用实验室合成的十二烷基苯磺酸镁配成固定相,以汞塞动态法涂柱制备了毛细管柱(固定液质量浓度为95g/L,柱尺寸为25 m×0.32 mm i.d.)所用溶剂为丙酮,并对柱性能进行了考察。实验表明这种色谱固定相对有机羧酸有独特的分离能力,出峰快,峰形窄而对称,即使对痕量的羧酸也可不经衍生直接进样定量分析。 相似文献
A new chromophore, C1 , based on a similar DπA‐structure as in the FTC ‐chromophore but with a hydroxyalkyl spacer perpendicular to the direction of the dipole moment was synthesized. Both chromophores and the CLD ‐chromophore were used to prepare high Tg nonlinear optical vinyl polymers. The influence of the position of the spacer on the DπA‐system on the NLO response of the resulting polymers was investigated.
A straightforward modification of the resolution of the identity (RI) approximation to the Coulomb interaction is described. In the limit of basis sets that are dominated by high angular momentum functions the observed speedups in realistic test systems reach a factor of 2 compared to the standard RI algorithm, and a factor of up to 300 compared to the standard algorithm to form the Coulomb matrix. More moderate savings on the order of 0-20% are obtained for the more commonly used smaller basis sets. A series of test calculations is reported to illustrate the efficiency of the algorithm. 相似文献
The chemical compositions of the initial bark of the Siberian firAbies sibirica and of the solid residues after extraction with carbon dioxide, water, and alcohol have been studied. On successive extraction, the yield of extractive substances amounted to 25.05% of the absolutely dry bark. The carbon dioxide, aqueous, and alcoholic extracts obtained have been investigated. The carbon dioxide extract was found to contain 34.97% of essential oil, while only traces of it were detected in the aqueous and alcoholic extracts.Krasnoyarsk State Technological Academy. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 42–45, January–February, 1996. Original article submitted August 14, 1995. 相似文献