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171.
Tingzhen Li Yong Yang Zhichao Tao Haijun Wan Xia An Chenghua Zhang Hongwei Xiang Yongwang Li 《天然气化学杂志》2007,16(4):354-362
The effect of sulfate on Fischer-Tropsch synthesis performance was investigated in a slurry- phase continuously stirred tank reactor(CSTR)over a Fe-Mn catalyst.The physiochemical properties of the catalyst impregnated with different levels of sulfate were characterized by N_2 physisorption,X-ray photoelectron spectroscopy(XPS),H_2(or CO)temperature-programmed reduction(TPR),Mφssbauer spectroscopy,and CO_2 temperature-programmed desorption(TPD).The characterization results indicated that the impregnated sulfate slightly decreased the BET surface area and pore volume of the catalyst, suppressed the catalyst reduction and carburization in CO and syngas,and decreased the catalyst surface basicity.At the same time,the addition of small amounts of sulfate improved the activities of Fischer- Tropseh synthesis(FTS)and water gas shift(WGS),shifted the product to light hydrocarbons(C_1-C_(11)) and suppressed the formation of heavy products(C_(12 )).Addition of SO_4~(2-)to the catalyst improved the FTS activity at a sulfur loading of 0.05-0.80 g per 100 g Fe,and S-05 catalyst gave the highest CO conversion(62.3%),and beyond this sulfur level the activity of the catalyst decreased. 相似文献
172.
Using laser flash photolysis/transient absorption technique for the study of two photon photodissociation of carbon disulfide in acetonitrile solution at 266 nm, the transient UV-Vis absorption spectrum of Rydberg state CS2 (6sσg) within 240-370 nm and subsequent dissociation product CS (α^3П) with the maximum absorption at 260 nm were directly observed. The lifetime of CS (α^3П) in the nitrogen and oxygen saturated solution is also studied in our experiment. 相似文献
173.
本文采用多柱自动切换气相色谱仪和真空全脱气装置对变压器和互感器用油中的气体进行了系统的分析,除可测定油中的氢、甲烷、乙炔、乙烯、乙烷、二氧化碳和一氧化碳等气体外,还可根据不同需要测定氮、氧以及C3和C4烃的含量。本方法已用于诊断变压器和互感器内部变化及故障。 相似文献
174.
110例脑卒中患者血清中铁,锌,铜,锰,硒,铬,钴,镍的含量水平与对照组比较,结果显示:1.血清的,铜和铬的含量升高,锌,钴和镍的含量降低,两者之间的差异均有高度显著性,P〈0.01;2.血清锰和硒的含量与对照组差异无显著性,P〉0.05;3.在临床上述元素含量变化可用于脑座中的辅助诊断和治疗。 相似文献
175.
The adsorption of (R)- and (S)-2-phenylpropionamide (PPA, C(9)H(11)ON) molecules on a Cu(111) surface has been investigated using the density functional method with supercell models. The adsorption orientations of both (R)- and (S)-PPA molecules on the surface are the same: the phenyl rings are approximately parallel to the Cu(111) surface and positioned in the hollow sites, the amino and methyl groups occupy two-bridge sites, and the carbonyl occupies the top site. After the adsorption, the bond lengths in the two enantiomers are almost unchanged, but the changes for two dihedral angles show differences, especially for (R)-PPA molecule. The first angles between the (N,C9,C7) plane and the (C9,C7,C6) plane are 19.4 and 0.7 degrees for (R)- and (S)-PPA molecules, respectively, and the second angles between the (C8,C7,C6) plane and the (C7,C6,C5) plane are 74.8 and 0.4 degrees for (R)- and (S)-PPA molecules, respectively. The adsorption energies of (R)- and (S)-PPA molecules are calculated to be -34 and -26 kJ mol(-1), respectively. The simulated scanning tunneling microscopy (STM) images of (R)- and (S)-PPA molecules on the Cu(111) surface display different features and are coincident with the experimental ones. The interaction between the adsorption molecule and the metal surface is found to be responsible for the discrimination of (R)- and (S)-PPA molecules on the surface. 相似文献
176.
Liu H Zhang X Gao H Wang N Jin S Cai B Yao X Cai G 《Chemical & pharmaceutical bulletin》2005,53(10):1310-1313
Phytochemical study of the ethanol extract of the seeds of Aesculus assamica led to the isolation of two new triterpenoid saponins. The structure of the new compounds were elucidated on the basis of spectral data to be 28-O-acetyl-21-O-(4-O-angeloyl)-6-deoxy-beta-glucopyranosyl-3-O-[beta-glucopyranosyl(1-2)-O-[beta-glucopyranosyl(1-4)]-beta-glucuronopyranosyl]protoaescigenin (1), and 21-O-(4-O-angeloyl)-6-deoxy-beta-glucopyranosyl-3-O-[beta-glucopyranosyl(1-2)-O-[beta-glucopyranosyl(1-4)]-beta-glucuronopyranosyl]protoaescigenin (2). Their in vitro bioactivity against plant pathogenic fungus Pyricularia oryzae and cytotoxicity against K562 and HCT-15 cell lines were evaluated. 相似文献
177.
178.
In the reaction of methane and carbon dioxide to C2 hydrocabons under non-equilibrium plasma, methane conversion was decreased,but selectivity of C2 hydroxarbons was increased when using La2O3/γ-Al2O3 as catalyst. So the yield of C2 hydrocarbons was higher than using plasma alone. The synergism of La2O3/γ-Al2O3 and plasma gave methane conversion of 24.9% and C2 yield of 18.1%. The distribution of C2 hydrocarbons changed when Pd-La2O3/γ-Al2O3 was used as catalyst,the major C2 product was ethylene. 相似文献
179.
A chemiluminescence signal at 425 nm was observed when ferric state myoglobin was mixed with luminol in alkaline medium. Because the signal was remarkably enhanced in the presence of Fe(CN)6
4–, analytical applications were investigated in a flow-injection system. The increase in chemiluminescence was linearly dependent on myoglobin concentration in the range 0.1 to 100 nmol L–1, and the limit of detection was 0.04 nmol L–1 with relative standard deviation 3.2% (3). It was also found that binding of Mb with the ligands CN–, SCN–, and F– significantly inhibited the chemiluminescence reaction. The linear dynamic ranges for the ligands were 1.0–300.0, 0.1–3.0, and 0.5–100.0 nmol L–1, and the limits of detection (S/N=3) 0.4, 0.04, and 0.2 nmol L–1, for F–, CN–, and SCN–, respectively. The relative standard deviations were 5.32%, 6.13%, and 3.38% for 0.1 nmol L–1 CN–, 0.5 nmol L–1 SCN–, and 1.0 nmol L–1 F–, respectively. At a flow rate of 2.0 mL min–1 the assay could be accomplished in 1 min, including sampling and washing. The method has been successfully applied to the determination of myoglobin in human urine and F– in water samples. A possible mechanism of chemiluminescence production by myoglobin and luminol is presented. 相似文献
180.