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241.
Kimata M Terashima T Kurita N Satsukawa H Harada A Kodama K Takehana K Imanaka Y Takamasu T Kihou K Lee CH Kito H Eisaki H Iyo A Fukazawa H Kohori Y Harima H Uji S 《Physical review letters》2011,107(16):166402
Cyclotron resonance (CR) measurements for the Fe-based superconductor KFe(2)As(2) are performed. One signal for CR is observed, and is attributed to the two-dimensional α Fermi surface at the Γ point. We found a large discrepancy in the effective masses of CR [(3.4±0.05)m(e) (m(e) is the free-electron mass)] and de Haas-van Alphen results, a direct evidence of mass enhancement due to electronic correlation. A comparison of the CR and de Haas-van Alphen results shows that both intra- and interband electronic correlations contribute to the mass enhancement in KFe(2)As(2). 相似文献
242.
Shock waves were explored in the thermoacoustic spontaneous gas oscillations occurring in a gas column with a steep temperature gradient. The results show that a periodic shock occurs in the traveling wave mode in a looped tube but not in the standing wave mode in a resonator. Measurements of the harmonic components of the acoustic intensity reveal a clear difference between them. The temperature gradient acts as an acoustic energy source for the harmonic components of the shock wave in the traveling wave mode but as an acoustic energy sink of the second harmonic in the standing wave mode. 相似文献
243.
Kano T Yamamoto A Song S Maruoka K 《Chemical communications (Cambridge, England)》2011,47(15):4358-4360
Catalytic asymmetric syntheses of various isoxazoline-N-oxides have been accomplished by asymmetric phase-transfer conjugate addition of bromomalonate to nitroolefins and subsequent ring-closing O-alkylation. 相似文献
244.
Kazuo Sakai Ryosuke Katsumi Hiroshi Ohi Taichi Usui Yoshiharu Ishido 《Journal of carbohydrate chemistry》2013,32(5):553-565
Abstract A β-D-galactosidase from Bacillus circulans induced β-D-galactopyranosyl transfer from lactose predominantly to a secondary (OH-4) rather than the primary hydroxyl group (OH-6) of 2-acetamido-2-deoxy-D-glucopyranose. 4-O-β-D-Galacto-pyranosyl-2-acetamido-2-deoxy-D-glucopyranose (N-acetyl-lactosamine) was thus readily synthesized on a gram scale and conveniently isolated by chromatography on a column of charcoal-Celite. On the other hand, the glycosyl transfer to the 6-position predominantly was efficiently induced to give 6-O-β-D-galactopyranosyl-2-acetamido-2-deoxy-D-glucopyranose (N-acetyl-allolactosamine) by consecutive use of β-D-galactosidases from Kluyveromyces lactis and B. circulans. These enzyme reactions were efficient enough to allow the one-pot preparation of the desired disaccharides. 相似文献
245.
Taichi KusakabeKeisuke Kato 《Tetrahedron》2011,67(7):1511-1517
A gold (III)-catalyzed cascade reaction of propargyl acetates bearing an extra terminal alkyne (1) afforded γ-keto esters 3 and lactones 4. These products should be generated through allenyl ketone intermediate B via a 1,2-acyloxy cyclization/fragmentation/cycloisomerization/hydrolysis sequence. On the other hand, the cascade reaction of α-acetoxy ketones bearing terminal alkynes 5 afforded lactone 6 via allenyl ketone intermediate A. This reaction involves a [3,3]-sigmatropic acyloxy rearrangement/cycloisomerization/hydrolysis sequence. 相似文献
246.
Susumu Saito Keiko Hatanaka Taichi Kano Hisashi Yamamoto 《Angewandte Chemie (International ed. in English)》1998,37(24):3378-3381
A C 2 -symmetrical phenol was used as a chiral auxiliary in the asymmetric aldol reaction of chiral acetates with various aldehydes [Eq. (a)]. The reaction proceeds readily under mild conditions to provide aldol adducts with high enantioselectivity. LDA=lithium diisopropylamide. 相似文献
247.
248.
We have successfully synthesized two kinds of novel well-defined chain-end-functionalized polystyrenes with one, two, three, and four perfluorooctyl (C8F17) groups and structurally analogous block copolymers, poly[styrene-b-4-(3-perfluoroocyl)propoxystyrene], by means of living anionic polymerization, followed by the Williamson reaction with C8F17(CH2)3Br. The surface properties and compositions of the films prepared from both C8F17-functionalized polymers have been characterized by contact angles using water and dodecane droplets and angle-dependent XPS measurement. It was observed that C8F17 groups were segregated and preferentially enriched at their topmost surfaces and the extent of the enrichment increased with the number of C8F17 group. The dependence of extent of C8F17 group enrichment on fluorine content however appears to be different between chain-end-functionalized polymer and block copolymer. 相似文献
249.
The supramolecular network formation through inclusion complexation between α‐cyclodextrin‐based molecular tube (MT) and poly(ethylene oxide) monocetylether‐graft‐dextran (5C16PEO‐g‐Dex40) was demonstrated. From isothermal titration calorimetric (ITC) measurement, it was confirmed that MT formed an inclusion complex with two C16PEO side chains in 5C16PEO‐g‐Dex40. From viscosity measurements, the specific viscosity of the solution containing MT and 5C16PEO‐g‐Dex40 was much larger than that containing 5C16PEO‐g‐Dex40. It is considered that MT participates in the supramolecular network formation of 5C16PEO‐g‐Dex40 through inclusion complexation with two C16PEOs grafted to independent Dex40s. 相似文献