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121.
The positron annihilation lifetime method (PAL) has been applied to study the characteristics of polyethylenes (PEs) at low temperatures between 273 and 100 K. It has been found that the intensity (I
3) of the long-lived component of positronium (Ps) showed an increase in non-annealed PE and annealed PE in vacuo. However, PAL in PEs annealed in an atmosphere containing oxygen did not show such an increase. It has been indicated that the latter effect is due to formation of carbonyl groups through oxidation during the annealing. 相似文献
122.
123.
Osamu Hatori Kazumi Hino Takeshi Miura Hirokazu Oka 《Mediterranean Journal of Mathematics》2009,6(1):47-59
Let and be uniform algebras and p(z,w) = zmwn a twovariable monomial. We characterize maps T from certain subsets of into such that holds for all f and g in the domain of T; peripherally monomial-preserving maps. Furthermore and are proved to be isometrical isomorphic as Banach algebras. If the greatest common divisor of m and n is 1, then T is extended to an isometrical linear isomorphism; a weighted composition operator. An example of peripherally monomial-preserving
surjections between uniform algebras which is not linear, nor multiplicative, nor injective is given when the greatest common
divisor is strictly greater than 1.
The first, third and fourth authors were partly supported by the Grantsin-Aid for Scientific Research, The Ministry of Education,
Science, Sports and Culture, Japan. 相似文献
124.
1,6-Enynes reacted with arylboronic acids in the presence of a catalytic amount of a rhodium(I) complex under mild conditions to give (Z)-1-(1-arylethylidene)-2-vinylcyclopentanes. The regioselective addition of an arylrhodium(I) species across the carbon-carbon triple bond triggered the cyclization process. Intramolecular carborhodation onto the pendent alkene in a 5-exo mode furnished a five-membered ring. Finally, the rhodium(I) methoxide generated by beta-methoxy elimination reacted with the arylboronic acid to promote the next catalytic cycle. 相似文献
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126.
Secondary 2-thiophenecarboxamides efficiently undergo unique triarylation accompanied by formal decarbamoylation under palladium catalysis. 3-Substituted thiophenes, especially having an electron-withdrawing group, can also be triarylated. 相似文献
127.
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130.
In the presence of palladium salts, oxidation of 2-nitrostyrenes 1 with nitrous acid alkyl esters 2 resulted in the formation of 2-nitrophenylacetaldehyde dialkyl acetals 3. Reductive cyclization of the acetals 3 with iron powder in acetic acid afforded indoles 5 in good yield. 相似文献