The random copolymers of styrene and 2,5-bis[(4-methoxyphenyloxycarbonyl)styrene] (MPCS) with different copolymerization ratio were synthesized by conventional free radical polymerization. The copolymer having high mo...The random copolymers of styrene and 2,5-bis[(4-methoxyphenyloxycarbonyl)styrene] (MPCS) with different copolymerization ratio were synthesized by conventional free radical polymerization. The copolymer having high molecular weight was experimentally elucidated using a combination of proton nuclear magnetic resonance spectroscopy and gel permeation chromatography. The liquid crystalline behavior of the copolymer was studied using differential scanning calorimetry, X-ray diffractometry and polarized optical microscopy. It was found that the liquid crystalline behavior was dependent on the content of styrene. Experimental results show that the copolymer could turn into a liquid crystalline phase at about 180°C when the content of styrene was less than 20%. The mechanical properties of the copolymer were also studied. Preliminary results indicate that the tensile strength decreases while the tensile modulus increases as the content of MPCS is increased.展开更多
目的 分析丹参口服液中4个酚酸成分含量在2种不同储存条件下的变化,同时探讨其相关性。方法 以加速1月、2月、3月、6月为加速试验组,以长期3月、6月、9月、12月作为长期试验组。通过HPLC法对6个批次的丹参口服液中活性成分进行为期12个...目的 分析丹参口服液中4个酚酸成分含量在2种不同储存条件下的变化,同时探讨其相关性。方法 以加速1月、2月、3月、6月为加速试验组,以长期3月、6月、9月、12月作为长期试验组。通过HPLC法对6个批次的丹参口服液中活性成分进行为期12个月的稳定性考察;组间对比用 t 检验,当 P <0.05时,差异具统计学意义。结果 ①两组中的丹酚酸B含量和pH值,均随着时间的延长而降低,丹参素含量与之相反;原儿茶醛、迷迭香酸含量则随时间增加无明显变化。②加速试验组(40℃)相对长期试验组(25℃),在3月、6月其丹酚酸B含量均明显降低( P <0.05),丹参素含量均明显升高( P<0.05);pH值、迷迭香酸、原儿茶醛含量,组间对比无明显差异。③丹参素与丹酚酸B呈极强负相关(相关系数为-0.915),与迷迭香酸、原儿茶醛呈强正相关(相关系数分别为0.722、0.665);丹酚酸B与原儿茶醛强负相关(-0.726),与迷迭香酸负相关(-0.427);pH值与丹酚酸B强正相关(0.789),与丹参素、迷迭香酸强负相关(-0.906、-0.822),与原儿茶醛无明显相关性(-0.303)。结论 通过分析表明,丹参口服液中活性成分丹酚酸B、丹参素、迷迭香酸及原儿茶醛的含量之间具有相关性,丹酚酸B与丹参素之间呈显著负相关( P <0.05);温度、pH值、贮存时间对活性成分丹酚酸B、丹参素有明显影响,pH值越大,温度越高,储存时间越长,丹酚酸B越容易降解。展开更多
基金This work was supported by the National Natural Science Foundation of China (No. 20134010) and the Ministry ofEducation of China for the Science and Research Fund (No. 104005).
文摘The random copolymers of styrene and 2,5-bis[(4-methoxyphenyloxycarbonyl)styrene] (MPCS) with different copolymerization ratio were synthesized by conventional free radical polymerization. The copolymer having high molecular weight was experimentally elucidated using a combination of proton nuclear magnetic resonance spectroscopy and gel permeation chromatography. The liquid crystalline behavior of the copolymer was studied using differential scanning calorimetry, X-ray diffractometry and polarized optical microscopy. It was found that the liquid crystalline behavior was dependent on the content of styrene. Experimental results show that the copolymer could turn into a liquid crystalline phase at about 180°C when the content of styrene was less than 20%. The mechanical properties of the copolymer were also studied. Preliminary results indicate that the tensile strength decreases while the tensile modulus increases as the content of MPCS is increased.
文摘目的 分析丹参口服液中4个酚酸成分含量在2种不同储存条件下的变化,同时探讨其相关性。方法 以加速1月、2月、3月、6月为加速试验组,以长期3月、6月、9月、12月作为长期试验组。通过HPLC法对6个批次的丹参口服液中活性成分进行为期12个月的稳定性考察;组间对比用 t 检验,当 P <0.05时,差异具统计学意义。结果 ①两组中的丹酚酸B含量和pH值,均随着时间的延长而降低,丹参素含量与之相反;原儿茶醛、迷迭香酸含量则随时间增加无明显变化。②加速试验组(40℃)相对长期试验组(25℃),在3月、6月其丹酚酸B含量均明显降低( P <0.05),丹参素含量均明显升高( P<0.05);pH值、迷迭香酸、原儿茶醛含量,组间对比无明显差异。③丹参素与丹酚酸B呈极强负相关(相关系数为-0.915),与迷迭香酸、原儿茶醛呈强正相关(相关系数分别为0.722、0.665);丹酚酸B与原儿茶醛强负相关(-0.726),与迷迭香酸负相关(-0.427);pH值与丹酚酸B强正相关(0.789),与丹参素、迷迭香酸强负相关(-0.906、-0.822),与原儿茶醛无明显相关性(-0.303)。结论 通过分析表明,丹参口服液中活性成分丹酚酸B、丹参素、迷迭香酸及原儿茶醛的含量之间具有相关性,丹酚酸B与丹参素之间呈显著负相关( P <0.05);温度、pH值、贮存时间对活性成分丹酚酸B、丹参素有明显影响,pH值越大,温度越高,储存时间越长,丹酚酸B越容易降解。
