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971.
J. H. Liu L. P. Wang Q. M. Xiao Z. Yao H. Ding 《Plasma Chemistry and Plasma Processing》2010,30(3):349-361
This work reports laser ionization combined with Time-Of-Flight (TOF) mass spectrometry investigation on intermediate species in the hydrocarbon plasma of atmospheric-pressure fast-flow pulsed dc-discharge. All neutral intermediate species including transient radicals from benzene/Ar discharge have been characterized by a molecular beam sampling combined with TOF mass spectrometry. This shows that with a hydrocarbon gas mixture of 0.3% C6H6 in Ar discharge the intermediate species consist of simple radicals (such as C2, C5H5, C7H7) and polycyclic organic molecules (C10H8, C13H10, C14H10). Theoretical studies on total energies and ionization potentials of the intermediate species have been carried out using the hybrid density functional theory. Effect of the ionization potential on mass spectral intensity has been discussed. Based on the observed data, the possible major neutral reaction channels of the plasma chemistry have been discussed. The developed experimental method has implications in volatile organic compounds removing and impurities diagnosis in Tokamak edge-plasma. 相似文献
972.
The effect of gas flow rate on crystal structures of electrospun and gas-jet/electrospun poly(vinylidene fluoride) (PVDF) fibers was investigated.PVDF fibers were prepared by electrospinning and gas-jet/electrospinning of its N,N-dimethylformamide (DMF) solutions.The morphology of the PVDF fibers was investigated by scanning electron microscopy (SEM).With an increase of the gas flow rate,the average diameters of PVDF fibers were decreased.The crystal structures and thermal properties of the PVDF fibers w... 相似文献
973.
Planar or quasi-planar octa- and ennea-coordinate aluminum and gallium in boron rings 总被引:1,自引:1,他引:1
GUO JinChang YAO WenZhi LI Zhuo LI SiDian Institute of Materials Science Department of Chemistry Xinzhou Teachers’ University Xinzhou China International School of Software Wuhan University Wuhan 《中国科学B辑(英文版)》2009,52(5):566-570
An ab initio theoretical investigation has been performed on planar or quasi-planar octa-and ennea-coordinate Al and Ga centered in X@B8- and X@B9 (X=Al, Ga). These high symmetry molecular wheels all turned out to be true minima of the systems and σ+π double aromatic in nature, similar to the previously characterized D8h B@B8- both electronically and geometrically. Adiabatic and vertical detachment energies of the anions and the ionization potentials of the neutrals have been calculated to aid their eventua... 相似文献
974.
In this work Bi(SbxNbyTaz)O4 (x + y + z = 1) samples are prepared using mixed-oxide method. A pseudo-ternary phase diagram of Bi(Sb,Nb,Ta)O4 system is given below the melting point. It is composed of a monoclinic phase region, an orthorhombic phase region and a monoclinic–orthorhombic co-existing phase region. In the orthorhombic phase region, the transformation from orthorhombic to triclinic phase is found to be sensitive to the composition and sintering temperature. Both the transformation from monoclinic to orthorhombic structure and the transformation from orthorhombic to triclinic structure have been studied by the cell parameters. 相似文献
975.
Ke Xin Huang Yu Bing Feng Wei Yao Lei Xiang Yang Feng Wang Hai Bo Li Su Zeng Jing Xu Gong Ming Hui Hu Yu Zhao Xiu Mei Wu Xiao Kun Li Jia Qu 《中国化学快报》2009,20(10):1187-1190
Four naturally rare 5,6,7-trimethoxy-2,3-cis-dihydroflavonols(3-6) and two 5,6,7-trimethoxy-2,3-trans-dihydroflavonols(7-8) were designed and synthesized.Their antioxidative properties were evaluated by way of examining their scavenging capacities towards DPPH and O_2~(·-) free radicals,as well as by measuring their inhibitory ability against LPO.Both the 2,3-trans and the 2,3- cis conformers exhibited certain quenching abilities to DPPH and O_2~(·-) radicals,while most of the synthetic dihydroflavonols ... 相似文献
976.
使用反馈式微机控制双注乳化仪,在晶体生长过程中一定时间内,加入一定量的草酸盐,制得了草酸根离子处于晶体颗粒次表面的板状溴碘化银微晶乳剂.对其实验过程的考察和感光性能的测试结果表明:1)草酸根掺杂于次表面的溴碘化银乳剂与未掺杂乳剂相比较,经过化学增感后,或光谱增感后的乳剂,其感光度有明显提高(Sd/S0≥1.5),即具有明显的增感效应;2)无论是经过化学增感,还是经光谱增感后的乳剂,草酸根掺杂溴碘化银颗粒乳剂的灰雾水平都不高. 相似文献
977.
Dong-Bao Hu Xiao-Mei Yang Li-Feng Yao Ling-Xia Zhang Shu-Ye Ma Shi-Wen Yu Tao-Hong Li Xiao-Guang Xie 《Journal of Molecular Structure》2009,915(1-3):188-192
The mechanisms for the three products ZrS+, and ZrOS+ of the title reaction have been studied by using B3LYP/6-311+G* and CCSD(T)/SDD+6-311+G* methods. It is found that both ZrS+ and formations involve the same O/S exchange process via a four-center transition state TS12 to form an intermediate IM2. Exception of that IM2 can dissociate into the ZrS+ product, a favorable intramolecular rearrangement mechanism associated with the formation has been identified, which explains why ZrS+ was excluded as a precusor for the formation and why the lower efficiency of the ZrS+ formation was observed in experiment. For the formation of ZrOS+, two parallel channels (path A and B) yielding their corresponding product isomer have been identified. Path B involving an insertion–elimination mechanism with a calculated barrier underestimated by ca. 25.0 kJ/mol should be attributed to the threshold of 114.8 ± 12.5 kJ/mol assigned in the experiment. But path A should make some contributions to the formation of ZrOS+ at elevated energy. 相似文献
978.
Direct electrochemical and electrocatalytic behavior of hemoglobin (Hb) immobilized on glass carbon electrode (GCE) containing gelatine (Gel) films was investigated. The characteristics of Hb/Gel film modified GC electrode were performed by using SEM microscopy, UV-vis spectroscopy and electrochemical methods. The immobilized Hb showed a couple of quasi-reversible redox peak with a formal potential of −0.38 V (versus SCE) in 0.1 M pH 7.0 PBS. The formal potential changed linearly from pH 4.03 to 8.41 with a slope value of −52.0 mV pH−1, which suggested that a proton transfer was accompanied with each electron transfer (ET) in the electrochemical reaction. The Hb/gelatine/GCE displayed a rapid amperometric response to the reduction of H2O2 and nitrite. 相似文献
979.
Tetrazole Photoclick Chemistry: Reinvestigating Its Suitability as a Bioorthogonal Reaction and Potential Applications 下载免费PDF全文
Dr. Zhengqiu Li Linghui Qian Prof. Dr. Lin Li Dr. Jan C. Bernhammer Prof. Dr. Han Vinh Huynh Prof. Dr. Jun‐Seok Lee Prof. Dr. Shao Q. Yao 《Angewandte Chemie (International ed. in English)》2016,55(6):2002-2006
The bioorthogonality of tetrazole photoclick chemistry has been reassessed. Upon photolysis of a tetrazole, the highly reactive nitrile imine formed undergoes rapid nucleophilic reaction with a variety of nucleophiles present in a biological system, along with the expected cycloaddition with alkenes. The alternative use of the tetrazole photoclick reaction was thus explored: tetrazoles were incorporated into Bodipy and Acedan dyes, providing novel photo‐crosslinkers with one‐ and two‐photon fluorescence Turn‐ON properties that may be developed into protein‐detecting biosensors. Further introduction of these photo‐activatable, fluorogenic moieties into staurosporine resulted in the corresponding probes capable of photoinduced, no‐wash imaging of endogenous kinase activities in live mammalian cells. 相似文献
980.