排序方式: 共有35条查询结果,搜索用时 15 毫秒
31.
Jian GAO Jian-ping XIE Jian-nan DING Jian KANG Hai-na CHENG Guan-zhou QIU 《中国有色金属学会会刊》2006,16(6):1417-1420
The magnetic nanoparticles were extracted from Leptospirillum ferriphilum, strain YSK, isolated from acid mine drainages by treatment with sodium dodecyl sulfate(SDS) and centrifugation through a sucrose density gradient. Transmission electron microscopy(TEM) indicates that the nanoparticles are approximately spherical with a mean diameter of 44 nm, and magnetite crystals in this size range are single magnetic domains. Energy-dispersive X-ray analysis shows that the nanoparticles primarily contain two kinds of elements, iron and oxygen. Thus it can be concluded that the magnetic particles are magnetosomes. Generally, it is thought that cellular magnetotaxis is a direct consequence of the cell possessing magnetosomes. The discovery of magnetosomes in strain YSK can provide the theoretical basis for screening efficient bioleaching bacteria which are specific to different magnetic minerals under an outer magnetic field. 相似文献
32.
以2%辣椒素乙醇溶液均匀喷雾添加于糙米,研究辣椒素对储粮害虫玉米象和赤拟谷盗的拒食和增殖作用。结果表明:辣椒素添加量为4,2g/kg.糙米时,玉米象和赤拟谷盗表现出明显的拒食现象,30d内糙米的因虫损失率,玉米象两个浓度处理组仅为空白对照的26.4%和35.4%;赤拟谷盗处理组仅为空白对照的24.8%和30.6%;辣椒素的添加剂量为0.5g/kg.糙米时,玉米象组、赤拟谷盗组增殖数量分别为空白组的9.23%,26.1%;辣椒素的添加剂量为2g/kg.糙米时,玉米象组存活数仅1头,赤拟谷盗存活数为0。辣椒素的添加使玉米象和赤拟谷盗的增殖受到了明显抑制。 相似文献
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34.
Mu?LiEmail author Yigang?He Ying?Long 《Analog Integrated Circuits and Signal Processing》2012,71(2):283-291
For applications requiring low-voltage low-power and real-time processing, a novel scheme for the VLSI implementation of wavelet
transform (WT) using switched-current (SI) circuits is presented. SI circuits are well suited for these applications since
the dilation constant across different scales of the transform can be implemented, and controlled by both the aspect-ratio
of the transistors and the clock frequency. The quality of such implementation depends on the accuracy of the corresponding
wavelet approximation. First, an optimized procedure based on differential evolution algorithm (DE) is applied to approximate
the transfer function of a linear steady-state system whose impulse response is the required wavelet. The proposed approach
significantly improves the accuracy of approximation wavelets. Next, the approximation of time-domain wavelet function is
implemented by the SI analog filters. Finally, the design of the complete SI filter based on first-order and biquad section
as main building block is detailed. Simulations demonstrate the performance of the proposed approach to analog WT implementation. 相似文献
35.
《中国有色金属学会会刊》2021,31(10):3192-3204
Based on volume of fluid (VoF) interface capturing method and shear-stress transport (SST) k-ω turbulence model, numerical simulation was performed to reveal the flow mechanism of metal melts in melt delivery nozzle (MDN) during gas atomization (GA) process. The experimental validation indicated that the numerical models could give a reasonable prediction on the melt flow process in the MDN. With the decrease of the MDN inner-diameter, the melt flow resistance increased for both molten aluminum and iron, especially achieving an order of 102 kPa in the case of the MDN inner-diameter ≤1 mm. Based on the conventional GA process, the positive pressure was imposed on the viscous aluminum alloy melt to overcome its flow resistance in the MDN, thus producing powders under different MDN inner-diameters. When the MDN inner-diameter was reduced from 4 to 2 mm, the yield of fine powder (<150 μm) soared from 54.7% to 94.2%. The surface quality of powders has also been improved when using a smaller inner-diameter MDN. 相似文献