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951.
Glycotentacles: synthesis of cyclic glycopeptides, toward a tailored blocker of influenza virus hemagglutinin 总被引:1,自引:0,他引:1
952.
953.
Nishiwaki N Nishida D Ohnishi T Hidaka F Shimizu S Tamura M Hori K Tohda Y Ariga M 《The Journal of organic chemistry》2003,68(22):8650-8656
The acyl group of an alpha-aryl-beta-keto ester was readily transferred to N-, O-, and S-nucleophiles. The transacylation from arylated diethyl 3-oxoglutarate to amines led to unsymmetrical malonic acid amide esters in high yields. The present reaction proceeded under mild conditions without formation of detectable byproducts. Only simple experimental manipulations were required. This reaction was also found to be sensitive to steric factors, which enabled the chemoselective monoacylation of diamines and amino alcohols without any modifications such as protection. 相似文献
954.
Yamamoto Y Hata K Arakawa T Itoh K 《Chemical communications (Cambridge, England)》2003,(11):1290-1291
[2 + 2 + 2] cycloadditions of 1,2-bis(propiolyl)benzenes with monoalkynes were effectively catalysed by Cp*RuCl(cod) under mild conditions to give substituted anthraquinones in moderate to high yields. 相似文献
955.
956.
957.
T. Nishida M. Katada N. Osawa R. Sato T. Komatsu K. Matusita 《Hyperfine Interactions》1994,94(1):2119-2124
The119Sn-Mössbauer spectra ofxSnO·(70–x)SnF2·30P2O5 glasses (0 x70) measured at 78 K comprised a doublet due to Sn2+ (=3.30–3.36 mm s–1, = 1.70–1.72 mm s–1) and a weak singlet due to Sn4+ located at –0.23 mm s–1 with respect to BaSnO3. The and of Sn2+ were comparable to those of Sn2P2O7. Small Debye temperatures (146 and 155 K) were obtained from the low-temperature measurements. These results indicate that Sn2+ and Sn4+ occupied interstitial sites, being loosely and ionically bonded to distorted PO4–x
F
x
tetrahedra. 相似文献
958.
Omar Foda Kenji Iohara Michio Jimbo Rinat Kedem Tetsuji Miwa Hong Yan 《Letters in Mathematical Physics》1994,32(3):259-268
An elliptic deformation of $\widehat{s1}_2 $ is proposed. Our presentation of the algebra is based on the relationRLL = LLR *, whereR andR * are eight-vertexR-matrices with the elliptic moduli chosen differently. In the trigonometric limit, this algebra reduces to a quotient of that proposed by Reshetikhin and Semenov-Tian-Shansky. Conjectures concerning highest-weight modules and vertex operators are formulated, and the physical interpretation ofR * is discussed. 相似文献
959.
Jun Akimitsu Jiro Amano Masaki Yoshinari Michio Kokubun Tatsuya Iwasaki Satoshi Okuma Nobuhiko Nishida Kusuo Nishiyama Nobuo Mori 《Hyperfine Interactions》1994,85(1):187-192
We report SR measurements of Pr2CuO4– and (Pr2–xCex)CuO4– single crystals in the temperature range 4.2K300K. Two spin reorientation phase transitions were observed, although neutron scattering experiment could not detect these phase transitions. These allow us to conclude that magnetic moments of the Cu atoms order in an antiferromagnetic noncollinear cross like structure including a hidden canting spin arrangement. 相似文献
960.
Recent progress of the preparation of novel materials for catalysts utilizing metal-containing silsesquioxanes are reviewed
in the following categories: (i) activities of vanadium or titanium-containing silsesquioxanes as homogeneous catalysts for
oxidative reactions, (ii) preparation of immobilized or polymeric catalysts, and (iii) preparation of porous oxide catalysts
utilizing metal-containing silsesquioxanes. The present authors found that the liquid phase photo-oxidation of cyclohexane
in the presence of a vanadium-containing silsesquioxane as a homogeneous catalyst selectively afforded cyclohexanol and cyclohexanone
in high yields. Facile synthetic methods for group 4 metal-containing silsesquioxanes with functionalized silyl (or germyl)
groups are presented. Remarkably, titanocene(IV)-containing silsesquioxanes have been synthesized for the first time. The
presence of alkenylsilyl substituents shows a promotional effect on the epoxidation of cycloalkenes, which was found to be
more significant for titanium-bridged silsesquioxanes. By utilizing these silsesquioxanes, polymeric, starburst-like, and
dendritic silsesquioxanes were prepared as well as novel caged or macrocyclic molecules with organic–inorganic hybrid structures.
The controlled calcination of these metal-containing silsesquioxanes at around 823 K produces porous oxides with high BET
surface areas of 300–520 m2g−1 and uniformly-controlled micropores of 0.5–0.6 nm diameter. The oxides are found to include a well-dispersed metallic oxide
species. From group 13 elements-containing silsesquioxanes Br?nsted acidic oxides are produced. Among them, aluminum-containing
oxides show excellent activities for the cracking of cumene even at low temperature, 523 K, in spite of their amorphous nature. 相似文献