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51.
Yanqing Tian Xiaohe Xu Yingying Zhao Xinyi Tang Fengyu Su Xiaoguang Zhao Enle Zhou 《Liquid crystals》1995,19(3):295-300
The synthesis of three new series of chiral Schiff's bases containing benzilideneaniline and 2-hydroxybenzilideneaniline moieties as mesogenic cores is presented. Differential scanning calorimetry, optical polarizing microscopy and X-ray diffraction measurements were used to study the phase transition temperatures and behaviour. The results reveal that most of these materials show chiral smectic mesomorphism. 相似文献
52.
The temperature dependence of the Cd hyperfine field in a trivacancy complex in Ni between 25 and300 K is reported. It was found that, unlike the Cd substitutional field in Ni which follows the temperature dependence of the magnetization, the Cd hyperfine field in a trivacancy complex is essentially temperature independent. This temperature anomaly is compared with other temperature anomaly of impurity hyperfine fields in ferromagnetic hosts. 相似文献
53.
软x射线近贴显微技术 总被引:1,自引:0,他引:1
软x射线近贴显微技术不但可使活的生物样品成象,分辨率高于光学显微镜,而且人为的样品准备程序在该技术中都可避免。本文描述了用高功率激光打靶产生的等离子体作为软x射线源而进行的近贴显微研究,并得到了分辨率好于1μm的结果。 相似文献
54.
光照与彩陶俑表面色变关系的实验研究 总被引:1,自引:0,他引:1
本文以秦彩俑表面色彩为研究对象,通过光照实验与色彩变化的色度测量,分析了光照引起彩俑颜料色变的规律,为秦彩俑这一大型重点文物的色彩保护提供了科学理论依据. 相似文献
55.
56.
一类泛函微分方程周期解的存在性与应用 总被引:6,自引:1,他引:5
本文给出了一类滞后型泛函微分方程有一个周期解的四个充分性定理,其结果明显地优于著名的Yoshizawa周期解定理,最后给出了应用实例。 相似文献
57.
Zhigang Zhang Jianping Deng Weiguo Zhao Jianmin Wang Wantai Yang 《Journal of polymer science. Part A, Polymer chemistry》2007,45(3):500-508
A novel chiral N‐propargylsulfamide monomer ( 1a ) and its enantiomer ( 1b ) were synthesized and polymerized with (nbd)Rh+B?(C6H5)4 as a catalyst providing poly(1) (poly( 1a ) and poly( 1b )) in high yields (≥99%). Poly(1) could take stable helices in less polar solvents (chloroform and THF), demonstrated by strong circular dichroism signals and UV–vis absorption peaks at about 415 nm and the large specific rotations; but in more polar solvents including DMF and DMSO, poly(1) failed to form helix. Quantitative evaluation with anisotropy factor showed that the helical screw sense had a relatively high thermal stability. These results together with the IR spectra measured in solvents showed that hydrogen bonding between the neighboring sulfamide groups is one of the main driving forces for poly(1) to adopt stable helices. In addition, copolymerization of monomer 1a and monomer 2 was conducted, the solubility of poly(1) was improved drastically. However, the copolymerization had adverse effects on the formation of stable helices in the copolymers. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 500–508, 2007 相似文献
58.
Gui-Chang Wang Ling Jiang Yoshitada Morikawa Junji Nakamura Zun-Sheng Cai Yin-Ming Pan Xue-Zhuang Zhao 《Surface science》2004,570(3):205-217
The adsorption behavior and thermal activation of carbon dioxide on the Cu(1 1 1), Cu(1 0 0), and Cu(1 1 0) surfaces have been investigated by means of density functional theory calculations and cluster models and periodic slabs. According to the cluster models, the optimized results indicate that the basis set of C and O atoms has a distinct effect on the adsorption energy, but an indistinct one on the equilibrium geometry. For the CO2/Cu(hkl) adsorption systems studied here, the final structure of adsorbed CO2 is near linear and the preferred modes for the adsorption of CO2 onto the Cu(1 1 1), Cu(1 0 0), and Cu(1 1 0) surfaces are the side-on adsorption at the cross bridge site with an adsorption energy of 13.06 kJ/mol, the side-on adsorption at the short bridge site (13.54 kJ/mol), and the end-on adsorption on the on-top site with C–O bonds located along the short bridge site (26.01 kJ/mol), respectively. However, the calculated adsorption energies from periodic slabs are lower as compared to the experimental data as well as the cluster model data, indicating that the periodic slab approach of generalized gradient approximation in the density function theory may be not suitable to obtain quantitative information on the interaction of CO2 with Cu(hkl) surfaces. 相似文献
59.
关于李萨如图形讨论的小结 总被引:4,自引:0,他引:4
对《大学物理》和其它一些刊物上多年来关于李萨如图形的讨论作了归纳和分析。 相似文献
60.