Nonlinear vibration response of a complex aeroengine under the rubbing fault

Nonlinear Dynamics - Rolling bearing and squeeze film damper will introduce structural nonlinearity into the dynamic model of aeroengine. Rubbing will occur due to the clearance reduction design of...     

ICP-AES中Ca、Al之间相互干扰的研究

本文在不同条件下比较详细地研究了Ca与Al在ICP-AES中的相互干扰,结果表明:这种干扰的垂直空间分布与其它元素的基体效应不同,特别在低观察区域Ca、Al之间呈现较为明显的相互抑制效应,说明Ca和Al之间产生了溶质挥发干扰。对分析条件特别是入射功率、载气流量及观察高度进行最优化可以使这种干扰减至最小。     

菲林B近红外分光光度法测定维生素C

在pH 3的三氯乙酸酸性介质中,菲林B可以定量地将还原型维生素C氧化成脱氢型维生素C,利用脱氢型维生素C在920 nm处有最大吸光度,测定其含量,建立了一种测定维生素C的新方法,并研究了影响反应的各种因素。该方法对维生素C的检出限为0.17 mg/L;线性范围为0.5~10 mg/L,对水果中维生素C含量测定的RSD<2.31%;回收率为99.7%~101.1%,比2,4-二硝基苯肼分光光度法测定结果的相对偏差<±1.6%。     

ICP-AES中基体干扰效应及其机理研究——Ⅰ.基体干扰效应的一般分布规律

本文以Na、ca、Al、Zn作为主要基体元素,在不同ICP发射光谱仪上考察了20多条分析谱线受到的干扰情况,初步总结了基体干扰效应的一般规律。结果表明,在常用分析条件下,一般金属元素具有与易电离元素类似的基体效应,即在较低观察区域对测定谱线信号产生增感,而在正常观察区域产生抑制;从增感转向抑制的零干扰点主要出现在感应圈上方8～14mm的观察区域,这一结果为实际分析条件的优化提供了有益的依据。     

Development and validation of a UPLC‐MS/MS method for the determination of cucurbitacin B in rat plasma and application to a pharmacokinetic study

Cucurbitacin B (CuB), one of the most abundant forms of cucurbitacins, is a promising natural anticancer drug candidate. Although the anticancer activity of CuB has been well demonstrated, information regarding the pharmacokinetics is limited. A rapid, selective and sensitive UPLC‐MS/MS for CuB was developed and validated using hemslecin A (HeA) as internal standard (IS). Plasma samples were pre‐treated by liquid–liquid extraction with dichloromethane. Separation was achieved on a reversed‐phase C₁₈ column (50 × 4.6 mm, 5 µm) at 35°C using isocratic elution with water–methanol (25:75, v/v) at a flow rate of 0.3 mL/min. The analytes were monitored by a triple quadrupole tandem mass spectrometer with positive electrospray ionization mode. The calibration curve was linear (r > 0.995) in a concentration range of 0.3–100 ng/mL with a limit of quantification of 0.3 ng/mL. Intra‐ and inter‐day accuracy and precision were validated by percentage relative error and relative standard deviation, respectively, which were both lower than the limit of 15%. This assay was successfully applied to a pharmacokinetic study of CuB in Wistar rats. Copyright © 2015 John Wiley & Sons, Ltd.     

Terpenoids from Loxocalyx urticifolius

Two new diterpenoids, loxocalyxin A ( 1 ) and 13‐epiloxocalyxin A ( 2 ), and two new sesquiterpenoids, loxocalyxins B and C ( 3 and 4 , resp.), together with three known compounds, were isolated from the MeOH extract of the whole plant of Loxocalyx urticifolius Hemsl . The structures of the new compounds were established by means of spectroscopic analysis including one‐ and two‐dimensional NMR spectroscopy. All new structures were confirmed by X‐ray crystallographic analysis. Their absolute configurations were established.     

化学反应-顶空气相色谱法测定气相二氧化硅表面硅羟基

建立了一种基于化学反应-顶空气相色谱测定气相二氧化硅表面硅羟基含量的新方法.实验取气相二氧化硅放入顶空瓶中于105℃烘箱中加热2 h去除水分,将甲苯稀释的格氏试剂注入密闭的顶空瓶中,格氏试剂与气相二氧化硅表面硅羟基快速反应产生甲烷(CH4),甲烷量与气相二氧化硅表面硅羟基含量成正比.经过气相色谱-氢火焰离子化检测器测定...     

中药现代化基础理论研究的几点思考

我国中药现代化基础理论研究应立足于提高我国人口素质及健康水平,促进国民经济发展（国家目标）。以传统中医药理论为基础,以现代生物医学与技术为指导（指导思想）,围绕以下几个方面来进行：（１）治疗常见病、疑难病、多发病新药的创制;（２）为创制新药所需要的稳...     

基于甲基苯丙胺和吗啡的胶体金免疫层析试剂盒检测法的可靠性评价

通过固相萃取-液相色谱-多级质谱(SPE-LC-MS/MS)联用技术和毒品胶体金免疫层析试剂盒检测法对13种中药及调味品样品中甲基苯丙胺及吗啡分别进行定量分析,依据LC-MS/MS检测结果,对毒品胶体金免疫层析试剂盒检测法进行可靠性评价。实验结果表明:型号1试剂盒对甲基苯丙胺和吗啡的特异性均不高,检测准确率分别为57.7%与78.8%;型号2试剂盒对甲基苯丙胺的特异性不足,准确率为73.1%,但对吗啡的检测准确率达到100%。在利用毒品胶体金免疫层析试剂盒进行毒品快速筛查时,应注重排除干扰因素以提高免疫胶体金层析试剂盒的检测准确度。