我国军用标准物质汇集

简要概述了标准物质的发展状况,汇集了军工所需的并经国家技术监督局审批发布的一级标准物质及其研制单位。     

Surface recombination in breakdown time delay experiments: Effect of different cathode materials

The late afterglow in nitrogen with iron electrode is studied by the breakdown time delay method, i.e., by measuring the breakdown time delay t_d as a function of the afterglow time . It is proposed that the cause of the secondary electrons initiating the breakdown is the energy of the surface recombination of nitrogen atoms on the iron electrode. The gas-phase and macrokinetic diffusive models are used to describe the experimental breakdown time delay data. By fitting the theoretical curve to the experimental data: (1) it has been confirmed that the recombination on the molybdenum glass is of the second order and the value of the surface recombination coefficient is determined at 4 mbar; (2) it has been shown that the surface recombination on the iron electrode is of the second order, and the effective recombination coefficients are determined; (3) the analytical form of the recombination coefficient as a function of the adsorption characteristics of surfaces and the pressure of the parent gas has been derived. In addition, the orders of surface recombination on the molybdenum-, aluminum-, and gold-plated electrode were determined by the same method.     

铜中杂质成分标准物质的研制

介绍铜中9种杂质成分标准物质的研制方法。以1号纯铜为基体，配入硫、铁、铅、锌、镍、铋、锑、磷、砷及锡共10种杂质成分，采用雾化喷粉加工工艺，保证了样品的均匀性。对样品表面作了抗氧化保护处理。采取多家实验室协作定值的方式对除砷外的9种杂质成分进行定值。5年的跟踪检验结果表明，该标准物质稳定性良好。     

The Birch reduction-dialkylation reaction. Scope and limitations

The Birch reduction-dialkylation reaction has been studied with different aromatic carboxylic acids and primary and secondary bromides. From these results it can be concluded that it is a reasonably general reaction. However, we found important exceptions with the primary bromides: allyl bromide, β-phenethyl bromide, and 5-bromo-2-methyl-2-pentene. The unusual behavior of allyl bromide is briefly discussed.     

微量元素对胎儿发育影响的临床研究

为了解小于胎龄儿的血锌、铜、铅的变化 ,对 3 8例小于胎龄儿 (其中 1 2例有先天缺陷 )进行了血锌、铜、铅三种微量元素检测 ,并与 3 1例健康足月适于胎龄儿比较。结果表明 ,3 8例小于胎龄儿血锌、铜、铅结果分别为 49 4± 1 9 88μmol/L、 1 0 7± 3 3 μmol/L、 1 5± 0 83 μmol/L ;与正常对照组 (分别为 62 3 9± 1 5 2 9μmol/L、 1 1 0 2± 1 73 μmol/L、 0 82± 0 3 9μmol/L)比较 ,血锌明显低于正常组 ,t=-2 88,P <0 0 1 ;血铅明显高于对照组 ,t =4 6,P <0 0 1 ,有显著性差异。两组血铜无明显差异。小于胎龄儿血锌降低 ,血铅增高 ,而且其先天性缺陷者占3 5 .5 8% ,证明胎儿的低锌高铅状态对其生长发育有重要影响。     

微量元素锌促进儿童生长发育临床研究

报道以微量元素锌治疗缺锌患儿１１８例并与１１４例作对照观察．结果发现，衡量生长发育与营养的敏感指标：身高、体重、血清白蛋白及血色素等参数，治疗组比对照组都显著提高（Ｐ值＜０．０１）．证明锌制剂对缺锌儿童有显著的促进生长发育及改善营养状态作用，作者并对锌的作用机理作了论述．     

The effects of the nature of catalyst and of the solvent on the stereoselectivity in amine-catalyzed asymmetric synthesis of substituted cyclohexa-1,3-dienes from prenal and monoesters of ylidenemalonic acids

In the amine-catalyzed reactions of prenal with (Z)-5-methyl-2-(methoxycarbonyl)hexa-2,4-dienoic or (Z)-3-phenyl-2-(ethoxycarbonyl)prop-2-enoic acid chiral β-amino alcohols provide for higher enantiomeric purity of the resulting alkyl 4-methyl-6-(2-methylprop-1-enyl)-and 4-methyl-6-phenylcyclohexa-1,3-dienoates than that provided by related chiral amines without hydroxy group. The values ofee attained in nonpolar solvents are higher than those observed in the polar ones. Substituting stoichiometric amounts of a chiral 1-amino-3-methylbuta-1,3-diene for a combination of prenal with 0.1 equiv. of the corresponding chiral amine results in the products of much lower enantiomeric purity. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 84–92, January, 1998.     

Total synthesis of (+)-xyloketal D, a secondary metabolite from the mangrove fungus Xylaria sp.

(+)-Xyloketal D was prepared in a one-pot multistep domino reaction by heating optically active 5-hydroxy-4-methyl-3-methylenepentan-2-one (R) in toluene with 2,4-dihydroxyacetophenone. The absolute configuration of the natural product was confirmed by preparation of the starting enone from a lactone of established absolute configuration.     

Prediction of H-Bonding Motifs for Pyrazoles and Oximes Using the Cambridge Structural Database

H-bonding motifs for pyrazoles and oximes have been examined in the Cambridge Structural Database. The accessible surface of the N atoms has been found to be useful as a discriminator to divide structures into dimer and catemer motifs for both pyrazoles and oximes. Low accessibility favors dimers and tetramers and high values favor catemers and trimers. Total molecular volume shows some correlation for oximes, while high values favor dimers. Empirical rules were successfully applied to predict the motifs of eight new structures in the subsequent release of the CSD.     

硬木热解过程中颗粒内部二次反应的数值研究Ⅱ.数值模拟结果

为了研究生物质（硬木）热解过程中颗粒内部的二次反应，对流化床环境下单颗粒生物质热解模型进行了求解。计算针对典型大颗粒和典型小颗粒在流化床反应器反应条件下的热解过程，对不同大小颗粒内部各种产物的生成、消耗、积累以及逃逸行为进行了定量描述。计算结果表明：对于直径为2mm的小颗粒，颗粒内二次裂解的份额可以忽略，但是对于直径10mm的大颗粒，热争过程中有超过20%的一次焦油参加了颗粒内部二次反应，颗粒内二次裂解显著地改变了热解产物分布，改变了热解产物的品质。