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基于DDS技术的可调方波干扰的多功能信号发生器研究
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作者 韩泽光 胡敏 郝瑞琴 《机械与电子》 2010年第10期3-7,共5页
利用单片机控制灵活的特点,采用软件方式实现信号生成和添加干扰.为方便添加方波干扰,系统采用模拟直接数字频率合成(DDS)基本工作原理方法,使用片外存储器替代DDS芯片的ROM波形查询表实现相幅转换.系统采用AT89C51单片机实现数据处理,D... 利用单片机控制灵活的特点,采用软件方式实现信号生成和添加干扰.为方便添加方波干扰,系统采用模拟直接数字频率合成(DDS)基本工作原理方法,使用片外存储器替代DDS芯片的ROM波形查询表实现相幅转换.系统采用AT89C51单片机实现数据处理,DAC0832实现D/A转换,采用4×4键盘完成参数设定,液晶12864显示波形参数和操作提示,实现了正弦波、方波、三角波信号生成、幅值和频率调节,方波干扰添加以及各种波形信号的参数控制. 展开更多
关键词 信号发生器 直接数字频率合成 单片机 可调干扰
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Interference RNA induction and drug target validation
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作者 金鑫 孙婷婷 +5 位作者 王琪 徐欢 魏铁军 贺秋晨 张礼和 周德敏 《Journal of Chinese Pharmaceutical Sciences》 CAS 2009年第4期293-301,共9页
The ability to knockdown the expression of an endogenous gene by RNAi has emerged as a powerful strategy for the rapid identification of specific gene functions. Vector-based constitutive expression of shRNA can resul... The ability to knockdown the expression of an endogenous gene by RNAi has emerged as a powerful strategy for the rapid identification of specific gene functions. Vector-based constitutive expression of shRNA can result in stable and efficient knockdown of target genes. However, constitutive expression of shRNA imposes major limitations when analyzing the fimction of genes whose expression is vital for the survival of an organism. Inducible RNAi systems can circumvent this limitation by enabling the inhibition of expression of an essential gene only when the inducing agent is present, and the level of knockdown of the essential gene can be controlled and adjusted by the concentration of inducing agent. In this review, we briefly summarize the recent development of various inducible RNAi systems and their potential applications in drug target validation. 展开更多
关键词 RNA interference Stable transduction Inducible RNAi Target validation Xenograft animal model
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