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为了对彩绘文物颜料进行无损判别分析,该文采集了12种彩绘常用颜料参考样品的漫反射光谱,根据光谱曲线外形将参考样品分为红黄色系及蓝绿色系两类。使用主成分分析(PCA)分别对两个色系参考样品的光谱数据集进行降维,抽提出最有代表性的3个主成分,利用成分得分散点图确认了颜料间的类间差异,并通过成分矩阵探讨了对该差异贡献率最高的光谱波长区间。在此基础上,采用线性判别分析(LDA)对PCA的分析结果进行建模,拟合判别函数并将其应用于2件颐和园仁寿殿上架彩画文物样品颜料的分析。基于样品判别得分散点图与各类别参考样品间的距离,判定文物使用的颜料分别为铁红和群青。研究表明,该文构建的判别函数能够准确区分颜料的种类,可用于彩绘文物样品的无损分析鉴别。文物样品的污染或老化可能会影响分析,需事先进行表面清理。 相似文献
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对因子分析法在质谱成像数据分析中的应用进行了研究。本方法分析的质谱成像数据来源于空气动力辅助离子源质谱成像技术,所用样品为含有3种不同颜料(红色、蓝色、黑色)的笔迹样品。对该样品的成像数据进行因子分析后,将成像数据分为了背景、黑色、蓝色和红色因子。分析结果显示,m/z 443.2,478.4,322.2(344.2)分别在红色、蓝色、黑色因子中的贡献值远大于其它质荷比,因此是3种颜料的特征质荷比。此结果与实际情况相符,证明使用因子分析方法对质谱成像数据进行分析和特征提取是可行的。对因子分析与主成分分析的成像数据处理结果进行了比较,结果显示,因子分析可以更简单和定量地对特征质荷比进行取舍,在生物标志物提取、疾病诊断、药理分析等方面有较大的应用潜力。 相似文献
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选取距今约1000多年、五代十国时期规模最大的江苏南京南唐二陵壁画为研究对象,采用热裂解-气相色谱/质谱联用(Py-GC/MS)分析技术,在对蛋清标准样品测试条件进行优化的基础上,评估了8种无机矿物颜料(方解石、铅丹、赭石、朱砂、石青、石绿、雌黄和雄黄)对蛋清裂解产物的影响,建立了针对墓葬壁画中蛋清鉴别的Py-GC/MS分析方法。文物样品的分析结果表明,壁画地仗和灰浆中均有加入蛋清作为胶结材料,同时使用酶联免疫吸附测定(ELISA)验证了Py-GC/MS分析结果,进一步说明Py-GC/MS是一种针对墓葬壁画中蛋清成分可靠的分析方法,为墓葬壁画有机胶结材料的研究提供了方法借鉴。 相似文献
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纳米多级结构枣核型多孔氧化亚铜的合成及拉曼性质 总被引:1,自引:0,他引:1
通过简单温和的水相还原反应, 在表面活性剂十二烷基苯磺酸钠(SDBS)的协同下合成了亚微米级枣核型多孔氧化亚铜纳米多级结构. 通过改变盐酸的加入量可以实现纳米粒子尺寸在300-900 nm范围可调. X射线衍射(XRD)和透射电子显微镜(TEM)分析表明, 亚微米粒子由小于10 nm的晶粒构成. 基于实验结果, 我们提出生长-刻蚀竞争生长模型来解释枣核型空心多孔结构的形成机制, 同时说明了尺寸调节机理. 利用激光拉曼光谱仪研究了样品的光学性质, 与相似尺寸的亚微米实心多面体的拉曼响应信号对比发现, 枣核型空心多孔结构的拉曼光谱表现出新颖的特性. 这些结果补充了氧化亚铜的拉曼光谱样本, 对文物表面颜料的无损拉曼检测具有一定的指导意义. 相似文献
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将改性膨润土引入到丙烯酰胺基水凝胶体系中,通过控制组分比例、温度和反应时间等因素,成功构筑了粘接修复型膨润土基水凝胶(AR-gel)材料,并实现了对破损和断裂的砂岩文物的高效修复.AR-gel中膨润土的存在提高了其与砂岩文物之间的兼容性,展现出了极好的粘接性,且粘接修复完整的文物接缝处无明显粘接痕迹,无泛白变色现象,不影响被粘接文物的整体美观;同时,粘接过程中的溢胶,可用水轻易去除.修复过后的砂岩形貌与性能与砂岩对照样品基本一致,表明了AR-gel高粘接性能的同时,不会对砂岩基体造成二次破坏.通过严苛的冻融老化循环和盐结晶湿热循环老化试验验证了该AR-gel材料对砂岩的耐久性粘接保护,并分析了保护机理:砂岩与AR-gel间通过强氢键、Si-O-Si键、Si-O-M键、质子化和离子键、机械咬合等作用牢固结合在一起.此外,AR-gel对玻璃、金属、砂岩、陶瓷和陶器等各种材质的文物均具有极好的粘接性能.本研究工作为开发耐久性文物粘接修复保护材料提供了新方法和新思路. 相似文献
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针对在实际多元质量控制中经常遇到的奇异样品问题,本研究提出了一种稳健偏最小二乘类模型.本方法基于Stahel-Donoho奇异度和样品重加权策略,用稳健的类中心和模型误差构造稳健的决策区间.将本方法用于清真香肠的红外分析,建立了稳健的质量控制方法.在香肠样品的不同部位进行取样,充分研磨后制备溴化钾压片,以空气为背景,测量4000~400 cm-1范围的红外透射光谱.基于73个清真香肠样品和78个非清真样品的光谱数据,研究了新提出的稳健类模型的统计效率和稳健性.在有奇异样品存在的情况下,本方法能有效检出奇异样品,为新样品的预测提供稳健的决策区间.排除奇异样品后,基于原始光谱的模型灵敏性为0.846,特异性为0.936;基于标准正态变量法的模型灵敏性为0.923,特异性为0.974. 相似文献
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利用手持技术改进测定乙醇分子结构实验 总被引:1,自引:0,他引:1
利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。 相似文献
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Mustafa R. Ibrahim Zacharia A. Fataftah Paul von Ragu Schleyer Peter D. Stout 《Journal of computational chemistry》1987,8(8):1131-1138
Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases. 相似文献
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由于石化行业的生产需要,其材质的使用具有多样性和广泛性,经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识,根据光谱仪的测试能力及标样的采集,实现了一个或几个元素测量范围的扩展,并对其测量的影响因素进行了研究。 相似文献
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V. I. Bol'shakova L. I. Demenkova É. N. Shmidt V. A. Pentegova 《Chemistry of Natural Compounds》1989,24(6):691-694
The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988. 相似文献
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V. I. Bol'shakova L. I. Demenkova É. N. Shmidt V. A. Pentegova 《Chemistry of Natural Compounds》1988,24(6):691-694
The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae. 相似文献
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Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin
E. I. Kapinus V. A. Ganzha B. M. Dzhagarov E. I. Sagun V. B. Pavlenko 《Theoretical and Experimental Chemistry》1989,25(2):146-151
The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989. 相似文献
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The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted
indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator
model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was
established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing
analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997. 相似文献