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71.
The paper considers the dynamic process of contact interaction of infinite impulse-loaded strips arranged with a gap. The
behavior of the strips is described by linear elastic dynamics equations. The contact problem is solved by the collocation
method. The process of impact of two and three strips is analyzed. The calculation results are compared with data obtained
by using the finite-element method. 相似文献
72.
反相高效液相色谱法测定棒柄花中反式-4-(1-丙烯基)苯酚-β-D-吡喃葡萄糖苷 总被引:1,自引:1,他引:0
用反相高效液相色谱法建立棒柄花中反式-4-(1-丙烯基)苯酚-β-D-吡喃葡萄糖苷的含量测定方法,并测定其含量。色谱柱Reliasil-C18(250 mm×4.6 mm,5μm),流动相乙腈-水(体积比22∶78),流速1.0mL/m in,检测波长257 nm。结果待测组分在0.080 4~0.281 4μg范围内与峰面积线性关系良好,相关系数为0.999 5,平均加标回收率为98%,RSD为1.8%(n=6)。本法简便、快速、重复性好、结果准确可靠。 相似文献
73.
74.
Diffusion of lithium cations in C60 single crystals driven by an electric field has been studied. It was found that the stoichiometry of C60 single crystals can be changed with respect to lithium by injection of Li+ ions through the heterojunction Li7SiPO8|C60 and electrons through the heterojunction C60| Graphite. The double charge injection changes the stoichiometry of lithium in a C60 single crystal and increases both the lithium ionic and electronic conductivity. The electronic conductivity in LixC60 crystals is non-metallic in nature. The temperature dependence of the electronic conductivity lithium doped C60 single crystals was investigated. It was found that electrons occupied the lowest singlet exited states (LUMO) and that this
leads to the appearance of an intensive EPR signal. The temperature dependence of the concentration of paramagnetic centers
was investigated.
Paper presented at the 6th Euroconference on Solid State Ionics, Cetraro, Calabria, Italy, Sept. 12–19, 1999. 相似文献
75.
E. M. Averyanov V. A. Zhuikov V. YA. Zyryanov V. F. Shabanov 《Molecular Crystals and Liquid Crystals》2013,570(1-2):135-149
A method of experimental determination of the Lorentz-factor tensor in uniaxial liquid crystals is suggested. The specific features of the local field tensor of the light wave in a nematic liquid crystal with low optical anisotropy have been investigated experimentally. Anisotropy of the local field and Lorentz-factor tensors has been found to decrease with the decreasing optical and molecular-optical anisotropies. These results appear to contradict the existing polarization theories of liquid crystals. The local field problem in cholesteric liquid crystals has been considered. A new approach to the local field problem in uniaxial liquid crystals with arbitrary optical anisotropy is developed and the experimental results are explained. 相似文献
76.
Yu. A. Ossipyan V. S. Bobrov Yu. S. Grushko R. A. Dilanyan O. V. Zharikov M. A. Lebyodkin V.Sh. Sheckhtman 《Applied Physics A: Materials Science & Processing》1993,56(5):413-416
First experimental data on the plasticity, strength and microhardness of C60 fullerite crystals are reported. It is concluded that the mechanical properties of the crystals studied are isotropic, and the values of their breaking point are low. The obtained results are compared with those for other materials (graphite, indium etc.). 相似文献
77.
Isosteviol (ent-16-ketobeyeran-19-oic acid, I) is a tetracyclic diterpenoid with a beyerane skeleton obtained by acid hydrolysis of stevioside.1 Several tetracyclic diterpenoids, specially the kaurenes, have important biological activities. Recent studies on the microbial transformation of isosteviol have revealed that it is metabolized by Cunninghamella bainieri, Actinoplanes sp., Mucor recurvatus, and Cunninghamella blackesleeana to yield five new metabolites.2 The hydroxylation pattern of these bioactive compounds may influence their binding on to the receptors, as was proposed for the Rabdosia diterpenoids. Therefore, the introduction of hydroxyl groups or unsaturated bonds in saturated and non-hydroxylated diterpenoids, like isosteviol, may enhance existing properties or lead to new biological activities. Although some beyeranes have been subjected to biotransformations by fungi,4 there are few report in the literature related the chemical transformation of Isosteviol. In the present study, we try to develop the chemical transformation of isosteviol and other beyeranes in order to obtaining some bioactive compounds with beyerane skeleton. Seven isosteviol derivatives, Ⅱ-Ⅷ, were therefore synthesized and characterized. The X-ray crystal strcture of H(R = H) was also determined. 相似文献
78.
采用溶胶-凝胶法分别在K9玻璃、单晶硅和石英玻璃基底上制备了纳米TiO2和SiO2薄膜。利用SEM、UV-Vis及反射式椭圆偏振光谱仪对薄膜的微观结构及光学特性进行了表征和分析。结果表明:3种基底中, 单晶硅基底上TiO2和SiO2薄膜折射率最大;在非晶态K9玻璃和石英玻璃基底上TiO2薄膜折射率和透光率差异较大;SiO2薄膜在非晶态基底上折射率、透光率相近;3种基底上薄膜的折射率和消光系数都有随波长增大而减小的趋势, 同时Cauchy模型能较好的描述单晶硅基底上两种薄膜在400~800 nm波段的光学性能。 相似文献
79.
80.
I. O. Bashkin V. E. Antonov A. V. Bazhenov I. K. Bdikin D. N. Borisenko E. P. Krinichnaya A. P. Moravsky A. I. Harkunov Yu. M. Shul’ga Yu. A. Ossipyan E. G. Ponyatovsky 《JETP Letters》2004,79(5):226-230
Compounds containing 6.3–6.5 wt % H and thermally stable in vacuum up to 500°C were obtained by annealing graphite nanofibers and single-walled carbon nanotubes in hydrogen atmosphere under a pressure of 9 GPa at temperatures up to 45°C. A change in the X-ray diffraction patterns indicates that the crystal lattice of graphite nanofibers swells upon hydrogenation and that the structure is recovered after the removal of hydrogen. It was established by IR spectroscopy that hydrogenation enhances light transmission by nanomaterials in the energy range studied (400–5000 cm?1) and results in the appearance of absorption bands at 2860–2920 cm?1 that are characteristic of the C–H stretching vibrations. The removal of about 40% of hydrogen absorbed under pressure fully suppresses the C–H vibrational peaks. The experimental results are evidence of two hydrogen states in the materials at room temperature; a noticeable portion of hydrogen forms C–H bonds, but the most of the hydrogen is situated between the graphene layers or inside the nanotubes. 相似文献