joaquim A. Nobrega Nivaldo Baccan 《Microchemical Journal》2004,77(2):185-190
In this investigation, samples of whole bovine milk were diluted with water-soluble tertiary amines solution and introduced in two axially viewed inductively coupled plasma optical emission spectrometer (ICP OES) instruments equipped with different interfaces (shear gas and end-on gas interface). The accuracy and the Mg II (280.2 nm)/Mg I (285.2 nm) ratio were evaluated. Higher values for Mg II/Mg I were observed with the shear gas interface. However, these values were less affected by changes of instrumental parameters when using the end-on gas interface. Results with suitable accuracy were obtained for a certified reference material of powdered whole milk (NIST SRM 8435) using instruments equipped with each interface. 相似文献
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