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71.
应用5-参数Morse势方法模拟了O-Ni表面相互作用势,考察了氧原子在镍三个低指数表面的吸附特性.同时构造了羟基与Ni(100)、Ni(110)和Ni(111)表面相互作用的推广LEPS势,获得了羟基在表面的吸附位、吸附几何、结合能及本征振动等数据.理论结果表明,羟基垂直吸附于镍表面的高对称位是稳定的,垂直吸附于Ni(100)表面4-重洞位的吸附能为96.98 kJ•mol-1,垂直吸附于Ni(111)表面3-重洞位的吸附能为96.00 kJ•mol-1,在Ni(110)表面存在两种吸附态:垂直吸附于长桥位的吸附能为99.38 kJ•mol-1,倾斜14°吸附于赝势三重位吸附能为96.98 kJ•mol-1.理论结果与实验结果符合得较好. 相似文献
72.
快速老化模型小鼠海马蛋白质组学初步研究 总被引:1,自引:0,他引:1
应用双向凝胶电泳结合质谱鉴定, 分析比较6月龄和12月龄快速老化模型小鼠(Senescence-accele-rated mouse, SAM)的快速老化亚系SAM-prone/8(SAMP8)及抗快速老化亚系SAM-resistance/1(SAMR1)海马蛋白表达的差异, 从蛋白质水平初步探讨与老化相关的学习记忆功能障碍的发生机制. 结果表明, 与同龄SAMR1比较, 6月龄SAMP8海马中有15个蛋白点表达显著上调, 5个蛋白点表达显著下调; 12月龄SAMP8海马中有12个蛋白点表达显著上调, 2个蛋白点表达显著下调, 2个蛋白点只在SAMP8中有表达. 应用质谱分析结合数据库检索, 共鉴定了22种蛋白质. 6月龄和12月龄SAMP8与SAMR1海马中表达有明显变化的蛋白按功能可分为如下4类: (1) 能量代谢相关蛋白; (2) 线粒体功能相关蛋白; (3) 信号转导相关蛋白; (4) 其它蛋白. 研究结果表明, SAMP8和SAMR1海马蛋白表达存在明显差异, 其中一些蛋白与SAMP8随龄出现的学习记忆功能减退相关, 并可能为研究或发现促智药物作用的新蛋白靶标提供线索. 相似文献
73.
讨论了两相和三相多组分体系中杠杆原理的两种形式。对两组分体系,利用三相线上的杠杆原理关系式和凝固点降低公式,解释了熔化物体系冷却过程中的步冷曲线。另外,还讨论了三组分体系相图中,同一直线段上三个物系点之间的类杠杆原理关系式。该关系式可以用于不同浓度溶液的配制和三相体系相图的绘制。 相似文献
74.
We investigate the adsorptions of Ar on Al (111) and Ir (111) surfaces at the four high symmetry sites, i.e., top, bridge, fcc- and hcp-hollow sites at the coverage of 0.25 monolayer (ML) using the density functional theory within the generalized gradient approximation of Perdew, Burke and Ernzerhof functions. The geometric structures, the binding energies, the electronic properties of argon atoms adsorbed on Al (111) and Ir (111) surfaces, the difference in electron density between on the Al (111) surface and on the Ir (111) surface and the total density of states are calculated. Our studies indicate that the most stable adsorption site of Ar on the Al (111) surface is found to be the fcc-hollow site for the (2 × 2) structure. The corresponding binding energy of an argon atom at this site is 0.538 eV/Ar atom at a coverage of 0.25 ML. For the Ar adsorption on Ir (111) surface at the same coverage, the most favourable site is the hcp-hollow site, with a corresponding binding energy of 0.493 eV. The total density of states (TDOS) is analysed for Ar adsorption on Al (111) surface and it is concluded that the adsorption behaviour is dominated by the interaction between 3s, 3p orbits of Ar atom and the 3p orbit of the base Al metal and the formation of sp hybrid orbital. For Ar adsorption on Ir (111) surface, the conclusion is that the main interaction in the process of Ar adsorption on Ir (111) surface comes from the 3s and 3p orbits of argon atom and 5d orbit of Ir atom. 相似文献
75.
76.
Determination of the temporal structure of femtosecond laser pulses by means of laser-induced air plasma 下载免费PDF全文
A new approach is presented to reveal the temporal structure of femtosecond laser pulses by recording the corresponding time-resolved shadowgraphs of the laser-induced air plasma. It is shown that the temporal structures of femtosecond laser pulses, normally not observable by the ordinary intensity autocorrelator, can be detected through intuitively analyzing the ultrafast evolution process of the air plasma induced by the femtosecond laser pulses under examination. With this method, existence of pre- and post-pulses has been clearly unveiled within the time window of ±150 fs in reference with the main 50-fs laser pulses output from a commercial 1-kHz femtosecond laser amplifier. The unique advantage of the proposed method is that it can directly provide valuable information about the pulse temporal structures' effect on the laser-induced ionization or material ablation. 相似文献
77.
78.
Using the scattering matrix method, we investigate the thermal transport m a nanostructure at low temperarures. It is found that phonon transport exhibits some novel and interesting features: resonant transmission, resonant reflection, and small thermal conductance. A comparison between thermal conductances is performed when stress-free and hard-wall boundary conditions are applied for acoustic modes, respectively. The result indicates that the characteristics of the thermal conductance versus temperature for different types of boundary conditions are qualitatively different. 相似文献
79.
Zhu Hai-Liang Hang Qing-Wei Zhao Jing Duan Chun-Ying Tang Wen-Xia Fu De-Gang 《Transition Metal Chemistry》1999,24(2):131-134
The synthesis, crystal structure and magnetic properties of the imidazolate-bridged dinuclear copper(II) complex [LCu2(Im)](ClO4)3(H2O) ·1/2(MeCN), (ImH=imidazole, L=bis-p-xylylBISDIEN) have been studied. Single crystal X-ray diffraction determination reveals the distorted square planar geometries of the imidazolate bridged dicopper(II) center are incorporated within the dinucleating macrocycle. The Cu—Cu separation in the complex is 6.005Å. Magnetic measurements reveal an antiferromagnetic exchange interaction with a coupling constant of J=–26.52cm–1. The enzymatic activity of the title complex is 5.9 percent of that of the protein. 相似文献
80.
Wen-Xia Wang Lingling Zhang Zhandong Liang 《Journal of Mathematical Analysis and Applications》2006,320(2):510-527
In this paper, by using the cone theory and the monotone iterative technique, we investigate the existence of maximal and minimal solutions of the initial value problem for second order impulsive differential equations which nonlinearly involve the derivative x′ in Banach space and give an example to illustrate our results. 相似文献