Organolithium addition to 5,6-disubstituted pyrimidines

The addition of organolithium reagents to the azomethine bond of 5,6-disubstituted pyrimidines provided, in every case, a single adduct. When reacted with either ethyl chloro-formate or hydrogen chloride, these adducts gave a single dihydro pyrimidine. The resulting N-H dihydro pyrimidines were oxidized with potassium permanganate to the corresponding pyrimidines.     

The synthesis and characterization of amine-terminated poly(aryl ether ketone)s as a function of side group and molecular weight

It is shown that amine-terminated poly(aryl ether ketone)s based on the reaction of 4,4'-difluorobenzophenone, and a substituted hydroquinone [either methylhydroquinone (MePK), t-butylhydroquinone (tBPK), or phenylhydroquinone (PhPK)] of controlled molecular weight and high amine-termination efficiency can be synthesized by a two-step reaction technique. Attempts to synthesize analogous materials by a one-step method were shown to be unsuccessful. The side groups are shown to have a large influence on the aromatic proton chemical shifts and this effect is characterized. The side groups and molecular weight are also shown to influence the thermal transitions of the respective polymers. The tBPK polymer possessed the highest glass transition temperature, while the MePK polymer was found to be the only semi-crystalline polymer; a unit cell is proposed. The side groups and molecular weight effects are also characterized as a function of thermal stability and mechanical properties. © 1994 John Wiley & Sons, Inc.     

Iodine stabilised 640 nm helium-neon laser

The wavelength of a helium-neon laser operating at 640 nm coincides with two strong absorption lines in the spectrum of iodine-127 when the gain tube is filled with neon-22. The absorption lines have been identified by measuring their hyperfine structure and the performance of the laser has been investigated. The beat frequency pair variance between two similar lasers was 7.6 kHz for a 10-second averaging time and the wavelength of component g of the 8-5 P(10) line was measured as 640.2834686 nm.     

相对论性核碰撞中φ介子增强

用强子和弦级联模型LUCIAE系统地研究了相对论性p+p和Pb+Pb碰撞中φ介子产生.在模型框架内实验测得的158AGeV/cPb+Pb碰撞中φ介子产额相对于同能量p+p碰撞的增强现象,依赖于弦发射胶子的集体效应和奇异夸克压低约化两机制,在一定程度内能得到解释.