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941.
942.
No abstract.
March 30, 2000 相似文献
943.
944.
A new gelator of urea‐containing triazine derivatives was synthesized and tested in order to explore the gelation potential in different organic solvents. This compound has been found to form organogels with a variety of organic solvents such as decalin and other solvents. The resulting thermo‐reversible gel was characterized by using the dropping ball method and a number of other instruments. The melting temperature of the gel increased with the gel concentration. The intermolecular hydrogen bonding of gelation was demonstrated through an FT‐IR spectrometer. UV‐Vis and fluorescence analysis showed that the gel displayed various optical effects in different organic solvents. The blue fluorescence of the gel in decalin and the quenched effect of gel in CHCl3 were displayed, respectively. Morphological features in decalin and CHCl3 were studied by applying atomic force microscopy (AFM), and the morphological features demonstrated that there were different aggregations in different solvents. In conductivity electrolyte experiments, the organogel electrolytes indicated high conductivity (σ) comparable to the corresponding NaClO4/THF solution. The conductivity of gel electrolytes was increased with electrolyte salt. 相似文献
945.
The Bergman kernel function plays an important role in several complex variables. Thereexists the Bergman kernel function on any bounded domain in Cn. But we can get the Bergmankernel functions in explicit formulas for a few types of domains only, for instance, the boundedhomogeneous domains and the egg domains in some cases.Yin Weiping defined four types of generalized Hua domainsGHE1(N1,… Nr; m, n,p1…,pr, k)where wj = (wi1,…, wjNj ),j = 1, 2,…, r. RI(m, n), RⅡ(p), RⅢ(q), and RⅣ… 相似文献
946.
Qianying Sheng Wenqing Zhang Yan Wang Yi Zhao Haiyan Liu Junhong Qian Bo Zhang Qing Wang Ping Hu 《大学化学》1986,36(1):2002027-0
In order to solve the issues of traditional teaching methods in the undergraduate basic theory course, the blended learning mode was put forward by taking analytical chemistry as an example. With concept of student-centered, personalized teaching, together with assistant means, was introduced to achieve the breakthrough in solving the problems. We hope to reinforce the adaptability and targeting of the course teaching. 相似文献
947.
Chong Jia Yong Su Qingtao Zhou Minjun Xin Yousheng Lv Weihai Kong 《Applied Surface Science》2008,254(8):2331-2335
Large scale flower-like ZnO nanosheets have been synthesized on Zinc foil by a simple hydrothermal method. Their morphology and microstructures were characterized and analyzed by X-ray spectroscopy (XRD), field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HRTEM). The as-synthesized flower-like nanosheets are hexagonal phase single crystal with 200-300 nm in width, 50 nm in thickness. The growth process follows the liquid phase epitaxial growth mechanism. In this approach, the ZnO buffer is used as substrate for the growth of flower-like ZnO nanosheets. The growth direction of the nanosheets is the preferential [0 0 0 1] growth direction of ZnO. The photoluminescence spectrum of the sample exhibits only a sharp and strong UV emission centered at 386 nm, which indicates that the flower-like ZnO nanosheets on Zn foil are of good optical property. 相似文献
948.
This paper is concerned with eigenvalues of perturbed second-order vector discrete Sturm–Liouville problems. By some variational properties of eigenvalues of discrete Sturm–Liouville problems, error estimates of eigenvalues of perturbed problems, sufficiently close to a given Sturm–Liouville problem, are given under a certain non-singularity condition. Perturbations of the coefficient functions of the difference equation, the weight function, and the coefficients of the boundary condition are all considered. This, together with higher-dimension involved, results in a certain complexity of the problem and difficulty of study. As a direct consequence, continuous dependence of eigenvalues on problems is obtained under the non-singularity condition. In addition, an example is presented to illustrate the necessity of the non-singularity condition. 相似文献
949.
Su Wang Nanfei Chen Chin-Sheng Chen Xinxiong Zhu 《Finite Elements in Analysis and Design》2009,45(8-9):592-596
Advances in materials and rapid prototyping technology, makes developing rapid-prototype heterogeneous parts possible. This paper proposes a finite element-based approach for modeling heterogeneous parts to facilitate rapid prototyping. In this approach, traditional geometrical and topological data are blended with materials information in the CAD model. It builds on a CAD system to create parts’ geometry which is then subdivided into a set of tetrahedral finite elements. With this, the design problem of material distribution in the whole body can be handled at the finite element level. The material composition of each point inside a finite element is formulated in terms of four control nodes of the finite element and a blending function. Moreover, design rules for modeling heterogeneous parts are introduced in the paper, making the modeling solution more robust. 相似文献
950.
To expand the application of cellulose in the field of fluorescence techniques, the cotton cellulose was labeled with norfloxacin
(Cell-NF) via a three-step reaction, involving alkali treatment, epoxy activation, and opening of the epoxy rings with norfloxacin
molecules. And the coordination complexes of Cell-NF with rare earth ions terbium (Cell-NF-Tb) and europium (Cell-NF-Eu) were
obtained. The products were detected by IR, TG, XPS, UV and fluorescence spectra. Results showed that the norfloxacin content
of the labeled cellulose was about 6.73 w% and the start temperature of decomposition of the Cell-NF was raised by 40°C compared
with the stock cotton cellulose. When excited at 340 nm, the Cell-NF, Cell-NF-Tb, and Cell-NF-Eu in the solid state could
emit violet (430 nm), green (549 nm) and red (620 nm) light, respectively. 相似文献