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排序方式: 共有49条查询结果,搜索用时 15 毫秒
1.
Two metal/insulator composites, copper/low-density polyethylene (LDPE) microcomposites and copper/LDPE nanocomposites, were prepared in a uniform metal mass fraction. The corrosion characteristics of the two composites in the simulated uterine solution have been studied by cyclic voltammetry, potentiodynamic polarization measurement and electrochemical impedance spectroscopy. Results obtained during this study show that there are obvious differences on the corrosive rates and mechanisms between the two materials. The nanocomposites have stable corrosive reaction, hardly passivation, low corrosion rate and high transformation ratio of copper to soluble cupric ions compared with microcomposites, which indicate that the nanocomposites are perfect to be the novel material for intrauterine device. The corrosion behaviour of the microcomposites was controlled by both the processes of the pervasion of Cu2+ and the transfer of the charge, while that of the nanocomposites was only controlled by the transfer of the charge. This paper also compared the corrosion behaviours of the composites and bulk copper in the simulated uterine solution, there were more insoluble subproducts in the corrosion process of bulk copper than the composites. Further, the electrochemical method in this study is proved to be useful to characterize the corrosion behaviour of high electrical resistivity materials. 相似文献
2.
Rexiati Maimaiti Chaoqun Zhu Yanghai Zhang Qiyue Ding Wei Guo 《International journal of molecular sciences》2021,22(6)
Pre-mRNA splicing plays an important role in muscle function and diseases. The RNA binding motif 20 (RBM20) is a splicing factor that is predominantly expressed in muscle tissues and primarily regulates pre-mRNA splicing of Ttn, encoding a giant muscle protein titin that is responsible for muscle function and diseases. RBM20-mediated Ttn splicing has been mostly studied in heart muscle, but not in skeletal muscle. In this study, we investigated splicing specificity in different muscle types in Rbm20 knockout rats and hormonal effects on RBM20-mediated splicing both in cellulo and in vivo studies. The results revealed that RBM20 is differentially expressed across muscles and RBM20-mediated splicing is muscle-type specific. In the presence of RBM20, Ttn splicing responds to hormones in a muscle-type dependent manner, while in the absence of RBM20, Ttn splicing is not affected by hormones. In differentiated and undifferentiated C2C12 cells, RBM20-mediated splicing in response to hormonal effects is mainly through genomic signaling pathway. The knowledge gained from this study may help further understand muscle-specific gene splicing in response to hormone stimuli in different muscle types. 相似文献
3.
以N,N-二甲基甲酰胺为分散剂,亚硒酸钠和钨酸钠为原料,采用溶剂热法制备了由超薄二维层状纳米片堆叠而成的花状硒化钨纳米材料,并研究了其气敏性能。通过X射线粉末衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)等方法对合成材料进行了结构表征。结果表明:合成的花状纳米硒化钨为六方晶相,在三乙胺、氨水、三甲胺、苯胺、甲酰胺等胺类气体的检测中,对三乙胺气体具有高选择性和超快的响应恢复速率。在最佳工作温度220 ℃下,传感器对体积分数为50×10-6的三乙胺的响应灵敏度达到20.1,其响应、恢复时间分别为6 s和3 s,最低检出限为0.3×10-6。对硒化钨材料的气敏机理也进行了讨论,该材料在气敏领域有着潜在的应用前景。 相似文献
4.
Motivated by the low structural fidelity for near-regular textures in current texture synthesis algorithms, we propose and implement an alternative texture synthesis method for near-regular texture. We view such textures as statistical departures from regular patterns and argue that a thorough understanding of their structures in terms of their translation symmetries can enhance existing methods of texture synthesis. We demonstrate the perils of texture synthesis for near-regular texture and the promise of faithfully preserving the regularity as well as the randomness in a near-regular texture sample. 相似文献
5.
A computational model for periodic pattern perception based on frieze and wallpaper groups 总被引:3,自引:0,他引:3
Liu Y Collins RT Tsin Y 《IEEE transactions on pattern analysis and machine intelligence》2004,26(3):354-371
We present a computational model for periodic pattern perception based on the mathematical theory of crystallographic groups. In each N-dimensional Euclidean space, a finite number of symmetry groups can characterize the structures of an infinite variety of periodic patterns. In 2D space, there are seven frieze groups describing monochrome patterns that repeat along one direction and 17 wallpaper groups for patterns that repeat along two linearly independent directions to tile the plane. We develop a set of computer algorithms that "understand" a given periodic pattern by automatically finding its underlying lattice, identifying its symmetry group, and extracting its representative motifs. We also extend this computational model for near-periodic patterns using geometric AIC. Applications of such a computational model include pattern indexing, texture synthesis, image compression, and gait analysis. 相似文献
6.
The gas-sensing properties of titanium oxide (TiO2)-doped zinc oxide (ZnO) thick film sensor specimens to typical ethanol vapor under UV light activation at room temperature have been investigated. Zinc nanoparticles were mixed with commercial TiO2 in various weight percentage (0%, 1%, 5%, and 10%) and sintered at 650 °C for 2 h to prepare the thick film sensors. The sensors exhibit better photosensitivity and gas sensitivity to ethanol analyte. The response and recovery times are within 8 s. TiO2 doping can improve the sensors stability and reproducibility. X-ray diffraction (XRD) and scanning electron microscopy (SEM) characterization of the film materials revealed that Zn2TiO4 and TiO2 phases hindered the rod- or needle-like structure growth and subsequently affected the gas sensitivity. UV absorption spectra of the sensing film material completely dispersed in ethanol solution exhibited that the red shifts were caused with the doping of a small amount of TiO2 into ZnO then blue shift was caused with higher TiO2 level. The results of the UV spectra are well consistent with the photosensitive performance. The maximum sensitivity can be achieved by doping the amount of TiO2 (5 wt%). 相似文献
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探讨了零件(工件)氮化变形机理,分析了影响氮化变形各种因素及发生氮化变形的一般规律,并通过实验研究,提出了控制变形的措施. 相似文献
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10.
文章对凤凰二级水电站计算机监控系统设计中结构模式,现地控制单元(LCU)、自动化元件、抗干扰和防雷及二次接线的选择进行分析,对水电站计算机监控系统设计具有一定参考和借鉴作用。 相似文献