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141.
A 36-membered macrocyclic hexaoxime was quantitatively obtained by [3 + 3] condensation of dialdehyde 2 with diamine 3 using La3+ (core metal) and Zn2+ (shell metal) as a novel core/shell template, while the yield was very low in the absence of the metal ions. The high yield can be attributed to the efficient formation of a 3:3:1 complex of dialdehyde 2, Zn2+, and La3+, which readily gives the macrocycle keeping the Zn3La core/shell tetranuclear cluster structure. 相似文献
142.
We developed a capillary electrophoresis with chemiluminescence detection system using 2-methyl-6-p-methoxyphenylethynylimidazopyrazinone as a chemiluminescence reagent for determination of antioxidants of superoxide anions. 2-Methyl-6-p-methoxyphenylethynylimidazopyrazinone reacted with superoxide anions generated through the reaction of hypoxanthine and xanthine oxidase, and then emitted chemiluminescence. Suppression of the chemiluminescence in the presence of antioxidants for superoxide anions was introduced as a detection principle for antioxidants into the capillary electrophoresis with chemiluminescence detection system. After optimizing the analytical conditions, various antioxidants, such as superoxide dismutase, nitroblue tetrazolium, ascorbic acid, and catechin, were subjected to the present system. They gave negative peaks due to the quenching effect; the detection limits of superoxide dismutase, nitroblue tetrazolium, ascorbic acid, and catechin were 1, 100, 100, and 10 μM, respectively (S/N = 2). A model sample consisting of superoxide dismutase and nitroblue tetrazolium was satisfactorily separated and detected within ca. 10 min. We also applied the present system to analysis of catechin in green tea as a real sample. 相似文献
143.
Taniguchi S Kuroda K Doi K Tanabe M Shibata T Yoshida T Hatano T 《Chemical & pharmaceutical bulletin》2007,55(2):268-272
Gambir, the aqueous extract from Uncaria gambir (Rubiaceae), has been used as an astringent medicine in Asian countries. Investigation of the constituents in the extract led to the isolation of four chalcane-flavan dimers, gambiriin A1 (6), A2 (7), B1 (8), and B2 (9), in addition to (+)-catechin (1), (+)-epicatechin (2), and dimeric proanthocyanidins, procyanidin B1 (3), procyanidin B3 (4), and gambiriin C (5). The spectroscopic and chemical data obtained in the present study indicated that their previously proposed structures 6a, 7a, 8a, and 9a should be revised to 6, 7, 8, and 9, respectively. 相似文献
144.
Taniguchi Y Ikehara T Kamo N Watanabe Y Yamasaki H Toyoshima Y 《Photochemistry and photobiology》2007,83(2):311-316
The photoreceptor phoborhodopsin (ppR; also called sensory rhodopsin II) forms a complex with its cognate the Halobacterial transducer II (pHtrII) in the membrane, through which changes in the environmental light conditions are transmitted to the cytoplasm in Natronomonas pharaonis to evoke negative phototaxis. We have applied a fluorescence resonance energy transfer (FRET)-based method for investigation of the light-induced conformational changes of the ppR/pHtrII complex. Several far-red dyes were examined as possible fluorescence donors or acceptors because of the absence of the spectral overlap of these dyes with all the photointermediates of ppR. The flash-induced changes of distances between the donor and an acceptor linked to cysteine residues which were genetically introduced at given positions in pHtrII(1-159) and ppR were determined from FRET efficiency changes. The dye-labeled complex was studied as solubilized in 0.1% n-dodecyl-beta-D-maltoside (DDM). The FRET-derived changes in distances from V78 and A79 in pHtrII to V185 in ppR were consistent with the crystal structure data (Moukhametzianov, R. et al. [2006] Nature, 440, 115-119). The distance from D102 in pHtrII linker region to V185 in ppR increased by 0.33 angstroms upon the flash excitation. These changes arose within 70 ms (the dead time of instrument) and decayed with a rate of 1.1 +/- 0.2 s. Thus, sub-angstrom-scale distance changes in the ppR/pHtrII complex were detected with this FRET-based method using far-red fluorescent dyes; this method should be a valuable tool to investigate conformation changes in the transducer, in particular its dynamics. 相似文献
145.
Takashi Taniguchi 《Transactions of the American Mathematical Society》2007,359(11):5517-5524
In this article, we give a refinement of the mean value theorem for the class number of quadratic extensions obtained by Goldfeld-Hoffstein and Datskovsky. More specifically, we determine the proportional constants of the mean value for fields that satisfy any local conditions including wild ramification at places dividing .
146.
S. Yamada A. Taniguchi K. Okano K. Aoki 《The European Physical Journal A - Hadrons and Nuclei》2000,7(3):327-334
The β-decay of 146La was studied using the on-line isotope separator KUR-ISOL. Gamma-gamma angular correlation measurements were performed with
a 4-Ge detectors system. Spin assignments of three levels were made: 3+ for the 1576.5 keV level, 4+ for the 1627.1 keV level and 5+ for the 1810.2 keV level. The mixing ratios (E2/M1) were deduced to be δ183.2= 0.25 ± 0.08, δ638.9= 0.33 ± 0.05, δ959.0= 1.19+0.16
−0.14, δ1015.9= 5.4+3.1
−1.5 and δ1318.1= 6.5+1.7
−1.1. These were compared to the calculated values obtained in three cases involving different Majorana force parameter values.
The band structure of 146Ce is discussed based on the results of calculation using the IBM-2 theory.
Received: 20 September 1999 / Revised version: 8 February 2000 相似文献
147.
Wenjun Lu Yoshinori Yamaoka Yuki Taniguchi Tsugio Kitamura Ken Takaki Yuzo Fujiwara 《Journal of organometallic chemistry》1999,580(2):10442
Aromatic compounds such as benzene, toluene, chlorobenzene, anisole, and naphthalene were carboxylated by palladium(II) acetate catalyst with carbon monoxide in the presence of potassium peroxodisulfate in trifluoroacetic acid (TFA) at room temperature under atmospheric pressure. The aromatic carboxylic acids were formed in good yields; for example, the carboxylation of benzene with carbon monoxide proceeds quantitatively under the optimal conditions. 相似文献
148.
Miraculous J. Bhaseen Ian I. Kogan Oleg A. Soloviev Nobuhiko Taniguchi Alexei M. Tsvelik 《Nuclear Physics B》2000,580(3):1355-720
We suggest a procedure for calculating correlation functions of the local densities of states (DOS) at the plateau transitions in the integer quantum Hall effect (IQHE). We argue that their correlation functions are appropriately described in terms of the SL(
)/SU(2) WZNW model (at the usual Ka
–Moody point and with the level 6≤k≤8 ). In this model we have identified the operators corresponding to the local DOS, and derived the partial differential equation determining their correlation functions. The OPEs for powers of the local DOS obtained from this equation are in agreement with available results. 相似文献
149.
Shuntaro Mataka Kouichiro Shigaki Tsuyoshi Sawada Yoshihara Mitoma Masahiko Taniguchi Thies Thiemann Kazuya Ohga Naoyoshi Egashira 《Angewandte Chemie (International ed. in English)》1998,37(18):2532-2534
Through clever bridging of orthocyclophanes (in this case by acetalization), molecules such as 1 can be formed with four benzene rings in a stacked face-to-face arrangement. UV/Vis spectroscopic and electrochemical properties of 1 are governed by π–π through-space interactions within the molecule. 相似文献
150.