在铁粉存在下,以商用N,N-二甲基甲酰胺(DMF)作溶剂,90℃、氮气保护下,二芳基二硒醚与α-溴代羰基化合物反应,得到一系列α-芳硒基羰基化合物.考察了温度、时间、溶剂及铁粉用量对反应的影响,其中,温度对反应的影响最为明显.α-溴代羰基...在铁粉存在下,以商用N,N-二甲基甲酰胺(DMF)作溶剂,90℃、氮气保护下,二芳基二硒醚与α-溴代羰基化合物反应,得到一系列α-芳硒基羰基化合物.考察了温度、时间、溶剂及铁粉用量对反应的影响,其中,温度对反应的影响最为明显.α-溴代羰基化合物中羰基上取代基对反应有很大影响,取代基为苯基时,转化率较甲基或烷氧基时低.反应机理可能是铁插入Se—Se键中形成亲核性Se Fe Se,随后与亲电底物α-溴代羰基化合物发生亲核取代.本方法使用铁粉促进断裂Se—Se键具有原料安全无毒、廉价易得、实验操作简便等优点.展开更多
Eleven nutrition elements and 5 quality elements of garlic （Allium sativum L.） in different Se, S level and their interaction pot experiments were analyzed by atom absorbing spectrophotometer, titration and fixing s...Eleven nutrition elements and 5 quality elements of garlic （Allium sativum L.） in different Se, S level and their interaction pot experiments were analyzed by atom absorbing spectrophotometer, titration and fixing sulfur method. The mineral elements were analyzed by the Principal Component Analysis and the Factor Analysis on the SPSS 10.0 and three main factors were picked. The results showed that Se, S and Se-S cooperated application enhanced the garlic nutrition quality by increasing mineral nutrition. The garlic Vc was the highest after using higher Se compared middle S level （S 20 mg/kg soil ＋ Se 40 mg/kg soil）. Lower Se level compared middle S level （S 40 mg/kg soil ＋ Se 20 mg/kg soil） get the highest garlic abio-Se in all treatments. The garlic organic Se content was the highest after using higher Se compared middle S （S 40 mg/kg soil ＋ Se 40 mg/kg soil）. The treatment lower S compared lower Se level get the highest garlic allicin in all treatment. It showed that the fresh eating factor was affected by the element Se. The flavor factor and health care factor were affected by both Se and S.展开更多
锂-硒电池因其超高的体积能量密度和硒的高电导率而被认为是一种极具有发展前景的锂离子电池。然而,循环过程中电极严重的体积膨胀和多硒化物溶解,以及硒的低负载,阻碍了锂-硒电池应用的发展。解决这三个问题的一种行之有效的方法是将...锂-硒电池因其超高的体积能量密度和硒的高电导率而被认为是一种极具有发展前景的锂离子电池。然而,循环过程中电极严重的体积膨胀和多硒化物溶解,以及硒的低负载,阻碍了锂-硒电池应用的发展。解决这三个问题的一种行之有效的方法是将硒限制在具有丰富孔体积的碳基质中,并同时增强硒与碳的界面相互作用。通过将Se浸入酒石酸盐衍生的蜂窝状三维多孔炭中,合成出了一种具有Se―C键的蜂窝状三维多孔炭@硒(HPC@Se)的新型正极材料用于锂-Se电池。得到的蜂窝状三维多孔炭的孔体积可达1.794 cm^(3)g^(-1),能够均匀包封65%硒。此外,硒与碳之间的强化学键有利于稳定硒,从而进一步缓解其巨大的体积膨胀和多硒化物的溶解,还可促进循环过程中的电荷转移。该HPC@Se正极呈现出极好的循环性能和倍率性能。在0.2 C的电流密度下,经200次循环后,其比容量可保持在561 m Ahg^(-1)(为理论比容量的83%),每次循环的比容量衰减率仅为0.058%。此外,在5 C的高电流密度下,HPC@Se正极还可以达到472.8 m Ahg^(-1)的可观容量。展开更多
文摘在铁粉存在下,以商用N,N-二甲基甲酰胺(DMF)作溶剂,90℃、氮气保护下,二芳基二硒醚与α-溴代羰基化合物反应,得到一系列α-芳硒基羰基化合物.考察了温度、时间、溶剂及铁粉用量对反应的影响,其中,温度对反应的影响最为明显.α-溴代羰基化合物中羰基上取代基对反应有很大影响,取代基为苯基时,转化率较甲基或烷氧基时低.反应机理可能是铁插入Se—Se键中形成亲核性Se Fe Se,随后与亲电底物α-溴代羰基化合物发生亲核取代.本方法使用铁粉促进断裂Se—Se键具有原料安全无毒、廉价易得、实验操作简便等优点.
文摘Eleven nutrition elements and 5 quality elements of garlic （Allium sativum L.） in different Se, S level and their interaction pot experiments were analyzed by atom absorbing spectrophotometer, titration and fixing sulfur method. The mineral elements were analyzed by the Principal Component Analysis and the Factor Analysis on the SPSS 10.0 and three main factors were picked. The results showed that Se, S and Se-S cooperated application enhanced the garlic nutrition quality by increasing mineral nutrition. The garlic Vc was the highest after using higher Se compared middle S level （S 20 mg/kg soil ＋ Se 40 mg/kg soil）. Lower Se level compared middle S level （S 40 mg/kg soil ＋ Se 20 mg/kg soil） get the highest garlic abio-Se in all treatments. The garlic organic Se content was the highest after using higher Se compared middle S （S 40 mg/kg soil ＋ Se 40 mg/kg soil）. The treatment lower S compared lower Se level get the highest garlic allicin in all treatment. It showed that the fresh eating factor was affected by the element Se. The flavor factor and health care factor were affected by both Se and S.
文摘锂-硒电池因其超高的体积能量密度和硒的高电导率而被认为是一种极具有发展前景的锂离子电池。然而,循环过程中电极严重的体积膨胀和多硒化物溶解,以及硒的低负载,阻碍了锂-硒电池应用的发展。解决这三个问题的一种行之有效的方法是将硒限制在具有丰富孔体积的碳基质中,并同时增强硒与碳的界面相互作用。通过将Se浸入酒石酸盐衍生的蜂窝状三维多孔炭中,合成出了一种具有Se―C键的蜂窝状三维多孔炭@硒(HPC@Se)的新型正极材料用于锂-Se电池。得到的蜂窝状三维多孔炭的孔体积可达1.794 cm^(3)g^(-1),能够均匀包封65%硒。此外,硒与碳之间的强化学键有利于稳定硒,从而进一步缓解其巨大的体积膨胀和多硒化物的溶解,还可促进循环过程中的电荷转移。该HPC@Se正极呈现出极好的循环性能和倍率性能。在0.2 C的电流密度下,经200次循环后,其比容量可保持在561 m Ahg^(-1)(为理论比容量的83%),每次循环的比容量衰减率仅为0.058%。此外,在5 C的高电流密度下,HPC@Se正极还可以达到472.8 m Ahg^(-1)的可观容量。
