Analysis of Flavonoid Aglycons in Rhododendron of Sichuan Liangshan

IntroductionRhododendron is a widespread natural plant ofover 70 0 types[13] with differentmedicinal values.Rhododendron extracts,for example,are used inmedicines for chronic tracheitis,for suppressingcough,as antiphlogistic and anodyne,and forhighblood pressure[4 6] .The flavonoids and volatile oilsin Rhododendron leaves were reported to beeffective for the treatment of asthma and otherpulmonary complaints[7,8] . Liquor Jinjuan (anendemic antiphlogistic medicine) made usingRhododendron leav…     

从几次典型战例看中国女排快攻战术的重要性

<正> 洛杉矶奥运会以后,国际女子排坛中、美、日“三足鼎立”已转为中、古、苏“三强争雄”之势,尤其是古巴,对我国女排构成相当大威胁,成为我队的主要劲敌。一系列世界性大赛之后,我国女排几名主力队员相继退役。在这样新的形势下,中国女排应该采用何种对策,坚持     

凸集上的非线性算子的固有元及固有值

本文利用拓扑度研究集上的具边界条件的非线性集压缩算子的不动点。固有元及固有值的存在性,推广了[3,5,6]中的相应结论,部分回答了[4]的一个猜测。     

Application of backflush and micro-flow techniques to the analysis of C5—C13 hydrocarbons in crude oils and its geochemical significance

An Agilent 6890N GC equipped with both FID and Agilent 5975 MSD analyzer has been employed to analyze C₅—C₁₃ hydrocarbon fractions of crude oils. A technical combination of program temperature volatilizer injection, backflush and micro-flow controller afforded a fine separation of C₅—C₁₃ compounds on a PONA column with the heavy part of crude oils being cut off before entering the analytical column. Both GC-FID chromatogram and GC-MS mass chromatograms (MID and full scan) could be obtained at the same time. The retension time differences of nC₆—nC₁₃ alkanes between GC and TIC were in the range of 0.02—0.58 minutes. Totally 286 peaks have been assigned group compositions. Results on 8 typical oil samples from CNPC Key Laboratory Crude Oil Library showed that the characteristics of C₆—C₁₃ hydrocarbon group composition could be used in oil-oil correlation studies.     

QuEChERS结合UPLC-MS/MS测定菠菜中5种氨基甲酸酯类农药残留

建立了基于QuEChERS技术的超高效液相色谱-串联质谱法(UPLC-MS/MS),对菠菜中的5种氨基甲酸酯类农药残留量进行测定。样品均质后,以乙腈-水(体积比50∶50)提取后,盐析离心,乙腈层用N-丙基乙二胺净化后供UPLC-MS/MS测定。采用电喷雾离子源ESI正离子模式电离,质谱多反应监测模式对目标母离子和子离子进行扫描测定。5种氨基甲酸酯类农药在0.1~20.0μg/L的基质曲线范围内呈良好线性关系,相关系数r大于0.9991,3个水平的平均加标回收率为91.0%~101.0%,方法检出限和定量限分别为0.10~0.20μg/kg和0.25~0.50μg/kg,相对标准偏差为2.15%~5.57%。该方法具有操作简便、快速高效、回收率高、灵敏度高、重复性好等优点,可用于测定菠菜中的5种氨基甲酸酯类农药残留量。     

碱处理结合盐辅助分散液液微萃取GC-MS/MS检测即食鱼制品中7种N-亚硝胺

为提高N-亚硝胺的相关检测效率,建立了碱处理结合盐辅助分散液液微萃取(SADLLME)气相色谱-串联质谱法(GC-MS/MS)检测即食鱼制品中7种N-亚硝胺的新方法。样品经氢氧化钡溶液热处理,转移目标物至水溶液中,在辅助盐硫酸钠近饱和条件下,以二氯甲烷为萃取剂进行SADLLME,应用GC-MS/MS进行检测。方法检出限为0.10~0.19μg/kg, 定量限为0.28~0.56μg/kg;加标水平为1、5、10μg/kg时,加标回收率为79.19%~117.40%,相对标准偏差为1.06%~10.30%。结果表明:此方法灵敏、可靠,选择性好,样品前处理简单,能够满足相关食品中N-亚硝胺检测的需要。     

刺柏果精油化学成分研究

经色谱－质谱联用仪对刺柏（Ｊｕｎｉｐｅｒｕｓ ｆｏｒｍｏｓａｎａ Ｈａｙａｔａ）果油分析，定性定量地鉴定对４７个化合物。其中主要成分为ａ－蒎烯，ｒ－杜松烯，月桂烯和柠檬烯等，同欧洲刺柏（Ｊｕｎｉｐｅｒｕｓ ｃｏｍｍｕｎｉｓ Ｌｉｎ）果油化学成分对比表明，两种刺柏有大致相同的主要成分，有相似的香气，刺柏果精油可用于饮料，食品用日用化学品的加香调香及医药。     

风冷柴油机塑料风扇的研制

介绍了玻璃纤维(GF)增强尼龙-66(PA-66)制塑料风扇的结构尺寸和减少其蠕变和应力松弛及保证柴油机正常运转的技术措施。该柴油机塑料风扇比西德的FL511系列风冷柴油机的铝合金风扇有静压效率高、冷却效果好、功率消耗低、节能、质轻、噪音小,特别是成本低等优点。     

LC二分频器与电子分频器的性能比较

对模拟音频电子电路的两种不同分频方法进行了对比分析，阐述了两种分频技术的优劣之处，并着重介绍了电子分频器的性能及其分频技术的原理。