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991.
992.
采用密度泛函DFT中的B3LYP方法,选择LANL2DZ双ζ基组,优化并得到了Yn=(n=2—8)小团簇的基态平衡结构,同时计算出其电离势.结果表明,钇原子之间形成团簇最稳定的结构是倾向于平均配位数最大,其电离势没有“奇-偶”振荡或“幻数”效应,表明Yn团簇光致电离开始主要发生在Y原子局域化的4d轨道上的电子而不是在5s上.对Tomasz提出的钇团簇电离势的解析式进行合理地修正,修正后电离势解析式的计算值与实验值更接近.
关键词:
Y团簇
密度泛函
平衡几何结构
电离势 相似文献
993.
南美白对虾两养殖群体遗传多样性的比较分析 总被引:1,自引:1,他引:0
采用同工酶电泳技术和随机扩增DNA多态技术对浙江省养殖的普通南美白对虾(简称P群体,下同)和SPF南美白对虾子一代(简称S群体,下同)两个群体的遗传多样性进行比较分析.结果表明,编码南美白对虾肌肉7种同工酶的18个基因位点中,EST-1、EST-2、EST-3和MDH-1位点具有多态现象;P群体和S群体的多态位点比例均为22.22%,平均杂合度分别为0.0666和0.0542;两群体间的遗传相似系数为0.9968,Nei遗传距离为0.0032.而利用随机扩增多态DNA(RAPD)技术,共检测出110个RAPD位点,其中P群体的多态位点数56个,多态位点比例为50.91%,S群体的多态位点数52个,多态位点比例为47.27%;P群体和S群体内个体间平均遗传相似度分别为0.8623和0.8742;两群体间的遗传相似度为0.9815,遗传距离为0.0185.无论是同工酶电泳结果还是RAPD分析结果都表明浙江省养殖的SPF南美白对虾子一代的遗传多样性水平比普通南关白对虾要低. 相似文献
994.
995.
《Radiation Physics and Chemistry》2007,76(8-9):1511-1514
Two highly sensitive thermoluminescent (TL) materials (Al2O3:C and CaSO4:Tm) were investigated for environmental monitoring. We compared their response to low and to high linear energy transfer (LET) radiations in order to develop a two-element TL system.The relative TL efficiency for α-particle irradiation as compared to γ-exposure was about 0.04 and 0.5 for Al2O3:C and CaSO4:Tm, respectively. Measurements of external environmental radiation doses in an international balloon experiment were performed with our highly-sensitive TL system having various sensitivities to low and to high LET radiations. 相似文献
996.
The inhibitory effects of five berberines alkaloids (BAs) from rhizoma of Coptis chinensis Franch, a traditional Chinese medicinal (TCM) herb, on Bacillus shigae (B. shigae) growth were investigated by microcalorimetry. The power-time curves of B. shigae with and without BAs were acquired; meanwhile, the extent and duration of inhibitory effects on the metabolism were evaluated by growth rate constants (k1, k2), half inhibitory ratio (IC50), maximum heat output (Pmax), and peak time (tp). The values of k1 and k2 of B. shigae in the presence of the five BAs decreased with the increasing concentrations of BAs. Moreover, Pmax was reduced, and the value of tp increased with increasing concentrations of the five drugs. The inhibitory activity varied with different drugs. IC50 of the five BAs was respectively 75 μg/mL for berberine, 90 μg/mL for coptisine, 115 μg/mL for palmatine, 220 μg/mL for epiberberine, and 400 μg/mL for jatrorrhizine. The sequence of antimicrobial activity of the five BAs berberine > coptisine > palmatine > epiberberine > jatrorrhizine. The functional groups methylenedioxy at C2 and C3 on phenyl ring improve antimicrobial activity more strongly than methoxyl at C2 and C3 on phenyl ring. However, the effect of bacteriostasis is not significant with methylenedioxy or methoxyl at C9 and C10 on phenyl ring. 相似文献
997.
《International Journal of Plasticity》2005,21(4):723-739
Uniaxial tension tests have been carried out along different angles from the rolling direction for both as-received and pre-strained sheet. By comparing the differences in the flow stress vs. orientation curves between the as-received and pre-strained sheets, the effect of pre-straining on material anisotropy is studied. It is demonstrated that the conventional methodology for determining material anisotropy would overestimate the pre-straining effect and would result in a completely erroneous yield surface. 相似文献
998.
《International Journal of Solids and Structures》2005,42(16-17):4738-4757
An efficient procedure to analyze damage evolution in brittle coatings under influence of thermal loads is suggested. The approach is based on a general computational scheme to determine damage evolution parameters, which incorporates an analytical solution of the appropriate interim boundary-value thermoelasticity problem. For thin inhomogeneous coatings, the simplification in the analysis is achieved by application of the mathematical model with generalized boundary conditions of thermomechanical conjugation of the substrate with environment via the coating. Efficiency of the suggested approach is illustrated by an example of damage evolution in the alumina coating on the titanium-alloy and tungsten substrates under uniform heating. 相似文献
999.
Criteria for strict monotonicity, lower local uniform monotonicity, upper local uniform monotonicity, and uniform monotonicity of Musielak-Orlicz spaces over any σ-finite and complete measure space, endowed with the Amemiya norm are given. The fact that the spaces are considered over arbitrary σ-finite measure space is essential because, as it is shown in Example 3, the Musielak-Orlicz spaces need not be strictly monotone even if their restrictions to the nonatomic part and the purely atomic part are strictly monotone. 相似文献
1000.
《Journal of magnetism and magnetic materials》2005,294(2):133-140
Nanostructured magnetic materials present a wide range of magnetic relaxation phenomena. One problem in studying nanomagnetic granular materials is the strong dependence of the relaxation with the anisotropy barrier which, even for systems with narrow size distributions, brings difficulties in the analysis of the experimental data. Molecular magnetism, with the chemists’ bottom-up approach to build molecular nanostructures, provides this field with some beautiful model systems, well ordered crystals of single molecule magnets, single molecule chains, molecular magnetic multilayers and others novelties to appear. Most of these systems present slow relaxation and the study of these well-characterized nanomaterials may elucidate many features that are difficult to grasp in the non molecular materials. 相似文献