美国总统林肯《葛底斯堡演讲》词中的最后一句“…that government of the people,by the people,for the pelple”(民有、民治、民享)的政府非常有名,被人传诵,然而英国人竟同美国人开了一个天大的玩笑,将句中的 of,by,for 分别改成 of...美国总统林肯《葛底斯堡演讲》词中的最后一句“…that government of the people,by the people,for the pelple”(民有、民治、民享)的政府非常有名,被人传诵,然而英国人竟同美国人开了一个天大的玩笑,将句中的 of,by,for 分别改成 off,buy 和 fool,结果是,美国政府成了 government off the people,buy the people and fool the people(一个脱离人民、收买人民、愚弄人民的政府)。仅换三词,原句意义已荡然无存了。展开更多
A uniform experimental design procedure was used to investigate the effects of some operating parameters on the extraction of emodin from Polygonum cuspidatum Sieb. et Zucc. products. Variables tested were volume rati...A uniform experimental design procedure was used to investigate the effects of some operating parameters on the extraction of emodin from Polygonum cuspidatum Sieb. et Zucc. products. Variables tested were volume ratio of material to solvent, size of material, extraction time and temperature and composition of extraction solvent （mixtures of acetone-water）. Each variable was tested at seven levels; 7 experiments were performed in random order. Analyses of the extracts were performed by high-performance liquid chromatography with diode array detection（HPLC-DAD）. Analytical responses were processed by using a forward regression analysis, in order to find polynomial function describing the relationship between variables and responses. For all the analytes the experimental conditions for providing the highest extraction yield inside the experimental domain considered were found. Finally, a simple, rapid and accurate analytical method was developed for the determination of emodin by high performance liquid chromatography. The separation is achieved within 25 rain on an ODS column using methanol and water as gradient mobiles. Emodin can be quantified by using external standard method detecting at 436 nm. Good linearity is obtained with correlation coefficient exceeding 0.9986 and the detection limit and the quantification limit are 1.53 and 3.23 mg/L respectively. This method shows good reproducibility for the quantification of the emodin with intra-day and inter-day relative standard deviation less than 2.3% and 5.6% respectively. Under optimized extraction conditions, the recovery of the standard is 96.5%. The validated method is successfully applied to quantify the emodin in seven Polygonum cuspidatum sieb. Et zucc. products, which provided an idea for the pre-treatment of determination of active compounds in traditional Chinese medicines.展开更多
文摘美国总统林肯《葛底斯堡演讲》词中的最后一句“…that government of the people,by the people,for the pelple”(民有、民治、民享)的政府非常有名,被人传诵,然而英国人竟同美国人开了一个天大的玩笑,将句中的 of,by,for 分别改成 off,buy 和 fool,结果是,美国政府成了 government off the people,buy the people and fool the people(一个脱离人民、收买人民、愚弄人民的政府)。仅换三词,原句意义已荡然无存了。
基金Project (04JJ3081) supported by Hunan Province Natural Science Foundation of China
文摘A uniform experimental design procedure was used to investigate the effects of some operating parameters on the extraction of emodin from Polygonum cuspidatum Sieb. et Zucc. products. Variables tested were volume ratio of material to solvent, size of material, extraction time and temperature and composition of extraction solvent （mixtures of acetone-water）. Each variable was tested at seven levels; 7 experiments were performed in random order. Analyses of the extracts were performed by high-performance liquid chromatography with diode array detection（HPLC-DAD）. Analytical responses were processed by using a forward regression analysis, in order to find polynomial function describing the relationship between variables and responses. For all the analytes the experimental conditions for providing the highest extraction yield inside the experimental domain considered were found. Finally, a simple, rapid and accurate analytical method was developed for the determination of emodin by high performance liquid chromatography. The separation is achieved within 25 rain on an ODS column using methanol and water as gradient mobiles. Emodin can be quantified by using external standard method detecting at 436 nm. Good linearity is obtained with correlation coefficient exceeding 0.9986 and the detection limit and the quantification limit are 1.53 and 3.23 mg/L respectively. This method shows good reproducibility for the quantification of the emodin with intra-day and inter-day relative standard deviation less than 2.3% and 5.6% respectively. Under optimized extraction conditions, the recovery of the standard is 96.5%. The validated method is successfully applied to quantify the emodin in seven Polygonum cuspidatum sieb. Et zucc. products, which provided an idea for the pre-treatment of determination of active compounds in traditional Chinese medicines.
