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991.
Dung Nguyen Tien Thanh Do Minh Huong Nguyen Thi Thuy Phan Thi Hoan Nguyen Thi Thanh Dinh Thi Mai Van Trang Nguyen Son Ninh The 《Structural chemistry》2020,31(6):2435-2450
Structural Chemistry - Quinolone and isoquinolone alkaloids, which were found in the plant kingdom, are now potential antioxidants. In this case study, a quantum calculated procedure utilizing the... 相似文献
992.
Seung Hyun Moon Kyung Lee Park Jun Won Baek Hyun Ju Lee Ji-Hwan Choi Yeonju Lee Bun Yeoul Lee 《Journal of polymer science. Part A, Polymer chemistry》2020,58(9):1253-1261
Cycloolefin copolymers (COCs, which are produced via ethylene/cycloolefin copolymerization) and cycloolefin polymers (COPs, which are synthesized by a rather complicated two-step process via ring-opening metathesis polymerization and subsequent hydrogenation) are commercialized materials used especially widely in optical applications. Although a COP can be used after processing into a film, films made from conventional COCs are too brittle. Optical-grade COCs and COPs are generally known as amorphous polymers. By contrast, here, a quasi-alternating ethylene/norbornene copolymer (norbornene content 56 mol%), prepared from a constrained-geometry Hf complex, shows some melting (Tm) signals in a broad temperature range (150–200°C) in the first heating scan of differential scanning calorimetry (DSC) when the samples are prepared by precipitation from a toluene solution. In the second heating scan, only glass transition (Tg) signals are observed at ~140°C with disappearance of Tm signals. The quasi-alternating ethylene/norbornene copolymer has better mechanical properties (greater elongation at break) than random congeners, which do not show any melting signal, though elongation at break is still inferior to that of the COP which shows the melting signal in the first heating scan of DSC. The enhanced mechanical properties of the quasi-alternating ethylene/norbornene copolymer and commercial-grade COP may be ascribed to semicrystallinity observed in the first heating scan. 相似文献
993.
AbstractAs the insulating medium, SF6 is widely used in gas insulation equipment. Partial discharge and local overheating can cause the decomposition of SF6, resulting in a decrease in insulation strength of the equipment. The detection of SF6 decomposition gas can be used for on-line insulation detection of gas insulation equipment in electric power industry. In order to develop a new sensor gas sensing material for gas detecting. In this work, based on the first-principles density functional calculation (DFT) method of DMol3, the adsorption of SF6 decomposition gas on (5,0) Z-type Rh-BNNT in different ways was explored. The adsorption energy, adsorption distance, charge transfer as well as density of states were discussed. The results show that the adsorption strength between SO2 molecule with Rh-BNNT is larger than with SOF2 molecule, combined with desorption time, theoretically predicts Rh -BNNT have the potential to be a material for SO2 gas sensors. 相似文献
994.
Jingxin Dai Dr. Wenhui Zhao Lingbo Xing Dr. Jian Shang Huanxin Ju Dr. Xiong Zhou Dr. Jing Liu Dr. Qiwei Chen Prof. Dr. Yongfeng Wang Junfa Zhu Prof. Dr. Kai Wu 《Chemphyschem》2019,20(18):2367-2375
Surface-assisted Ullmann coupling was widely applied to construct various molecular nanostructures on surfaces due to its reliability and controllability. By using 4,4′′-dichloro-1,1′:3′,1′′-terphenyl (DCTP) as the precursor, covalently bonded zig-zag oligophenylene chains and hexagonal hyperbenzene rings, e. g., [18]-honeycombenes, were successfully fabricated on Ag(111) via dechlorinated Ullmann coupling reaction. Stepwise annealing was applied to investigate the reaction process in detail. Scanning tunneling microscopy and synchrotron X-ray photoemission spectroscopy were utilized to explore the thermal evolution of the DCTP molecules on Ag(111) under ultrahigh vacuum conditions, evidencing the existence of intact DCTP molecules, chemisorbed Cl atoms, covalently bonded DCTP dimers as well as organometallic C−Ag−C-containing intermediates. These results may help understand dechlorinated Ullmann coupling reaction of aryl chlorides on metal surfaces. 相似文献
995.
2-Nitroaryl aldehydes, ketones, and imines were reductively cyclized to 2,1-benzisoxazoles with good yields in the presence of indium and iodine in MeOH. Under a similar condition, N-(2-nitrobenzylidene)anilines were produced mixtures of 2,1-benzisoxazoles and 3-anilino-2-phenyl-2H-indazoles. 相似文献
996.
TheheteropolytungstateisoneofthemostchallengingprojectsininorganicchemistryduetoitsaPPlicationonsolidstatechemistly,catalysis,biochemistry,separationandanalysis,etcl-4.Inthispaper,thepreparationmethodandluminescencepropertiesofEu' -dopedNanPZW22O83wereinvestigated.Therelationshipbetweentheluminescentpropertiesandcrystalstructurewasdiscussed.ExperimentalThesampleswerepreparedbysolidstatereactionfrommixturesofN'PZO7'10HZO,WOe,NaZWO"ZHzOandEuZO3.Thestoichiometricalmixtureswerecalcined… 相似文献
997.
Real-time systems are increasingly used in applications whose failure may result in large economic and human costs. Since many such systems operate in environments that are non-deterministic, and possibly hazardous, it is extremely important that the systems be dependable, namely the deadlines of tasks must be met even in the presence of particular failures. In order to enhance the dependability of a real-time system, we study the problem of scheduling a set of real-time tasks to meet their deadlines in the presence of processor failures. We first prove that the problem of scheduling a set of non-preemptive tasks on more than two processors to tolerate one arbitrary processor failure is NP-complete even when the tasks share a common deadline. Heuristic algorithms are then proposed to solve this problem. The schedules generated by the heuristic algorithms can tolerate one arbitrary processor failure in the worst case. The analysis and experimental data show that the performance of the algorithms is near-optimal. 相似文献
998.
999.
自从Canham观察到多孔硅(PS)的可见光致发光后,由于其可望成为可与Ⅲ—Ⅴ族半导体材料相媲美的新型光电子材料而引起了科学界极大的兴趣.目前,制备多孔硅一般都采用电化学腐蚀方法. 相似文献
1000.
Many remarkable cubic theorems involving theta functions can be found in Ramanujan's Lost Notebook. Using addition formulas, the Jacobi triple product identity and the quintuple product identity, we establish several theorems to prove Ramanujan's cubic identities. 相似文献