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51.
Summary The effects of concentration, separation and spectral similarity as factors influencing the accuracy of iterative target testing
factor analysis (ITT-FA) are investigated for three component systems by the application of analysis of variance (ANOVAR).
ANOVAR is applied over a range of peak separations to map the changing effects of the three factors with increasing overlap.
Two error responses were measured and analysed, (a) Relative cluster error (RCE) a measure of the error over all peaks in
a cluster and (b) Relative peak error (RPE) the error of an individual peak. Multicomponent analysis (MCA) a method requiringa priori spectral information, is used as a referee method for ITT-FA. 相似文献
52.
Summary The possibilities and limitation of automated solute identification via UV/VIS spectroscopy in HPLC are demonstrated and applications in toxicologic analysis are described. A standard isocratic system is used. The influence of various chromatographic parameters on retention time is shown. A retention time window of ±15% is required. In addition to retention time, derived spectral data are calculated (minima and maxima of derivatives, area counts under standardized spectral ranges, absorption at various wavelength) and used for positive solute identification. It is possible to identify solutes with a high degree of certainty in urine and plasma if their concentration is at least 10 ppm. 相似文献
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54.
Summary The effect of drying conditions on the preservation of chlorophyll pigments in mint and basil have been investigated in order to determine the effects of drying temperature and whether or not there was a prior blanching.Pigments extracted from fresh and dried samples were analyzed by reversed phase high performance liquid chromatography coupled to a photodiode array detector; isocratic separation was performed on a Zorbax ODS C18 column.The purity of the chromatographic peaks of chlorophylls and breakdown products was investigated. The visible spectra of standard samples of chlorophylls and pheophytins were compared, using least squares normalization with those of peaks from the extracts of fresh and dried mint and basil. The study has shown that chlorophylls were better preserved when drying was preceded by a short blanching; if samples were not blanched before drying, the degradation of chlorophylls a and b was best prevented by drying at low temperatures. 相似文献
55.
Xianpeng Yin Hao Dong Shiqiang Wang Yun Liang Ning Gao Wanlin Zhang Li Tian Fuwei Sun Guangtao Li 《中国化学快报》2019,30(1):179-182
In this work, large area gold-nanoparticle-cluster pillar array with a gold mirror as high-performance SERS substrate was facilely fabricated by combined use of nanosphere lithography and self-assembly approach. 相似文献
56.
Sokkalingam Punidha 《Tetrahedron》2004,60(38):8437-8444
A new method has been developed to synthesize 21,23-dithiaporphyrins having one pyridyl group at the meso position. The method required easily available unknown precursors and the condensation resulted in mono meso-pyridyl 21,23-dithiaporphyrins as single products in 8-11% yield. Two of the three mono meso-pyridyl N2S2 porphyrins were used to synthesize non-covalent unsymmetrical porphyrin dimers containing one N2S2 and one N4 porphyrin cores. 相似文献
57.
针对学生在学习指针过程中遇到的困难及使用指针过程中出现的常见错误,讨论指针的概念、指针与数组的关系、指针与函数的关系、指针作为函数参数的实质,帮助学生克服困难和错误。 相似文献
58.
59.
该文利用非线性随机效应模型在欧氏空间的BW几何结构,求出了固定效应参数估计的渐近性质与随机展开式。利用随机展开式,求出固定效应参数的偏差和方差的曲率表示式。 相似文献
60.
一种结构紧凑的新型微带单脉冲天线阵 总被引:2,自引:0,他引:2
该文提出了一种新的“十”字型微带结构单脉冲天线和差网络。用这种网络成功地设计并加工了微带单脉冲阵列天线。这个天线阵由 4个 8× 8幅度为均匀分布的微带天线子阵组成。和差网络和天线阵处于同一平面 ,因而具有结构紧凑、简单 ,加工方便和成本低的优点。根据实测结果 ,水平方向的和方向图与差方向图均与理论预估吻合良好 ,表明和差网络的设计是成功的。如果天线阵的幅度分布按低副瓣设计 ,则也可以用在微带低副瓣天线阵上。分析和实测都表明 ,这种天线阵还具有比常规天线阵带宽更宽的优点。 相似文献