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排序方式: 共有146条查询结果,搜索用时 15 毫秒
31.
Mingqiang Huang Zhenya Wang Yong Yang Liqing Hao Wenwu Zhao Xiaoming Gao Li Fang Weijun Zhang 《International journal of quantum chemistry》2007,107(5):1092-1098
The hydroxycyclohexadienyl peroxy radicals (HO? C6H6? O2) produced from the reaction of OH‐benzene adduct with O2 were studied with density functional theory (DFT) calculations to determine their characteristics. The optimized geometries, vibrational frequencies, and total energies of 2‐hydroxycyclohexadienyl peroxy radical IIs and 4‐hydroxycyclohexadienyl peroxy radical IIIs were calculated at the following theoretical levels, B3LYP/6‐31G(d), B3LYP/6‐311G(d,p), and B3LYP/6‐311+G(d,p). Both were shown to contain a red‐shifted intramolecular hydrogen bond (O? H … O? H bond). According to atoms‐in‐molecules (AIM) analysis, the intramolecular hydrogen bond in the 2‐hydroxycyclohexadienyl peroxy radical IIs is stronger than that one in 4‐hydroxycyclohexadienyl peroxy radical IIIs, and the former is the most stable conformation among its isomers. Generally speaking, hydrogen bonding in these radicals plays an important role to make them more stable. Based on natural bond orbital (NBO) analysis, the stabilization energy between orbitals is the main factor to produce red‐shifted intramolecular hydrogen bond within these peroxy radicals. The hyperconjugative interactions can promote the transfer of some electron density to the O? H antibonding orbital, while the increased electron density in the O? H antibonding orbital leads to the elongation of the O? H bond and the red shift of the O? H stretching frequency. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 相似文献
32.
Zhaohui Ren Gang XuXiao Wei Zhenya LiuYonggang Wang Zhen XiaoGe Shen Gaorong Han 《Journal of Crystal Growth》2009,311(21):4593-4597
Ring- and single-crystal-like superstructures of Fe-doped PbTiO3 nanocrystals have been prepared by a simple hydrothermal method using (poly ethylene glycol) (PEG) as a surfactant. Two oriented-attachment forms of the nanocrystals favor the formation of the rings in view of geometry. Magnetism measurement shows that Fe-doped PbTiO3 sample is ferromagnetic even at room temperature. It is proposed that the magnetic dipole interactions and the presence of PEG molecules could together contribute to the formation of ring- and single-crystal-like superstructures composed of Fe-doped PbTiO3 nanocrystals. 相似文献
33.
Ruihong Kong Xiaobin Shan Sisheng Wang Yunwu Zhang Liusi Sheng Liqing Hao Zhenya Wang 《Journal of Electron Spectroscopy and Related Phenomena》2007,160(1-3):49-53
The photoionization of Ne·CO complex in the energy region of 13.8–14.2 eV was investigated with photoionization mass spectrometry using a synchrotron radiation source in Hefei. The ionization energy (IE) of Ne·CO is determined to be 13.965 eV from its photoionization efficiency curve whose characterization is affected by the photoabsorption of CO molecule. The equilibrium geometry and harmonic vibrational frequencies of Ne·CO and Ne·CO+ are calculated using cc-pVTZ basis sets at the QCISD level of theory. The results indicate that they are of a skewed T-shaped structure and show the configuration changes accompanying the ionization of Ne·CO complex. The parameters of thermo-chemistry of Ne·CO and Ne·CO+ are calculated using Gaussian-2 method, which provide information concerning the reduction of the ionization potentials of CO in the Ne·CO complex, relative to that of the bare molecule. 相似文献
34.
Yan Z 《Chaos (Woodbury, N.Y.)》2005,15(2):23902
First, a Q-S (lag or anticipated) synchronization of continuous-time dynamical systems is defined. Second, based on a backstepping design with one controller, a systematic, concrete, and automatic scheme is developed to investigate the Q-S (lag or anticipated) synchronization between the drive system and response system with a strict-feedback form. Two identical hyperchaotic Tamasevicius-Namajunas-Cenys(TNC) systems as well as the hyperchaotic TNC system and hyperchaotic Rossler system are chosen to illustrate the proposed scheme. Numerical simulations are used to verify the effectiveness of the proposed scheme. The scheme can also be extended to study Q-S (lag or anticipated) synchronization between other dynamical systems with strict-feedback forms. With the aid of symbolic-numeric computation, the scheme can be performed to yield automatically the scalar controller in computer. 相似文献
35.
广义组合KdV-mKdV方程的显式精确解 总被引:1,自引:0,他引:1
Abstract. With the aid of Mathematica and Wu-elimination method,via using a new generalizedansatz and well-known Riccati equation,thirty-two families of explicit and exact solutions forthe generalized combined KdV and mKdV equation are obtained,which contain new solitarywave solutions and periodic wave solutions. This approach can also be applied to other nonlinearevolution equations. 相似文献
36.
Zhenya Yan 《Journal of Mathematical Analysis and Applications》2011,380(2):689-4279
We report the analytical one- and two-rogon-like solutions for the two-dimensional nonlocal nonlinear Schrödinger equation by means of the similarity transformation. These obtained solutions can be used to describe the possible physical mechanisms for rogue-like wave phenomenon. Moreover, the free function of space y involved in the obtained solutions excites the abundant structures of rogue-like wave propagations. The Hermite-Gaussian function of space y (normalized function) is, in particular, chosen to depict the dynamical behaviors for rogue-like wave phenomenon. 相似文献
37.
38.
Weiwei Huang Baogang Zhang Miao Li Nan Chen Chuanping Feng Zhenya Zhang 《Journal of Solid State Electrochemistry》2013,17(4):1013-1020
An intensified electrochemical process in an undivided cell using Cu–Zn alloy as cathode and Ti/IrO2–Pt as anode combined with bipolar iron particles (electro-iron system) has been developed. The performance of nitrate reduction was evaluated using synthetic groundwater. Results showed that the nitrate-N dropped rapidly from 50 to less than 10 mg/L within 100 min in the developed system at current densities in the range of 5–30 mA/cm2. Sodium chloride addition was found to have a positive effect on the system performance. No nitrite-N was detected during the electrolysis in the presence of sodium chloride. The concentration of total iron ion in the solutions was found to be less than 0.25 mg/L after 100 min electrolysis. Furthermore, the electrical energy consumption for nitrate reduction in the electro-iron system was saved by approximately 29.4–34.8 % at 5–30 mA/cm2. The developed system has been proved to promote electrochemical nitrate reduction and greatly improve the electrical energy efficiency. 相似文献
39.
Danyi Lu Jiayu Zhang Zhenya Yang Hongming Liu Sha Li Baojian Wu Zhiguo Ma 《Journal of separation science》2013,36(12):1945-1952
We aim to determine the chemical constituents of three species of Cistanches Herba using HPLC coupled with diode array detection and high‐resolution MS. Ten phenylethanoid glycosides were identified and further quantified as marker substances by HPLC coupled with diode array detection method. The separation was conducted using an Agilent TC‐C18 column with 0.1% formic acid and methanol as the mobile phases under gradient elution. The analytical method was fully validated in terms of linearity, sensitivity, precision, repeatability as well as recovery, and subsequently applied to evaluate the quality of 36 batches of Cistanche plants. The chemometric procedures (i.e., hierarchical clustering analysis and principal component analysis) were used to compare different species of Cistanches Herba, leading to successful classification of the Cistanche samples in accordance with their origins. In conclusion, this study provides a chemical basis for quality control of Cistanches Herba. 相似文献
40.
Y型沸石脱铝机制和铝状态的NMR研究 总被引:2,自引:2,他引:0
对Y型沸石原粉及几种不同脱铝样品进行了几种不同NMR方法的测量,确定了不同处理过程的脱铝机制和骨架内外铝状态的变化,29Si MAS NMR谱给出了骨架Si、Al分布的信息,反映了不同方法处理样品其脱铝机制的差异,据此可以控制Y沸石脱铝过程获得更高的硅铝比,27Al MAS NMR谱、二维章动NMR及1H-27Al CP/MAS NMR测量表明:水热处理的Y沸石中存在4种不同的铝状态。综合29Si和27Al MAS NMR观测,可相当程度地推断Y型沸石分子筛脱铝改性所发生的内部过程。 相似文献