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991.
The zinc(II) atom in the molecule of [(C5H4N)3N]ZnI2 is tetrahedrally coordinated to two nitrogen atoms of the tris(2‐pyridyl)amine ligand and two iodides. The coordination moieties are connected to give a linear structure by intermolecular π–π interactions between the pyridyl rings. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
992.
A mesogenic crosslinking agent M-1 was synthesized to minimize the perturbations of non-mesogenic crosslinking agents in liquid crystalline elastomers. The synthesis of new side chain liquid crystalline elastomers containing the rigid mesogenic crosslinking agent M-1 and nematic monomer M-2 by a one-step hydrosilylation reaction is described. The chemical structures of the monomers and network polymers obtained were confirmed by FTIR and 1H NMR spectroscopy. The mesomorphic properties and phase behaviour were investigated by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction. The influence of the crosslinking units on phase behaviour is discussed. Liquid crystalline elastomers containing less than 15 mol % of the crosslinking units showed elasticity, reversible phase transitions and a threaded texture. The experimental results demonstrated that the glass transition temperature of polymers P-1-7 increased with increasing concentration of crosslinking agent M-1; but the isotropic temperature and liquid crystalline range decreased slightly. 相似文献
993.
Zongqian Shi Shenli Jia Jun Fu Zheng Wang 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2003,31(2):289-294
It is well known that axial magnetic fields (AMFs) can keep vacuum arc in diffuse mode at high current. According to our recent research and other published papers, it has been found that vacuum arc can be maintained in high-current diffuse mode at much higher current if nonuniform AMF is applied, that the axial magnetic field is higher at contact periphery than at center. The influence of spatial distribution of AMF on vacuum arc is mainly studied in this paper. Furthermore, two types of AMF contacts with new structures to generate nonuniform AMF are presented. 相似文献
994.
Zhi Huai SI Guo Chang WANG* He Xian LI Jia Long YUAN Bing Lin HE State Key Laboratory of Functional Polymer Materials for Adsorption Separation Institute of Polymer Chemistry Nankai University Tianjin 《中国化学快报》2003,14(1)
The aggregation of amphiphilic block copolymers is a crucial phenomenon that controls various applications, and has been extensively treated in the literature1-3. Pyrene is a widely used fluorescence probe for the relative intensities of the vibrational fine structure (five bands) of its fluorescence spectra have been found to be sensitive to the polarity of its environment, the so-called Ham effect4. We report the studies of the aggregation properties of a PS-b-PAA copolymer using pyrene … 相似文献
995.
利用钠荧光散射激光雷达对中层顶(75~105km)高度的钠原子层进行探测,以钠原子作为示踪物,通过反演得到了该区域大气密度起伏随高度分布和随时间变化关系.结果表明,中层顶附近大气密度起伏远大于平流层和对流层,在2h内,密度起伏可达5%,3日平均Richordson数为0.46. 相似文献
996.
在不同实验条件下,用微波等离子体化学气相沉积设备在硬质合金(WC+6%Co)衬底上沉积了 具有不同结构特征的金刚石薄膜.用Raman谱表征薄膜的品质和应力,用压痕实验表征薄膜的 附着性能,考察了薄膜中sp2杂化碳含量、形核密度、薄膜厚度对薄膜附着性能 的影响.结 果表明:sp2杂化碳的缓冲作用使薄膜中sp2杂化碳的含量对薄膜中 残余应力有较大的影 响,从而使薄膜压痕开裂直径统计性地随sp2杂化碳含量的增加而减小;仅仅依 靠超声遗 留的金刚石晶籽提高形核密度并不能有效改变薄膜与硬质合金基体之间的化学结合状况,从 而不能有效提高薄膜在衬底上的附着性能;在薄膜较薄时,晶粒之间没有压应力的存在,开 裂直径并不明显随厚度增加而增加,只有当薄膜厚度增加到一定值,晶粒之间才有较强压应 力存在,开裂直径随厚度的增加而较为迅速地增加.
关键词:
金刚石薄膜
附着性能
2杂化碳')" href="#">sp2杂化碳
成核密度
薄膜厚度 相似文献
997.
Xiaodong Hou Qiaobo Li Yong He Lin Jia Yang Li Yingdan Zhu Amin Cao 《Journal of Polymer Science.Polymer Physics》2009,47(14):1393-1405
Spontaneous stereocomplex aggregation of diblock poly(styrene)‐b‐poly(L ‐lactide) PS‐b‐PLLA/poly(D ‐lactide) PDLA pairs has been investigated under ambient temperature in tetrahydrofuran solution. First, diblock PS260‐b‐PLLA165 and PS260‐b‐PDLA162 bearing similar lengths of respective PLLA and PDLA blocks were synthesized through controlled atom‐transfer radical polymerization of styrene, and a subsequent living ring‐opening polymerization of optically pure lactides, and their structures were further characterized by nuclear magnetic resonance spectroscopy (NMR) and gel‐permeation chromatography (GPC). Subsequently, new enantiomeric poly(D ‐lactide) stabilized core‐shell fluorescent CdSe quantum dots (CdSe/PDLA QD) were designed and prepared as sensitive fluorescence labels to shed new lights on the spontaneous stereocomplex aggregation in THF, which was mediated by stereocomplexation of the PLLA and PDLA chains. Upon simply mixing two individual THF solution of diblock PS260‐b‐PLLA165 and HO‐PDLA30‐SH, spontaneous stereocomplex aggregation was studied, and the aggregated uniform spherical particles were observed by scanning electronic microscopy (SEM) to exhibit average particle diameters of 2.0 μm. Finally, utilizing the prepared CdSe/PDLA QDs as new fluorescent labels, morphologies of the spontaneous aggregates by new diblock PS260‐b‐PLLA165/HO‐PDLA30‐SH pair were for the first time directly visualized by a confocal laser scanning fluorescence microscopy (CLSFM). These results might suggest alternative ways to simply prepare functional fluorescent particles with tunable diameter sizes and would be helpful to understand the mechanism of stereocomplex particle aggregation. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1393–1405, 2009 相似文献
998.
Yanping Wang Li Zhou Guoming Sun Jie Xue Zhifeng Jia Xinyuan Zhu Deyue Yan 《Journal of Polymer Science.Polymer Physics》2008,46(12):1114-1120
Poly(ethylene glycol) (PEG) can form either the inclusion complex with α‐cyclodextrins (α‐CDs) through host–guest interactions or the interpolymer complex with poly(acrylic acid) (PAA) through hydrogen‐bonding interaction. Mixing α‐CD, PEG, and PAA ternary components in an aqueous solution, the competition between host–guest and hydrogen‐bonding interactions occurs. Increasing feed ratio of α‐CD:EG:AA from 0:1:1 to 0.2:1:1 (molar ratio), various interesting supramolecular polymer systems, such as hydrogen‐bonding complex, dynamic polyrotaxane, crystalline inclusion complex, and thermoresponsive hydrogel, are successively obtained. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1114–1120, 2008 相似文献
999.
O-Propargylic hydroxylamines undergo smooth 5-endo-dig cyclisations upon exposure to 3 equiv of molecular iodine to give respectable yields of the corresponding 4-iodo-2,5-dihydroisoxazoles, which should find a number of applications as intermediates for syntheses amongst this useful class of heterocycles. 相似文献
1000.