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101.
Takashi Sugimoto Kazuhisa Ikemoto Shizuaki Murata Masahiro Tazawa Takahide Nomura Yasumichi Hagino Hiroshi Ichinose Toshiharu Nagatsu 《Helvetica chimica acta》2001,84(4):918-927
The structure of the native pteridine in Tetrahymena pyriformis was determined as (6R)‐5,6,7,8‐tetrahydro‐D ‐monapterin (=(6R)‐2‐amino‐5,6,7,8‐tetrahydro‐6‐[(1R,2R)‐1,2,3‐trihydroxypropyl]pteridin‐4(3H)‐one; 4 ). First, the configuration of the 1,2,3‐trihydroxypropyl side chain was confirmed as D ‐threo by the fluorescence‐detected circular dichroism (FDCD) spectrum of its aromatic pterin derivative 2 obtained by I2 oxidation (Fig. 1). The configuration at the 6‐position of 4 was determined as (R) by comparison of its hexaacetyl derivative 6 with authentic (6R)‐ and (6S)‐hexaacetyl‐5,6,7,8‐tetrahydro‐D ‐monapterins 6 and 7 , respectively, in the HPLC, LC/MS, and LC‐MS/MS (Figs. 3 – 6). (6R)‐5,6,7,8‐Tetrahydro‐D ‐monapterin ( 4 ) is a newly discovered natural tetrahydropterin. 相似文献
102.
Takahide Mizawa Katsuhiko Takenaka Tomoo Shiomi 《Journal of polymer science. Part A, Polymer chemistry》1999,37(17):3464-3472
In order to synthesize end-functionalized polymers with conjugated dienyl groups, living polymeric anions of polystyrene and polyisoprene were allowed to react with 5-bromo-1,3-pentadiene, 1, and 7-bromo-1,3-heptadiene, 2. The reaction of polystyryl anion and/or polyisoprenyl anion with 1 gave polymers whose end-functionalities were 65–80% regardless of the reaction conditions. On the other hand, almost quantitative functionalization was achieved when a large excess amount of 2 was used as a terminator. When 1,1-diphenylalkyl anion and enolate anion derived from t-butyl methacrylate were used, the degree of end-functionality were 70–80% at best. The resulting end-functionalized polymers were characterized by size exclusion chromatography (SEC), 1H and 13C-NMR and thin layer chromatography coupled with a flame ionization detector (TLC-FID). © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3464–3472, 1999 相似文献
103.
We present a relation between the Bessel potential spaces and the Riesz potential spaces. The ideas of the proof are to characterize each potential spaces and to give a correspondence between individual Bessel potentials and Riesz potentials. 相似文献
104.
The Mizoroki-Heck reaction was carried out using a fluorous ether F-626 as the solvent and a fluorous Pd carbene complex as the catalyst. When carboxylic acids are the products, separation of both the F-626 and the Pd catalyst from the products can be conveniently carried out by simple filtration. The F-626 filtrates containing the Pd catalyst can be recycled. 相似文献
105.
Sumanta Bhattacharya Takanori Shimawaki Xiaobin Peng A. Ashokkumar Shuji Aonuma Takahide Kimura Naoki Komatsu 《Chemical physics letters》2006,430(4-6):435-442
We have tailored some interesting mono- and diporphyrins, viz., 5, 10, 15, 20-tetrakis(octadecyloxyphenyl)-21H,23H-porphyrin (TP), 5, 15-bis(3, 5-dioctylphenyl)-2, 8, 12, 18-tetramethyl-3, 7, 13, 17-tetradodecyl-21H,23H-porphyrin (AP) and 1, 3-bis(10′,20′-diundecyl-21′H,23′H-porphyrin-5′-yl)benzene (DP) as host molecules to study their complexation behavior with C60 and C70. Fluorescence spectroscopic measurements showed that emission of TP, AP and DP in toluene was quenched in the presence of C60 or C70. Large binding constants (K) in the magnitude of 1.5 × 104 dm3 mol−1 have been obtained for the 1:1 complexes of C70 with TP, AP and DP. However, the C60 complexes have exhibited 8.5 times smaller K compared to C70 complexes. Ab initio theoretical calculations give a good support in favor of strong complexation between C70 and porphyrins. 相似文献
106.
Morohashi I Sakamoto T Sotobayashi H Kawanishi T Hosako I Tsuchiya M 《Optics letters》2008,33(11):1192-1194
By combining a Mach-Zehnder-modulator-based flat comb generator (MZ-FCG) with a dispersion-flattened dispersion-decreasing fiber, femtosecond pulses have been generated from a cw light. Near-Fourier-transform-limit picosecond pulses generated from the MZ-FCG were compressed into femtosecond order by pulse compression. Our system enables flexible tuning of the repetition rate and pulse width, because those depend on the driving signal of the MZ-FCG. Pulse trains of 200 fs width were continuously and stably generated without mode hopping, with a repetition rate range from 5 to 17 GHz. Our system consists of a modulator and compression fiber; thus, the configuration is simpler and more stable. 相似文献
107.
We have observed a superconductor-insulator transition in one-dimensional (1D) arrays of small Josephson junctions by changing both the resistance R(S) of normal metal resistors shunting each junction and the ratio of the Josephson coupling energy E(J) to the charging energy E(C). The phase boundary lies at R(S) approximately R(Q) (R(Q) identical with h/4e(2)=6.45 kOmega) when E(J)/E(C) is smaller than about unity. We discuss the obtained phase diagram in terms of theoretical models of the dissipation-driven quantum phase transition, with particular attention to differences from 2D arrays. 相似文献
108.
109.
110.
Bhattacharya S Hashimoto M Fujimoto A Kimura T Uno H Komatsu N 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,70(2):416-424
The present paper highlights the photophysical aspects of the topologically new Ni(II)-diporphyrin (Ni(2)-1)/fullerene host-guest ensembles. Both absorption and fluorescence studies reveal that Ni(2)-1 undergoes efficient complexation with both C(60) and C(70) in toluene medium. In the fluorescence study, remarkable enhancement of the fluorescence intensity of Ni(2)-1 was observed by the addition of C(60), while normal quenching of fluorescence occurred in case of C(70). From the fluorescence and UV-vis studies, the binding constants of Ni(2)-1 with C(60) and C(70) were determined to be approximately 1.7 x 10(4) and approximately 2.7 x 10(4) dm(3) mol(-1), respectively. Ab initio theoretical calculations reveal that C(70)/Ni(2)-1 complex favor end-on orientation of C(70) rather than side-on approach. 相似文献