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排序方式: 共有91条查询结果,搜索用时 531 毫秒
1.
Ein elektronenreiches cyclisches (Alkyl)(amino)carben auf Au(111)-, Ag(111)- und Cu(111)-Oberflächen
Anne Bakker Dr. Matthias Freitag Elena Kolodzeiski Peter Bellotti Dr. Alexander Timmer Dr. Jindong Ren Bertram Schulze Lammers Daniel Moock Prof. Dr. Herbert W. Roesky Dr. Harry Mönig Dr. Saeed Amirjalayer Prof. Dr. Harald Fuchs Prof. Dr. Frank Glorius 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(32):13745-13749
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Dr. Jindong Ren Dr. Henning Klaasen Melanie C. Witteler Lena Viergutz Prof. Dr. Johannes Neugebauer Dr. Hong-Ying Gao Prof. Dr. Armido Studer Prof. Dr. Harald Fuchs 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(70):16727-16732
The reactivity of aryl triflates in on-surface C−C coupling is reported. It is shown that the triflate group in aryl triflates enables regioselective homo coupling with preceding or concomitant hydrodetriflation on Cu(111). Three different symmetrical π-systems with two and three triflate functionalities were used as monomers leading to oligomeric conjugated π-systems. The cascade, comprising different intermediates at different reaction temperatures as observed for one of the molecules, proceeds via initial removal of the trifluoromethyl sulfonyl group to give an aryloxy radical which in turn is deoxygenated to the corresponding aryl radical. Thermodynamically driven regioselective 1,2-hydrogen atom transfer leads to a translocated aryl radical which in turn undergoes coupling. For a sterically more hindered bistriflate, where one ortho position was blocked, dehydrogenative coupling occurred at remote position with good regioselectivity. Starting materials, intermediates as well as products were analyzed by scanning tunneling microscopy. Structures and suggested mechanism were further supported by DFT calculations. 相似文献
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Qin Wang Yong Jiang Nina Wei Jindong Li Mei Zhang Linwei Chen 《Journal of separation science》2023,46(24):2300518
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本文针对板弯曲边界元方法中计算边界曲率等高阶导数项时边界积分方程中出现的高阶奇异积分项,通过对未知挠曲函数作渐近展开并加以适当摄动,获得了渐近收敛的边界积分方程。采用这一方法计算板边界上的曲率分布,获得了满意的数值结果。 相似文献
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Weiguo Zhang Junyu Xu Jing Cao Chao Fang Jindong Zhu Tao Lu Ding Du 《Tetrahedron》2017,73(23):3249-3254
An in situ activation of isatin-derived α,β-unsaturated acids 2 for the generation of isatin-derived α,β-unsaturated acyl azoliums II was described. The acyl azoliums II were successfully applied to undergo a formal [3 + 3] annulation with 1,3-dicarbonyl compounds to access functionalized 3,4′-spirooxindole δ-lactones 4. A scale-up synthesis and an enantioselective variant of this protocol were also investigated. The stable and easily prepared acids 2 may be further utilized as promising versatile electrophilic 1,3-synthons for divergent synthesis of spirooxindoles. 相似文献
7.
Simultaneous Determination of Four Sudan Dyes in Egg Yolks by Molecularly Imprinted SPE Coupled with LC-UV Detection 总被引:1,自引:0,他引:1
Jindong Qiao Hongyuan Yan Hui Wang Yupei Wu Pengyu Pan Yuru Geng 《Chromatographia》2011,73(3-4):227-233
A highly selective molecularly imprinted solid-phase extraction (MISPE) combined with liquid chromatography-ultraviolet detection was developed for the simultaneous isolation and determination of four Sudan dyes (I, II, III and IV) in egg-yolk products. The imprinted microspheres synthesized by suspension polymerization using phenylamine?Cnaphthol as mimic template show high selectivity and affinity to the four kinds of Sudan dyes and were successfully applied as selective sorbents of solid-phase extraction for the simultaneous determination of the four Sudans from egg-yolk samples. Good linearity was obtained in a range of 0.062?C10 ??g g?1 and the average recoveries of the four Sudans at three spiked levels ranged from 94.1 to 102.5% with the relative standard deviations less than 5.8%. The developed extraction protocol eliminated the effect of template leakage on quantitative analysis and could be applied for the determination of Sudans in complicated food samples. 相似文献
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A kind of function-valued Padé-type approximant via the formal orthogonal polynomials (FPTAVOP) is introduced on the polynomial space and an algorithm is sketched by means of the formal orthogonal polynomials. This method can be applied to approximate characteristic values and the corresponding characteristic function of Fredholm integral equation of the second kind. Moreover, theoretical analyses show that FPTAVOP method is the most effective one for accelerating the convergence of a sequence of functions. In addition, a typical numerical example is presented to illustrate when the estimates of characteristic value and characteristic function by using this new method are more accurate than other methods. 相似文献