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11.
Nobuya Iwamoto Norimasa Umesaki Shigeru Goto Teiichi Hanada Naohiro Soga 《Journal of Non》1985,70(1):177-185
The structure of Na2OGa2O3SiO2 glasses of four different compositions containing up to 45 mol. % Ga2O3 has been determined by the X-ray diffraction method. The radial distribution function D(r) obtained indicates that Ga3+ ions are in fourfold coordination and GaO4 tetrahedra are formed in these glasses. The reduced intensity function S·i(S) and radial distribution function D(r) which were calculated based on a structural model for A-25, 0.25(Ga2O3)·0.75(Na2O·2SiO2)/3 glass agreed well with the observed ones. 相似文献
12.
Green tea extract containing catechin mixtures was treated with gallic acid using laccase (EC 1.10.3.2) to improve its function as a food material. After enzymatic oxidation, two new products were detected on an HPLC chromatogram. These products were purified by extraction with ethyl acetate, sequential column chromatographies, and crystallization. On the basis of 1H/13C NMR, MALDI-TOF/high resolution MS, and UV-visible absorption spectral analyses, they were confirmed to be epitheaflagallin (5) and epitheaflagallin 3-O-gallate (6). This enzymatic process allows us to preferentially convert catechin derivatives in a crude mixture of green tea into different compounds. 相似文献
13.
YiKai Zhou Mohamed Almokhtar Hitoshi Kubo Nobuya Mori Shuichi Emura Shigehiko Hasegawa Hajime Asahi 《Solid State Communications》2012,152(14):1270-1273
Symmetric GaGdN/AlGaN (Gd concentration: 2%) and GaN/AlGaN double quantum well superlattices (DQW-SLs) were grown by radio-frequency plasma-assisted molecular-beam epitaxy on GaN (0001) templates. Atomic steps were observed on all the sample surfaces by atomic force microscope. X-ray diffraction θ/2θ scan curves exhibited well-defined satellite structures. Room temperature ferromagnetism was confirmed for the GaGdN/AlGaN DQW-SL samples by using alternating gradient magnetometer. Strong photoluminescence was observed from both GaGdN and GaN QWs at higher energy side of GaN excitonic peak. Magneto-photoluminescence spectra for GaGdN/AlGaN DQW-SL samples showed a large magnetic field dependence of the excitonic energy by applying a magnetic field up to 7 T. The observed strong redshift of excitonic PL indicated an enhancement of Zeeman splitting of the free carrier energy levels in magnetic GaGdN/AlGaN DQW-SL. Enhanced g-factor was estimated to be about 60 for GaGdN/AlGaN DQW-SL sample with QW thickness of 1 nm. 相似文献
14.
Zhou CJ Shioda S Yada T Inagaki N Pleasure SJ Kikuyama S 《Current protein & peptide science》2002,3(4):423-439
Pituitary adenylate cyclase-activating polypeptide (PACAP) was originally isolated from the ovine brain in 1989 as a novel hypothalamic hormone that potently activates adenylate cyclase to produce cyclic AMP in pituitary cells. This neuropeptide belongs to the secretin/glucagon/vasoactive intestinal peptide (VIP) superfamily, and exists in two amidated forms as PACAP38 (38-amino acid residues) and PACAP27 derived from the same precursor. The primary structure of PACAP has been remarkably conserved throughout evolution among tunicata, ichthyopsida, amphibia and mammalia, and a PACAP-like neuropeptide has also been determined in Drosophila. Both PACAP and its receptors are mainly distributed in the nervous and endocrine systems showing pleiotropic functions with high potency. There are three types of receptors with high PACAP-binding affinity and with different tissue-distribution patterns. All of them belong to G-protein-coupled receptor superfamily with seven transmembrane domains. PAC(1) is the PACAP-specific receptor and exists in at least eight splice variants which couple to different intracellular signal transduction pathways. VPAC(1) and VPAC(2) are the common receptors for both PACAP and VIP, which are coupled to adenylate cyclase. This review article presents and discusses an update on PACAP research and its pleiotropic physiological functions based on multiple receptor-mediated signaling mechanisms in both the central and peripheral nervous system, including the regulation of hypothalamic neurosecretion, homeostatic control of circadian clock and behavioral actions, involvement in learning and memory processes, neuroprotective effects such as anti-apoptosis and response to injury and inflammation, and neural ontogenetic functions on proliferation/differentiation processes from early stages. 相似文献
15.
Toshio Ito Nobuya Tomiyoshi Koki Nakamura Shizuo Azuma Makoto Izawa Fumio Maruyama Mitsutoshi Yanagiya Haruhisa Shirahama Takeshi Matsumoto 《Tetrahedron》1984,40(1):241-255
The total synthesis of dl-coriolin has been achieved in a stereoselective way. The key tricyclic intermediate was synthesized from dicyclopentadiene through a route which involved an SN2 reaction at a neopentylic position. 相似文献
16.
Masahide Yasuda Yoshimasa Nishinaka Takumi Nakazono Takeshi Hamasaki Nobuya Nakamura Tsutomu Shiragami Chyongjin Pac Kensuke Shima 《Photochemistry and photobiology》1998,67(2):192-197
It was found that tetra-o-acyl riboflavins efficiently photosensitize the monomerization of the cis, syn-cyclobutane dimers of 1,3-dimethylthymine and 1,3-dimethyluracil in aqueous solution in the presence of such anionic surfactants as sodium dodecyl sulfate and sodium hexadecyl sulfate at concentrations higher than their critical micelle concentration, while little monomerization of the dimers was photosensitized by the flavins in the absence of the surfactants and even in the presence of cationic and nonionic surfactants. 相似文献
17.
Nearest-neighbor recognition measurements have established that the effects of deuterium substitution on phospholipid mixing are exceedingly small. Thus, the mixing behavior of an exchangeable phospholipid bearing two stearoyl chains with a homologue containing two myristoyl chains in gel-fluid bilayers, fluid bilayers, cholesterol-rich fluid bilayers, and gel-fluid bilayers that have been enriched with cholesterol correspond to a difference in the free energy of mixing that is less than 2.2 cal/mol of hydrogen in all cases. These findings provide the strongest evidence to date in support of the use of deuterated phospholipids as "nonperturbing" probes for structural and dynamic studies of bilayer membranes. 相似文献
18.
The isomerization kinetics of panipenem (INN: (+)-(5R,6S)-3-[(S)-1-(acetimidoylpyrrolidin-3-yl)thio]-6-[(R)-hydroxyethyl]-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid, CAS No. 87726-17-8) in aqueous solution were investigated. An equilibrium between the Z-form and E-form was observed, and it was found that the isomerization rates were affected by the pH of the solution. Under acidic conditions, the isomerization rates were small. However, the isomerization rates were increased with the pH value. This phenomenon resulted from the extent of proton dissociation from the acetimidoyl group. 相似文献
19.
20.
The preparation of 2',3'-epimino-carbocyclic analogues of adenosine is reported. The reaction of p-tosyl azide with N-substituted 2-azabicyclo[2.2.1]hept-5-en-3-one (ABH) (1a) provided aziridine-fused ABH (2), which was converted to 2',3'-epimino-carbocyclic nucleosides (11). 相似文献