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By using the continuation theorem of coincidence degree theory and constructing suitable Lyapunov functions, the global exponential stability and periodicity are investigated for a class of delayed high-order Hopfield neural networks (HHNNs) with impulses, which are new and complement previously known results. Finally, an example with numerical simulation is given to show the effectiveness of the proposed method and results. The numerical simulation shows that our models can occur in many forms of complexities including periodic oscillation and the Gui chaotic strange attractor. 相似文献
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Zhi‐Yong Xiao Xia‐Chang Wang Gui‐Ping Zhang Zhong‐Liang Huang Li‐Hong Hu 《Helvetica chimica acta》2010,93(4):803-810
Five new terpenoids, including four eudesmane‐type sesquiterpenoids, 1 – 4 , and one labdane‐type diterpenoid, 6 , together with ten known compounds, were isolated from the roots of Chloranthus spicatus. The structures and their relative configurations were mainly established by 1D‐ and 2D‐NMR spectra, and MS experiments. 相似文献
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Yue‐Hu Wang Qian‐Yun Sun Fu‐Mei Yang Chun‐Lin Long Fu‐Wei Zhao Gui‐Hua Tang Hong‐Mei Niu Huan Wang Qiao‐Qin Huang Jin‐Jin Xu Li‐Juan Ma 《Helvetica chimica acta》2010,93(12):2467-2477
Ten new phenolic compounds including the six neolignans 1 – 3 and 6 – 8 and four caffeoyl derivatives, i.e., myo‐inositol 1‐caffeate ( 9 ), myo‐inositol 6‐caffeate ( 10 ), myo‐inositol 5‐caffeate ( 11 ), and paucine 3′‐β‐D ‐glucopyranoside ( 12 ) were isolated from the whole plants of Selaginella moellendorffii (caffeic acid=3‐(3,4‐dihydroxyphenyl)prop‐2‐enoic acid). Their structures were established by spectroscopic and chemical methods. 相似文献
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Ying Liu Chong‐an Di Dr. Chunyan Du Yunqi Liu Prof. Kun Lu Wenfeng Qiu Dr. Gui Yu Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(7):2231-2239
A series of fused thiophenes composed of fused α‐oligothiophene units as building blocks, end‐capped with either styrene or 1‐pentyl‐4‐vinylbenzene groups, has been synthesized through Stille coupling reactions. The compounds have been fully characterized by means of 1H NMR spectrometry, high‐resolution mass spectrometry, and elemental analysis. The molecules present a trans–trans configuration between their double bonds, which has been verified and confirmed by Fourier‐transform infrared spectroscopy and single‐crystal X‐ray diffraction analysis. The X‐ray crystal structures showed π–π overlap and sulfur–sulfur interactions between the adjacent molecules. The decomposition temperatures were all found to be above 300 °C, indicating that compounds of this series possess excellent thermal stability. The fact that no phase transition occurs at low temperature indicates that they should be well‐suited for application in devices. Moreover, they possess low HOMO energy levels, based on cyclic voltammetry measurements, and suitable energy gaps, as determined from their thin‐film UV/Vis spectra. Thin‐film X‐ray diffraction analysis and atomic force microscopy revealed high crystallinity on supporting substrates. In addition, as the substrate temperature has a significant influence on the morphology and the degree of crystallinity, the device performance could be optimized by varying the substrate temperature. These materials were found to exhibit optimal field‐effect performance, with a mobility of 0.17 cm2 V?1 s?1 and an on/off ratio of 105, at a substrate temperature of 70 °C. 相似文献
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Hong Ping HE Yue Mao SHEN Xiao Sheng YANG Bin Gui WANG Ling LI Xiao Jiang HAO * Laboratory of Phytochemistry Kunming Institute of Botany the Chinese Academy of Sciences Kunming . The Key Laboratory of Chemistry for Natural Prod 《中国化学快报》2001,(1)
Spiraea japonica L. (Rosaceae) is widely distributed in Yunnan Provence, P. R. China. Previous chemical investigations on S. japonica and its varieties have led to the report of 7 new atisane-type diterpenoids and 38 new diterpene alkaloids of atisine- and hetisine-type1-11. This paper describes the isolation and structure elucidation of two new diterpene alkaloids named spiratines A and B (1-2). Their structures were elucidated on the basis of 1D and 2D NMR experiments (HMQC, HMBC, 1… 相似文献