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941.
Yuka MisonoAkira Ito Jun MatsumotoShigeru Sakamoto Kentaro YamaguchiMasami Ishibashi 《Tetrahedron letters》2003,44(24):4479-4481
Physarigins A-C (1-3), three new pigments have been isolated from a cultured plasmodium of myxomycete Physarum rigidum and their structures were elucidated by spectral data. 相似文献
942.
Saito T Maruyama R Ono S Yasukawa N Kodaira K Nishizawa M Ito S Inoue M 《Applied biochemistry and biotechnology》2003,111(3):185-190
Benzil (1) was selectively reduced to (S)-benzoin (2) in the presence of a wild-type Bacillus cereus Tim-r01. A 92% yield of 2 with 94% enantiomeric excess ratio was attained in phosphate-buffered saline (PBS) (pH 7.5) by using glucose as a nutrient at 37 degrees C for 12 h. Compound 2 was not reduced further to hydrobenzoin (3) at all. The reduction activity differed greatly depending on the strain of B. cereus. Under these conditions the B. cereus strains IFO3001, IFO15305, IAM1110, IAM1229, IAM1656, and IAM1729 gave 2 in yields ranging from 23 to 46% and the configuration of 2 was (S)-form (7 to 86% ee). 相似文献
943.
944.
Hiroya Ito 《Mathematical Methods in the Applied Sciences》1994,17(7):525-549
We establish the best constants in the Poincaré-type and the trace-type inequalities for the quadratic form $ \lambda ||\,{\rm div}\,{\rm u}\,||_{L^2 }^2 \, + \,2\,\mu \,||\,\,(\nabla {\rm u}\, + \,\nabla {\rm u}^{\rm T})/2\,||_{L^2 }^2 $ which is fundamental in elasticity theory, on the space of H1 vector fields u on a slab vanishing on one or both of its sides. We similarly calculate those constants for the case of H1 divergence-free vector fields. Our method, which is fairly general, has another practical application to the quadratic form ∑j,k(ajk?ku, ?ju)L2 with coefficients a jk = akj ε C in H1 scalar functions u on a slab. 相似文献
945.
946.
Magnetic states of Cu1 sublattice in YBa2Cu3O
y
: 1%57Fe compounds with 6.09 y6.98 were investigated by57Fe Mössbauer spectroscopy at 1.68T300 K. It has been found that, upon reducingy, the magnetic transition temperatureT
ml changes from 3.3 to 12 K aroundy6.4 where the superconductivity disappears. The magnetic phase diagram for the Cu1 sublattice is plotted. 相似文献
947.
Hayashi T Nakashima Y Ito K Ikegami T Aritome I Suzuki A Hisaeda Y 《Organic letters》2003,5(16):2845-2848
[structure: see text] A pyrrolic macrocycle, beta-tetrakis(trifluoromethyl)porphycene, is the first example of a fluorine-containing porphycene. Four electron-withdrawing CF(3) substituents provide a highly distorted structure and an attractive electron-deficient nature for the porphycene framework. From the electrochemical study, it is found that the LUMO energy level for the beta-trifluoromethylporphycene is 1.24 V more stabilized compared to that for etioporphyrin. Moreover, the deprotonation of the inner N[bond]H proton in the porphycene was observed upon the addition of DBU. 相似文献
948.
Iwase Y Takahashi M Takemura Y Ju-ichi M Ito C Furukawa H Yano M 《Chemical & pharmaceutical bulletin》2001,49(10):1356-1358
Two new flavanones and one chalcone were isolated from the peel of Citrus kinokuni Hort. ex Tanaka and identified as (2S)-5,6,7,8,4'-pentamethoxyflavanone (1), (2S)-5,6,7,3',4'-pentamethoxyflavanone (2) and 2'-hydroxy-3,4,3',4',6'-pentamethoxychalcone (3). The structures of new compounds were elucidated by spectroscopic analysis. 相似文献
949.
Y Ito S Yano K Watanabe E Yamanaka N Aimi S Sakai 《Chemical & pharmaceutical bulletin》1990,38(6):1702-1706
We investigated the selectivities and structure requirements for alpha-1 and alpha-2 adrenoceptor blocking activities of yohimbine (YO) and its 12 related analogs, such as beta-yohimbine (beta-YO), dihydrocorynantheine (DHC) and (-)indoloquinolizidine ((-)IQ). The affinity of YO analogs to alpha-adrenoceptor was assessed by measuring their blockade of pressor responses to epinephrine in pithed rats. Among YO structure groups, the potency order was YO greater than DHC = beta-YO greater than geissoschizine methylether greater than 14 beta-hydroxy YO greater than 14 beta-benzoyloxy YO (inactive). (-)IQ was slightly less potent than YO, but much stronger than (+)IQ. Among (+/-)IQ structure groups, the potency order was (+/-)IQ greater than (+/-)1,12b-trans-1-hydroxy IQ much greater than (+/-)1,12b-cis-1-hydroxy IQ (inactive). (+/-)Borrerine was active, but (+/-)desmethylborrerine was inactive. The alpha-1 blocking activities of the four compounds YO, beta-YO, DHC and (-)IQ, were assessed in experiments of pressor responses to methoxamine in pithed rats and contractile responses to methoxamine in the rat vas deferens. The potency order was (-)IQ greater than YO greater than DHC greater than beta-YO. Furthermore, the alpha-2 blocking activities of the four analogs were assessed in experiments of pressor responses to clonidine and inhibition of electrically driven cardioacceleration by clonidine, in pithed rats. The potency order was YO greater than beta-YO greater than (-)IQ greater than DHC. Based on the potency ratio between alpha-1 and alpha-2 blocking activities, DHC or YO was most selective for alpha-1 or alpha-2 subtype, respectively, among the four YO analogs.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
950.
This review discusses recent advances in the science and technology of Coulter counting. The Coulter counting principle has been used to determine the size, concentration, and in favorable cases the surface charge, of nanometer-scale colloidal particles, viruses, DNA and other polymers, and metal ions. A resurgence of interest in the field of COulter counting is occurring because of the advent of new technologies that permit fabrication of membranes containing single, robust, and chemically well-defined channels having smaller and more uniform sizes than could be prepared in the past. These channels are prepared from biological materials, such as self-assembling membrane proteins, and from synthetic materials such as polymers, carbon nanotubes, and silicon-based inorganic materials. In addition to particle characterization, there have been a few recent examples of using Coulter counters to study chemical processes, such as the dehybridization of DNA. 相似文献