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991.
A convenient and regioselective sulfonylation/cyclization of 1,6-enynes with arylazo sulfones has been developed to access a series of sulfonylated γ-butyrolactams.The present reaction could be efficiently conducted under catalyst-and additive-free conditions,in which C-S and C-C bonds were selectively constructed in one-pot procedure. 相似文献
992.
Garnick Kelly Wetherby Anthony E. Sweeney Brian Scott Thomas A. Wei Cong 《Journal of Radioanalytical and Nuclear Chemistry》2021,330(3):979-984
Journal of Radioanalytical and Nuclear Chemistry - A rapid analytical method for quantifying 90Sr in infant formula prior to secular equilibrium is presented. The approach is dependent on the use... 相似文献
993.
Huijie He Xu Fang Dr. Dong Zhai Wei Zhou Yimeng Li Wenling Zhao Dr. Chengcheng Liu Dr. Zhen Li Prof. Weiqiao Deng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(58):14390-14395
Imines are important intermediates in drug synthesis. Photocatalytic aerobic oxidative coupling of amines has been considered as a clean and promising way to produce imines and has attracted great attention. Herein, we designed and synthesized a novel two-dimensional porphyrin-based covalent organic framework (Por-BC-COF) which adopts an AA stacking mode with excellent crystallinity, high Brunauer–Emmett–Teller surface areas (1200 m2 g−1), wide light absorption range (200–1300 nm) and good stability in a variety of organic solvents. Por-BC-COF can be used as a metal-free heterogeneous photocatalyst for the photocatalytic oxidation of amines to imines under visible light and red light with a high yield (97 %). This work presents a novel and efficient COF photocatalyst in the application of light-driven organic synthesis. 相似文献
994.
鲍曼不动杆菌已成为最普遍的医院致病菌,且耐药情况严峻.LpxC作为新抗菌药物靶点被大量研究,但鲍曼不动杆菌LpxC晶体尚未解析得到,基于其结构的药物设计等工作无法开展.以铜绿假单胞菌LpxC晶体结构为模板,通过同源模建方法获得鲍曼不动杆菌LpxC结构模型.较好的Ramachandran plot分布和Profile-3D结果验证了模型的合理性.用分子动力学模拟优化鲍曼不动杆菌LpxC模型,修补部分不合理构象.后续分子对接结果显示S构型的苄氧乙酰基羟肟酸类抑制剂比R构型分子能更有效地结合在F191,H237和K238组成的较浅口袋中,这可能是S构型抑制剂活性更高的主要因素,模拟结果与实验数据吻合较好. 相似文献
995.
996.
997.
Lei Li Guangyuan Wang Shanshan Wei Xilong Yan Ligong Chen 《Research on Chemical Intermediates》2013,39(2):615-620
A modified procedure for synthesis of the side chain of ceftazidime-activated thioester has been established. This key intermediate of ceftazidime was obtained by a more eco-friendly process than conventional methods, and the yield was much higher (up to 92.4 %). It was found that different organic bases (triethylamine or pyridine) used in this reaction had different effects. The reaction conditions were also optimized to make the route more competitive and suitable for large-scale industrial production. 相似文献
998.
Quasi-one-dimensional organic conductors are highly unconventional materials, which exhibit a wide variety of phenomena, including spin density waves, quantum Hall effect, and superconductivity. In this paper, we review some experimental and theoretical developments concerning the superconducting state of these systems, where a particular emphasis is placed on the possibility of triplet superconductivity. This possibility is supported by various experiments including upper critical field, Knight shift and NMR relaxation time measurements on the Bechgaard salt bistetramethyltetraselenafulvalene hexafluorophosphate [(TMTSF)2PF6]. However, similar NMR results are still lacking for another compound (TMTSF)2ClO4 and other members of the Bechgaard salts family. Furthermore, the pairing mechanism and order parameter symmetry are not yet fully known. Therefore, we include a discussion of both triplet and singlet pairing states, and analyse briefly the possibility that the symmetries of the superconducting order parameters are different for various compounds. Finally, we also discuss some open questions regarding the superconducting state of these systems. 相似文献
999.
1000.
The location set covering problem continues to be an important and challenging spatial optimization problem. The range of practical planning applications underscores its importance, spanning fire station siting, warning siren positioning, security monitoring and nature reserve design, to name but a few. It is challenging on a number of fronts. First, it can be difficult to solve for medium to large size problem instances, which are often encountered in combination with geographic information systems (GIS) based analysis. Second, the need to cover a region efficiently often brings about complications associated with the abstraction of geographic space. Representation as points can lead to significant gaps in actual coverage, whereas representation as polygons can result in a substantial overestimate of facilities needed. Computational complexity along with spatial abstraction sensitivity combine to make advances in solving this problem much needed. To this end, a solution framework for ensuring complete coverage of a region with a minimum number of facilities is proposed that eliminates potential error. Applications to emergency warning siren and fire station siting are presented to demonstrate the effectiveness of the developed approach. The approach can be applied to convex, non-convex and non-contiguous regions and is unaffected by arbitrary initial spatial representations of space. 相似文献