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排序方式: 共有10000条查询结果,搜索用时 14 毫秒
991.
Lixin Ma Changmei Cheng Xiaohong Liu Yufen Zhao Anlin Wang Piet Herdewijn 《Chemometrics and Intelligent Laboratory Systems》2004,70(2):123-128
A back propagation (BP) neural network (NN) method has been developed to predict the stability of RNA/DNA duplex. Calculated Tm of hybrid formation with the present parameters fits the experimental values within reasonable errors (AD=1.2887 K, SEP=1.782, R2=0.9673 for NN1; AD=2.1388 K, SEP=3.506, R2=0.8889 for NN2). And it has the advantage that the determinations of thermodynamic parameters (TP) are not needed. 相似文献
992.
Thermal conductivity of gallium arsenic nitride (GaAsN) epilayer on gallium arsenide (GaAs) substrate prepared by molecular beam epitaxy technique was measured using pulsed photothermal reflectance technique. Three-layer model incorporated thermal boundary resistance was applied to extract the thermal properties from the sample's photothermal response. Within the thickness ranging from 20 to 80 nm, no thickness dependent relationship with thermal conductivity of GaAsN epilayer was found, and the average thermal conductivity is approximately 27 W/mK at room temperature. The thermal boundary resistance at the Au/GaAsN interface is in the order of 10−8 m2K/W. 相似文献
993.
Morphology of graphite in hot-compressed nodular iron 总被引:1,自引:0,他引:1
X. Zhao T. F. Jing Y. W. Gao G. Y. Qiao J. F. Zhou W. Wang 《Journal of Materials Science》2004,39(19):6093-6096
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A physical model of interfacial waves in annular two-phase flow was studied in both microgravity and normal gravity. The wave
structure was obtained for local film thickness and velocity measurements using a conductance probe technique. It was found
that the wave height, and not its width, is strongly affected by changing the gravity level. In fact, the wave height in normal
gravity is more than twice that in microgravity. Using an analogous approach to a turbulent, single-phase flow in a rough
tube, a preliminary mathematical model was proposed to calculate the wave amplitude. The model fits well with the experimental
data and shows that the wave height in normal gravity is approximately 1.7 times the combined thickness of the viscous sublayer
and transition zones in the turbulent gas stream. The wave height in microgravity was estimated to be approximately 80% of
the total thickness. 相似文献
998.
G. Yan Y. Feng B. Q. Fu C. F. Liu P. X. Zhang X. Z. Wu L. Zhou Y. Zhao A. K. Pradhan 《Journal of Materials Science》2004,39(15):4893-4898
The experimental thermodynamic of MgB2 synthesis process and phase compositions have been investigated by diffraction thermal analysis (DTA) technology and X-ray diffraction. The fabrication of MgB2 bulks and superconducting properties at the temperatures range from 600 to 800°C were reported. And microstructure of MgB2 bulks were observed by scanning electron microscope (SEM). A method was developed to determine the porosity of MgB2 and the highest density can be obtained in MgB2 prepared at 650°C at ambient pressure. It is found that the vapor pressure of Mg increases remarkably at high temperature, leading to the high porosity in MgB2 samples. MgB2 bulk with good superconducting property and fine microstructure was synthesized at 750°C. 相似文献
999.
Nanoporous alumina membranes containing parallel regular pores of uniform size and normal to substrate surface were fabricated by anodically oxidizing high purity aluminum foils in acid solutions and their elastic modulus was investigated. The continuous out-of-plane displacement and current load of the porous membranes were obtained through bulge test combining real-time ESPI (electronic speckle pattern interferometry) observation system. Then the elastic modulus was calculated through an analytical model and the pore distortion after load was characterized by HRSEM (high resolution scan electron microscope). Measurement of mechanical properties indicates unusual mechanical behavior of these anodic alumina films compared with bulk alumina materials. This observation may help shed light on fracture mechanism of these films with nanopore arrays and bring further understanding on connecting of micro-meso structure and mechanical properties. 相似文献
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