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991.
992.
研究了具有比例时滞的细胞神经网络的平衡点的全局稳定性。通过建立李亚普诺夫函数,得到全局渐进稳定的充分条件。 相似文献
993.
994.
A series of fluorinated fullerene-fused 1,3-dioxolanes have been facilely and efficiently synthesized in the presence of easily available LiClO4·3H2O. The influences of the number of fluoro-substituents and their positions linked to the phenyl ring on the isolated yield of fullerene-fused 1,3-dioxolanes have been studied in detail. Based on reaction facts, a possible reaction mechanism for the formation of fluorinated fullerene-fused 1,3-dioxolanes has been proposed. Furthermore, detailed ultraviolet absorption spectra, fluorescence emission spectra, and cyclic voltammogram further explain the optical properties and electronic transmission capabilities of the products. 相似文献
995.
Palladium‐catalyzed synthesis of 6‐allylcoumarins using organotin reagents as multicoupling organometallic nucleophiles 下载免费PDF全文
Han Yan Wenzheng Yin Pin Liu Jia Liu Meichen Hu Cheng Gu Yang Yao Weihua Zhang 《应用有机金属化学》2014,28(10):747-749
Derivatives of 6‐iodocoumarin undergoing a direct Stille cross‐coupling reaction with organotin compounds in the presence of a catalytic amount of Pd(PPh3)4 in dimethylformamide at 80°C is described in this study. It is the first report of the palladium‐catalyzed coupling of iodocoumarins with allyltributyltin under mild conditions to form alkylcoumarin compounds in good yields. © 2014 The Authors. Applied Organometallic Chemistry published by John Wiley & Sons, Ltd. 相似文献
996.
Chunhui Dai Yuxiang Wang Yiwu Quan Qingmin Chen Yixiang Cheng Chengjian Zhu 《Journal of polymer science. Part A, Polymer chemistry》2014,52(21):3080-3086
The β‐diketonate‐based achiral polymer P‐1 could be synthesized by the polymerization of 3,7‐dibromo‐2,8‐dimethoxy‐5,5‐dioctyl‐5H‐dibenzo[b,d]silole ( M1 ) with (Z)?1,3‐bis(4‐ethynylphenyl)?3‐hydroxyprop‐en‐1‐one ( M2 ) via typical Sonogashira coupling reaction. The β‐diketonate unit in the main chain backbone of P‐1 can further coordinate with Eu(TTA)x [TTA? = 4,4,4‐trifluoro‐1‐(thiophen‐2‐yl)butane‐1,3‐dionate anion, X = 1, 2, 3] to afford corresponding Eu(III)‐containing polymer complexes. The resulting achiral polymer complex P‐2 (X = 2) can exhibit strong circular dichroism (CD) response toward both N‐Boc‐l and d‐ proline enantiomers. The CD signal was preliminarily attributed to coordination induction between chiral N‐Boc‐proline and the Eu(III) complex moiety. The linear regression analysis of CD sensing shows a good agreement between the magnitude of molar ellipticity and concentration of chiral N‐Boc‐l or d‐ proline, which indicates this kind Eu(III)‐containing achiral polymer complex can be used as a chiral probe for enantioselective recognition of N‐Boc‐l or d‐ proline enantiomers based on Cotton effect of CD spectra. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3080–3086 相似文献
997.
Increasing fermentable sugar yields per gram of biomass depends strongly on optimal selection of varieties and optimization of pretreatment conditions. In this study, dilute acid pretreatment of bagasse from six varieties of sugarcane was investigated in connection with enzymatic hydrolysis for maximum combined sugar yield (CSY). The CSY from the varieties were also compared with the results from industrial bagasse. The results revealed considerable differences in CSY between the varieties. Up to 22.7 % differences in CSY at the optimal conditions was observed. The combined sugar yield difference between the best performing variety and the industrial bagasse was 34.1 %. High ratio of carbohydrates to lignin and low ash content favored the release of sugar from the substrates. At mild pretreatment conditions, the differences in bioconversion efficiency between varieties were greater than at severe condition. This observation suggests that under less severe conditions the glucose recovery was largely determined by chemical composition of biomass. The results from this study support the possibility of increasing sugar yields or improving the conversion efficiency when pretreatment optimization is performed on varieties with improved properties. 相似文献
998.
Cong-De Huo Xia-Zhen Bao Dong-Cheng Hu Xiao-Dong Jia Chou-Gu Sun Cheng Wang 《中国化学快报》2014,25(5):699-701
A solid complex,readily prepared from commercially available sodium triphenylphosphine-m-sulfonate(TPPMS) and carbon tetrabromide,can be used as an easily recoverable and reusable catalyst system for one-pot condensation of 2-naphthol with aldehydes to construct 14-aryl(alkyl)-14H-dibenzo[a j]-xanthene derivatives and one-pot condensation of 2-naphthol with aldehydes and cyclic 1 3-dicarbonyl compounds to construct 12-aryl(alkyl)-8 9 10 12-tetrahydrobenzo[a]xanthen-11-one derivatives. 相似文献
999.
1000.