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应用再造核质点法(RKPM)进行了结构裂纹计算问题的研究。将不连续处理技术一可视准则和衍射方法应用于RKPM来模拟裂纹附近场函数,实现二维和三维裂纹体的分析。避免了有限元方法中裂纹附近复杂的网格剖分工作。应用面向对象技术在计算程序中实现了二维和三维裂纹体的应力场计算分析,并且将结构离散工作和裂缝网格构造工作分离,从而提高计算效率。简单的算例表明应用RKPM方法在二维和三维含裂纹结构计算是有效的。  相似文献   
84.
A new class of hexameric Ln12‐containing 60‐tungstogermanates, [Na(H2O)6?Eu12(OH)12(H2O)18Ge2(GeW10O38)6]39? ( Eu12 ), [Na(H2O)6?Gd12(OH)6(H2O)24Ge(GeW10O38)6]37? ( Gd12 ), and [(H2O)6?Dy12(H2O)24(GeW10O38)6]36? ( Dy12 ), comprising six di‐Ln‐embedded {β(4,11)‐GeW10} subunits was prepared by reaction of [α‐GeW9O34]10? with LnIII ions in weakly acidic (pH 5) aqueous medium. Depending on the size of the LnIII ion, the assemblies feature selective capture of two (for Eu12 ), one (for Gd12 ), or zero (for Dy12 ) extra GeIV ions. The selective encapsulation of a cationic sodium hexaaqua complex [Na(H2O)6]+ was observed for Eu12 and Gd12 , whereas Dy12 incorporates a neutral, distorted‐octahedral (H2O)6 cluster. The three compounds were characterized by single‐crystal XRD, ESI‐MS, photoluminescence, and magnetic studies. Dy12 was shown to be a single‐molecule magnet.  相似文献   
85.
本工作研究了带含氧冠醚、氮杂冠醚、酚醛型冠醚、开链冠醚的四种聚合物作为三相催化剂在氰代、碘代和二氯卡宾反应中的催化活性,其中以冠醚环上带有叔胺氮原子的氮杂冠醚聚合物催化活性最好。  相似文献   
86.
Monolayer polystyrene spheres (∼400 nm) array templates were assembled orderly on clean glass substrates by dip-coating method from emulsion of polystyrene (PS). Porous ZnO thin films were also prepared by dip-coating method to fill the interstices among the close-packed PS templates with ZnO and annealing to remove the PS templates. Results showed that ZnO sol concentration and dipping time of PS templates in sol had great influences on the morphology of ordered porous ZnO thin films. There was a shrinkage ratio of about 30% from pore to PS. SEM observation showed that the PS array templates had face-centered cubic close-packing. X-ray diffraction (XRD) spectra showed the porous ZnO thin film was wurtzite structure. The optical transmittance decreased with decreasing wavelength of lights, but was kept above 80% beyond the wavelength of 550 nm. Optical band-gap of the porous ZnO thin film annealed at 500°C was 3.22 eV.  相似文献   
87.
黄正国  程龙 《分析化学》2000,28(11):1331-1335
通过电化学生长法在4-氨基硫酚自组装膜修饰金电极上制备了包含杂多酸(SiMo11VO^5-40和聚合物阳极离子PDDA的多层膜修饰电极。用循环伏安法研究了该多层膜的电化学行为,结果表明,Mo的第3个还原峰随多层膜层数的增加显著增长,而另两个还原峰增长缓慢。该修饰电极的峰电位随PH的增加而线性负移,表明有氢离子参与杂多酸的氧化还原反应。该修饰电极对BrO^-3和NHO2的还原反应有良好的催化作用,催化电流随着层数的增加而增长,并且Mo的第三个还原峰电流与CRrO^-3有良好的线性关系。  相似文献   
88.
Copolymerization behavior of ethylene (E) and propylene (P) using ansa‐dimethylsilylene(fluorenyl)(amido)dimethyltitanium complex was investigated. P was more reactive than E regardless of the chain‐end monomer unit, which was very unusual in the coordination polymerization system. The terpolymerizations of E, P and norbornene (NB) or 5‐ethylidene‐2‐norbornene (5E2N) were also performed. The each content in the E/P/NB terpolymer was independently controlled by the initial concentration of NB and E/P feed ratio. Glass transition temperature (Tg) of the terpolymer was raised in proportion to the NB content and close to that of the corresponding NB/E random copolymer with the same NB content. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 685–691  相似文献   
89.
Spiroacetal moieties containing linear telechelic polymers (LTPs) with two terminal epoxy groups were facilely synthesized via the successive thiol-ene and thiol-epoxy click additions. The LTPs were incorporated into epoxy matrix to fabricate the transparent and toughening thermosets. In term of the miscibility of epoxy with the adduct of ethanedithiol and 3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5]undecane (BTU), it is proposed that the size of the formed nanostructures was small enough to allow light penetrate. Therefore, the modified thermosets were transparent, which was further confirmed by small-angle X-ray scattering (SAXS) measurements. The LTPs with an alternating structure of rigid spiroacetal moiety and soft thioether could formed heterogeneous crosslinked networks (HCNs) and obviously toughen epoxy thermosets. Flexural strength increased from 1.06 GPa for neat epoxy to 2.09 GPa for toughening thermosets modified with 15 wt% LTPs. The stress field intensity (KIC) value reached up to 3.93 by more than 125% compared with that of the control sample (1.75). This work uncovered the role of HCNs on performance and paved a way for technological advances toward transparent and toughening materials in epoxy thermosets.  相似文献   
90.
Huang  Zhengguo  Yu  Lei  Dai  Yumei 《Structural chemistry》2010,21(4):855-862
The complexes formed via hydrogen bonding interactions between cysteine and propanoic acid have been studied at the density three-parameter hybrid functional DFT-B3LYP/6-311++G(d,p) level regarding their geometries, energies, vibrational frequencies, and topological features of the electron density. The quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analysis was employed to elucidate the interaction characteristics in cysteine–propanoic acid (Cys–Prop) complexes. More than 10 kinds of hydrogen bonds (H-bonds) including intra- and inter-molecular H-bonds have been found in Cys–Prop complexes. The results show that both the strength of H-bonds and the deformation are important factors for the stability of Cys–Prop complexes. The strongest H-bonds (O2HA···O1B and O2HA···O1B) exist in the most stable Cys–Prop complex. The stronger H-bonds formed between hydroxyl and O (or N) atom usually stronger than those involve C (or S) atom. Relationships between the electron density (ρ) of BCP and H-bond length as well as the Fock matrix element (F ij) has also been investigated and used to study the nature of H-bonds. Moreover, the results show that the change of the bond length linearly correlates with the corresponding frequency shift.  相似文献   
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