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981.
辛硫磷和氯氰菊酯复配制剂的高效液相色谱分析 总被引:1,自引:0,他引:1
提出了同时测定辛硫磷和(高效)氯氰菊酯含量的主同效液相色谱分析方法。采用正相柱、235nm紫外检测,石油醚/乙腈流动相系统实现辛硫磷及其杂质与(高效)氯氰菊酯异构体的良好分离。 相似文献
982.
Michele De Luca 《Microchemical Journal》2006,83(1):24-34
This work describes a novel experimental design aimed at building a calibration set constituted by samples containing a different number of components. The algorithm performs a reiteration process to maintain the number of samples at the lower value as possible and to ensure an homogeneous presence of all the concentration levels. The mixture design was applied to a drug system composed by one-to-four components in different combination. The resolution of the system was performed by three multivariate UV spectrophotometric methods utilizing principal component regression (PCR) and partial last squares (PLS1 and PLS2) algorithms. The calibration set was composed by 61 references on four concentration levels, including 15 samples for each quaternary, ternary and binary composition and 16 one-component samples. The calibration models were optimized through a careful selection of number of factors and wavelength zones, in such a way as to remove interferences from instrumental noise and excipients present in the pharmaceutical formulations. The prediction power of the regression models were verified and compared by analysis of an external prediction set. The models were finally used to assay pharmaceutical specialities containing the studied drugs in one-to-four formulations. 相似文献
983.
The major storage proteins from six rye varieties, grown under the same conditions in 1997 and 1998 in Rønhave, Denmark, were analyzed by two‐dimensional (2‐D) polyacrylamide gel electrophoresis. The proteins were extracted from ground rye kernels with 70% ethanol and separated by 2‐D electrophoresis. The gels were scanned, compared using ImageMaster® software and the data sets were analyzed by principal component analysis (PCA) using THE UNSCRAMBLER software. Afterwards MATLAB was used to make a cluster analysis of the varieties based on PCA. The analysis of the gels showed, that the protein patterns (number of different proteins and their isoelectric points and molecular weights) from the six rye varieties were different. Based on the presence of unique cultivar‐specific spots it was possible to differentiate between all six varieties if the two harvest years were investigated separately. When the results were combined from the two years five varieties could be differentiated. The results from the PCA confirmed the finding of the unique spots and cluster analysis was made in order to illustrate the results. The combination of the results from 2‐D electrophoresis and other grain characteristics showed that one protein spot was located close to the parameters bread volume and bread height. 相似文献
984.
正规苯型烃的命名及对称性分类贾金萍王爱坤(河北科技大学)何文辰(河北工业大学,天津300130)关键词本型烃正规苯型烃苯型烃(稠环芳烃)是一系列苯环稠接而成的化合物,是介于苯与石墨间的多种有机化合物的统称。如能在氢气氛中将石墨裂解就有可能得到各种苯型... 相似文献
985.
986.
The effect of pressure on order destruction and order creation in linear or branched alkane mixtures
The pressure dependence of the excess enthalpy H
E
, dH
E
/dP, has been calculated from experimental excess volumes V
E
and dV
E
/dT using dH
E
/dP=V
E
–TdV
E
/dT. dH
E
/dP at zero pressure are reported at 25°C and equimolar concentration for the mixtures: cyclohexane with the series of normal alkanes (n-C
n
, where n=6,8,10,12,14 and 16) and with the series of highly branched alkanes (br-C
n
, where n=6,8,12 and 16), benzene, toluene and p-xylene +n-C
n
and 1-chloronaphthalene +n-C
n
and br-C
n
. Experimental and Flory theory dH
E
/dP values are in good agreement for the whole cyclohexane +br-C
n
series. For the n-C
n
series, dH
E
/dP becomes increasingly positive deviating from the Flory predictions. This discrepancy is due to the presence of short-range orientational order in the higher n-C
n
pure liquids which makes dH/dP more negative and which, upon mixing, is destroyed producing a positive contribution to dH
E
/dP not accounted for by the theory. The discrepancy between theoretical and experimental dH
E
/dP is large for benzene, but progressively smaller for toluene, p-xylene and 1-chloronaphthalene. These results are consistent with creation of order between the aromatic plate-like molecule and the long n-C
n
in solution. For 1-chloronaphthalene +n-C
n
, this order creation process produces a negative contribution to dH
E
/dP which balances the positive order-destruction contribution originated by the rupture, upon mixing, of short-range orientational order in pure n-C
n
. 相似文献
987.
氮酮 (正十二烷基杂氮庚酮AZONE)是促进皮肤对药物吸收的促进剂 ,广泛用于外用药的各种制剂之中[1,2 ] 。它是高沸点化合物 ,其沸点用一般方法很难测定。我们以邻苯二甲酸二丁酯、乙二醇为标准物 ,甘油为对照物 ,用DSC(差示扫描量热 )法测定了氮酮的正常沸点和汽化焓 ,为实际生产提供了非常有用的数据。1 实验准确称取邻苯二甲酸二丁酯、乙二醇两种标准物 ,用CDR 1差动扫描量热仪 ,自然气氛Al2 O3 为参比物 ,升温速率 80° min ,分别进行DSC测定 (标定热值时将样品池密封、标定温度值时样品池要用钢针打一微孔后再压合… 相似文献
988.
Graciela M. Escandar Héctor C. Goicoechea Arsenio Muñoz de la Peña Alejandro C. Olivieri 《Analytica chimica acta》2014
An introduction to multi-way calibration based on second- and higher-order data generation and processing is provided, with emphasis on practical experimental aspects. After a discussion concerning a proper nomenclature scheme, a suitable classification of the obtainable data, and the general features of the available algorithms and their underlying models, a series of examples is discussed in detail, with the purpose of illustrating the great potentiality of the field for the analytical community. Emphasis is directed toward the most popular multi-way data, i.e., second-order or matrix data, which can be conveniently measured in a variety of instruments. Third-order data are being increasingly studied and are also discussed, along with the less explored field of fourth-order data. The estimation of figures of merit, which analysts need to report during method development, is now sufficiently mature to be provided for the general audience. 相似文献
989.
990.
Leonid Kuzmin 《Physica C: Superconductivity and its Applications》2010,470(21):1933-1936
A novel type of the zero-biased thermo-electric bolometer (TEB) is proposed. The bolometer is based on a charge-to-voltage converter (CVC) with a superconductor–insulator–normal (SIN) tunnel junction and a superconducting absorber. The absorption of photons in the absorber leads to excitation of quasiparticles with some fraction of charge imbalance, tunneling through the SIN junction in zero-biased mode and generation of voltage. The thermoelectric voltage is determined by accumulation of tunneling charge in an external capacitance. Conversion efficiency is very high and voltage values comparable with a superconducting gap are easily achieved. The zero-biased CVC–TEB can be effectively used for creation of an array of bolometers and multi-pixel detection systems. 相似文献