有机硅试剂参与过渡金属催化的C-H官能团化反应形成C-C键的研究进展

作为一类重要的有机金属试剂,有机硅试剂在有机合成化学的C—C键形成中得到了广泛应用.综述了近年来有机硅试剂参与的过渡金属催化下C—H官能团化反应形成C—C键的研究进展,重点介绍了Pd催化下C—H官能团化的Hiyama偶联反应.     

基于腔体滤波器的可调谐微波开关的设计

为了满足无人机数据链路测试中信号转换的需求,提出一种可调谐的S波段分波道微波转换开关设计方案,其中采用开关控制电路对输入微波信号进行分波道选择,两路加载集总电容的三阶方杆梳状腔体滤波器对微波信号进行选频、滤波,同时可通过调节调谐螺钉实现两波道中心谐振频点同频或异频,调谐中心频率范围可达20 MHz,自由度较高;微波开关经参数仿真结果满足设计要求,研制完成的微波开关经过实际测试和应用验证,各项技术指标满足使用要求,同时该微波转换开关具有大功率、低损耗、高隔离度等优点,性能稳定、自由度高、易于实现,可满足无人机数据链测试诊断的信号转接要求。     

人面果树皮中口 山 酮 化合物及其DPPH自由基的清除活性

从人面果乙酸乙酯提取物中分离出5个新的口 山 酮 化合物garcinenone A (1), B (3), C (4), D (7) and E (8)和7个已知化合物,其结构经过波谱技术,特别是2D-NMR技术来鉴定。Jacareubin (2), 1,4,6-trihydroxy-5-methoxy-7-(3-methyl-2-buteny1)xanthone (6), subeliptenone B (11) 和symphoxanthone (12)为首次从该植物中分离出来。在DPPH自由基的清除活性实验中,所有的化合物都显示抗氧化活性,其IC50的值在 6.0-23.2 mM。结果表明人面果是潜在的有前景的天然抗氧化剂。     

Analytical modeling on the geo-stress and casing damage prevention with the thermo-hydro-mechanical (THM) coupling of multi-field physics

Journal of Thermal Analysis and Calorimetry - Understanding the rule of squeezing force on casing changing with the working parameters of wells, such as steam injection pressure, steam injection...     

Chain orientation and headgroup structure in Langmuir monolayers of stearic acid and metal stearate (Ag, Co, Zn, and Pb) studied by infrared reflection-absorption spectroscopy

The monolayers of stearic acid at the air-water interface on pure water and ion-containing subphases have been studied using infrared reflection-absorption spectroscopy. In the presence of Co(2+), Zn(2+), and Pb(2+), ordered hydrocarbon chains and hexagonal subcell structure remain almost unchanged in comparison with those for the monolayer on pure water at the surface pressure of 20 m/Nm. In the cases of Co(2+) and Zn(2+), the H-bonded monodentate and unsymmetric bidentate chelating structure within the headgroups were formed, and in the case of Pb(2+), three types of structures, bidentate chelating, unsymmetric chelating, and bidentate bridging coordinations, were formed. The hydrocarbon chains in the monolayers are uniaxially oriented at a tilt angle of approximately 0 degrees with respect to the surface normal in contrast to a tilt angle of approximately 20 degrees on pure water surface at 20 m/Nm by the computer simulation of theoretical calculation to experimental data. In the presence of Ag(+), multilayers were developed with the highly ordered hydrocarbon chains in a triclinic subcell structure and a bidentate bridging structure within the headgroups. The multilayers were composed of three monolayers and the hydrocarbon chains in each monolayer were oriented at an angle of approximately 30 degrees away from the surface normal with their C-C-C planes almost perpendicular to the water surface.     

Efficient synthesis of the key intermediate triptophenolide methyl ether for the synthesis of (−)-triptolide

An efficient synthesis of triptophenolide methyl ether 4 from the readily available abietic acid 3 in nine steps is described and successfully applied to the synthesis of (−)-triptolide 1. The route is of characteristic of low cost, high yield and easy operation. In addition, every reaction in this route has been successfully scaled-up to a 100 g substrate level without loss of yield.     

一个算术函数及其有关的恒等式

对任意的正整数q,设A(q)表示模q在区间1≤m≤q中所有正则数的集合。在A(q)基础上引入一个新的算术函数,借助初等方法以及三角和性质研究了该函数的算术性质;利用此算术性质研究了包含该函数的一个无穷级数的计算问题,给出了此算术函数等于1时的具体形式,进而给出了一个包含该函数的一个有趣的恒等式。     

Total synthesis of novel D-ring-modified triptolide analogues: structure-cytotoxic activity relationship studies on the D-ring of triptolide

The total synthesis of a trans-position butenolide analogue of triptolide 3 and the semi-synthesis of analogue 4, with a furan ring, and compound 5, without a planar D-ring, are described. Studies into the antitumor activity of these compounds suggest that the five-membered unsaturated lactone ring (D-ring) of triptolide is essential to its potent anticancer activity and the C18 carbonyl group may exert an important influence on the interaction between triptolide and the target molecule(s) responsible for initiating their cytotoxic effects.