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球型和棒状金纳米粒子的光谱性质比较 被引量:5
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作者 张兴霞 周群 +1 位作者 庞芬只 郑军伟 《光谱实验室》 CAS CSCD 2005年第3期457-460,共4页
柠檬酸钠还原和诱导晶种生长法合成了球型和棒状金纳米粒子。金纳米粒子的吸收光谱表明,表面等离子体共振(SPR)强烈依赖于金属粒子的形状,球型粒子表现为单-SPR谱峰,而棒状粒子则具有横向和纵向SPR谱峰,且纵向SPR峰位和强度取决于棒状... 柠檬酸钠还原和诱导晶种生长法合成了球型和棒状金纳米粒子。金纳米粒子的吸收光谱表明,表面等离子体共振(SPR)强烈依赖于金属粒子的形状,球型粒子表现为单-SPR谱峰,而棒状粒子则具有横向和纵向SPR谱峰,且纵向SPR峰位和强度取决于棒状粒子的径横比。棒状金纳米粒子对吸附的对巯基苯甲酸分子的拉曼散射比球型金纳米粒子具有更强的表面增强性能,归因于棒状粒子高能晶面上的吸附可能导致的更强的化学增强效应。 展开更多
关键词 金纳米粒子 表面等离子体共振 表面增强拉曼光谱 射电 对巯基苯甲酸
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年轻恒星形成过程的分子谱线诊断
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作者 席尚忠 秦胜利 +1 位作者 邓李才 杨戟 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2001年第4期456-458,共3页
恒星是宇宙的基本天体 ,理解恒星的起源和早期演化是天体物理最有兴趣的课题之一。目前了解的恒星形成的一个基本图象是 ,恒星是由一个足够大质量的星际分子气体云在其自引力作用下塌缩而形成。在早期塌缩过程中形成一颗原恒星 (胚胎 ) ... 恒星是宇宙的基本天体 ,理解恒星的起源和早期演化是天体物理最有兴趣的课题之一。目前了解的恒星形成的一个基本图象是 ,恒星是由一个足够大质量的星际分子气体云在其自引力作用下塌缩而形成。在早期塌缩过程中形成一颗原恒星 (胚胎 ) ,并且伴随环绕该原恒星的吸积盘。原恒星吸积星际介质中的分子物质 ,通过吸积盘转移到原恒星表面 ,原恒星的质量随着增大。在吸积过程中也同时伴随物质向外的剧烈喷发。由于盘的存在 ,这种喷发通常沿垂直于盘的方向进行 ,出现双极的空间分布。在天文观测上 ,一种典型的表现是分子气体的外向流 ,观测表现为从原恒星双极的红蓝移气体运动[1] 。由于恒星形成于星际分子中 ,因此 ,对星际分子的谱线探测是研究恒星形成的强有力手段。现在已经发现和证认的星际分子总数有一百多种 ,其中丰富度最高的气体是H2 。在所有的星际分子中 ,丰度仅次于H2的CO分子的转动跃迁谱易激发 ,相对于星际介质的不透明度小 ,观测上易于实现 ,因此 ,CO分子就成为探索原恒星形成的有力探针。在毫米波段出现的J=1- 0和J=2 - 1跃迁谱线以及CO同位素的谱线是最常使用的观测探针。八十年代以来又陆续发现了环形分子SiC2 、C3 H、C3 H2 及含磷分子PN和CN等 ,给宇宙中有机世界的探测提供了丰富的线索。 展开更多
关键词 射电光谱 星际分子 分子云 恒星 形成过程 分子谱线 诊断
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Fe-Mn/Al_2O_3 catalysts for low temperature selective catalytic reduction of NO with NH_3 被引量:7
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作者 王晓波 伍士国 +3 位作者 邹伟欣 虞硕涵 归柯庭 董林 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2016年第8期1314-1323,共10页
A series of Fe‐Mn/Al2O3 catalysts were prepared and studied for low temperature selective catalytic reduction (SCR) of NO with NH3 in a fixed‐bed reactor. The effects of Fe and Mn on NO conversion and the deactiva... A series of Fe‐Mn/Al2O3 catalysts were prepared and studied for low temperature selective catalytic reduction (SCR) of NO with NH3 in a fixed‐bed reactor. The effects of Fe and Mn on NO conversion and the deactivation of the catalysts were studied. N2 adsorption‐desorption, X‐ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, H2 temperature‐programmed reduction, NH3 temperature‐programmed desorption, X‐ray photoelectron spectroscopy (XPS), thermal gravimetric analysis and Fourier transform infrared spectroscopy were used to character‐ize the catalysts. The 8Fe‐8Mn/Al2O3 catalyst gave 99%of NO conversion at 150?? and more than 92.6%NO conversion was obtained in a wide low temperature range of 90–210??. XPS analysis demonstrated that the Fe3+was the main iron valence state on the catalyst surface and the addition of Mn increased the accumulation of Fe on the surface. The higher specific surface area, enhanced dispersion of amorphous Fe and Mn, improved reduction properties and surface acidity, lower binding energy, higher Mn4+/Mn3+ratio and more adsorbed oxygen species resulted in higher NO conversion for the 8Fe‐8Mn/Al2O3 catalyst. In addition, the SCR activity of the 8Fe‐8Mn/Al2O3 cata‐lyst was only slightly decreased in the presence of H2O and SO2, which indicated that the catalyst had better tolerance to H2O and SO2. The reaction temperature was crucial for the SO2 resistance of catalyst and the decrease of catalytic activity caused by SO2 was mainly due to the sulfate salts formed on the catalyst. 展开更多
关键词 Nitrogen monoxide Low-temperature selective catalytic reduction Fe-Mn catalyst X-ray photoelectron spectroscopy Sulfur dioxide Fourier transform infrared spectroscopy
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Synchrotron-Radiation Photoemission Study of Growth and Stability of Au Clusters on Rutile TiO2(110)-1×1 被引量:1
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作者 于欣 许令顺 +3 位作者 张文华 姜志全 朱俊发 黄伟新 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2009年第4期339-345,447,共8页
The growth and thermal stability of Au clusters on a partially-reduced rutile TiO2 (110)-1 × 1 surface were investigated by high-resolution photoelectron spectroscopy using synchrotron- radiation-light. The val... The growth and thermal stability of Au clusters on a partially-reduced rutile TiO2 (110)-1 × 1 surface were investigated by high-resolution photoelectron spectroscopy using synchrotron- radiation-light. The valence-band photoelectron spectroscopy results demonstrate that the Ti^3+3d feature attenuates quickly with the initial deposition of Au clusters, implying that Au clusters nucleate at the oxygen vacancy sites. The Au4f core-level photoelectron spectroscopy results directly prove the existence of charge transfer from oxygen vacancies to Au clusters. The thermal stability of Au clusters on the partially-reduced and stoichiometric TiO2(110) surfaces was also comparatively investigated by the annealing experiments. With the same film thickness, Au clusters are more thermally stable on the partially-reduced TiO2(110) surface than on the stoichiometric TiO2(110) surface. Meanwhile, large Au nanoparticles are more thermally stable than fine Au nanoparticles. 展开更多
关键词 Synchrotron-radiation photoelectron spectroscopy Au cluster TiO2(110) Charge transfer Thermal stability
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Interface Reaction of SiO_2/Ta and Its Influence on Cu Diffusion 被引量:1
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作者 龙世兵 马纪东 +4 位作者 于广华 赵洪辰 朱逢吾 张国海 夏洋 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2002年第10期1046-1050,共5页
Ta/NiFe film is deposited on Si substrate precoated with SiO_2 by magnetron sputtering.SiO_2/Ta interface and Ta_5Si_3 standard sample are investigated by using X-ray photoelectron spectroscopy (XPS) and peak decompos... Ta/NiFe film is deposited on Si substrate precoated with SiO_2 by magnetron sputtering.SiO_2/Ta interface and Ta_5Si_3 standard sample are investigated by using X-ray photoelectron spectroscopy (XPS) and peak decomposition technique.The results show that there is a thermodynamically favorable reaction at the SiO_2/Ta interface:37Ta+15SiO_2=5Ta_5Si_3+6Ta_2O_5.The more stable products Ta_5Si_3 and Ta_2O_5 may be beneficial to stop the diffusion of Cu into SiO_2. 展开更多
关键词 copper interconnection in ULSI diffusion barrier interface reaction X-ray photoelectron spectroscopy
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Photoionization Mass Spectrometric and Kinetic Modeling of Low-pressure Pyrolysis of Benzene 被引量:2
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作者 杨玖重 赵龙 +2 位作者 蔡江淮 齐飞 李玉阳 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2013年第3期245-251,I0003,共8页
Pyrolysis of benzene at 30 Torr was studied from 1360 K to 1820 K in this work. Synchrotron vacuum ultraviolet photoionization mass spectrometry was employed to detect the pyroly- sis products such as radicals, isomer... Pyrolysis of benzene at 30 Torr was studied from 1360 K to 1820 K in this work. Synchrotron vacuum ultraviolet photoionization mass spectrometry was employed to detect the pyroly- sis products such as radicals, isomers and polycyclic aromatic hydrocarbons, and measure their mole fraction profiles versus temperature. A low-pressure pyrolysis model of benzene was developed and validated by the experimental results. Rate of production analysis was performed to reveal the major reaction networks in both fuel decomposition and aromatic growth processes. It is concluded that benzene is mainly decomposed via H-abstraction reaction to produce phenyl and partly decomposed via unimolecular decomposition reac- tions to produce propargyl or phenyl. The decomposition process stops at the formation of acetylene and polyyne species like diacetylene and 1,3,5-hexatriyne due to their high thermal stabilities. Besides, the aromatic growth process in the low-pressure pyrolysis of benzene is concluded to initiate from benzene and phenyl, and is controlled by the even carbon growth mechanism due to the inhibited formation of C5 and C7 species which play important roles in the odd carbon growth mechanism. 展开更多
关键词 BENZENE Low-pressure pyrolysis PAH formation Synchrotron vacuum ultra-violet photoionization mass spectrometry Kinetic model
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The Determination of Heavy Metal Elements in Honey by MWD-ICP-AES 被引量:3
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作者 陈文 王湘君 +5 位作者 赵阳 苏利兴 张哲 莫兰发 欧阳敏 黄梁 《Agricultural Science & Technology》 CAS 2014年第6期890-894,共5页
In order to build method for measuring of elements in honey, the contents of Ba, Cu, Pb, Cd, As, Hg, Cr, Mn, Se had been determined by microwave diges- tion (MWD) and actively coupled plasma atomic emission spectrom... In order to build method for measuring of elements in honey, the contents of Ba, Cu, Pb, Cd, As, Hg, Cr, Mn, Se had been determined by microwave diges- tion (MWD) and actively coupled plasma atomic emission spectrometry (ICP-AES). The results show that, the range of heavy metal elements were in the range of 0- 10.0 mg/L, with good linear relationship. In addition, all correlation coefficients kept higher than 0.999, and the recovery rate of ample added with standard solution was in 94.1%-110%. By comparison with the result of chemical experiment, the method was quickly accessible and convenient, widely used in the measurement of elements in honey, with satisfactory results. 展开更多
关键词 HONEY ICP-AES MWD ELEMENT
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AFM and XPS Study on the Surface and Interface States of CuPc and SiO_2 Films
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作者 陈金伙 王永顺 +2 位作者 朱海华 胡加兴 张福甲 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2006年第8期1360-1366,共7页
A CuPc/SiO2 sample is fabricated. Its morphology is characterized by atomic force microscopy, and the electron states are investigated by X-ray photoelectron spectroscopy. In order to investigate these spectra in deta... A CuPc/SiO2 sample is fabricated. Its morphology is characterized by atomic force microscopy, and the electron states are investigated by X-ray photoelectron spectroscopy. In order to investigate these spectra in detail, all of these spectra are normalized to the height of the most intense peak,and each component is fitted with a single Gaussian function. Analysis shows that the O element has great bearing on the electron states and that SiO2 layers produced by spurting technology are better than those produced by oxidation technology. 展开更多
关键词 CuPc/SiO2 X-ray photoelectron spectroscopy surface and interface analysis
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Analysis of PTCDA/ITO Surface and Interface Using X-ray Photoelectron Spectroscopy and Atomic Force Microscopy
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作者 欧谷平 宋珍 +1 位作者 桂文明 张福甲 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2006年第2期229-234,共6页
The electronic states of the surface and interface of 3,4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA)/indium-tin-oxide (ITO) thin film are investigated using X-ray photoelectron spectroscopy (XPS). A- tom... The electronic states of the surface and interface of 3,4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA)/indium-tin-oxide (ITO) thin film are investigated using X-ray photoelectron spectroscopy (XPS). A- tomic force microscopy (AFM) is also applied to investigate the pattern of PTCDA/ITO film. XPS results show that there are two main peaks,which are associated with C atoms in the perylene rings and acid anhydride groups, located at 284.6 and 288.7eV, respectively,in the Cls spectrum of the original surface. It can be deduced from the emergence of a small peak at 290.4eV in the Cls spectrum that some C atoms are oxidized by O atoms from ITO. The binding energies of O atoms in C-O bonds and C--O---C bonds are 531.5 and 533.4eV respectively. At the interface,the peak at the high binding energy in the Cls spectrum disappears,and the peak value shifts about 0.2eV to lower binding energy, There is a significant 1.5eV chemical shift to lower binding energy in the Ols spectrum. These observations indicate that perylene rings inside PTCDA molecules are combined with In vacancies in the ITO at the interface. The AFM results show that PTCDA molecules formed an island-like structure a height of about 14nm. The sizes of the crystal grains are about 100--300nm. The island-like pattern comes from the delocalized π bonds of adjacent molecules in PTCDA and the combination of vacancies in ITO with perylene rings at the PTCDA/ITO interface. 展开更多
关键词 AFM XPS PTCDA
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Effect of Rapid Thermal Annealing Ambient on Gettering Efficiency and Surface Microstructure in 300mm CZ Silicon Wafers
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作者 冯泉林 何自强 +1 位作者 常青 周旗钢 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2008年第5期822-826,共5页
The effect of rapid thermal annealing (RTA) ambient on denuded zone and oxygen precipitates in Czochralski (CZ) silicon wafers is studied in this paper. N2 and a N2/NH3 mixture are used as RTA ambient. It is demon... The effect of rapid thermal annealing (RTA) ambient on denuded zone and oxygen precipitates in Czochralski (CZ) silicon wafers is studied in this paper. N2 and a N2/NH3 mixture are used as RTA ambient. It is demonstrated that a high density of oxygen precipitates and thin denuded zone are obtained in N2/NH3 ambient,while a relatively lower density of oxygen precipitates and thicker denuded zone are observed in N2 ambient. As the RTA duration times increased, the oxygen precipitate density increased and the denuded zone depth decreased. X-ray photoelectron spectroscopy (XPS) data and atomic force microscope (AFM) results show that there RTA process,which can explain the different effect of RTA was a surface nitriding reaction during the N2/NH3 ambient ambient. 展开更多
关键词 300mm CZ silicon wafer denuded zone intrinsic gettering RTA XPS AFM
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The Determination of Heavy Metal Elements in Sipunculs nudus by MWD-ICP-AES 被引量:1
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作者 陈文 王湘君 +5 位作者 赵阳 苏利兴 张哲 莫兰发 欧阳敏 黄梁 《Agricultural Science & Technology》 CAS 2014年第5期724-728,共5页
In order to develop a method for measuring of elements in Sipunculus nudus, the contents of Cu, Pb, Cd, Cr, Mn, As, Hg and Ba were determined by actively coupled plasma atomic emission spectrometry (MWD) and microwa... In order to develop a method for measuring of elements in Sipunculus nudus, the contents of Cu, Pb, Cd, Cr, Mn, As, Hg and Ba were determined by actively coupled plasma atomic emission spectrometry (MWD) and microwave digestion (ICP-AES). The results showed that correlation coefficients al kept higher than 0.999 and the recovery rates of sample added standard solutions were in 98%-114%. The results indicated that the contents of Cu, Pb, Cd, Cr, Mn, As, Hg and Ba were 17.119, 3.781, 0.695, 7.351, 1997.982, 0.620, 0.144, 4.249 mg/kg respectively. The contents of Mn exceeded national limit by hundredfold, Cd sevenfold, Pd fourfold, Cd three-and-a-half-fold, and As onefold. Sipunculs nudus became seriously pol uted. Therefore, it is necessary to formulate robust policies to fol ow closely and pay close attention to coastal areas pol ution around Dongfang City. 展开更多
关键词 Sipunculs nudus ICP-AES MWD Heavy metal ELEMENT
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Analysis of Wettability and X-ray Photoelectron Spectroscopy of Wheat Straw/SPI
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作者 刘志明 沈江华 《Agricultural Science & Technology》 CAS 2012年第4期815-817,共3页
[Objective] The aim was to improve the adhesive bonding property of wheat straw surface to prepare wheat straw particleboard of soy protein isolate (SPI) adhesive through chemical and enzyme treatments. [Method] Eva... [Objective] The aim was to improve the adhesive bonding property of wheat straw surface to prepare wheat straw particleboard of soy protein isolate (SPI) adhesive through chemical and enzyme treatments. [Method] Evaluation and analysis were made on wettability of wheat straws in the control group and treated groups (chemical and enzyme treatments) by means of measurement of contact angle and calculation of spreading-penetration parameters (K). In addition, we made analysis on surface elements through X-ray photoelectron spectroscopy (XPS). [Result] The re- sults showed that K value of straw treated with sodium hydroxide, hydrogen peroxide and lipase increased by 58.0%, 48.7% and 83.2% compared to that of control group, respectively. The XPS analysis indicated that rapid decrease of silicon content and destruction of wax layer greatly contributed to wettability improvement of wheat straw surface. [Conclusion] The chemical and lipase treatments of wheat straw provided technical support for manufacture of wheat straw particle boand. 展开更多
关键词 Wheat straw WETTABILITY Soy protein isolate adhesive X-ray photoelec- tron spectroscopy
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Ni/Mo/N催化剂合成及其在噻吩存在体系下苯加氢反应中的应用(英文) 被引量:4
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作者 褚绮 冯杰 +1 位作者 李文英 谢克昌 《催化学报》 SCIE EI CAS CSCD 北大核心 2013年第1期159-166,共8页
Ni/Mo/N间隙型催化剂具有高的加氢活性及良好耐硫性, 可应用于煤液化油加氢精制高性能喷气燃料. N原子由于只占据晶格间隙位置, 在进入Ni/Mo过程中会因不占据晶格中的特定晶位, 容易从金属晶格溢出导致无法形成稳定的Ni/Mo/N间隙型催化... Ni/Mo/N间隙型催化剂具有高的加氢活性及良好耐硫性, 可应用于煤液化油加氢精制高性能喷气燃料. N原子由于只占据晶格间隙位置, 在进入Ni/Mo过程中会因不占据晶格中的特定晶位, 容易从金属晶格溢出导致无法形成稳定的Ni/Mo/N间隙型催化剂. 为此, 本文利用前驱体晶型控制的方式来实现Ni/Mo/N催化剂合成. 采用络合物分解一步法, 考察了不同结晶过程和老化时间对合成的Ni/Mo/N催化剂用于苯加氢反应活性影响, 并采用X射线衍射、X射线光电子能谱和透射电镜-能量色散X射线光谱对催化剂结构组成进行表征. XRD分析结果显示, 钼酸铵[(NH4)6Mo7O24·4H2O]、乙酸镍[Ni(CH3COO)2·4H2O]和六亚甲基四胺(HMT)添加顺序、结晶过程和老化时间直接影响催化剂组成, 并决定Ni/Mo/N晶相的形成. 结晶过程慢速搅拌速度和短老化时间有利于合成含Ni2Mo3N, Mo2C和Ni晶相的高活性Ni/Mo/N间隙型催化剂, 使苯加氢制环己烷模型反应苯的最大转化率达93%, 环己烷选择性为100%. 含0.01 wt%噻吩的存在使苯转化率由72%降至50%, XPS分析结果表明, 催化剂表面形成的MoS2是催化剂活性降低的重要因素. 展开更多
关键词 NI MO N催化剂 苯加氢 噻吩 X射线衍射 射电镜-能量色散X射线光谱 X射线光电子能谱
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Visible-Light Activities of Erbium Doped BiVO4 Photocatalysts
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作者 张爱平 张进治 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2010年第1期73-78,I0002,共7页
Er-doped BiVO4 composite photocatalyst was hydrothermal synthesized and characterized by X-ray powder diffraction, scanning electron microscopy, energy-dispersive X-ray Spectroscopy, X-ray photoelectron spectroscopy, ... Er-doped BiVO4 composite photocatalyst was hydrothermal synthesized and characterized by X-ray powder diffraction, scanning electron microscopy, energy-dispersive X-ray Spectroscopy, X-ray photoelectron spectroscopy, and UV-Vis diffuse reflectance spectra techniques. The activity of the catalyst was determined by oxidative decomposition of methyl orange in aqueous solution under visible-light irradiation. X-ray photoelectron spectroscopy and energy-dispersive X-ray Spectroscopy analysis revealed that the doped Er existed in the form of Er2O3. It also showed that the Er doping can enhance the visible-light absorption abilities of catalysts and their visible-light-driven photocatalytic activities in comparison with those of pure BiVO4. 展开更多
关键词 PHOTOCATALYSIS Composite photocatalyst VISIBLE-LIGHT
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The effect of the support on the surface composition of PtCu alloy nanocatalysts: In situ XPS and HS-LEIS studies 被引量:6
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作者 黄俊杰 宋艳英 +3 位作者 马冬冬 郑燕萍 陈明树 万惠霖 《Chinese Journal of Catalysis》 CSCD 北大核心 2017年第7期1229-1236,共8页
Supported PtCu alloys have been broadly applied in heterogeneous catalysis and electrocatalysis owing to their excellent catalytic performance and high CO tolerance. It is important to analyze the outermost surface c... Supported PtCu alloys have been broadly applied in heterogeneous catalysis and electrocatalysis owing to their excellent catalytic performance and high CO tolerance. It is important to analyze the outermost surface composition of the supported alloy nanoparticles to understand the nature of the catalytically active sites. In this paper, homogeneous face-centered cubic PtCu nanoparticles with a narrow particle size distribution were successfully fabricated and dispersed on a high-surface-area Ti〇2 powder support. The samples were oxidized and reduced in situ and then introduced into the ultrahigh vacuum chamber to measure the topmost surface composition by high-sensitivity low-energy ion scattering spectroscopy, and to determine the oxidation states of the elements by X-ray photoelectron spectroscopy. The surface composition and morphology, elemental distribu-tion, and oxidation states of the components were found to be significantly affected by the support and treatment conditions. The PtCu is de-alloyed upon oxidation with CuO wetting on the TiO2 sur-face and re-alloyed upon reduction. Phase diagrams of the surface composition and the bulk com-position were plotted and compared for the supported and unsupported materials. 展开更多
关键词 PtCu alloy Bimetal catalyst Surface composition Phase diagram In situ XPS-LEIS
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Vacuum Ultraviolet Photoionization and Dissociative Photoionization of Capecitabine, 5'-Deoxy-5-fluorocytidine, and 5'-Deoxy-5-fluorouridine
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作者 王健 汤文建 +2 位作者 叶丽丽 张李东 潘洋 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2013年第1期20-26,I0003,共8页
Vacuum ultraviolet (VUV) photoionization and dissociative photoionization of capecitabine and its metabolites, 51-deoxy-5-fiuorocytidine (5'-DFCR) and 51-deoxy-5- fiuorouridine (5'- DFUR), were investigated wi... Vacuum ultraviolet (VUV) photoionization and dissociative photoionization of capecitabine and its metabolites, 51-deoxy-5-fiuorocytidine (5'-DFCR) and 51-deoxy-5- fiuorouridine (5'- DFUR), were investigated with infrared laser desorption/tunable synchrotron VUV photoionization mass spectrometry. Molecular ions (M+) with small amounts of fragments can be found for these compounds at relatively low photon energies, while more fragment ions would be produced by increasing the photon energies. (M-H2O)+, (base+H)+, (base+2H)+, (base+30)+, (base+60)+, and sugar moiety were proposed for these nucleoside drugs with similar backbones. Decomposition channels for the major fragments were discussed in detail. Moreover, ab initio calculations were introduced to study the dehydration pathways of three fluoro-nucleosides. Corresponding appearance energies for the (M-H2O)+ ions were computed. 展开更多
关键词 CAPECITABINE 5'-Deoxy-5-fluorocytidine 5t-Deoxy-5-fluorouridine Photoion-ization Mass spectrometry Synchrotron radiation
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Product Identification and Mass Spectrometric Analysis of n-Butane and i-Butane Pyrolysis at Low Pressure 被引量:1
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作者 张义军 苑文浩 +3 位作者 蔡江淮 张李东 齐飞 李玉阳 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2013年第2期151-156,I0003,共7页
The pyrolysis of n-butane and i-butane at low pressure was investigated from 823-1823 K in an electrically heated flow reactor using synchrotron vacuum ultraviolet photoionization mass spectrometry. More than 20 speci... The pyrolysis of n-butane and i-butane at low pressure was investigated from 823-1823 K in an electrically heated flow reactor using synchrotron vacuum ultraviolet photoionization mass spectrometry. More than 20 species, especially several radicals and isomers, were detected and identified from the measurements of photoionization efficiency (PIE) spectra. Based on the mass spectrometric analysis, the characteristics of n-butane and i-butane pyrolysis were discussed, which provided experimental evidences for the discussion of decomposition pathways of butane isomers. It is concluded that the isomeric structures of n-butane and i-butane have strong influence on their main decomposition pathways, and lead to dramatic differences in their mass spectra and PIE spectra such as the different dominant products and isomeric structures of butene products. Furthermore, compared with n-butane,i-butane can produce strong signals of benzene at low temperature in its pyrolysis due to the enhanced formation of benzene precursors like propargyl and C4 species, which provides experimental clues to explain the higher sooting tendencies of iso-alkanes than n-alkanes. 展开更多
关键词 N-BUTANE /-Butane Flow reactor pyrolysis Synchrotron vacuum ultravioletphotoionization mass spectrometry Product identification Mass spectrometric analysis
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Effect and mechanism of dolomite with different size fractions on hematite flotation using sodium oleate as collector 被引量:7
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作者 罗溪梅 印万忠 +3 位作者 王云帆 孙传尧 马英强 刘建 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第3期529-534,共6页
The effect of dolomite with different particle size fractions on hematite flotation was studied using sodium oleate as collector at p H of about 9. The effect mechanism of dolomite on hematite flotation was investigat... The effect of dolomite with different particle size fractions on hematite flotation was studied using sodium oleate as collector at p H of about 9. The effect mechanism of dolomite on hematite flotation was investigated by means of solution chemistry, ultraviolet spectrophotometry(UV), inductively coupled plasma atomic emission spectrometry(ICP-AES) and X-ray photoelectron spectroscopy(XPS). It is observed that dolomite with different size fractions has depressing effect on hematite flotation using sodium oleate as collector, and dolomite could be the "mineral depressant" of hematite using sodium oleate as collector. The reasons for that are concerned with sodium oleate consumption and the adsorption onto hematite of dissolved species of dolomite. 展开更多
关键词 DOLOMITE HEMATITE sodium oleate mineral dissolution depressing effect
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Electric characteristics of Nd_2O_3 doped BaTiO_3 ceramics 被引量:5
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作者 郝素娥 韦永德 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2003年第4期388-391,共4页
Nd2O3 doped BaTiO3ceramics(the additive content was respectively 0.001, 0.002, 0.003, 0.005, 0.01 molar ratio)were prepared by Sol-Gel method to study their dielectric characteristics and electric conductivities thr... Nd2O3 doped BaTiO3ceramics(the additive content was respectively 0.001, 0.002, 0.003, 0.005, 0.01 molar ratio)were prepared by Sol-Gel method to study their dielectric characteristics and electric conductivities through X-ray photoelectron spectrum (XPS). The results showed that the dielectric characteristics of Nd2O3 doped BaTiO3 ceramics were improved by doping. When Nd2O3 content was 0.003 mol, the results were even better, the dielectric constant was increased, the dielectric loss was decreased, the Curie-temperature (Tc) was 110 ℃, and the frequency characteristic was also good. The resistivity of Nd2O3 doped BaTiO3 ceramics was lower than that of pure BaTiO3 ceramics, when Nd2O3 content was 0.001 mol,the resistivity was (2.364×)108 Ω·m, the smallest. The grain resistance of Nd2O3 doped BaTiO3 ceramics exhibited NTC effect, but the grain boundary resistance showed PTC effect, and the grain boundary resistance was larger than that of the grain resistance, so the PTC effect originated from the grain boundary. The analysis of the element binding energy through X-ray photoelectron spectrum were indicated that the quantivalence of Ba2+and Ti4+in Nd2O3 doped BaTiO3 ceramics was variable, and resulted in the improvement of the conductibility of BaTiO3 ceramics. 展开更多
关键词 BaTiO_3 ceramics Nd_2O_3 doped dielectric characteristic electric conductivity
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Catalytic Performance of Carbon Materials Supported Pd Nanoparticles in Selective Hydrogenation of Acetylene 被引量:2
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作者 姚繁繁 霍羽佳 马运生 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2017年第5期559-565,I0002,共8页
Pd/C catalysts were prepared by deposited Pd nanoparticles (NPs) on different carbon supports including activated carbon (AC), graphite oxide (GO), and reduced graphite oxide (rGO) using sol-immobilization met... Pd/C catalysts were prepared by deposited Pd nanoparticles (NPs) on different carbon supports including activated carbon (AC), graphite oxide (GO), and reduced graphite oxide (rGO) using sol-immobilization method. Through transmission electron microscopy, powder X-ray di raction, and X-ray photoelectron spectroscopy, the role of the carbon supports for the catalytic performances of Pd/C catalysts was examined in selective hydrogenation of acetylene. The results indicate that Pd/AC exhibited higher activity and selectivity than Pd/GO and Pd/rGO in the gas phase selective hydrogenation of acetylene. Thermal and chemical treatment of AC supports also have some effect on the catalytic performance of Pd/AC catalysts. The differences in the activity and selectivity of various Pd/C catalysts were partly attributed to the metal-support interaction. 展开更多
关键词 Selective hydrogenation of acetylene Pd Active carbon Graphite oxide Reduced graphite oxide X-ray photoelectron spectroscopy
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