A new gold self-relay catalytic annulation/nucleophilic substitution cascade of 1,3-enyne acetates with cyclic ether acetals is reported,enabling highly diastereoselective access to cyclic etherified cyclopentenones w...A new gold self-relay catalytic annulation/nucleophilic substitution cascade of 1,3-enyne acetates with cyclic ether acetals is reported,enabling highly diastereoselective access to cyclic etherified cyclopentenones with cyclic quaternary centers in moderate to good yields and>19∶1 dr.This catalysis enables the direct construction of two types of carboncyclic skeletons by adjusting the olefin types of 1,3-enyne acetates.When 1,3-enyne acetates bearing a cyclic alkene unit were used,5~6 fused bicarbocyclic products were diastereoselectively synthesized,whereas the reaction of acyclic 1,3-enyne acetates resulted in five-memebered carbocyclic framework.Notably,cyclic ether acetals are commonly used as protecting groups in traditional multistep organic syntheses,and in this reaction,such reagents serve as electrophilic cyclic ether precursors,achieving new uses for old reagents.The current method demonstrates good functional group compatibility,a broad substrate scope and high diastereoselectivity,providing a new synthetic strategy toward functionalized cyclopentenones.展开更多
随着电压等级提高、输送功率增大,系统无功功率变化更加频繁,不利于熄弧,输电线路安全稳定运行受到严重威胁。基于交直流混合无功补偿线路研究了混合无功补偿装置(hybrid reactive power compensation,HRPC)补偿度对潜供电流与恢复电压...随着电压等级提高、输送功率增大,系统无功功率变化更加频繁,不利于熄弧,输电线路安全稳定运行受到严重威胁。基于交直流混合无功补偿线路研究了混合无功补偿装置(hybrid reactive power compensation,HRPC)补偿度对潜供电流与恢复电压影响,分析分级可控高抗与小电抗联动控制的措施对潜供电弧抑制效果,提出一种改进型旁路断路器时序控制策略。结果表明,串补度20%、补偿度70%及小电抗700 mH时,潜供电流与恢复电压幅值最小,抑制效果最佳。此外,采用潜供电弧熄灭后旁路断路器断开的控制策略能够进一步加快熄弧速率,提高单相重合闸成功率。研究成果为HRPC在远距离大容量混联线路中应用提供理论依据和技术支撑。展开更多
可控型混合无功补偿(hybrid reactive power compensation,HRPC)对输电线路暂态特性的影响亟待研究。在分析可控型混合无功补偿结构功能的基础上,以晋东南-南阳-荆门特高压示范线路为背景,建立特高压混合无功补偿线路单相接地故障等效模...可控型混合无功补偿(hybrid reactive power compensation,HRPC)对输电线路暂态特性的影响亟待研究。在分析可控型混合无功补偿结构功能的基础上,以晋东南-南阳-荆门特高压示范线路为背景,建立特高压混合无功补偿线路单相接地故障等效模型,研究可控串联补偿+可控并联电抗器(thyristor controlled series compensation+thyristor controlled transformer,TSCT+TCT)混合无功补偿对断路器开断特性的影响。基于拉氏变换和等值参数集中电路,分析瞬态恢复电压(transient recovery voltage,TRV)影响因素,得出瞬态恢复电压随可控型混合无功补偿度变化规律。利用PSCAD/EMTDC,研究安装可控型混合无功补偿前后对瞬态恢复电压的影响,验证分析方法的有效性。结果表明:随着可控型混合无功补偿度的增加,TRV峰值和上升率R RRV不断增大,而TCT对瞬态恢复电压影响较小。展开更多
目的研究慢性不可预知应激(CUS)对小鼠性行为的影响及其可能分子机制。方法将20只雄性C57BL/6J小鼠随机均分为Control组和CUS组,并平衡两组间小鼠的体质量,对照组3~5只/笼,正常喂养;CUS组给予21 d CUS结合单笼饲养,建立抑郁模型。21 d后...目的研究慢性不可预知应激(CUS)对小鼠性行为的影响及其可能分子机制。方法将20只雄性C57BL/6J小鼠随机均分为Control组和CUS组,并平衡两组间小鼠的体质量,对照组3~5只/笼,正常喂养;CUS组给予21 d CUS结合单笼饲养,建立抑郁模型。21 d后,进行糖水偏好实验和强迫游泳实验验证CUS的效果。通过嗅觉偏好测试和雌鼠尿液嗅实验检测小鼠的性行为,检测小鼠腹侧被盖区(VTA)脑源性神经营养因子(BDNF)蛋白和mRNA的表达。结果CUS导致小鼠糖水偏好降低(P<0.05),强迫游泳不动时间增加(P<0.05)等抑郁样行为,小鼠嗅觉偏好测试中在雌鼠垫料一侧的时间与在雄鼠垫料一侧的时间无差异,雌鼠尿液嗅实验中闻嗅雌鼠尿液的时间减少(P<0.05)等性行为受损,且CUS小鼠VTA脑区BDNF的蛋白表达降低,BDNF总mRNA和ExonⅠ、ExonⅡmRNA表达量下降,差异有统计学意义(P<0.05)。结论CUS致抑郁小鼠性行为受损和VTA脑区BDNF表达下降,表明BDNF信号通路可能参与CUS致小鼠性行为受损的调控。展开更多
文摘A new gold self-relay catalytic annulation/nucleophilic substitution cascade of 1,3-enyne acetates with cyclic ether acetals is reported,enabling highly diastereoselective access to cyclic etherified cyclopentenones with cyclic quaternary centers in moderate to good yields and>19∶1 dr.This catalysis enables the direct construction of two types of carboncyclic skeletons by adjusting the olefin types of 1,3-enyne acetates.When 1,3-enyne acetates bearing a cyclic alkene unit were used,5~6 fused bicarbocyclic products were diastereoselectively synthesized,whereas the reaction of acyclic 1,3-enyne acetates resulted in five-memebered carbocyclic framework.Notably,cyclic ether acetals are commonly used as protecting groups in traditional multistep organic syntheses,and in this reaction,such reagents serve as electrophilic cyclic ether precursors,achieving new uses for old reagents.The current method demonstrates good functional group compatibility,a broad substrate scope and high diastereoselectivity,providing a new synthetic strategy toward functionalized cyclopentenones.
文摘随着电压等级提高、输送功率增大,系统无功功率变化更加频繁,不利于熄弧,输电线路安全稳定运行受到严重威胁。基于交直流混合无功补偿线路研究了混合无功补偿装置(hybrid reactive power compensation,HRPC)补偿度对潜供电流与恢复电压影响,分析分级可控高抗与小电抗联动控制的措施对潜供电弧抑制效果,提出一种改进型旁路断路器时序控制策略。结果表明,串补度20%、补偿度70%及小电抗700 mH时,潜供电流与恢复电压幅值最小,抑制效果最佳。此外,采用潜供电弧熄灭后旁路断路器断开的控制策略能够进一步加快熄弧速率,提高单相重合闸成功率。研究成果为HRPC在远距离大容量混联线路中应用提供理论依据和技术支撑。
文摘目的研究慢性不可预知应激(CUS)对小鼠性行为的影响及其可能分子机制。方法将20只雄性C57BL/6J小鼠随机均分为Control组和CUS组,并平衡两组间小鼠的体质量,对照组3~5只/笼,正常喂养;CUS组给予21 d CUS结合单笼饲养,建立抑郁模型。21 d后,进行糖水偏好实验和强迫游泳实验验证CUS的效果。通过嗅觉偏好测试和雌鼠尿液嗅实验检测小鼠的性行为,检测小鼠腹侧被盖区(VTA)脑源性神经营养因子(BDNF)蛋白和mRNA的表达。结果CUS导致小鼠糖水偏好降低(P<0.05),强迫游泳不动时间增加(P<0.05)等抑郁样行为,小鼠嗅觉偏好测试中在雌鼠垫料一侧的时间与在雄鼠垫料一侧的时间无差异,雌鼠尿液嗅实验中闻嗅雌鼠尿液的时间减少(P<0.05)等性行为受损,且CUS小鼠VTA脑区BDNF的蛋白表达降低,BDNF总mRNA和ExonⅠ、ExonⅡmRNA表达量下降,差异有统计学意义(P<0.05)。结论CUS致抑郁小鼠性行为受损和VTA脑区BDNF表达下降,表明BDNF信号通路可能参与CUS致小鼠性行为受损的调控。
