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991.
A series of Zn(II)-Schiff bases I, II and III complexes were synthesized by reaction of o-phenylenediamine with 3-methylsalicylaldehyde, 4-methylsalicylaldehyde and 5-methylsalicylaldehyde. These complexes were characterized using FT-IR, UV-Vis, Diffuse reflectance UV-Vis, elemental analysis and conductivity. Complex III was characterized by XRD single crystal, which crystallizes in the triclinic system, space group P-1, with lattice parameters a?=?9.5444(2) Å, b?=?11.9407(2) Å, c?=?21.1732(3) Å, V?=?2390.24(7) Å3, D c ?=?1.408 Mg m?3, Z?=?4, F(000)?=?1050, GOF?=?0.981, R1?=?0.0502, wR2?=?0.1205. Luminescence property of these complexes was investigated in DMF solution and in the solid state. Computational study of the electronic properties of complex III showed good agreement with the experimental data. 相似文献
992.
By controlling the reflux time and the quantity of the shell materials, different sizes of thioglycollic acid (TGA) modified
CdTe/CdSe core/shell quantum dots were synthesized in aqueous solution. This type of QDs was used for sensitive and selective
determination of ascorbic acid in commercial tablets. Under optimal conditions, a good linearity was observed between the
relative fluorescence (FL) intensity and the concentration of ascorbic acid in the range of 4.0 to 64.0 μg/mL with a correlation
coefficient of 0.9968. The limit of detection was 2.4 μg/mL. This method was applied to the determination of the ascorbic
acid in Vitamin C tablets and Vitamin C Yinqiao pills, and satisfactory results were obtained. 相似文献
993.
We demonstrate widely tunable soliton and dispersive wave source generation in a highly nonlinear tellurite microstructured
fiber pumped by a 1550 nm femtosecond fiber laser. The spectral range covered by the soliton and dispersive wave source is
as wide as 1100 nm from 1150 to 2250 nm. It is shown that the spectral linewidth of the soliton and dispersive wave can be
controlled by changing the length of the tellurite microstructured fiber easily owing to the dispersion-induced pulse broadening
effects. This light source using tellurite microstructured fiber could open wide applications. 相似文献
994.
Enhanced soliton trapping of dispersive waves in a tapered tellurite microstructured fiber pumped by a 1556 nm femtosecond
fiber laser is demonstrated. The short wavelength edge of supercontinuum light is extended from 960 to 600 nm after tapering
the tellurite microstructured fiber, which is caused by the enhanced soliton trapping of dispersive waves owing to the changing
group velocities in tapered fibers. Wide-band supercontinuum light source spanning from 600 to >2400 nm is generated in tapered
tellurite micro-structured fibers. Our experimental and simulated results show that short length (several centimeters) zero-dispersion-wave
length decreasing highly nonlinear fiber has a potential for generating wideband supercontinuum light source expanding from
visible to mid-infrared region. 相似文献
995.
Speech acquisition by a cochlear implant (CI) is typically performed by a single omnidirectional microphone. In order to improve
the signal-to-noise ratio (SNR) of sound collected from the forward direction, the delay beamforming method is applied to
satisfy the size and processing limitations. The optimal delay time and weighting parameters, selected by our proposed graphical
method, yielded a beam pattern that strongly enhanced speech from the front, while noise from lateral and rear directions
were sharply weakened, making the method appropriate for use in CI applications. 相似文献
996.
997.
Yew Hoong Leong Jaguthsing Dindyal Tin Lam Toh Khiok Seng Quek Eng Guan Tay Sieu Tee Lou 《ZDM》2011,43(6-7):819-831
Problem solving is at the heart of the Singapore Mathematics curriculum. However, it remains a challenge for teachers to realise this curricular goal in practice. Here, we review the efforts of Singapore mathematics teacher educators in incorporating problem-solving (teaching) competency in teacher education and PD programmes. We discuss conceptual and practical issues, actions taken and changes made in building teachers?? capacity to enact a problem-solving curriculum in a school-based design experiment project. In the project, teachers learnt problem solving, observed and then carried out lessons, using the ??Mathematics Practical????akin to the science practical??as key to instruction and assessment. 相似文献
998.
At present, the methods of constructing vector valued rational interpolation function in rectangular mesh are mainly presented by means of the branched continued fractions. In order to get vector valued rational interpolation function with lower degree and better approximation effect, the paper divides rectangular mesh into pieces by choosing nonnegative integer parameters d1 (0 〈 dl ≤ m) and d2 (0 ≤ d2≤ n), builds bivariate polynomial vector interpolation for each piece, then combines with them properly. As compared with previous methods, the new method given by this paper is easy to compute and the degree for the interpolants is lower. 相似文献
999.
1000.
In the present study, a GPU accelerated 1D space–time CESE method is developed and applied to shock tube problems with and without condensation. We have demonstrated how to implement the CESE algorithm to solve 1D shock tube problems using an older generation GPU (the NVIDIA 9800 GT) with relatively limited memory. To optimize the code performance, we used Shared Memory and solved the inter-Block boundary problem in two ways, namely the branch scheme and the overlapping scheme. The implementations of these schemes are discussed in detail and their performances are compared for the Sod shock tube problems. For the Sod problem without condensation, the speedup over an Intel CPU E7300 is 23 for the branch scheme and 41 for the overlapping scheme, respectively. While for problems with condensation, both schemes achieve higher acceleration ratios, 53 and 71, respectively. The higher speedup of the condensation case can be ascribed to the source term calculation which has a local dependence on the mesh point and the SOURCE kernel has a higher acceleration ratio. 相似文献