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41.
Thepyrimidinesasaclassareknowntopossessextraordinarybiologicalpropertiesthataregenerallydistinguishedqualitativelybytheirapplicationsinpesticide,herbicide,bactericide,andmedicineinter-mediates犤1犦.Asurveyoftheseapplicationsandanum-beroftherelatedvariationsthataredevelopedrecent-ly,suchastheextraordinaryeffectiveherbicideofsulfonylsulfourea,revealsthebroadbiologicalimpor-tancejustbecauseofthewideoccurrenceofpyrimi-dinesringsystemsinthesemolecules犤2犦.Ithasbeenshownthatthemedicineintermediates… 相似文献
42.
43.
A five-step model for a quality assurance system is developed for an internal quality control check. It includes the quality
control of the decomposition method and the detection method as steps belonging together. The Wickbold combustion technique
as decomposition method in combination with atomic absorption spectrometry was chosen. The vaporization of the elements mercury,
arsenic, lead, antimony and selenium is based on combustion in an oxyhydrogen flame. To check the efficiency of the analytical
system, the uncertainty of results was calculated on the basis of the "Guide to the Expression of Uncertainty in Measurement".
Received: 13 January 1997 · Accepted: 29 March 1997 相似文献
44.
Kai‐lu Yu Chang‐jun Liu Yue‐ping Zhang Fei He Xin‐li Zhu Baldur Eliasson 《Plasma Chemistry and Plasma Processing》2004,24(3):393-403
PdO/Al2O3 catalysts prepared by glow discharge plasma treatment followed by thermal calcination show a much higher dispersion and a better catalytic activity for methane combustion at relatively low temperatures. The dispersion of palladium active species by such plasma prepared catalysts is 29.7%, 5.4 times higher than that of conventional catalysts. XPS analysis indicates that a surface enrichment of Pd active species (PdO) has been achieved after plasma treatment. The surface atomic composition of PdO of plasma prepared catalysts reaches 10.5%. XRD characterization also confirms a wellcrystallized PdO phase present on the plasma prepared catalyst. The lightoff temperature of the plasma prepared catalyst is 370°C, 50°C lower than that obtained from the conventional catalyst. 相似文献
45.
By using a micro-bomb calorimeter, the standard enthalpies of combustion of C60 and C70 have been determined to be - (25 947.1±8.5) and - (29 956.1 ± 8.9) kJ/mol respectively. A g. 1. c. analysis indicated that
the amounts of residual organic solvents in the samples were very small, and their effects on the final results were negligible.
The energy of combustion ofC60 determined in this work is in agreement in the uncertainty interval with that determined by means of traditional calorimeter
using macro amount of sample. The enthalpies of formation of these two substances have been derived. The strain energies in
the molecules of C60 and C70 were estimated by a bond energy scheme and by using corannulene as the model compound, the results estimated from different
methods are very close.
Project supported by the National Natural Science Foundation of China (Grant No. 29473143) 相似文献
46.
Sergey P. Verevkin Wei-Hong Peng Hans-Dieter Beckhaus Christoph Rüchardt 《Structural chemistry》1996,7(5-6):397-404
The standard enthalpies of combustion c
H
o of aliphatic diacetates1 and aromatic diacetates2 were measured calorimetrically. The enthalpies of vaporization vap
H
o or sublimation sub
H
o of1 and2 were obtained from the temperature function of the vapor pressure measured in a flow system. From f
H
o(g) of1 and2 new values of group increments for the estimation of standard enthalpies of formation of these classes of compounds were derived. The geminal interaction energy between the geminal acyloxy groups shows no anomeric stabilization.Geminal Substituent Effects, Part 12, for part 11 see Ref. 7. 相似文献
47.
CeO2—LnO1.5固溶体的表征及其甲烷催化燃烧性能 总被引:3,自引:0,他引:3
向CeO2中引入Ln3 离子后形成的CeO2-LnO1.5(Ln=La,Nd,Sm,Gd)固溶体(n(Ce):n(Ln)=1:1)是一种无贵金属的新型高效甲烷燃烧催化剂.比表面、XRD、Raman、TEM等分析证实,这类固溶体具有部分畸变的萤石结构,Ln3 进入晶格后诱发的结构变化使得团溶体的表面和本体能同时参与氧化还原反应.实验表明,该固态溶液体系是甲烷催化燃烧的良好催化剂. 相似文献
48.
建立高频燃烧红外吸收光谱法测定钨钛合金中碳含量的分析方法。在1980 W分析功率下,称取0.3 g样品,以2.0 g钨锡及0.5 g纯铁混合助熔,用高频红外分析仪测定碳。碳的含量在0.013%~0.050%范围内与红外吸收峰面积线性相关,相关系数为0.9993。碳的测定下限为3.6μg/g,方法检出限为1.08μg/g。该法测定结果的相对标准偏差为2.97%~4.11%(n=8),碳的加标回收率为96.2%~103.1%。该方法能够满足合金中碳含量的分析要求。 相似文献
49.
Sung Woo Moon Gun-Dae Lee Seong Soo Park Seong-Soo Hong 《Reaction Kinetics and Catalysis Letters》2004,82(2):303-310
Catalytic combustion of chlorobenzene over supported vanadium oxides has been investigated. TiO2 was prepared by the sol-gel method from titanium isopropoxide. The supported vanadium oxide catalysts have been prepared
by precipitation-deposition and impregnation method and characterized by XRD, FT-Raman and TPR. In the VOx/TiO2catalysts prepared using the impregnation method, when vanadium loading reaches 3 wt.%, the activity shows a maximum. However,
in the VOx/TiO2catalysts prepared by precipitation-deposition, when vanadium loading reaches 7 wt.%, the activity shows a maximum. This result
suggests that the precipitation-deposition can yield a higher metal loading on the support and a high dispersion compared
to the impregnation method.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
50.
Pilar Jiménez Maria Victoria Roux JiŘi Kulhánek Otto Exner 《Structural chemistry》1996,7(5-6):375-381
The energy of combustion of 2,5-dimethoxybenzoic acid has been determined using a static bomb calorimeter. The vapor pressures of the compound have been measured over a 18 K temperature interval by the Knudsen effusion technique. Heat capacity measurements betweenT=270 K andT=338 K were carried out by DSC. From these experimental results the standard molar enthalpies of combustion, sublimation, and formation in the crystalline and gaseous state at the temperature 298.15 K have been derived. With this compound, the series of mono- and dimethoxy-benzoic acids have been completed. Theirf H
m
o
values were expressed by an additive relationship, taking into account the number of methoxy groups and the number of all 1,2 interactions: an accuracy of 3.3 kJ·mol–1 was achieved. In an alternative approach the substituent effect of the methoxy groups was evaluated within the framework of isodesmic reactions. The effect of disubstitution was referred to mono derivatives and the excess energy—the so-called buttressing effect—was evaluated (2–24 kJ· mol–1 for individual bis derivatives). These values were explained in terms of the conformation of the methoxy group around the Car-O bond. 相似文献