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991.
Osamu Morikawa Hiroshi Yamaguchi Yoshiko Katsube Kazuyuki Abe Kazuhiro Kobayashi Hisatoshi Konishi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):2877-2886
The host–guest interaction of C-methylresorcin[4]arene and its derivative having four tert-butylsulfanylmethyl groups at the extra-annular positions was studied by 1 H NMR spectroscopy in CD3OD. Based on the association constants (Ka) and the complexation-induced NMR shifts (CIS), it was concluded that the bulky substituents create a deep cavity with a narrow entrance and improve the size and shape selectivity. 相似文献
992.
Santiago Cano-Casanova Julián López-Gómez Kazuhiro Takimoto 《Nonlinear Analysis: Theory, Methods & Applications》2012
This paper studies a weighted quasilinear perturbation, through the mean curvature flow operator, of the classical linear heat equation. The mean curvature has the effect of maintaining bounded all classical positive steady states of the model, though their derivatives must be somewhere unbounded. The dynamics of the positive solutions of the model is fully described. 相似文献
993.
<正>The metal-free combination of catalytic amounts of PPh_3,B(C_6F_5)_3,and PhSiH_3 can efficiently hydrosilylate aldehydes, ketones,aldimines and ketimines to afford the corresponding reduction products in good yields. 相似文献
994.
Kazuhiro Onodera 《Advances in Mathematics》2010,224(3):895-909
We study the extremal values of multiple gamma and sine functions in the fundamental intervals. We show the number and locations of the extremal points, and prove that all the local maximum and minimum values are greater and less than one, respectively. 相似文献
995.
Fengxiang Yin Kazuhiro Takanabe Masao Katayama Jun Kubota Kazunari Domen 《Electrochemistry communications》2010,12(9):1177-1179
M–Ti/carbon black electrocatalysts (M: Mn, Fe, Co, Ni, Cu, Mo) were prepared by the polymerized complex (PC) method and subsequent nitridation under ammonia flow, and were investigated as cathodes for the oxygen reduction reaction (ORR) in 0.1 M H2SO4 aq. Among the metals investigated, Co and Fe gave high onset potentials of 0.86 and 0.87 V vs. RHE, respectively. In comparison with the Co-only catalyst, the Co–Ti catalyst showed higher current, reflecting high density of Co-related active sites. The presence of Ti was also essential for the electrode stability under severe acidic and oxidizing conditions. 相似文献
996.
997.
Takao Shoji Dr. Shokaku Kim Prof. Kazuhiro Chiba 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(14):4069-4072
Azanucleosides, in which the 4′‐oxygen atom has been replaced with a nitrogen atom, have drawn much attention owing to their anticancer and antivirus activity, and tolerance towards nucleases. However, the traditional synthetic strategy requires multiple steps and harsh conditions, thereby limiting the structural and functional diversity of the products. Herein we describe the synthesis of azanucleosides by an electrochemical reaction in a lithium perchlorate–nitroethane medium, followed by postmodification at the 4′‐N position. N ‐Acryloyl prolinol derivatives were converted into azanucleosides by anodic activation of the N ‐α‐C−H bond. Moreover, the use of nitroethane instead of nitromethane lowered the oxidation potential of the N ‐acryloyl prolinols and increased the Faradic yield. The prepared azanucleosides were efficiently functionalized at the 4′‐N ‐acryloyl group with a lipophilic alkanethiol and a fluorescent dye by conjugate addition and olefin cross‐metathesis, respectively. 相似文献
998.
Kazuhiro Nakabayashi Kazuya Matsumoto Tomoya Higashihara Mitsuru Ueda 《Journal of polymer science. Part A, Polymer chemistry》2008,46(22):7332-7341
Sulfonated multiblock copoly(ether sulfone)s applicable to proton exchange membrane fuel cells (PEMFCs) were synthesized by the coupling reaction of the hydroxyl‐terminated hydrophilic and hydrophobic oligomers with different lengths in the presence of highly reactive decafluorobiphenyl (DFB) as a chain extender to investigate the influence of each length on the membranes' properties, such as water uptake, proton conductivity, and morphology. Multiblock copolymers with high molecular weights (Mn > 50,000, Mw > 150,000) were obtained under mild reaction conditions. The resulting membranes demonstrated good oxidative stability for hot Fenton's reagent and maintained high water uptake (7.3–18.7 wt %) under a low relative humidity (50% RH). Proton conductivity of all membranes at 80 °C and 95% RH was higher than that of Nafion 117 membrane, and good proton conductivity of 7.0 × 10?3 S/cm was obtained at 80 °C and 50% RH by optimizing the oligomer lengths. The surface morphology of the membranes was investigated by tapping mode atomic force microscopy (AFM), which showed that the multiblock copolymer membranes had a clearer surface hydrophilic/hydrophobic‐separated structure than that of the random copolymer, and contributed to good and effective proton conduction. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7332–7341, 2008 相似文献
999.
A triribonucleotide 3-5 U, which is fully protected by an allyl group at the 2′-hydroxy and phosphoric acid positions was synthesized, the deprotection being quantitatively achieved by use of a catalytic amount of CpRu(η3-C3H5)(2-quinolinecarboxylato) in methanol. The reaction is completed within 30 min at ambient temperature. The utility of the simple allyl protecting group has the potential to open a new pathway in the synthesis of RNA-related compounds. 相似文献
1000.
Tomio Shimizu Yoshiyuki Hayashi Masayuki Miki Kazuhiro Teramura 《Journal of heterocyclic chemistry》1990,27(6):1669-1671
Pyrazolo[5,1-c][1,4]benzoxazines were prepared by the reaction of 2-(allyloxy)phenylhydrazine with arylaldehydes in the presence of hydrochloric acid. The formation of the fused heterocycles can be explained by intramolecular 1,3-dipolar cycloaddition reaction of cationic dipole, i.e‥, hydrazonium chlorides. 相似文献