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排序方式: 共有174条查询结果,搜索用时 31 毫秒
1.
2.
SiC-based field-effect gas sensors with catalytic platinum electrodes (Pt-MOSiC) have been subjected to a series of gas response measurements. Structural analysis of the Pt electrodes revealed that the gas sensitivity and the selectivity of Pt-MOSiC gas sensors depend on two major parameters: the porosity and the catalytic activity of the Pt electrodes. Pt-MOSiC gas sensors with thick, dense Pt electrodes only exhibit hydrogen sensitivity, whereas Pt-MOSiCs with thin porous gates exhibit a broad range of gas sensitivities similar to resistive metal-oxide gas sensors. A model is put forward that explains the nonhydrogen gas response of Pt-MOSiC devices and of conventional polycrystalline metal-oxide materials on a common basis. 相似文献
3.
用精确饲喂技术评价了 3个品种的中国双低油菜和 1个加拿大卡诺拉的脱脂种籽和商品饼粕的能量和氨基酸的有效性。结果表明 ,4个脱脂种籽的氮校正真代谢能和氨基酸真消化率没有差异 (P >0 .0 5 ) ;而 4个商品饼粕的脱脂样品的氮校正真代谢能和氨基酸真消化率有极显著或显著差异。研究结果证实 ,不适当的加工方式不仅降低了氨基酸的有效性 ,而且影响家禽对能量的利用效率。 相似文献
4.
5.
Guenter Ahlers 《Journal of Low Temperature Physics》1978,31(3-4):429-439
Measurements of the dependence of the thermal conductivity (T, ) of 4He vapor on the density are presented at 3.3 and 4.5 K. The initial dependence upon near = 0 agrees with the prediction of the modified Enskog theory; but at higher densities there are departures from the prediction. The excess thermal conductivity (T, ) – (T, 0) is independent of T within experimental error. 相似文献
6.
The bandwidth of the ball-screw drive is limited by the first natural frequency of the mechanical structure. As opposed to conventional drives where the axial bearing stiffness is kept high to obtain higher natural frequencies, this paper proposes to use lower axial bearing stiffness accompanied by a strong damper in parallel with the ball-screw structure. The proposed method, which is experimentally demonstrated, increases the bandwidth of the drive considerably provided that a cost effective and practical damper is available. 相似文献
7.
Guenter Ahlers 《Journal of Low Temperature Physics》1969,1(6):609-631
In this paper available measurements of the attenuation and dispersion of first sound near the superfluid transition in He4 are re-examined. Particular attention is given to the effect of the gravitational inhomogeneity upon the measurements, and the thermodynamic velocity is used to obtain the dispersion contribution from measured velocities at nonzero frequencies. The re-interpreted results are discussed in terms of current theories. Although there is partial agreement between experiment and theory, a number of aspects of the problem requires further theoretical and experimental investigation. 相似文献
8.
Hsueh-hua Chuang Biard J.R. Guenter J. Johnson R. Evans G.A. Butler J.K. 《Quantum Electronics, IEEE Journal of》2007,43(11):1028-1040
This paper presents an iterative model for the analysis of the current distribution in vertical-cavity surface-emitting lasers (VCSELs) using a SPICE-like approach. The model includes a degeneracy correction for operation at and above threshold. The effect of the resistance due to the p-distributed Bragg reflector (p-DBR) mirror layers and the oxide layer on performance is investigated. Higher sheet resistance under the oxide layer reduces the threshold current, but reduces the current range over which single transverse mode operation occurs. The voltage drop across the p-DBR region dominates spatial hole burning, which is moderated by lateral drift and diffusion. This simple iterative model is applied to commercially available oxide-confined VCSELs. 相似文献
9.
The effect of chlorine and oxygen concentrations on the removal of mercury at an FGD-batch reactor 总被引:2,自引:0,他引:2
A series of laboratory scale experiments were conducted in an FGD-batch reactor. A synthetic flue gas was produced and directed through a CaCO3 suspension contained in a glass reactor vessel. The suspension temperature was set at 54 °C through a water bath. In order to observe the distribution of mercury species in the system, solid, liquid and gaseous samples were taken and analysed. For gaseous mercury determination, continuous measurements were carried out, up and downstream the reactor. Furthermore, the concentration of chlorine in the scrubber solution of the system was varied from 0 to 62 g/l under different oxidative conditions.In a first approach, a concentration drop of elemental mercury coming out of the system was observed. The latter occurs only when high concentrations of Cl− are present, combined with a high O2 availability in the scrubber. It was also observed that mercury species distribution in the different phases varies, depending on the available chemical form of chlorine and oxygen concentration. 相似文献
10.
Jesse A. Ahlers Jordan A. Grasser Brett T. Loveless Darrin S. Muggli 《Catalysis Letters》2007,114(3-4):185-191
At room temperature in the absence of gas-phase oxygen, reduced Cu on Cu/ZnO extracts oxygen from the ZnO lattice to reoxidize
the surface. After 120 min at room temperature, diffusion of lattice oxygen reoxidizes reduced Cu/ZnO to 3% of its completely
oxidized state. When gas-phase oxygen is present, it promotes the partial reoxidation of the reduced Cu/ZnO surface at room-temperature. 相似文献