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81.
Journal of Heuristics - In this paper, we present a method to identify forum posts expressing user intentions in online discussion forums. The results of this task, for example buying intentions,... 相似文献
82.
Journal of Sol-Gel Science and Technology - The aim of the study was to prepare magnetic photo-Fenton catalysts based on CoFe2O4 by polyethylene glycol-assisted sol-gel method for the degradation... 相似文献
83.
A Diazido Mannose Analogue as a Chemoenzymatic Synthon for Synthesizing Di‐N‐acetyllegionaminic Acid‐Containing Glycosides
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Dr. Abhishek Santra An Xiao Dr. Hai Yu Wanqing Li Dr. Yanhong Li Linh Ngo Dr. John B. McArthur Prof. Dr. Xi Chen 《Angewandte Chemie (International ed. in English)》2018,57(11):2929-2933
A chemoenzymatic synthon was designed to expand the scope of the chemoenzymatic synthesis of carbohydrates. The synthon was enzymatically converted into carbohydrate analogues, which were readily derivatized chemically to produce the desired targets. The strategy is demonstrated for the synthesis of glycosides containing 7,9‐di‐N‐acetyllegionaminic acid (Leg5,7Ac2), a bacterial nonulosonic acid (NulO) analogue of sialic acid. A versatile library of α2‐3/6‐linked Leg5,7Ac2‐glycosides was built by using chemically synthesized 2,4‐diazido‐2,4,6‐trideoxymannose as a chemoenzymatic synthon for highly efficient one‐pot multienzyme (OPME) sialylation followed by downstream chemical conversion of the azido groups into acetamido groups. The syntheses required 10 steps from commercially available d ‐fucose and had an overall yield of 34–52 %, thus representing a significant improvement over previous methods. Free Leg5,7Ac2 monosaccharide was also synthesized by a sialic acid aldolase‐catalyzed reaction. 相似文献
84.
85.
Mantel ML Søbjerg LS Huynh TH Ebran JP Lindhardt AT Nielsen NC Skrydstrup T 《The Journal of organic chemistry》2008,73(9):3570-3573
The styryl benzene derivative (E, E)-1-fluoro-2,5-bis(3-hydroxycarbonyl-4-hydroxy)styrylbenzene (FSB), well-known for its binding to beta-amyloid peptide fibrils, was synthesized in an efficient manner exploiting two sequential palladium(0)-catalyzed coupling reactions in a 34% overall yield. This is a substantial improvement to the previously reported synthesis of FSB in 1.1%. 相似文献
86.
87.
Kiem PV Tri MD Tuong le VD Tung NH Hanh NN Quang TH Cuong NX Minh CV Choi EM Kim YH 《Chemical & pharmaceutical bulletin》2008,56(9):1270-1275
Two new phenyl glycosides, mangliesides A and B (1, 2), a new ionol glycoside, manglieside C (3), two new lignan glycosides, mangliesides D and E (4, 5), were isolated from the leaves of Manglietia phuthoensis, along with two known lignans, 3-methoxymagnolol (6) and obovatol (7). Their structures were established by means of 1D and 2D NMR, electrospray ionization (ESI)-MS and HR-ESI-MS experiments. Among them, compounds 2 and 5 significantly (p<0.05) increased the growth and differentiation of osteoblastic MC3T3-E1 cells in vitro. 相似文献
88.
89.
Wahyu Tri Cahyanto Wahyu Widanarto Mukhtar Effendi Hideaki Kasai 《Surface and interface analysis : SIA》2016,48(4):181-185
A density functional theory calculation is used to investigate the atomic oxygen (O) stability over platinum (Pt) and Pt‐based alloy surfaces. Here, the stability is connected with the preferential adsorption sites for O chemisorptions and the adsorption energy. Thus, the interaction mechanism between atomic O and metal surfaces is studied by using charge transfer analysis. In this present paper, atomic structure and binding energy of oxygen adsorption on the Pt(111) are in a very good agreement with experiment and previous density functional theory calculations. Furthermore, we obtained that the addition of ruthenium (Ru) and molybdenum (Mo) on the pure Pt surface enhances the adsorption energy. Our charge transfer analysis shows that the largest charge transfer contributing to the metal‐O bonding formation is observed in the case of O/PtRuMo surface followed by O/PtRu surface. This is in consistency with metal d‐orbital characteristic, where Mo has much more empty d‐orbital than Ru in correspondence to accept electrons from atomic oxygen. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
90.
Achille B. Nouga Emmanuel M. Mpondo Judith Caroline Ngo Nyobe Alain Njoya Luc M. Meva'a 《Natural product research》2016,30(3):305-310
Fractionation of the methanol extract of the leaves of Oricia renieri and Oricia suaveolens (Rutaceae) led to the isolation of 13 compounds including the hitherto unknown furoquinoline alkaloid named 6,7-methylenedioxy-5-hydroxy-8-methoxy-dictamnine (1) and a flavanone glycoside named 5-hydroxy-4′-methoxy-7-O-[α-l-rhamnopyranosyl(1?→5″)-β-d-apiofuranosyl]-flavanoside (2), together with 11 known compounds (3–13). The structures of the compounds were determined by comprehensive analyses of their 1D and 2D NMR, mass spectral data and comparison. All compounds isolated were examined for their activity against human carcinoma cell lines. The alkaloids 1, 5, 12, 13 and the phenolic 2, 8, 11 tested compounds exhibited non-selective moderate cytotoxic activity with IC50 8.7–15.9 μM whereas compounds 3, 4, 6, 7, 9 and 10 showed low activity. 相似文献