A series of novel 4'-O-carbamoyl analogs of clarithromycin were synthesized and evaluated for their in vitro antibacterial activity. All of the desired compounds showed excellent activity against erythromycin-susc...A series of novel 4'-O-carbamoyl analogs of clarithromycin were synthesized and evaluated for their in vitro antibacterial activity. All of the desired compounds showed excellent activity against erythromycin-susceptible S.pneumoniae.Particularly,4-fluorobenzyl carbamate 7a demonstrated potent activity against erythromycin-resistant S.pneumoniae encoded by the mef gene,and remarkably improved activity against erythromycin-resistant S.pneumoniae encoded by the erm gene,and the erm and mef genes.展开更多
提出了一种用于控制与保护开关电器的4~20 m A标准电流输出电路。阐述了基于脉宽调制技术实现数模转换的原理,在电路仿真的基础上设计了硬件电路,分析了电路的各个部分并详细讨论了实现脉宽调制输出的软件设计方法。对导致输出电流产生...提出了一种用于控制与保护开关电器的4~20 m A标准电流输出电路。阐述了基于脉宽调制技术实现数模转换的原理,在电路仿真的基础上设计了硬件电路,分析了电路的各个部分并详细讨论了实现脉宽调制输出的软件设计方法。对导致输出电流产生误差的因素作了进一步探讨,改进了相关器件选型,试验表明提高了电路精度和线性度。该电路抗干扰能力强、安全性高且比采用数模转换器实现方式的成本低,适合传输远程模拟量信号,可用于工业现场设备及自动化仪表的相关开发。展开更多
基金supported by Major R&D Program of New Drugs-National S&T Key Special Subject of China (No.2009ZX09103-115)National Natural Science Foundation of China(No.20872081)Natural Science Foundation of Shandong(No.Y2006C31)
文摘A series of novel 4'-O-carbamoyl analogs of clarithromycin were synthesized and evaluated for their in vitro antibacterial activity. All of the desired compounds showed excellent activity against erythromycin-susceptible S.pneumoniae.Particularly,4-fluorobenzyl carbamate 7a demonstrated potent activity against erythromycin-resistant S.pneumoniae encoded by the mef gene,and remarkably improved activity against erythromycin-resistant S.pneumoniae encoded by the erm gene,and the erm and mef genes.
文摘提出了一种用于控制与保护开关电器的4~20 m A标准电流输出电路。阐述了基于脉宽调制技术实现数模转换的原理,在电路仿真的基础上设计了硬件电路,分析了电路的各个部分并详细讨论了实现脉宽调制输出的软件设计方法。对导致输出电流产生误差的因素作了进一步探讨,改进了相关器件选型,试验表明提高了电路精度和线性度。该电路抗干扰能力强、安全性高且比采用数模转换器实现方式的成本低,适合传输远程模拟量信号,可用于工业现场设备及自动化仪表的相关开发。
