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991.
992.
The asymmetric torsional potential function, conformational energy difference, vibrational frequencies, and structural parameters of Cyclopropane-carboxaldehyde have been obtained from ab initio calculations at the 3–21G and/or 6-31G* baiss set levels. These results have allowed for a reinterpretation or clarification of some of the corresponding results obtained from experiment. The conformations that have the oxygen atom oriented cis and trans to the three-membered ring are observed and calculated to be the most stable and high energy forms in the gaseous phase, respectively. From the ab initio calculations using the 6–31 G* basis set, the energy difference between the two conformers is 114 cm–1. For the liquid, the trans conformer is more stable and is the only rotamer present in the annealed solid. Based on a combination of results obtained from ab initio calculations, microwave spectroscopy, and the electron diffraction technique,r
o structural parameters have been obtained for both conformations. 相似文献
993.
担载铂催化剂用于硝基苯催化加氢制对氨基苯酚的研究 总被引:4,自引:0,他引:4
研究了以活性炭、γA12O3、γ-A12O3-TiO2为载体,用浸渍法制备的铂含 量为1%的担载铂催化剂,用于硝基苯催化加氢制对氨基苯酚。发现Pt/γ-A12O3-TiO2催化剂有较高的活性、选择性和较长的寿命,催化剂循环使用10次后,对氨基酚的率仍高于80%,优于常用的Pt/C催化剂 。测定了催剂的比表面积、孔结构以 及活性金属铂的分散度,发现孔结构与催化剂性能之间没有规律性的关系;而铂在γ-A12 相似文献
994.
Recognition of 6-benzyladenine using a molecularly imprinted membrane on a cellulose acetate support
X. J. Qu Q. X. Meng S. Y. Ai J. Zhou L. S. Zhu 《Journal of Analytical Chemistry》2008,63(10):999-1004
A molecularly imprinted polymer membrane was prepared on a cellulose acetate support by the photopolymerization of methacrylic
acid and a cross linker, ethyleneglycol dimethacrylate, in the presence of the template molecules of 6-benzyladenine (BA). The polymeric membrane morphologies were visualized by scanning electron microscopy and its selectivity was evaluated by
a permeation test. The association ratio and apparent association constant of the complex formed between the methacrylic acid
and BA were determined by cyclic voltammetry, and are 1 : 1 and 204.9, respectively. These results indicated that there existed
some complementary cavities on the imprinted membrane corresponding in size, shape, and functional groups to the template
molecules of BA. Hence, the imprinted membrane was able to recognize BA. It is predicted that this molecularly imprinted membrane
may be applicable to the assay of BA or for the preparation of a molecularly imprinted polymer sensor for the determination
of BA in plant samples.
The text was submitted by the authors in English. 相似文献
995.
Lei Ai Guojia Fang Longyan Yuan Mingjun Wang Qilin Zhang Xingzhong Zhao 《Applied Surface Science》2008,254(8):2401-2405
Nickel oxide thin films were deposited on fused silica and Si(1 0 0) substrates at different substrate temperatures ranging from room temperature to 400 °C using radio frequency reactive magnetron sputtering from a Ni metal target in a mixture of O2 and Ar. With the increase of substrate temperature, nickel oxide films deposited on the Si substrates exhibit transition from amorphous to poly-crystalline structures with different preferred orientations of NiO(2 0 0) and (1 1 1). The films deposited at higher temperature exhibit higher Ni2+/Ni3+ ratio. With substrate temperature increasing from room temperature to 400 °C, the electrical resistivities of nickel oxide films increase from (2.8 ± 0.1) × 10−2 to (8.7 ± 0.1) Ω cm, and the optical band-gap energies increase from 3.65 to 3.88 eV. A p-nickel oxide/n-zinc oxide heterojunction was fabricated to confirm the p-type conduction of nickel oxide thin film, which exhibited a steadily rectifying behavior. 相似文献
996.
采用分子动力学方法模拟了碳在晶体硅基底上的沉积过程, 并分析计算了所沉积的类金刚石薄膜的面向及法向热导率. 对沉积过程的模拟表明, 薄膜密度及sp3杂化类型的碳原子所占比例均随沉积高度的增加而减小, 在碳原子以1 eV能量垂直入射的情况下, 在硅基底上沉积的薄膜密度约为2.8 g/cm3, sp3杂化类型的碳原子所占比例约为22%, 均低于碳在金刚石基底上沉积的情况. 采用Green-Kubo方法, 计算了所沉积类金刚石薄膜的热导率, 其面向热导率可以达到相同尺寸规则金刚石晶体的50%左右, 并且随着薄膜密度与sp3杂化类型碳原子所占比例的升高而升高. 相似文献
997.
The morphological evolution and growth mechanism of β‐BaB2O4 microcrystal in Li2B4O7‐BaB2O4 glass (Li2O‐B2O3‐BaO) matrix were investigated by optical in situ observation method. And the crystallization temperature Tc has been examined by differential thermal analysis (DTA). It demonstrates that homogeneous distribution of hexagonal shaped BBO microcrystals with size up to several tens of microns is typical when temperature is much higher than Tc, however, heterogeneous nucleation occurs when annealing temperature is close to Tc. For the latter case, crystal clusters that consist of several microcrystal grains are obvious. When the crystals in one specific cluster grows larger, crystal motion occurs in glass matrix while their orientation and symmetrical shape keep nearly no changes. Additionally, the BBO microcrystal has been determined to grow nearly in linear with time, which suggests a mechanism of interface‐controlled growth. Furthermore, the activation energy of BBO crystal growth in glass matrix is calculated which is around 2.4 eV. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
998.
The changes of the specific rotation and sign of optically active BINOL have been studied in polar/non-polar solvents and at the different pH values of solvent.It is considered that these changes are determined by the equilibriurn studies between cisoid and transoid conformations of BINOL with the same configuration(R or S) which related to the change of the dihedral angle between two naphthalene ring planes of BINOL. 相似文献
999.
月见草油中溶剂残留测定方法的改进 总被引:4,自引:0,他引:4
An improved method for the analysis of residual solvent in EPO by gas chromatographic headspaceanalysis is presented.A better accuracy and a lower detectable limit of this method in comparing with thoseof GB 5009.37-85 were obtained. 相似文献
1000.