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采用分光光度法测定注射用复方维生素(3)中微量草酸的方法.在氯化钾-盐酸缓冲液下,Fe3+和草酸的络合物能使Fe3+与磺基水杨酸的紫色络合物颜色变浅,测定显色反应后溶液的吸光度,试验中优化了显色反应时间、显色剂用量.结果显示,显色溶液最大吸收波长为503nm,草酸在0.006-0.036mg/mL浓度范围内,其吸光度与浓度呈良好线性关系,y=-17.552x+1.0283,r=0.9991.样品加样回收率为97.6%.本方法能准确检查注射用复方维生素(3)中微量草酸的含量. 相似文献
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Negative and Superluminal Group Velocity Propagation with Narrow Pulse in a Coaxial Photonic Crystal 总被引:2,自引:0,他引:2 下载免费PDF全文
We investigate the propagation of electric signal along a spatially periodic impedance mismatched transmission line group. Anomalous dispersion is caused by the periodically mismatched impedance structure and a forbidden band appears near 8 MHz in transmission. The group velocity of the amplitude-modulated signal is augmented up to infinity, even -3.89c (c the speed of light in vacuum) in the forbidden region with the amplitude of the modulated signal increasing. When the carrier sinusoid signal is modulated in amplitude by the modulating sinusoid signal, of which the peak is superimposed with a narrow pulse at fivefold frequency, the superluminal group velocity also occurs. The experiment failed to show whether the propagation velocity of narrow pulse exceeds c or not. 相似文献
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