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991.
Capillary electrophoresis with end-column amperometric detection of urinary 8-hydroxy-2'-deoxyguanosine 总被引:1,自引:0,他引:1
Urinary 8-hydroxy-2'-deoxyguanosine (8OHdG) is an excellent marker of oxidative DNA damage. Until now, urinary 8OHdG has been measured by high-performance liquid chromatography with electrochemical detection. A simple and sensitive method for the analysis of urinary 8OHdG by capillary electrophoresis with end-column amperometric detection has been developed in our laboratory. A single-step solid-phase extraction procedure was optimized and used for extracting 8OHdG from human urine. To improve the sensitivity of this method, a new focusing technique based on a dynamic pH junction was used. The limit of detection was 20 nM (signal-to-noise ratio S/N = 3), the linear range was 50 nM-10 microM, and the correlation coefficient was better than 0.999. The relative standard deviation (RSD) was found to be 0.57% for migration time, and 4.79% for peak current. To show the usefulness of the method, the urinary concentration of 8OHdG in nine healthy persons and ten cancer patients was determined. The urinary concentration of 8OHdG in cancer patients was significantly higher than that in healthy persons. 相似文献
992.
Abdelhakim Kaddouri 《Reaction Kinetics and Catalysis Letters》2004,82(2):401-409
The reaction of C2H6with lattice oxygen, O2- (in the absence of gaseous oxygen), or “adsorbedℍ oxygen (in the presence of gaseous oxygen) over NiMoO4 catalysts has been performed and compared to C3H8 activation. The results obtained indicate that adsorbed oxygen exhibits a higher reactivity to C2H6, while lattice oxygen is more reactive relative to C3H8. Kinetic studies of these two reactions in presence of molecular oxygen have indeed shown that the ethane oxidative dehydrogenation
(ODH) is dependent on the oxygen partial pressure, whilst on the contrary propane ODH is not. In order to confirm the presence
of “adsorbed” oxygen for ethane activation, ODH tests have been performed with N2O. On increasing temperature, the O- adsorbed species enhances the mild oxidation of ethane. The activation energy of ethane consumption EC2H6, relative to propane (EC3H8 = 133 kJ/mol) is 145 kJ/mol. A possible mechanism is proposed for the oxidative dehydrogenation of ethane.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
993.
The dielectric loss factor and permittivity of a series of 1, 2-polybutadienes with different contents of 1, 2-units and different contents of syndiotactie 1, 2-units were determined over a frequency range from 30Hz to 100KHz at different temperatures. The WLF equation was evaluated for various samples with T_θat 100KHz as a reference temperature and the master curves of various samples have been constructed, which are in accordance with those calculated by Havriliak-Negami equation. The frequency dependence of the dielectric relaxation of 1, 2-polybutadienes was investigated over a frequency range from 10~0 Hz to 10~(12) ZHz in terms of the experimental data and the master curves. 相似文献
994.
加氢脱氮催化剂中硫化钼结构的表征 总被引:1,自引:0,他引:1
众所周知,重油加氢脱氮(HDN)所用Mo-Ni/Al2O3催化剂需经预硫化后始有显著的活性,关于硫化的条件工业上已较成熟,但在持续反应过程中硫化催化剂的结构与活性间的关系则很复杂,如硫化钼的价态和结构、金属组分和担体间的相互作用、反应条件及原料对催化剂组分的影响,以及硫化态催化剂中MoS2结晶的形貌等都可以引起催化剂活性本质的变化. 相似文献
995.
A molecular mechanics software enhanced to perform empirical energy calculations on crystals (KESSHOU) was further developed to handle intermolecular electrostatic interactions as well. The packing of the molecules of 1,4-dicyanobenzene and 1,4-diisocyanobenzene in the crystal was studied. The role of the van der Waals and the electrostatic interactions in the balance of nonbonded atom-atom interactions is analyzed. The packing forces are dominated by van der Waals forces. The electrostatic interactions have higher stabilizing contribution for the dicyano isomer than for the diisocyano form. The dependence of the results on the size of the crystal, the molecular mechanics force field (MM2 vs MM3), and the dielectric constant are also assessed. Ab initio MP2/6–311G** geometries of the isolated molecules are in accordance with the observed benzene ring distortions determined by electron diffraction. 相似文献
996.
CeO2及Pt/CeO2催化剂上H2、O2的作用特性 总被引:12,自引:1,他引:12
采用TPD、TPR、FT-IR和TPEC等方法研究了CeO_2及Pt/CeO_2上H_2、O_2作用特性。结果表明, Pt促进CeO_2还原, 并形成高活动性氢物种。Pt的存在使吸H_2和放氢温度下阵达300 ℃。部分还原的CeO_2常温下吸附氧形成分子离子氧物种(O_2~-, O_2~(2-)), Pt的存在改变氧化铈催化剂在常温下氧吸附物种的形态, 以解离态存在。氧化铈上吸附的氧物种在升温时可部分脱附, 高于170 ℃时则转化为晶格氧。 相似文献
997.
Zur Synthese von fungizid wirksamen Isocamphanderivaten: Synthesen in der Isocamphanreihe, 34. Mitt.
Gerhard Buchbauer Helmut Spreitzer Margarete Kneidinger 《Monatshefte für Chemie / Chemical Monthly》1990,121(6-7):549-554
Summary Some esters of isocamphenilanic acid (4) have been prepared and tested for their fungicidal and insecticidal activity. Esters of various acids with isocamphanyl ethylalcohol (5) have also been synthesized and included in the fungicidal/acaricidal/insecticidal screening programme. All esters bear a geminal dimethyl group at C-3 of the bicyclus which is important because of its shielding effect. 相似文献
998.
I. V. Ukrainets A. A. Tkach L. V. Sidorenko O. V. Gorokhova 《Chemistry of Heterocyclic Compounds》2006,42(10):1301-1307
1-R-4-Hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxylic acid anilides have been prepared. It has been shown experimentally that
these compounds are brominated by molecular bromine in glacial acetic acid at position 4 of the anilide fragment. The antitubercular
properties of the compounds synthesized are discussed.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1508–1516, October, 2006. 相似文献
999.
Zr0.5Ti0.5O2(ZT) and Zr0.25Ti0.25Al0.5O2(ZTA) mixed oxides were prepared by co-precipitation method and characterized by low temperature adsorption-desorption, XRD and NH3-TPD. The activity of Pt/Zr0.5Ti0.5O2 and Pt/ Zr0.5Ti0.5Al0.5O2 catalysts was evaluated using the simulated gases. The results show that ZTA samples exhibit higher specific surface area, larger pore volume and proper surface acidic amount and acidity in comparison with ZT. The results of the catalytic test indicate that Pt/ZT and Pt/ZTA catalysts exhibit excellent low-temperature catalytic activity and lower light-off temperatures of hydrocarbon, carbon monoxide and nitrogen oxides, especially better conversion for nitrogen oxides (NOx). The addition of Al2O3 into ZT enhanced the anti-aging property of Pt/ ZTA catalysts due to the excellent textural, structural, surface acidity and thermal stability. 相似文献
1000.
Richa Pathak 《Tetrahedron》2007,63(2):451-460
Trifluoroacetic acid has been discovered to be a highly effective and efficient reagent for the tandem Claisen rearrangement and cyclization reaction to yield 3-arylmethylene-3,4-dihydro-1H-quinolin-2-ones from compounds obtained from the SN2 reaction between anilines and acetyl derivatives of Baylis-Hillman adducts of acrylates in the presence of DABCO. In contrast, similar compounds obtained from the acetyl derivatives of Baylis-Hillman adduct of acrylonitrile on treatment with trifluoroacetic acid directly furnish 3-arylmethyl-2-amino-quinoline via tandem Claisen rearrangement, cyclization and isomerization. 相似文献