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1.
A highly efficient Pd/C-catalyzed ligandless, heterogeneous Suzuki reaction of p-(un)substituted phenyl halide with (p-substituted phenyl)boronic acid in DMF/H2O solvent in a short reaction time (0.5 h) at 75 ℃ was developed. The key for such a catalytic system was the addition of 1 equivalent of tetrabutylammonium bromide. A wide variety of substituents can be tolerated and high yields of cross coupling products were achieved. The palladium catalyst can be easily recovered and reused without significantly decreasing its efficiency.  相似文献   
2.
二芳基乙烯;超声条件下芳基格氏试剂与4-烷基苯乙酮的反应  相似文献   
3.
Hu  Qiu-Fen  Zhang  Ling-Fang  Liu  Ming-Xin  Cai  Bing-Biao  Li  Yong  Zhou  Tao  Li  Man-Fei  Wang  Hua-Shun  Xu  Yong  Kong  Wei-Song  Zhou  Min  Yang  Guang-Yu  Jiang  Ju-Xing 《Chemistry of Natural Compounds》2022,58(3):511-515
Chemistry of Natural Compounds - Two new chromeno[3,2-c]pyridin derivatives, 8-acetyl-3-(hydroxymethyl)-7-methoxy-10H-chromeno[3,2-c]pyridin-10-one (1) and...  相似文献   
4.
根据人耳对声音信号相位不敏感的原理,采用时变全通滤波器,随机化每个声源输入信号的相位,从而减小声源输出信号之间的相关性,进而减小由于相关产生干涉而带来的梳状滤波失真。数值计算和实验结果均表明用时变全通滤波器随机化声源输入信号的相位能够有效地减小扩声系统中的梳状滤波失真。  相似文献   
5.
Mixed-matrix membrane (MMM) consisting of fillers in polymeric matrix offers a promising approach to develop high-performance membranes, while remain challenges in achieving ideal filler dispersion and interfacial morphology. Herein, we reported on a new kind of MMM with molecular-level dispersion of filler via a proposed reactive incorporation approach. Specifically, polyhedral oligomeric silsesquioxanes (POSS) with vinyl groups was grafted with ethoxy groups to build covalent bond with hydroxyl-terminated polydimethylsiloxane (PDMS) chains to fabricate PDMS MMMs uniformly dispersed with POSS molecules. The molecular dispersion of POSS in PDMS matrix was visualized by SEM, AFM, and TEM characterizations, as well as reflected by XRD analysis. The PDMS chain conformation affected by the reactive incorporation of POSS was investigated by analyzing the thermal and mechanical properties of the POSS/PDMS MMMs using DSC, TGA, and DMA measurements. Contact angle test was used to study the surface affinity and positron annihilation technique was employed to probe the free volumes, which are respectively associated with the sorption and diffusion behavior in the POSS/PDMS MMMs. The results demonstrated that molecular cages and crosslinking effect of POSS led to an increase of large free volumes while a decline of small free volumes. Therefore, the PDMS MMM with reactive incorporation of only 2 wt.% POSS simultaneously enhanced the butanol permeability (by 78%) and butanol/water selectivity (by 124%) for pristine PDMS membrane, transcending the performance limit of state-of-the-arts organophilic membranes. The proposed reactive incorporation approach may provide a platform of developing highly efficient membranes for molecular separation.  相似文献   
6.
C3N4硬膜的人工合成和鉴定 *   总被引:2,自引:0,他引:2       下载免费PDF全文
用微波等离子体化学气相沉积法 (MPCVD)在硅和铂衬底上得到高质量的C3N4薄膜 .计算了α-C3N4和β-C3N4单相X射线谱的峰位和强度 ,沉积膜的X射线谱具有两相的所有强峰 ,证明它是α- 和β- C3N4的混合物 .总的N/C比在1.0~2.0之间 .FT-IR和Raman谱支持C—N共价键的存在 .体积弹性模量达到349GPa .对薄膜特性的鉴定提出了一些看法.  相似文献   
7.
环己基乙炔;连二烯;液晶中间体;合成;消除反应  相似文献   
8.
在分析多通道单极子次级源控制系统的基础上,提出一种幅度调节型组合次级声源,这种组合源由两个单极子声源构成,单极子声源的间距远小于声波的波长。文中就组合次级源在自由场中对不同初级声源辐射噪声的控制进行理论分析和实验验证,并与同等条件下的单极子次级源控制系统的降噪性能进行了比较分析。数值计算和实验结果均表明,对于不同的初级声场,在次级通道数相同的情况下,组合次级源控制系统可以得到比单极子次级源控制系统高的降噪量。  相似文献   
9.
A radioisotope slow positron beam has been built at the Chung Yuan Christian University in Taiwan for the research and development in membrane science and technology. Doppler broadening energy spectra and positron annihilation lifetime have been measured as a function of positron energy up to 30 keV in a polyamide membrane prepared by the interfacial polymerization between triethylenetetraamine (TETA) and trimesoyl chloride (TMC) on modified porous polyacrylonitrile (PAN) asymmetric membrane. The multilayer structures and free-volume depth profile for this asymmetric membrane system are obtained. Positron annihilation spectroscopy coupled with a slow beam could provide new information about size selectivity of transporting molecules and guidance for molecular designs in polymeric membranes.  相似文献   
10.
研制出一种以时间分辨荧光微球作为标记,自驱动快速检测H-FABP的荧光免疫微流体测试卡.利用激光切割法在双面胶上简便、快速地切割出所设计的微通道结构,并采用激光切割法制作出聚甲基丙烯酸甲酯(PMMA)测试卡底板及上盖.使用提拉涂膜的方法在PMMA底板表面修饰马来酸酐官能团,有效地解决了捕获抗体在PMMA表面的固定问题.使用等离子体处理测试卡上盖改善其亲水性,使液体能够在微通道内自行流动.使用此测试卡可以实现对心型脂肪酸结合蛋白(H-FABP)的快速检测,线性检测范围为0.5~ 100 ng/mL,检出限为0.1 ng/mL(S/N=3),检测时间少于10 min,批内相对标准偏差(RSD) <10%,批间RSD<15%.本方法具有灵敏度高、检测时间短、结果准确等优点,可以满足临床检测的需求,具有良好的应用前景.  相似文献   
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