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排序方式: 共有311条查询结果,搜索用时 15 毫秒
121.
Tsutomu Furuya Tsuyoshi Koga Fumihiko Tanaka 《Journal of Polymer Science.Polymer Physics》2004,42(5):733-751
The influence of added surfactants on physical properties of associating polymer solutions was examined by a new statistical‐mechanical theory of associating polymer solutions with multiple junctions and by computer simulation. The sol–gel transition line, the spinodal line, and the number of elastically effective chains in the mixed networks were calculated as functions of the concentration of added surfactants. All of them exhibited nonmonotonic behavior as a result of the following two competing mechanisms. One was the formation of new mixed micelles by binding surfactants onto the polymer associative groups. These micelles serve as crosslink junctions and promote gelation. The other was the replacement of polymer associative groups in the already formed network junctions by added surfactants. Such replacement lowers connectivity of junctions and destroys networks. The critical micelle concentration was also calculated. The results are compared with the reported experimental data on poly(ethylene oxide)‐based associating polymers and hydrophobically modified cellulose derivatives. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 733–751, 2004 相似文献
122.
Fumihiko Hirosawa 《Mathematical Methods in the Applied Sciences》2003,26(9):783-799
We consider the Cauchy problem for second‐order strictly hyperbolic equations with time‐depending non‐regular coefficients. There is a possibility that singular coefficients make a regularity loss for the solution. The main purpose of this paper is to derive an optimal singularity for the coefficient that the Cauchy problem is C∞ well‐posed. Moreover, we will apply such a result to the estimate of the existence time of the solution for Kirchhoff equation. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
123.
Mitsuru Izumi Toshiaki Iwazumi Taisaku Seino Kunimitsu Uchinokura Ryozo Yoshizaki Etsuyuki Matsuura 《Solid State Communications》1984,49(5):423-426
Temperature dependences of the dc electrical resistance and far-infrared reflectance spectra are reported in a new type of halogenated niobium tetraselenide (NbSe4)xI. In the dc resistance measurement, successive resistance anomalies were observed between 270 K and 90 K. Far-infrared reflectance spectra clearly show that several new phonon modes appear below 260 K. These features evidently show the existence of at least one structural phase transition. 相似文献
124.
Takeshi Nakatani Tomohiro Matsushita Yutaka Miyatake Tomohito Nohno Atsushi Kobayashi Keiki Fukumoto Shunsuke Okamoto Azusa Nakamoto Fumihiko Matsui Ken Hattori Masato Kotsugi Yuji Saitoh Shigemasa Suga Hiroshi Daimon 《Progress in Surface Science》2003,71(5-8):217-239
A stereograph of atomic arrangement was displayed directly on the screen of display-type spherical-mirror analyzer without any computer-aided conversion process for the first time. This stereoscopic photograph enables viewing three-dimensional atomic arrangement. This technique was realized taking advantage of the phenomenon of circular dichroism in photoelectron angular distribution. The azimuthal shifts of forward focusing peaks in a photoelectron angular distribution taken with left and right helicity light in a special arrangement are the same as the parallaxes in a stereo view of atoms. Hence a stereoscopic recognition of three-dimensional atomic arrangement is possible, when the left eye and the right eye respectively view the two images obtained by left and right helicity light simultaneously. 相似文献
125.
Okura Ichiro Otsuka Keiichi Nakada Nobuharu Hasumi Fumihiko 《Applied biochemistry and biotechnology》1990,24(1):425-430
Applied Biochemistry and Biotechnology - The regeneration of nicotinamide-adenine dinucleotide (reduced form, NADH) by the reaction of NAD with hydrogen gas was carried out in the presence of the... 相似文献
126.
Takakazu Kojima Fumihiko Nagasaki Yozo Ohtsuka 《Journal of heterocyclic chemistry》1980,17(3):455-459
A series of 5,6-disubstituted 3-alkoxypyrazine-2-carbonitriles ( 2a-i ) were prepared from 5,6-disubstituted pyrazine-2,3-dicarbonitriles ( 1a-d ) by direct substitution with alcohols. Treatment of 1 with amines gave either pyrrolopyrazines ( 3a,b ) or substitution products ( 4,5 ). In a low temperature range, 1 afforded imidates and related compounds ( 6–11 ). The preference among these reactions depended on the 5,6-substituents and on the reaction conditions. 相似文献
127.
Kitayama A Yoshizaki H Ohmiya Y Ueda H Nagamune T 《Photochemistry and photobiology》2003,77(3):333-338
The thermal instability and pH-sensitive spectral property of firefly luciferase have hampered its use as a sensitive multicolor luminescent label or bioluminescent resonance energy transfer donor. With the intention of improving the thermostability of a previously found firefly Hotaria parvula luciferase mutant with minor pH-sensitive spectral change (V368A), further mutation (E356R) was introduced by taking a reportedly stabilized mutant of Photinus pyralis luciferase into account. The double mutant E356R/V368A showed significantly improved thermostability because > 90% activity remained after incubation for 1 h at 45 degrees C, with its specific activity being maintained. Unlike the wild type or V368A, E356R/V368A showed no change in the emission maximum of 568 nm even at pH 6.3, also implying a mutual relationship between thermostability and the proportion of yellow-green luminescent peak under acidic condition. 相似文献
128.
F Takano F Yoshizaki K Suzuki N Suya T Ando S Hisamichi 《Chemical & pharmaceutical bulletin》1990,38(5):1313-1316
Anti-ulcer activities of fruits of Trichosanthes kirilowii Maximowicz var. japonica Kitamura (50% ethanolic extract, TKE) were investigated in rats. TKE, at doses of 100-1000 mg/kg, showed potent protection against experimental gastric lesions, namely, those induced by water-immersion, histamine, serotonin, HCl.ethanol, 0.6 N HCl, 0.2 N NaOH, 35% NaCl, and Shay' ulcer and acetic acid-induced gastric ulcer. At doses of 500-1000 mg/kg, TKE decreased the gastric secretion and acid output in pylorus-ligation (for 7 h), but 100 mg/kg of TKE had no influence on the gastric secretion. On the other hand, TKE exerted inhibition on the contractile responses of the isolated ileum of mouse to acetylcholine. These results suggested that TKE has an anti-ulcer effect. 相似文献
129.
Headspace solid-phase microextraction-gas chromatography--mass spectrometry analysis of the volatile compounds of Evodia species fruits 总被引:3,自引:0,他引:3
Pellati F Benvenuti S Yoshizaki F Bertelli D Rossi MC 《Journal of chromatography. A》2005,1087(1-2):265-273
In this study the investigation of the aroma compounds of dried fruits of Evodia rutaecarpa (Juss.) Benth. and E. rutaecarpa (Juss.) Benth. var. officinalis (Dode) Huang (i.e. E. officinalis Dode) (Rutaceae family) was carried out to identify the odorous target components responsible for the characteristic aroma of these valuable natural products. To avoid the traditional and more time-consuming hydrodistillation, the analyses were carried out by means of headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS). The SPME headspace volatiles were collected using a divinylbenzene-carboxen-polydimethylsiloxane (DVB-CAR-PDMS) fiber. The extraction conditions were optimized using a response surface experimental design to analyze the effect of three factors: extraction temperature, equilibrium time and extraction time. The best response was obtained when the extraction temperature was around 80 degrees C, equilibrium time near 25 min and extraction time close to 18 min. Analyses were performed by GC-MS with a 5% diphenyl-95% dimethyl polysiloxane (30 m x 0.25 mm I.D., film thickness 0.25 microm) capillary column using He as the carrier gas and a programmed temperature run. The main components of the HS-SPME samples of E. rutaecarpa (concentration >3.0%) were limonene (33.79%), beta-elemene (10.78%), linalool (8.15%), myrcene (5.83%), valencene (4.73%), beta-caryophyllene (4.62%), linalyl acetate (4.13%) and alpha-terpineol (3.99%). As for E. officinalis, the major compounds were myrcene (32.79%), limonene (18.36%), beta-caryophyllene (9.92%), trans-beta-ocimene (6.04%), linalool (5.88%), beta-elemene (7.85%) and valencene (4.62%). 相似文献
130.
Oikawa M Shintaku T Fukuda N Sekljic H Fukase Y Yoshizaki H Fukase K Kusumoto S 《Organic & biomolecular chemistry》2004,2(24):3557-3565
The detailed conformational analysis of a single molecule of the tetraacyl biosynthetic precursor-type lipid A and its characteristic supramolecular assembly in aqueous SDS-micelles are described. Regular molecular arrangements were observed by detailed analysis of the NMR spectra of synthetically pure specimens, including regiospecifically 13C-labeled ones. NMR analysis of a biologically inactive precursor-type analogue with four shorter acyl chains demonstrated its conformational flexibility, indicating the importance of hydrophobic interactions for maintaining the conformation of such molecules. 相似文献