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61.
Wei Huang Qing He Yongpan Hu Yanguang Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(26):8768-8772
Conjugated polymers have emerged as promising candidates for photocatalytic H2 production owing to their structural designability and functional diversity. However, the fast recombination of photoexcited electrons and holes limits their H2 production rates. We have now designed molecular heterostructures of covalent triazine frameworks to facilitate charge‐carrier separation and promote photocatalytic H2 production. Benzothiadiazole and thiophene moieties were selectively incorporated into the covalent triazine frameworks as electron‐withdrawing and electron‐donating units, respectively, by a sequential polymerization strategy. The resulting hybrids exhibited much improved charge‐carrier‐separation efficiency as evidenced by photophysical and electrochemical characterization. An H2 evolution rate of 6.6 mmol g?1 h?1 was measured for the optimal sample under visible‐light irradiation (λ>420 nm), which is far superior to that of most reported conjugated‐polymer photocatalysts. 相似文献
62.
This article describes the concept of stereoelectronic effects in fundamental organic chemistry and summarizes such specific phenomenon through formation of covalent bonds, resonance structures, rearrangement of carbocations, formation of enolate anions, bimolecular nucleophilic substitution of haloalkanes, elimination of halocyclohexanes, and electrophilic addition of cyclohexenes. 相似文献
63.
Hongyang Zhao Yanpeng Xing Prof. Dr. Ping Lu Prof. Dr. Yanguang Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(42):15144-15150
Cyclopenta[b]quinolines and cyclohexa[b]quinolines were prepared via the reactions of α‐diazo ketones with N‐(2‐cyclopropylidenemethylphenyl)phosphanimines and N‐(2‐cyclobutylidenemethylphenyl) phosphanimine, respectively. The reaction proceeds in a cascade involving ketenimine formation, 6 π‐electron ring closure, and 1,3‐alkyl shift. A similar approach was developed for the synthesis of dihydropyrrolo‐[2,3‐b]quinolines from N‐(2‐cyclopropylidenemethylphenyl)phosphanimines and isocyanates. 相似文献
64.
65.
多重运输调度问题的表搜索算法 总被引:1,自引:0,他引:1
本文提出了多重运输调度问题的表搜索算法,实际运算表明,这些算法具有较快的收敛速度,为解决实际问题提供了一条有效的途径。 相似文献
66.
67.
Jinhao Zhao Feng Zhao Yanguang Wang Haibo Li Qijun Zhang Daniel Gunard Qiufu Ge Erqing Wei Hao Jiang Yihang Wu Lin Wang Hualiang Jiang Franoise Guritte Xiumei Wu ChristopherH.K. Cheng Shoei‐Sheng Lee Yu Zhao 《Helvetica chimica acta》2004,87(7):1832-1853
Two series of territrem B analogs, i.e., 5 – 10 , containing both the 2‐en‐1‐one‐A‐ring and the aromatic‐E‐ring pharmacophores were designed and synthesized from jujubogenin ( 4a ). The anti‐acetylcholinesterase (anti‐AChE), anti‐caspase‐3, and other biological activities of these territrem‐B analogs and their intermediates were assessed. Compound 9b, 22a , and 24f were shown to be weak inhibitors of AChE. None of the synthesized compounds exhibited significant inhibitory activity on caspase‐3. On the other hand, compounds 22e, 24a, 7b , and 8a showed mild cytotoxicity on cultured KB cells, with IC50 values of 2.0, 3.5, 6.5, and 14 μM , respectively. In addition, compounds 23b and 5f were active against injury arising from oxygen‐glucose deprivation. 相似文献
68.
A spray model and a droplet collision model are implemented into a radio frequency inductively coupled plasma model. The discrete parcel technique combined with the stochastic Monte Carlo method is used to solve the spray equation and determine the outcomes of droplet collisions in dense sprays. Plasma--spray interactions are considered by adding source terms to the conservation equations of mass, momentum and energy of the plasma phase. Two types of the outcomes of water droplets collisions, coalescence and grazing, are predicted and compared to the experimental and analytical results. The agreement is quite good. The effects of droplet collisions on droplet size distribution of the spray and the spray evaporation are investigated. It is found that the droplet collisions can increase the average droplets size of the spray. For the mono-disperse spray, the collisions can lead to a delay on the spray evaporation. However, for the poly-disperse spray, the effect of droplet collisions on the spray evaporation could not be predicted before the calculation due to the randomness of droplet collisions. 相似文献
69.
[reaction: see text]. An unexpected 1-methylimidazole-catalyzed reaction of dimethyl acetylenedicarboxylate (DMAD) with in situ generated arylketenes leading to the synthesis of dimethyl 2-arylidenesuccinates under mild conditions is described. A plausible mechanism has been proposed. 相似文献