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941.
N-Heterocyclic carbene (NHC) plays an important role in catalytic processes, as the catalyst it has shown high activities in organic reactions. Synthesis of chiral triazole carbene, the structure and the application of NHCs in asymmetric catalytic benzoin reactions are described. The aims are to broad students' vision and make students feel the charm of organic chemistry through extension of undergraduate curriculum content. Meanwhile, their ability of finding, analyzing and solving problems on the basis of generalizing and thinking about the knowledge will be improved. 相似文献
942.
Ying Lin Teng‐Ling Ye Yu Chen Dong‐Ge Ma Zhi‐Kuan Chen Yan‐Feng Dai Yong‐Xi Li 《Journal of polymer science. Part A, Polymer chemistry》2010,48(24):5930-5937
A new bipolar conjugated polyfluorene copolymer with triphenylamine and cyanophenylfluorene as side chains, poly{[9,9‐di(triphenylamine)fluorene]‐[9,9‐dihexyl‐fluorene]‐[2,7‐bis(4′‐cyanophenyl)‐9,9′‐spirobifluorene]} ( PTHCF ), was synthesized for studying the polymer backbone emission. Its absolute weight‐average molecular weight was determined as 4.85 × 104 by using gel permeation chromatography with a multiangle light scattering detector. In contrast to the electronic absorption spectrum in dilute solution, the absorbance of PTHCF in thin film was slightly blue shifted. By comparison of the solution and thin‐film photoluminescence (PL) spectra, a red shift of Δλ = 8–9 nm was observed in the thin‐film PL spectrum. The HOMO and LUMO energy levels of the resulting polymer were electrochemically estimated as ?5.68 and ?2.80 eV, respectively. Under the electric‐field intensity of 4.8 × 105 V cm?1, the obtained hole and electron mobilities were 2.41 × 10?4 and 1.40 × 10?4 cm2 V?1 s?1, respectively. An electroluminescence device with configuration of ITO/PEDOT:PSS/ PTHCF 70%+PBD30%/CsF/Ca/Al exhibited a deep‐blue emission as a result of excitons formed by the charges migrating along the full‐fluorene main chain. The incorporation of the bipolar side chains into the polymer structure prevented the intermolecular interaction of the fluorene moieties, balance charge injection/transport, and thereby improve the polymer backbone emission. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
943.
Sixteen chemical drugs, often found in adulterated Chinese medicine, were studied by high performance liquid chromatography/atmospheric ionization mass spectrometry. Under optimal conditions, three pairs of compounds were either coeluted or unresolved. The lack of chromatographic resolution and the lack of specificity in UV detection were overcome by a method based on high performance liquid chromatography/electrospray mass spectrometry. This method was capable of detecting the adulterants based on their retention times, molecular ions, and characteristic fragments resulting from in‐source collision induced dissociation. 相似文献
944.
A dammarane derivative dihydrojujubogenin-2-en-1-one, which possesses a skeleton and pharmacophore partially similar to those of Territrem B, a potent AChE inhibitor, was synthesized via three different paths. The anti-AChE activity of this compound and related analogue was measured. 相似文献
945.
The pyrolysis of Pubescens over Ni/C catalyst was studied at 350 °C in H2 flow. The presence of Ni/C catalyst efficiently improved the degradation of raw materials, and produced bio-oil with high content of phenols but low contents of acetic acid, furfural and water. In the reaction, Ni/C catalyst plays the role of catalytic decomposition and catalytic hydrogenation. The existence of the carbon carrier favors the formation of active Ni in small sizes with more defects, which results in high catalytic activity of Ni in biomass decomposition and selective production of phenols. 相似文献
946.
Shu‐Ping Wang Lei Liu Ling‐Ling Wang Peng Jiang Ji‐Quan Zhang Wei‐Dong Zhang Run‐Hui Liu 《Rapid communications in mass spectrometry : RCM》2010,24(11):1641-1652
Based on the serum pharmacochemistry technique and high‐performance liquid chromatography/diode‐array detection (HPLC/DAD) coupled with electrospray tandem mass spectrometry (HPLC/ESI‐MS/MS), a method for screening and analysis of the multiple absorbed bioactive components and metabolites of Jitai tablets (JTT) in orally dosed rat plasma was developed. Plasma was treated by methanol precipitation prior to liquid chromatography, and the separation was carried out on a Symmetry C18 column, with a linear gradient (0.1% formic acid/water/acetonitrile). Mass spectra were acquired in negative and positive ion modes, respectively. As a result, 26 bioactive components originated from JTT and 5 metabolites were tentatively identified in orally dosed rat plasma by comparing their retention times and MS spectra with those of authentic standards and literature data. It is concluded that an effective and reliable analytical method was set up for screening the bioactive components of Chinese herbal medicine, which provided a meaningful basis for further pharmacology and active mechanism research of JTT. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
947.
Ken‐Yen Liu Chiao‐Ling Hsu Shun‐Hsing Chang Jian‐Ging Chen Kuo‐Chuan Ho King‐Fu Lin 《Journal of polymer science. Part A, Polymer chemistry》2010,48(2):366-372
A new crosslinkable light sensitizer, Ru(2,2′‐bipyridine‐4,4′‐bicarboxylic acid)(4,4′‐bis(11‐dodecenyl)‐2,2′‐bipyridine)(NCS)2, denoted as Ru‐C for titanium oxide nanocrystalline‐based solar cells was synthesized with its crosslinking properties invesitigated by Fourier‐transform infrared and UV‐vis absorption spectroscopies. After crosslinking by itself or copolymerizing with methyacrylic acid, their sensitized solar cells with poly(methylacrylate)‐gelled electrolyte system not only attained more than 5% of power conversion efficiency at AM 1.5 illumination (100 mW/cm2), but also gave rise to long storage life. To the best our knowledge, this is the first crosslinkable dye ever applied to the DSSC in the literature. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 366–372, 2010 相似文献
948.
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
949.
Ying‐Ling Liu Chun‐Chieh Han Ta‐Chin Wei Yung Chang 《Journal of polymer science. Part A, Polymer chemistry》2010,48(10):2076-2083
This work reports the surface‐initiated atom transfer radical polymerization (ATRP) from hydrogen plasma‐treated porous poly(tetrafluoroethylene) (PTFE) membranes using the C? F groups as initiators. Hydrogen plasma treatment on PTFE membrane surfaces changes their chemical environment through defluorination and hydrogenation reactions. With the hydrogen plasma treatment, the C? F groups of the modified PTFE membrane surface become effective initiators of ATRP. Surface‐initiated ATRP of poly(ethylene glycol) methacrylate (PEGMA) is carried out to graft PPEGMA chains to PTFE membrane surfaces. The chain lengths of poly(PEGMA) (PPEGMA) grafted on PTFE surfaces increase with increasing the reaction time of ATRP. Furthermore, the chain ends of PPEGMA grown on PTFE membrane surfaces then serve as macroinitiators for the ATRP of N‐isopropylacrylamide (NIPAAm) to build up the PPEGMA‐b‐PNIPAAm block copolymer chains on the PTFE membrane surfaces. The chemical structures of the modified PTFE membranes are characterized using X‐ray photoelectron spectroscopy. The modification increases the surface hydrophilicity of the PTFE membranes with reductions in their water‐contact angles from 120° to 60°. The modified PTFE membranes also show temperature‐responsive properties and protein repulsion features owing to the presence of PNIPAAM and PPEGMA chains. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2076–2083, 2010 相似文献
950.
Yan Ling ZHANG Wei Sheng LIU Yang LI Xue Yi MA* Yao Zu CHEN National Laboratory of Applied Organic Chemistry Department of Chemistry Lanzhou University Lanzhou Department of Chemistry Zhejiang University Hangzhou 《中国化学快报》2001,(4)
The importance of Vitamin A for human health has been stressed in resent studies1, meanwhile its derivative so-called retinoic acid (RA) has been widely used as pharmaceutical to treat several types of skin disease and cancer2,3. However the application of retinoic acid is restrained for its poor water solubility, unstability and side effect on the human body.Cyclodextrins (CDs) are macrocyclic oligosaccharides built up from 6, 7, or 8 glucopyranose units called (, (, and (-CD, respectively… 相似文献