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121.
Lawes G Harris AB Kimura T Rogado N Cava RJ Aharony A Entin-Wohlman O Yildirim T Kenzelmann M Broholm C Ramirez AP 《Physical review letters》2005,95(8):087205
We show that long-range ferroelectric and incommensurate magnetic order appear simultaneously in a single phase transition in Ni3V2O8. The temperature and magnetic-field dependence of the spontaneous polarization show a strong coupling between magnetic and ferroelectric orders. We determine the magnetic symmetry using Landau theory for continuous phase transitions, which shows that the spin structure alone can break spatial inversion symmetry leading to ferroelectric order. This phenomenological theory explains our experimental observation that the spontaneous polarization is restricted to lie along the crystal b axis and predicts that the magnitude should be proportional to a magnetic order parameter. 相似文献
122.
123.
The electron transfer quenching of 2-aminopurine by guanine and 7-deazaguanine was investigated in B- and Z-DNA, and an increase in the fluorescence intensity of 2-aminopurine upon B- to Z-DNA transition was demonstrated. 相似文献
124.
Mayumi Kimura 《Tetrahedron letters》2004,45(8):1635-1637
The use of bromine for activation of zinc dust allowed smooth and reproducible reduction of iodide 1 to the corresponding zinc reagent 2. The zinc reagent 2 obtained by the present protocol was allowed to the Fukuyama coupling reaction with thiolactone 3 to provide a key intermediate 4 for (+)-biotin in high yield using a reasonably fair amount of 1 (1.4 equiv). 相似文献
125.
Suzuki M Nakajima Y Yumoto M Kimura M Shirai H Hanabusa K 《Organic & biomolecular chemistry》2004,2(8):1155-1159
Organogels are formed through a conventional organogelation involving a heating process and an in situ organogelation at room temperature. The conventional organogelation is carried out by dissolution of gelators by heating, while the in situ organogelation is performed by mixing of highly reactive methyl 2,6-diisocyanatohexanoate (LDI) or 2-isocyanatoethyl 2,6-diisocyanatohexanoate (LTI) and alkylamines. The in situ organogelation produced the organogels within several seconds after mixing. The organogels prepared by the in situ organogelation showed quite similar FT-IR spectra and SEM photographs to those formed by conventional organogelation. Moreover, the in situ organogelation using LTI and octylamine as well as dodecylamine produced organogels of acetone, ethyl acetate, and acetonitrile that gelators 5 and 6 cannot gel through conventional organogelation. 相似文献
126.
Highly enantioselective catalytic carbon dioxide incorporation reaction: nickel-catalyzed asymmetric carboxylative cyclization of bis-1,3-dienes 总被引:4,自引:0,他引:4
Takimoto M Nakamura Y Kimura K Mori M 《Journal of the American Chemical Society》2004,126(19):5956-5957
A method for nickel-catalyzed asymmetric carbon dioxide (CO2) incorporation via carbon-carbon bond formation was developed. In the presence of a catalytic amount of Ni(acac)2 and MeO-MOP, various bis-1,3-dienes reacted with CO2 (1 atm) and a diorganozinc reagent (Me2Zn or Ph2Zn) to afford cyclic carboxylic acids in good yields (71-100%) and with high enantioselectivities (90-96% ee). 相似文献
127.
Hawthorn DG Hill RW Proust C Ronning F Sutherland M Boaknin E Lupien C Tanatar MA Paglione J Wakimoto S Zhang H Taillefer L Kimura T Nohara M Takagi H Hussey NE 《Physical review letters》2003,90(19):197004
The transport of heat and charge in cuprates was measured in single crystals of La(2-x)Sr(x)CuO(4+delta) (LSCO) across the doping phase diagram at low temperatures. In underdoped LSCO, the thermal conductivity is found to decrease with increasing magnetic field in the T-->0 limit, in striking contrast to the increase observed in all superconductors, including cuprates at higher doping. In heavily underdoped LSCO, where superconductivity can be entirely suppressed with an applied magnetic field, we show that a novel thermal metal-to-insulator transition takes place upon going from the superconducting state to the field-induced normal state. 相似文献
128.
Kimura M Wada K Iwashima Y Ohta K Hanabusa K Shirai H Kobayashi N 《Chemical communications (Cambridge, England)》2003,(19):2504-2505
Sol-gel polymerization of tetraethoxysilane in the presence of amphiphilic phthalocyanine polymer 2 produced organic-inorganic composites with the rod-like phthalocaynine polymers incorporated within ordered hexagonal channels. 相似文献
129.
Akaike S Sumino M Sekine T Seo S Kimura N Ikegami F 《Chemical & pharmaceutical bulletin》2003,51(2):197-199
A new ent-clerodane diterpene, named bacchariol (1) was isolated from the aerial parts of Baccharis gaudichaudiana DC. (Compositae), together with known ent-clerodane diterpenes (2, 3), eight known flavonoids (4-11) and 3, 5-dicaffeoylquinic acid (12). Their structures were determined by spectroscopic analyses. Flavonoids (7, 8, 11) and 12 showed moderate scavenging activities toward 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radicals. 相似文献
130.
Kimura M Sakaguchi A Ohta K Hanabusa K Shirai H Kobayashi N 《Inorganic chemistry》2003,42(9):2821-2823
A new class of sterically hindered phthalocyanine has been synthesized and characterized. Pentaphenylbenzene units were introduced at the periphery of each phthalocyanine to yield a sterically protected metal center. The attachment of the bulky oligophenylbenzene units resulted in the complete isolation of individual MPc molecules. The pockets around a cobalt center affect selectivity in the ligation of pyridines that have different sizes and shapes. 相似文献