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131.
132.
Kiyoshi Ando 《Journal of Graph Theory》2009,60(2):99-129
An edge of a 5‐connected graph is said to be contractible if the contraction of the edge results in a 5‐connected graph. Let x be a vertex of a 5‐connected graph. We prove that if there are no contractible edges whose distance from x is two or less, then either there are two triangles with x in common each of which has a distinct degree five vertex other than x, or there is a specified structure called a K4?‐configuration with center x. As a corollary, we show that if a 5‐connected graph on n vertices has no contractible edges, then it has 2n/5 vertices of degree 5. © 2008 Wiley Periodicals, Inc. J Graph Theory 60: 99–129, 2009 相似文献
133.
Takaaki Horaguchi Eietsu Hasegawa Takahachi Shimizu Kiyoshi Tanemura Tsuneo Suzuki 《Journal of heterocyclic chemistry》1989,26(2):365-369
Cyclohepta[cd]benzofuran 2 was synthesized by heating (5-oxo-5H-benzocyclohepten-4-yloxy)acetic acid 16 with sodium acetate in acetic anhydride or by photocyclization of 16 in acetonitrile. Several reactions of cyclohepta[cd]benzofuran 2 were examined. Protonation of 2 with trifluoroacetic acid occurred at the 2-position to give a tropylium ion 17 . Catalytic hydrogenation of 2 with palladium on charcoal proceeded smoothly to give tetrahydrocyclohepta[cd]benzofuran 18 . The Diels-Alder reaction of 2 with tetracyano-ethylene produced an adduct 19 . Formylation of 2 with phosphorus oxychloride and dimethylformamide occurred easily at the 2-position to afford compound 20 . Cyclohepta[cd]benzofuran 2 has both properties of heptafulvene and benzofuran. 相似文献
134.
A single-bunch beam has been generated using a developed high-speed avalanche-type pulser in KURRI-LINAC in order to lift restrictions of the spectral resolution in the spectroscopic study and the delay time in the time-resolved measurement. Both of the rise and fall times of the developed pulser are 110 ps. The observation of CTR has confirmed the single-bunch beam. The degree of impurity of single bunch has been estimated to be 1.5% by the analysis of the interferogram. 相似文献
135.
136.
Takaaki Horaguchi Kazuhiro Miyazawa Eietsu Hasegawa Takahachi Shimizu Tsuneo Suzuki Kiyoshi Tanemura 《Journal of heterocyclic chemistry》1990,27(4):941-948
A variety of 2,5-dioxacyclohepta[jkl]-as-indacenes 5, 7–14 were synthesized as a new heterocycle by the treatment of diethyl (5,9-dioxobenzocyclohepten-1,4-diyloxy)diacetates 4a-e with potassium hydroxide or sodium hydride in dioxane. The mechanism of furan-ring formation from 4a-e was discussed. 相似文献
137.
Takeshi Ishikawa Yuji Mochizuki Shinji Amari Tatsuya Nakano Shigenori Tanaka Kiyoshi Tanaka 《Chemical physics letters》2008,463(1-3):189-194
We have developed a method named ‘fragment interaction analysis based on local MP2’ (abbreviated as FILM). This method enables us to decompose the interaction energy associated with dispersion interactions into contributions of localized occupied orbitals. In this study, the basis set dependence of the results derived from FILM was examined. The results suggested that the individual ratio of pair correlation energies of selected orbital pairs to the total dispersion interaction was almost independent of the basis set size. As an illustrative example, detailed analysis was performed on the human immunodeficiency virus type 1 protease complexed with lopinavir molecule. 相似文献
138.
Kiyoshi Endo Yosiyuki Kondo 《Journal of polymer science. Part A, Polymer chemistry》2008,46(8):2858-2863
Polymerization of 2‐pentene with [ArN?C(An)C(An)·NAr)NiBr2 (Ar?2,6‐iPr2C6H3)] ( 1‐Ni) /M‐MAO catalyst was investigated. A reactivity between trans‐2‐pentene and cis‐2‐pentene on the polymerization was quite different, and trans‐2‐pentene polymerized with 1‐Ni /M‐MAO catalyst to give a high molecular weight polymer. On the other hand, the polymerization of cis‐2‐butene with 1‐Ni /M‐MAO catalyst did not give any polymeric products. In the polymerization of mixture of trans‐ and cis‐2‐pentene with 1‐Ni /M‐MAO catalyst, the Mn of the polymer increased with an increase of the polymer yields. However, the relationship between polymer yield and the Mn of the polymer did not give a strict straight line, and the Mw/Mn also increased with increasing polymer yield. This suggests that side reactions were induced during the polymerization. The structures of the polymer obtained from the polymerization of 2‐ pentene with 1‐Ni /M‐MAO catalyst consists of ? CH2? CH2? CH(CH2CH3)? , ? CH2? CH2? CH2? CH(CH3)? , ? CH2? CH(CH2CH2CH3)? , and methylene sequence ? (CH2)n? (n ≥ 5) units, which is related to the chain walking mechanism. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2858–2863, 2008 相似文献
139.
Sorbitol was readily converted by heating in hydrophobic ionic liquids by the presence of ion exchange resins. Chemoseletivity of the dehydration depended on the choice of ion exchange resin; Nafion selectively produced isosorbide while Amberlite gave 1,5-anhydrosorbitol along with unreacted sorbitol. Ionic liquids used in the reaction were readily recovered by simple extraction procedure. With these procedures, we succeeded to prepare isosorbide in pure form, not contaminated with either ionic liquids or acid catalyst, by simple experimental procedure. 相似文献
140.
Nitroxyl radicals (nitroxides) with unpaired electron are widely used as antioxidants, contrast agents, and spin probes. Although piperidine nitroxyl radicals have many applications, these are mainly tetramethylpiperidine compounds, and only a few reports consider the substitution of N-O surround as a reaction site, such as 2,2,6,6-tetrasubstituted piperidine nitroxyl radicals. Our results revealed that the 2,6-position of the 2,2,6,6-tetramethylpiperidin-4-one compound was substituted by cyclohexyl groups to produce 2,2,6,6-tetrasubstituted piperidin-4-one derivatives under mild reaction conditions. An interesting result was obtained by using 15N-labeled NH4Cl instead of 14NH4Cl: it gave 15N-labeled 2,2,6,6-tetrasubstituted piperidin-4-one-1-oxyls with a high 15N content. In conclusion, the new method for the synthesis of nitroxyl radicals readily yields 2,2,6,6-tetrasubstituted piperidin-4-one under mild conditions. 相似文献