24-Methylenecholest-5-ene-7-oxo-3β,19-diacetate 5 was synthesized starting from stigmasterol via twelve step reactions in 4.1% overall yield. It can be served
The title compounds, PhX2SnCH2CH2CO2Me (X = C1, 1a; Br, lb; I, 1c), readilyunderwent transesterification into the corresponding analogues, PhX2SnCH2CH2CO2R when
铁路便携式信号设备故障记录分析装置是一种铁路信号设备故障的采集记录及分析装置,是对铁路信号集中监测系统的补充和完善。采用便携采集模块及综合采集设备进行现场采集,并
为了满足ARJ21的试飞要求,根据该机型测试参数多,采样率高,测试点分布广等特点,打破以往传统的基于PCM体系的数据采集方式,采用PCM和以太网混合结构的机载测试系统,即在飞机上建立多个测试系统,通过网络技术把各个测试系统联系起来,将机上的各个测试系统的数据进行融合处理,将测试参数提供给试飞工程师。实验证明,该系统满足ARJ21飞机试飞的需求,测试参数达到了各项测试指标。
An rapid and efficient synthesis of 2, 4, 6-triarylpyridines is reported using substituted benzaldehydes, substituted acetophenones and ammonia as starting mate
The propylene epoxidation over TS-1/SiO2 catalyst hydrothermally treated was investigated. It was found by EPR characterization that two types of Ti (Ⅳ)-supero
Two new eremophilanolides, tsoongianolide E and F, were isolated from Senecio tsoongianus. Their structures were elucidated on the basis of NMR and MS spectra.
Two new norditerpenoid alkaloids, spicatine A (1) and spicatine B (2) were isolated from the root of Aconitum spicatum. The new compounds were deduced on the ba
A novel cyclometalated iridium complex with 1, 3, 4-oxadiazole moiety was synthesized and characterized. Its UV and photoluminescent properties were studied. Th