排序方式: 共有138条查询结果,搜索用时 46 毫秒
81.
The Local Radial Basis Function-Differential Quadrature (RBF-DQ) method is applied to two-dimensional incompressible Navier-Stokes
equations in primitive form. Numerical results of heatlines and entropy generation due to heat transfer and fluid friction
have been obtained for laminar natural convection. The variations of the entropy generation for different Rayleigh numbers
are also investigated. Comparison between the present results and previous works demonstrated excellent agreements which verify
the accuracy and flexibility of the method in simulating the fluid mechanics and heat transfer problems. 相似文献
82.
Majid Soleimani Majid Ghahraman Afshar Atefeh Shafaat Gastón A. Crespo 《Electroanalysis》2013,25(5):1159-1168
We report here a novel carbon paste electrode (CPE) which is able to quantitatively sense tramadol under physiological conditions without sample preparation step. The selectivity of CPE is modified by applying molecularly imprinted polymer (MIP) technology. Multiwalled carbon nanotubes (MWCNTs) are incorporated in the structure of CPE to improve the conductivity and the ion‐to‐electron transduction. The electrode shows a wide dynamic linear range for tramadol from 10?7 to 10?3 M. The observed limit of detection and % RSD are 5×10?7 M and 1.8 %, respectively. Finally, the proposed method is applied to determine tramadol in urine and medicinal tablets. 相似文献
83.
MgBr2 supported on Fe3O4@SiO2 ~ urea nanoparticle: An efficient catalyst for ortho‐formylation of phenols and oxidation of benzylic alcohols
下载免费PDF全文
![点击此处可从《应用有机金属化学》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Urea was successfully immobilized on the surface of chloropropyl‐modified Fe3O4@SiO2 core–shell magnetic nanoparticles, then supported by MgBr2 and acts as a unique catalyst for oxidation of benzylic alcohols to aldehydes and ketones, and ortho‐formylation of phenols to salicylaldehydes. The prepared catalyst was characterized by FT‐IR, transmission electron microscopy, scanning electron microscopy, X‐ray powder diffraction, dispersive X‐ray spectroscopy, CHN and TGA. It was found that Fe3O4@SiO2 ~ urea/MgBr2 showed higher catalytic activity than homogenous MgBr2, and could be reused several times without significant loss of activity. 相似文献
84.
In this paper, spin-dependent transport through a spin diode composed of a quantum dot coupled to a normal metal and a ferromagnetic lead is studied. The current polarization and the spin accumulation are analyzed using the equations of motion method within the nonequilibrium Green’s function formalism. We present a suitable method for computing Green’s function without carrying out any self-consistent calculation. The influence of coupling strength and magnetic field on the spin current is studied and observed that this device cannot work as a spin diode under certain conditions. 相似文献
85.
Sulfur nanoparticles were successfully synthesized via novel water-in-oil microemulsion system. The microemulsion system contained cyclohexane as an oil phase, Triton X-100 as a surfactant, butanol as a co-surfactant and sodium polysulfide solution or hydrochloric acid solution as aqueous phase, respectively. The sulfur nanoparticles were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and Fourier transform infrared spectroscopy. The results showed that the as-prepared monoclinic sulfur nanoparticles exhibited high purity and spherical shape with an average size of about 22 nm. 相似文献
86.
Role of incoherent pumping and Er3+ ion concentration on subluminal and superluminal light propagation in Er3+-doped YAG crystal
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We study the absorption-dispersion process and group index of weak probe field in a four-level Er3+:YAG crystal.We find that the Er3+ion concentration and incoherent pumping field can influence the absorption-dispersion process and group index of weak probe field.Moreover,our results show that Er3+ion concentration plays a major role in lasing without inversion and absorption with inversion. 相似文献
87.
Ahmad Shaabani Ebrahim Soleimani 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2475-2482
The protonation of a highly reactive 1,4-dipole generated in the reaction between pyridine or isoquinoline and dialkyl acetylenedicarboxylates by the acidic C-H group of (ethoxycarbonylmethyl) triphenylphosphonium bromide leads to a vinyl pyridinium cation derivatives, which undergo a carbon-centered Michael type addition with the conjugate base of the CH-acid to produce highly functionalized stable 1,4-diionic nitrogen betaines. 相似文献
88.
Mathematical Notes - In this paper, we prove the existence of fixed points for any mapping that is a Banach G-contraction with respect to a c-distance on a cone metric space endowed with a graph. 相似文献
89.
90.