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61.
An elliptic curve over a supersimple field with exactly one extension of degree 2 has an s-generic point.
A. Martin-Pizarro would like to express his gratitude to the organisation of the Florida Logic year, in which he took part.
Martin-Pizarro research was supported by a DFG-Forschungsstipendium MA3310/1-1.
F. O. Wagner is a Membre junior de l’Institut Universitaire de France.
Work done during the semester on Model Theory and Applications in Algebra and Analysis at the Isaac Newton Institute for the
Mathematical Sciences, whose hospitality is gratefully acknowledged. 相似文献
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Coiled carbon nanostructure (CNS) is prepared by a catalytic chemical vapor deposition (CVD) process on copper/chromium films deposited by radio frequency (RF) sputtering. Uniform CNS with coiled structure is fabricated by changing the size of the catalyst particles. The effects of Cu catalyst size and RF sputtering power, on the growth of the coiled CNS are discussed, and the results importantly conclude that Cu-catalyzed CVD offers a preferable control of coiled CNS to optimize the field emission property for application. 相似文献
64.
The different approaches that have been taken in the development of analytical methods for the determination of nitrate within the field are reviewed. The emphasis has been placed on providing a critical appraisal of the chemistry that underpins current commercial systems and the need to remove the dependence on heavy metal and concentrated acid components. The search for more environmentally acceptable and user friendly systems has long been pursued and the present communication seeks to explore the recent development in portable testing technologies and how they might evolve in the future. In particular, the role of electrochemical techniques in the latter are investigated and their potential application compared and contrasted with the more traditional wet chemical detection strategies. 相似文献
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由J. T. Pindera提出的平面isodyne法是散光法的一种发展。具有非破坏性直接测取受力物体内部应力的特点。不需要大功率的激光器,条纹清晰,无畸变,对于平面应力问题可以得到应力分量的全部信息。在复合材料力学、断裂力学和接触问题等领域有广泛的应用前景。文章闸述了该方法的原理和技术,并应用它得到一受三点弯曲荷载的有裂纹的复合材料梁粘结层的应力分布。 相似文献
68.
研究了采用电感耦合等离子体-原子发射光谱法(ICP-AES)测定油田水中铜、锌、锰、镍、铬、铁、锶、钡8种元素的方法.方法检出限为0.0003-0.0048μg·mL-1,回收率在96.7%-102.0%之间,相对标准偏差为0.77%-3.57%.采用该方法对油田水样进行了分析,结果表明精密度和准确度均满足分析要求. 相似文献
69.
Xiao-Fei ZhangQing Xu Han-Xing LiuWen Chen Min Chen Bok-Hee Kim 《Physica B: Condensed Matter》2011,406(8):1571-1576
Nonlinear dielectric properties of Ba0.6Sr0.4TiO3 ceramics prepared by citrate method were investigated under bias electric field with respect to field history. X-ray diffraction analysis and temperature dependence of the dielectric constant (εr) confirmed a macroscopically paraelectric state for the specimen at room temperature. A slim polarization versus electric field (P-E) hysteresis loop of the specimen at room temperature indicated the existence of polar nano-regions (PNRs) superimposed on the paraelectric background. The nonlinear dielectric properties in continuous cycles of bias field sweep displayed a strong sensitivity to the field history. This phenomenon was qualitatively explained in terms of an irreversible polarization evolution of the PNRs under the bias fields. A considerable decline of the tunability with the cycle number suggests an appreciable contribution of the PNRs to the dielectric nonlinearity. The polarization and size of the PNRs were determined by fitting the dielectric constants to a multipolarization mechanism model. 相似文献
70.
Qing Zhao 《Solid State Communications》2011,151(22):1650-1653
2D planar field emission devices based on individual ZnO nanowires were achieved on Si/SiO2 substrate via a standard e-beam lithography method. The anode, cathode and ZnO nanowires were on the same substrate; so the electron field emission is changed to 2D. Using e-beam lithography, the emitter (cathode) to anode distance could be precisely controlled. Real time, in situ observation of the planar field emission was realized in a scanning electron microscope. For individual ZnO nanowires, an onset voltage of 200 V was obtained at 1 nA. This innovative approach provides a viable and practical methodology to directly implement into the integrated field emission electrical devices for achieving “on-chip” fabrication. 相似文献