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991.
Takatori K Nakayama M Futaishi N Yamada S Hirayama S Kajiwara M 《Chemical & pharmaceutical bulletin》2003,51(4):455-457
Robinson annulation on alumina occurred efficiently on heating with microwave irradiation. 相似文献
992.
A.?Zoubir J.?Eichenholz E.?Fujiwara D.?Grojo E.?Baleine A.?Rapaport M.?Bass B.?Chai M.?RichardsonEmail author 《Applied physics. B, Lasers and optics》2003,77(4):437-440
We have characterized non-critical phase-matching (NCPM) for both Type I and Type II second harmonic generation (SHG) in y-cut GdxY1-xCOB using a nanosecond optical parametric oscillator (OPO). The variation of the NCPM wavelength with temperature was investigated for different values of the compositional parameter x. Efficient SHG of 1064 nm was achieved by choosing the suitable compositional parameter x=0.28 and by tuning the temperature of the crystal to 52 °C. Using a 25-mm-long Gd0.28Y0.72COB crystal, conversion efficiencies of 41 and 43% were obtained respectively from a mode-locked Nd:YAG and a Q-switched Nd:YAG laser. PACS 42.25.Lc; 42.65.Ky; 42.70.Mp; 42.79.Nv 相似文献
993.
Fukutomi J Suzuki E Shimizu T Kimura A Fujiwara H 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2003,160(1):26-32
Experimental conditions that affect the degree of polarization of 129Xe gas were tested for a higher degree of polarization to facilitate a laboratory use of 129Xe NMR, primarily on the effect of addition of foreign gases. When He, N(2), or D(2) gas was added separately to pure Xe gas with natural isotope abundance, D(2) gas gave better results than the others in enhancing the degree of polarization in 129Xe atom. When these gases were added in mixture, however, N(2) plus He was proved to be more efficient than D(2) or He in enhancing the degree of polarization. As a result, the degree of polarization was found to be increased by more than an order, when diluent gases were properly mixed; polarization as high as 35% was reached at gas composition of 5% Xe, 10% N(2), and 85% He, whereas only a few percent was attainable when Xe gas was polarized without mixing any foreign gases [J. Magn. Reson. 150 (2), 156-160 (2001)]. These results were discussed on a basis of quenching and buffer effects of foreign gases. Polarization was also measured after separating the pure Xe gas from the mixture; value of 22% was obtained for the Xe gas isolated after solidification in liquid nitrogen trap. Build-up time of the polarization was also tested, which did not change remarkably depending on the gas composition. 相似文献
994.
995.
Steroidal saponins from Hemerocallis fulva var. kwanso 总被引:1,自引:0,他引:1
Konishi T Fujiwara Y Konoshima T Kiyosawa S Nishi M Miyahara K 《Chemical & pharmaceutical bulletin》2001,49(3):318-320
Two steroidal saponins, hemeroside A and B, were isolated from the aerial part of Hemerocallis fulva var. kwanso for the first time. The structures of these compounds were established as 24S-hydroxy-neotokorogenin 1-O-alpha-L-arabinopyranosyl 24-O-beta-D-glucopyranoside (1) and isorhodeasapogenin 3-O-beta-D-glucopyranosyl-(1-->3)-[beta-D-xylopyranosyl-(1-->2)]-beta-D-glucopyranosyl-(1-->4)-beta-D-galactopyranoside (2) through NMR experiments. 相似文献
996.
Electron energy-loss spectroscopy has been applied to the study of Si(111) surfaces covered with H2S, H2O and O2 at room temperature and the surfaces annealed at ~ 600°C. The experimental results strongly suggest that H2S and H2O adsorb in the molecular states at room temperature. It is proposed that O2 is first adsorbed in a molecular state, then adsorbs as atoms, and finally oxidizes forming SiO2. 相似文献
997.
This paper presents a method of estimating the excess attenuation of noise by a thick barrier. In this method, the excess attenuation of noise by a thick barrier is assumed to be composed of two parts, one being the effect of a virtual thin barrier with the same height and the other the effect of thickness. A single chart for estimating this thickness effect is offered under conditions which only permit an error of a few decibels. The validity of the method presented here is verified by comparing the estimated with the measured values. Consequently, this method may be useful for the purpose of estimating the excess attenuation of a band of noise by the barrier whose thickness is larger than half a wavelength. 相似文献
998.
Three types of the novel polymer ligands in which 6,8,15,17-tetramethyl-dibenzo-5,9,14,18-tetraaza-cyclotetradecene (L) is present as an integral part of the polymer backbone have been prepared. These polymer ligands are oligomers whose polymerization degree may be about five. Their complexing abilities and extractabilities for copper(II) and nickel(II) have been investigated. Among the polymer ligands, Poly-L3, which contains triethyleneglycol bis(p-phenylene) group as a linkage group, was found to be an excellent extractant for copper(II). 相似文献
999.
Okitsugu Fujiwara 《Operations Research Letters》1984,3(4):219-224
We consider a parametrized family of nonlinear programs where the feasible region is defined by equality constraints in a ball. The global optimal value is shown to be twice continuously differentiable over an open and dense set in the perturbation parameter space. 相似文献
1000.
H Fujiwara H Kadomatsu M Kurisu T Hihara K Kojima T Kamigaichi 《Solid State Communications》1982,42(7):509-511
The weak field a.c. susceptibility of EuSe was measured as functions of temperature from 1.5 to 15 K and of hydrostatic pressure up to 15 kbar. The Néel temperature did not change with pressure, and a new pressure-induced ferromagnetic phase appeared in the region above 4.6 K and above 4.5 kbar (triple point). 相似文献