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61.
I. K. Battisha A. El Beyally S. Abd El Mongy A. M. Nahrawi 《Journal of Sol-Gel Science and Technology》2007,41(2):129-137
Structural characteristics of pure silica gel (silica-xerogel, SiO2) and silica gel doped with some rare earth elements (REEs) such as, praseodymium Pr3+, and Europium Eu3+, Erbium Er3+ and Holmium Ho3+ ions, with different concentrations ranging from 1 up to 6%, in the form of monolith materials were prepared by sol-gel technique,
Using tetra-ethoxysilane as precursor materials, which are of particular interest for sol-gel integrated optics applications.
Some structural features of sol-gel derived monolith are analyzed, namely the structure of nano-particle momolith samples,
based on X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR). We show that the XRD spectra of α-crystobalite are
obtained for the pure samples at 1100°C and even by doping with the four REEs ions. 相似文献
62.
过渡金属酞等配合物(MPC)用手均相液相氧化中作催化剂已有不少报导,象许多均相催化剂一样,MPC用于均相反应存在着难于从反应体系中分离出来的问题.把均相配合物催化剂固载在无机氧化物如硅股或有机高分子载体上是解决这一问题的一种方法.我们曾尝试把MP。固载在分子筛载体和硅胶载体上,并用ESR研究其对O2的活化作用[1,2].本文报导MPc通过共价键键联固载在SiO2上,并研究其对O2的活化作用.1实验部分1.1试剂HSIC13为日本东京化成株式会社产品,二级试剂·发烟硫酸(SO。质量分数大于20%)为分析纯试剂.PCl5为化学纯试… 相似文献
63.
本标准物质系合金钢。主要成份有碳、硅、锰、磷、硫、铬、镍、钼、钒,同时还含有锡、铅、砷、锑、铋等微量元素,每种元素成份都具有良好的线性关系。它可作为量值传递和仲裁分析的依据,同时也可用于校验分析仪器与分析方法的正确性和可靠性。 相似文献
64.
65.
66.
M. Durga Prasad 《Theoretical chemistry accounts》1994,88(5):383-388
Summary Finite order expressions are derived for expectation values and transition matrix elements within the framework of the coupled cluster method. 相似文献
67.
Christopher M. Micklitsch 《Tetrahedron letters》2006,47(35):6277-6280
A family of penta- and hexadentate metal ligating α-amino acids, suitably protected for Fmoc solid-phase chemistry, has been prepared. These residues incorporate the mono-amides of ethanolaminetriacetic acid, ethylenediaminetriacetic acid, and ethylenediaminetetraacetic acid as side chains. Side chains are tethered varying distances (n) from the Cα-carbon to allow metal binding events to occur at distinct distances from the peptide backbone. These residues are designed to allow the facile installation of metal chelates along a peptide backbone. 相似文献
68.
用X-射线荧光光谱法,测定了387例内蒙古牧区蒙古族、汉族成人和儿童的发中铜(Cu)、锌(Zn)、铁(Fe)、锶(St)及钙(Ca)的含量,对同一地区蒙、汉族成人间,成人及儿童间发中五种元素含量进行了比较分析。结果表明:蒙汉族成人发中Cu,Zn、Fe含量不受种族及饮食习惯的影响,其含量无显著性差异;蒙汉族成人发中Sr和Ca含量存在着相平行的显著差异;牧区儿童发Zn含量与牧区成人发Zn含量差异无显著性意义,提示牧区儿童不缺Zn,可能与多动物性食物有关;牧区儿童发中Cu、Fe、Sr、Ca均显著低于牧区成人、可能与儿童发育旺盛和Zn摄入量高对Cu、Fe吸收发生抑制有关。 相似文献
69.
Henrik Fanø Clausen 《Journal of solid state chemistry》2005,178(11):3342-3351
Two new metal organic framework (MOF) structures have been obtained from the Zn-terephthalic acid (H2BDC)-dimethyl formamide (DMF) system and examined by single-crystal X-ray diffraction: Zn(C8H4O4)(C3H7NO), 1, monoclinic C2/m, a=11.1369(5), b=14.0217(7), , β=106.316(1)°, , , Z=4, R1=0.060, wR2=0.169, S=1.27; Zn(HCO2)3(C2H8N), 2, trigonal , a=8.1818(1), , , , Z=6, R1=0.014, wR2=0.039, S=1.11. Contrary to previously published structures in the same system, the crystals were obtained by solvothermal synthesis at 381 K. Structure 1 consists of 2-D layers stacked in an offset manner to accommodate DMF moieties coordinated to Zn2+ within voids in adjacent layers. Structure 2 consists of a 3-D network constructed from Zn2+ ions bridged by deprotonated formic acid moieties. Over time, the structure of 1 rearranges to Zn(C8H4O4)(C3H7NO)(H2O) [monoclinic P21/n, a=6.6456(2), b=15.2232(5), , β=104.110(2)°, , , Z=4, R1=0.048, wR2=0.100, S=1.07], which is identical to the known MOF-2 structure, obtained by crystallization at ambient conditions. The three structures were determined from crystals with similar crystal habits picked from a single solvothermal synthesis batch. The study demonstrates that MOF syntheses can give not only multiple crystal structures under different conditions, but also that numerous different structures, including some that are metastable, can be formed under identical conditions. 相似文献
70.
Muliadi Ramli Nasrullah Idris Kenichi Fukumoto Hideaki Niki Fujio Sakan Tadashi Maruyama Koo Hendrik Kurniawan Tjung Jie Lie Kiichiro Kagawa 《Spectrochimica Acta Part B: Atomic Spectroscopy》2007,62(12):1379-1389
A TEA CO2 laser (350 mJ–1.5 J, 10.6 μm, 200 ns, 10 Hz) was focused onto a metal sub-target under He as host gas at 1 atmospheric pressure with a small amount of impurity gas, such as water and ethanol vapors. It was found that the TEA CO2 laser with the help of the metal sub-target is favorable for generating a strong, large volume helium gas breakdown plasma at 1 atmospheric pressure, in which the helium metastable-excited state was then produced overwhelmingly. While the metal sub-target itself was never ablated. The helium metastable-excited state produced after the strong helium gas breakdown plasma was considered to play an important role in exciting the atoms. This was confirmed by the specific characteristics of the detected H emission, namely the strong intensity with low background, narrow spectral width, and the long lifetime. This technique can be used for gas and solid samples analysis. For nonmetal solid analysis, a metal mesh was introduced in front of the nonmetal sample surface to help initiation of the helium gas breakdown plasma. For metal sample, analysis can be carried out by combining the TEA CO2 laser and an Nd–YAG laser where the Nd–YAG laser is used to ablate the metal sample. The ablated atoms from the metal sample are then sent into the region of helium gas breakdown plasma induced by the TEA CO2 laser to be excited through the helium metastable-excited state. This technique can be extended to the analysis of other elements, not limited only to hydrogen, such as halogens. 相似文献