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911.
本文采用XRD,NH_3-TPD,IR以及TEM等方法考察了Pt/BaKL沸石中Ba~(2+)的作用。NH_3-TPD结果表明,交换Ba~(2+)后的L型沸石的酸性,由于阳离子的作用仅在弱酸范围内有些改变,但与载铂的沸石的催化活性无明显的对应关系。IR及XRD谱线表明,BaKL沸石中Ba~(2+)在最佳交换度(26.3%)时,随预培烧温度的提高,使Ba~(2+)处于沸石孔道中B、C、D位置,接近于最佳分布,此时IR谱线上1421cm~(-1)处有一新峰。当沸石负载铂后,因铂与Ba~(2+)的相互作用,新峰消失,导致铂粒在沸石上分布更加均匀;铂粒在1.5—3.0nm之间占有最大比例,使得Pt/BaKL沸石呈现芳构化活性及选择性高于Pt/KL沸石,分别为~98%和~95%。 相似文献
912.
Xu Z Gao N Chen H Dong S 《Langmuir : the ACS journal of surfaces and colloids》2005,21(23):10808-10813
Stable films of biopolymer chitosan and carbon nanotubes were prepared by a layer-by-layer self-assembly technique. Atomic force microscopy, scanning electron microscopy, cyclic voltammetry, and UV-vis spectroscopy were used to characterize the film assembly. Atomic force microscopy and scanning electron microscopy showed that an even, stable film was formed. The UV-vis spectroscopy and cyclic voltammetry study indicated the uniform growth of the film. The property of the self-assembled multilayer film in promoting protein electron transfer was demonstrated by incorporating microperoxidase-11 in the film. Microperoxidase-11 in the multilayer film could transfer electrons with the electrode indicating that carbon nanotubes could wire the protein to the electrode. The electrocatalytic activity of the microperoxidase-11 containing multilayer film-modified electrode toward H(2)O(2) and O(2) was investigated. The results showed that along with the increase in the assembled layers the electrocatalytic reduction potentials of H(2)O(2) and O(2) shifted positively. The prepared multilayer film of chitosan and carbon nanotubes containing protein was a sensitive interface for electrocatalytic study. 相似文献
913.
Shouzhi Pu Jingkun Xu Liang Shen Qiang Xiao Tianshe Yang Gang Liu 《Tetrahedron letters》2005,46(5):871-875
The photochromic diarylethene, 1,2-bis(2-methyl-5-(2-(1,3-dithiolpentane))-thien-3-yl)perfluorocyclopentene (BMDTP), has been synthesized in high yield and its structure was determined by X-ray crystallographic analysis. The compound undergoes a photochromic reaction both in solution and in the single crystalline phase. In addition, its fluorescence property in solution is discussed. 相似文献
914.
电沉积AuInSe2半导体薄膜上的电化学振荡现象 总被引:1,自引:0,他引:1
研究了电沉积制得的AuInSe2半导体薄膜上过氧化氢阴极还原过程中产生的电化学振荡行为,对影响该振荡行为的一些因素如半导体薄膜的后处理、溶液组成、传质、光照、化学浸渍作用等进行了分析,同时采用外界周期性光照和外接小幅度正弦波电位来调节振荡频率,为金铟硒半导体薄膜发展成为光电传感器件提供了一定的理论与实践基础. 相似文献
915.
Mujie Yang Jinlong Xu Zhiquan Shen 《Journal of polymer science. Part A, Polymer chemistry》1990,28(12):3231-3240
The study on homogeneous rare earth coordination catalysts, LnL3-Al(i-Bu)3-CCl4, for the copolymerization of styrene with acrylonitrile has been successfully carried out for the first time. Some features and kinetic behavior of copolymerization of styrene with acrylonitrile by Nd(P204)3-Al(i-Bu)3-CCl4 system are described. The catalyst sites appear to possess both coordinate anionic and free radical characteristics. The catalytic activity of various rare earth elements in Ln(P204)3 and ligands in NdL3 for the copolymerization have the following order, respectively: Yb > Er > Tb ~ Tm > Ho > Ce > Lu ~ Sm ~ La > Pr > Nd, and Nd(naph)3 > Nd(P204)3 ~ Nd(P507)3 > Nd(acac)3·3H2O. An alternating-rich copolymer of styrene-acrylonitrile with a high softening point (195–230°C) was obtained by the LnL3-Al(i-Bu)3-CCl4 systems in toluene at 80°C. 相似文献
916.
Jia Hui Xu Ting Ting Zhuang Yi Cao Dr. Jing Yang Jing Jia Wen Zheng Ying Wu Dr. Chun Fang Zhou Dr. Li Huang Ying Wang Prof. Dr. Ming Bo Yue Dr. Jian Hua Zhu Prof. Dr. 《化学:亚洲杂志》2007,2(8):996-1006
Copper oxide was incorporated into MCM‐41 by a one‐pot synthesis under acidic conditions to prepare a new mesoporous nitrosamines trap for protection of the environment. The resulting composites were characterized by XRD, N2 adsorption–desorption, and H2 temperature‐programmed reduction techniques, and their adsorption capabilities were assessed in the gaseous adsorption of N‐nitrosopyrrolidine (NPYR). The adsorption isotherms were consistent with the Freundlich equation. The copper salt was deposited onto MCM‐41 during the evaporation stage and was fixed on the host in the calcination process that followed. MCM‐41 was able to capture NPYR in air below 373 K but not at 453 K. Loading of copper oxide on MCM‐41 greatly improved its adsorption capability at elevated temperatures. The influence of the incorporation of copper into MCM‐41 samples and the adsorption behavior of these samples are discussed in detail. 相似文献
917.
基于荧光激发光谱和发射光谱对波长呈高斯分布的设定,本文推导出固定波长同步荧光光谱峰峰值位置、相对强度和半峰宽度等3个主要光谱参数的理论计算式。所提出的计算式应用于若干荧光物质光谱参数的计算,并和实测值、文献计算值作了对照。结果表明,和文献计算方法相比,本法与所研究物质的实际光谱参数较为接近,可为固定波长同步荧光光谱参数的理论计算提供一有效方法。 相似文献
918.
919.
Masahiko Imai Lu Gong Xu Kazuo Ametani Mituaki Tutiya 《Journal of polymer science. Part A, Polymer chemistry》1989,27(5):1763-1773
Polypropylene films were irradiated with 60Co γ-rays in vacuum or in air and stored in air. Just after irradiation, the concentration of carbonyl group of the sample irradiated in air only increased with dose. The concentrations of both samples increased with storage time. The more the absorbed doses, the higher the increasing rates. The increasing rate of the concentration of carbonyl group during irradiation in air was higher than those during storage in air. Just after irradiation, the tensile strengths and the elongations of the both samples somewhat increased with dose at the doses less than 5 Mrad, but decreased at doses more than 13 Mrad. The tensile strength and the elongation of the sample irradiated in air decreased with storage time. Those of the sample irradiated in vacuum also decreased with storage time but the decreasing rates were much smaller than those in the sample irradiated in air. The gel fractions of the samples irradiated in vacuum and annealed in vacuum were somewhat higher than those irradiated in vacuum and not annealed. To elucidate high oxidation rate in the sample irradiated in air during and after irradiation, reaction mechanisms were discussed. To clarify the difference of mechanical properties between the samples irradiated in vacuum and in air, the effect of crosslink was considered, together with the oxidation. 相似文献
920.
Using ethylenediamine as a template, two one-dimensional (1-D) aluminophosphate compounds [AlP(2)O(8)H][NH(3)CH(2)CH(2)NH(3)] (1) and [AlP(2)O(8)][NH(3)CH(2)CH(2)NH(3)][NH(4)] (2) have been prepared from a gel system: 1.0:x:y:44 Al(i-PrO)(3)-H(3)PO(4)-en-EG (x = 3.0-9.0, y = 1.0-11.0). Compound 1 consists of edge-sharing four-membered ring (MR) chains, denoted as AlPO-ESC, and compound 2 consists of corner-sharing 4-MR chains, denoted as AlPO-CSC. The molar ratio of en:H(3)PO(4) in the starting gel has an important influence on the final product. If en:H(3)PO(4) > or = 1, AlPO-CSC is obtained, while if en:H(3)PO(4) < 1, AlPO-ESC is formed. These two chains can transform to each other upon addition of some extra amount of en or H(3)PO(4) to the reaction mixture in which AlPO-ESC or AlPO-CSC is crystallized. On the basis of XRD and (27)Al and (31)P MAS NMR analyses, a possible chain-to-chain transformation mechanism is proposed. The corner-sharing 4-MR chains of AlPO-CSC, as well as the edge-sharing 4-MR chains of AlPO-ESC can be assembled to 3-D open-framework compound NiAlP(2)O(8).C(2)N(2)H(9) through Ni(2+) cations. It is noted that AlPO-CSC remains in the structure of NiAlP(2)O(8).C(2)N(2)H(9). It is believed that AlPO-ESC might be first transformed to AlPO-CSC followed by the assembly to 3-D open-framework of NiAlP(2)O(8).C(2)N(2)H(9) through Ni(2+) cations. 相似文献