高压大功率及模块化安装的卫星功率平台,采用S4R(Sequential Series Shunt Switch Regulator)功率调节技术。针对提高高压大功率空间EPS的效率及动态响应,采用非线性重叠调用和2阶噪声整形调制技术,解决了基于S4R型功率EPS单纯增加输出...高压大功率及模块化安装的卫星功率平台,采用S4R(Sequential Series Shunt Switch Regulator)功率调节技术。针对提高高压大功率空间EPS的效率及动态响应,采用非线性重叠调用和2阶噪声整形调制技术,解决了基于S4R型功率EPS单纯增加输出滤波电容来提高平台动态性能及效率问题。仿真及实验结果表明了该方法的有效性。展开更多
R)-Hydroxy-(S)-proline was N-protected by reaction with di-tert-butyl pyrocarbonate to give N-Boc-(4R)-hydroxy-(S)-proline, which was treated with NaH in anhydrous tetrahydrofuran and followed by etherification with P...R)-Hydroxy-(S)-proline was N-protected by reaction with di-tert-butyl pyrocarbonate to give N-Boc-(4R)-hydroxy-(S)-proline, which was treated with NaH in anhydrous tetrahydrofuran and followed by etherification with PhCH 2Br to form the N-Boc-(4R)-benzyloxy-(S)-proline, which, after removal of the protecting group with CF 3COOH gave the title compound. As an efficient catalyst for the direct asymmetryic aldol reaction the compound gave products in yield ranged from 58% to 77% with enantiomeric excess up to 88%.展开更多
A compound ethyl(5S,6R)-2-(4-methylphenyl)-6-[(1R)-tert-butyldimethylsilyloxyethy]-penem-3-carboxylate was synthesized through displacement,acylation and Wittig cyclization reaction of optically active material(3R,4R)...A compound ethyl(5S,6R)-2-(4-methylphenyl)-6-[(1R)-tert-butyldimethylsilyloxyethy]-penem-3-carboxylate was synthesized through displacement,acylation and Wittig cyclization reaction of optically active material(3R,4R)-3-[(1R)-tert-butyldimethylsilyloxyethyl]-4-acetoxy-2-azetidi-none(4AA)upon thionocarboxlic acid.The intermediates and the target product were characterized by 1HNMR,IR,elementary analysis and MS.展开更多
文摘高压大功率及模块化安装的卫星功率平台,采用S4R(Sequential Series Shunt Switch Regulator)功率调节技术。针对提高高压大功率空间EPS的效率及动态响应,采用非线性重叠调用和2阶噪声整形调制技术,解决了基于S4R型功率EPS单纯增加输出滤波电容来提高平台动态性能及效率问题。仿真及实验结果表明了该方法的有效性。
文摘R)-Hydroxy-(S)-proline was N-protected by reaction with di-tert-butyl pyrocarbonate to give N-Boc-(4R)-hydroxy-(S)-proline, which was treated with NaH in anhydrous tetrahydrofuran and followed by etherification with PhCH 2Br to form the N-Boc-(4R)-benzyloxy-(S)-proline, which, after removal of the protecting group with CF 3COOH gave the title compound. As an efficient catalyst for the direct asymmetryic aldol reaction the compound gave products in yield ranged from 58% to 77% with enantiomeric excess up to 88%.
文摘A compound ethyl(5S,6R)-2-(4-methylphenyl)-6-[(1R)-tert-butyldimethylsilyloxyethy]-penem-3-carboxylate was synthesized through displacement,acylation and Wittig cyclization reaction of optically active material(3R,4R)-3-[(1R)-tert-butyldimethylsilyloxyethyl]-4-acetoxy-2-azetidi-none(4AA)upon thionocarboxlic acid.The intermediates and the target product were characterized by 1HNMR,IR,elementary analysis and MS.
