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991.
992.
AnExplanationontheElectronIonizationMassSpectraofCrownEthersbyMNDOComputationalMethodYUANHu-shan,TANGMing-shengandWUYang-jie(... 相似文献
993.
The CGC analysis of 25 organophosphorus and organonitrogen pesticides was optimized on two different stationary phases, namely a 5% diphenyl dimethyl silicone (SE-54 type) and a 50% diphenyl dimethyl silicone (OV-17 type) by selecting the best temperature program conditions, using computer simulation. 相似文献
994.
Yang G Miao R Jin C Mei Y Tang H Hong J Guo Z Zhu L 《Journal of mass spectrometry : JMS》2005,40(8):1005-1016
Interaction of carboplatin with cytochrome c (Cyt. c) has been investigated by electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (MS/MS). ESI-MS studies revealed that the ring-opened adducts of carboplatin with Cyt. c were formed in the stoichiometric ratio of 1:1 and 2:1 at pH 5.0 and 37 degrees C and in the stoichiometric ratio of 1:1 only at pH 7.0 and 37 degrees C. It was also found that Cyt. c could be cleaved by carboplatin at pH 2.5 and 50 degrees C. The cleaved fragments of Cyt. c were determined by ESI-MS and MS/MS analysis to be Glu66 approximately Met80, Ac-Gly01 approximately Met65, Glu66 approximately Glu104, Ac-Gly01 approximately Met80 and Ile81 approximately Glu104. The carboplatin prefers to anchor to Met65 first, then to Met80. To further confirm the binding site of Met, AcMet-Gly was used as the model molecule to investigate its interaction with carboplatin and its hydrolysis reaction. On the basis of species detected during the reaction monitored by ESI-MS, a possible pathway of the cleavage reaction was proposed. 相似文献
995.
液体色谱,凝胶色谱分析低聚芳砜及其双烯大分子单体 总被引:2,自引:0,他引:2
本文用液相色谱和凝胶色谱对双酚A、双酚S型低聚芳砜及α,ω-双甲基丙烯酸聚芳砜酯大分子单体进行了组分分析,通过改合成条件、测定数均分子量等辅助手段确定液相色谱各峰的归属,计算其分子量及分子量分布指数,并对两种方法测定的结果进行了比较。用液相色谱观察低聚体每个组分的含量及其反应过程中的消长情况比凝胶色谱清晰。 相似文献
996.
This paper describes the screening for metabolites of butoprozine, a new anti-anginal drug, in dog bile by means of reverse-phase HPLC. Although it does involve a simple clean-up step to remove a substantial amount of endogenous bile compounds, this screening method nevertheless avoids extraction of metabolites and thus allows all metabolites to be introduced into the chromatographic system. A single run of 100 minutes from 100% water to 100% methanol in a linear gradient effects adequate separation of the great majority of metabolites without interference from remaining endogenous compounds. Two methods of differentiating between metabolite peaks and endogenous peaks have been worked out. The first one makes use of 14C-labeled butoprozine by measuring the amount of radioactivity in the column effluent while simultaneously recording the UV absorbance. The second method compares continuous gradient chromatograms of bile recorded before and after butoprozine administration under very similar conditions. The latter method can be applied to both radioactive and non-radioactive materials. 相似文献
997.
在量子化学对SiH与H2O和H2S反应计算的基础上,运用统计热力学和Wigner校正的Eyring过渡态理论,计算了上述两反应在200~2000 K温度范围内的热力学函数、平衡常数、频率因子A和速率常数随温度的变化。计算结果表明,两反应在低温下具有热力学优势,而在高温下具有动力学优势。比较两反应的计算结果发现,在相同的温度下,SiH与H2O反应比SiH与H2S反应放热较多,但速率常数却较小。SiH与H2O反应和前文报道的SiH与HF反应的比较表明,SiH与H2O反应放热较少,而且在相同温度下,速率常数也较小。 相似文献
998.
A general route for the synthesis of highly substituted aryl cyclopentanes has been developed involving Diels-Alder reaction of asymmetric dienes prepared from (+)-camphoric acid followed by aromatization of the resulting cyclohexene derivatives. Employing this protocol enantiospecific synthesis of (+)-herbertene and (+)-cuparene has been accomplished. 相似文献
999.
Fe-Mn, Co-Mn and Ni-Mn composite oxide catalysts based on high specific surface area MnO2 precursor were prepared and applied to catalytic combustion of CH4. Results were compared with that of unmodified MnOx and 1wt.% Pd/-Al2O3. Below 450°C, manganese oxide catalysts show higher activity than Pd/-Al2O3, while the modified manganese oxide catalysts exhibit higher activity than the unmodified one below 420°C. All catalysts were characterized by means of N2-BET, XRD, TG-DTA and H2-TPR. Due to the interaction between Fe, Co or Ni oxides and manganese oxide, the activity of the oxygen species of the modified catalysts is improved, which leads to the increase of their CH4 combustion activity. 相似文献
1000.
Eulogio Jimenez Luis Romani Maria Inmaculada Paz Andrade Geneviève Roux-Desgranges Jean-Pierre E. Grolier 《Journal of solution chemistry》1986,15(11):879-890
Molar excess volumes V
E
at 25°C have been determined by vibrating-tube densimetry, as a function of mole fraction x for different series of an alkanoate (H
2m+1
C
m
COOC
n
H
2n+1
)+cyclohexane. Three types of alkanoates were investigated, i.e., methanoates (m=0, with n=3 and 4), ethanoates (m=1, with n=2, 3, and 4) and propanoates (m=2, with n=1, 2, and 3). In addition, a Picker flow calorimeter was used to obtain molar excess heat capacities C
p
E
at constant pressure at the same temperature. V
E
is positive for all systems and rather symmetric, with V
E
(x=0.5) amounting to almost identical values in a series of mixtures containing an alkanoate isomer of same formula (say C4H8O2, C5H10O2, or C6H12O2). The composition dependence of C
p
E
is rather unusual in that two more or less marked minima are observed for most of the mixtures, especially when the alkanoate is a methanoate or an ethanoate. These results are discussed in terms of possible changes in conformation of both the ester and cyclohexane. 相似文献