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901.
本文研究了一类矩阵方程组解的秩的范围.利用矩阵的奇异值分解以及Frobenius范数的特征,得到了解的极值秩以及解的通式,并就这些问题的特殊情况进行了讨论,得到了一些结果. 相似文献
902.
Toshinori Taishi Hideaki Ise Yu Murao Takayuki Osawa Masashi Suezawa Yuki Tokumoto Yutaka Ohno Keigo Hoshikawa Ichiro Yonenaga 《Journal of Crystal Growth》2010,312(19):2783-2787
Oxygen-containing germanium (Ge) single crystals with low density of grown-in dislocations were grown by the Czochralski (CZ) technique from a Ge melt, both with and without a covering by boron oxide (B2O3) liquid. Interstitially dissolved oxygen concentrations in the crystals were determined by the absorption peak at 855 cm−1 in the infrared absorption spectra at room temperature. It was found that oxygen concentration in a Ge crystal grown from melt partially or fully covered with B2O3 liquid was about 1016 cm−3 and was almost the same as that in a Ge crystal grown without B2O3. Oxygen concentration in a Ge crystal was enhanced to be greater than 1017 cm−3 by growing a crystal from a melt fully covered with B2O3; with the addition of germanium oxide powder, the maximum oxygen concentration achieved was 5.5×1017 cm−3. The effective segregation coefficients of oxygen in the present Ge crystal growth were roughly estimated to be between 1.0 and 1.4. 相似文献
903.
E. Richter U. ZeimerS. Hagedorn M. WagnerF. Brunner M. WeyersG. Tränkle 《Journal of Crystal Growth》2010,312(18):2537-2541
The boule-like growth of GaN in a vertical AIXTRON HVPE reactor was studied. Extrinsic factors like properties of the starting substrate and fundamental growth parameters especially the vapor gas composition at the surface have crucial impact on the formation of inverse pyramidal defects. The partial pressure of GaCl strongly affects defect formation, in-plane strain, and crystalline quality. Optimized growth conditions resulted in growth rates of 300–500 μm/h. GaN layers with thicknesses of 2.6 and of 5.8 mm were grown at rates above 300 μm/h. The threading dislocation density reduces with an inverse proportionality to the GaN layer thickness. Thus, it is demonstrated that growth rates above 300 μm/h are promising for GaN boule growth. 相似文献
904.
Orthorhombic Fe5(PO4)4(OH)3·2H2O single crystalline dendritic nanostructures have been synthesized by a facile and reproducible hydrothermal method without the aid of any surfactants. The influences of synthetic parameters, such as reaction time, temperature, the amount of H2O2 solution, pH values, and types of iron precursors, on the crystal structures and morphologies of the resulting products have been investigated. The formation process of Fe5(PO4)4(OH)3·2H2O dendritic nanostructures is time dependent: amorphous FePO4·nH2O nanoparticles are formed firstly, and then Fe5(PO4)4(OH)3·2H2O dendrites are assembled via a crystallization-orientation attachment process, accompanying a color change from yellow to green. The shapes and sizes of Fe5(PO4)4(OH)3·2H2O products can be controlled by adjusting the amount of H2O2 solution, pH values, and types of iron precursors in the reaction system. 相似文献
905.
Sriparna Chatterjee O.D. Jayakumar Avesh K. Tyagi Pushan Ayyub 《Journal of Crystal Growth》2010,312(19):2724-2728
We report a simple, versatile, two-step fabrication technique for synthesizing a core–shell nanorod array whose architecture is specifically suited for use as an electrode in a dye sensitized solar cell (DSSC). The particular structure fabricated by us consists of a parallel array of 5 μm long and 150–200 nm wide Ag nanorod cores, each coated with a 15–20 nm thick ZnO shell. Importantly, the shell thickness is roughly uniform throughout the length of the rods, which are free standing but distinctly separated from each other. This would allow the dye to penetrate freely and cover the ZnO surface completely in a DSSC. 相似文献
906.
907.
Noah J. Tremblay Alon A. Gorodetsky Dr. Marshall P. Cox Theanne Schiros Dr. Bumjung Kim Rachel Steiner Zachary Bullard Aaron Sattler Woo‐Young So Dr. Yoshimitsu Itoh Dr. Michael F. Toney Dr. Hirohito Ogasawara Dr. Arthur P. Ramirez Prof. Ioannis Kymissis Dr. Michael L. Steigerwald Dr. Colin Nuckolls Prof. 《Chemphyschem》2010,11(4):742-742
908.
909.
Yu Nagao Akinori Takasu 《Journal of polymer science. Part A, Polymer chemistry》2010,48(19):4207-4218
Click Cu(I)‐catalyzed polymerizations of diynes that contained ester linkages and diazides were performed to produce polyesters (click polyesters) of large molecular weights [(~1.0–7.0 ) × 104], that contained main‐chain 1,4‐disubstitued triazoles in excellent yields. Incorporation of triazole improved the thermal properties and magnified the even‐odd effect of the methylene chain length. We also found that, by changing the positions of the triazole rings, the thermal properties of the polyesters could be controlled. The use of in situ azidation was a safe reaction, as explosive diazides are not used. In addition, the microwave heating was found to accelerate the polymerization rates. This is the first study that has applied click chemistry for the synthesis of a series of polyesters. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4207–4218, 2010 相似文献
910.
Isothermal calorimetry approach to evaluate shelf life of foods 总被引:7,自引:0,他引:7