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含Zn,Ag或Sc的Al-Li-Cu-Mg-Zr合金正电子寿命谱研究 总被引:1,自引:0,他引:1
在深低温到室温的不同温度下,测量了不同时效状态的Al-Li-Cu-Mg-Zr合金和含Zn,Ag或Sc的Al-Li-Cu-Mg-Zr合金的正电子寿命谱,对e^+寿命谱特征参数的分析表明,峰值时的使热空位大量回复,缺陷的数目减少,在深低温下,空位主要以单空位形式存在且随温度升高而激活运动复合成多空位,Zn或Ag的加入对空间的运动复合有束缚作用,而Sc却有助于空位的运动复合,所有实验样品低温下基体电子密 相似文献
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AD钙盐中的维生素A是以其乙酸酯的形态加入,而后者不溶于水。根据此性质,将AD钙盐试样用水浸取即可使维生素A与基体组分离,将不溶物分出,溶于乙醇中并定客为10mL,随即可在此试样乙醇溶液中用UV-分光光度法测定维生素A。在维生素A的吸收峰325nm波长处,用1cm石英吸收皿以乙醇作参比液测得其吸光度。用高纯度的维生素A乙醇酯(纯度99.9%)作标准制作标准曲线,得其线性回归方程为CVC=16.899A+0.059,r=0.9996,方法的回收率在97.7%至100.1%之间。此方法远较国家标准方法和药典方法简单、可行。 相似文献
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一、采用工读交替的“三明治”教学方式,注重培养学生的实际工作技能和实际动手能力。 英国为了培养企业适用的工程技术人才,许多学校实行了“工读交替制”的合作教育。这种方式便是人们常说的“三明治”(或“夹心饼干”式)教学计划。这种人才培养方法分为三个阶段,学生中学毕业后,先在企业工作实践一年,接着在学校里学习完二年或三年的课程,然后再到企业工作实践一年,即所谓的“1 2 1”和“1 3 1”教育计划。此外,英国还实行第一、二、四年在学校 相似文献
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Jia-Ning Liu 《中国物理 B》2021,30(11):116105-116105
Since it was proposed, memtransistors have been a leading candidate with powerful capabilities in the field of neural morphological networks. A memtransistor is an emerging structure combining the concepts of a memristor and a field-effect transistor with low-dimensional materials, so that both optical excitation and electrical stimuli can be used to modulate the memristive characteristics, which make it a promising multi-terminal hybrid device for synaptic structures. In this paper, a single CdS nanowire memtransistor has been constructed by the micromechanical exfoliation and alignment lithography methods. It is found that the CdS memtransistor has good non-volatile bipolar memristive characteristics, and the corresponding switching ratio is as high as 106 in the dark. While under illumination, the behavior of the CdS memtransistor is similar to that of a transistor or a memristor depending on the incident wavelengths, and the memristive switching ratio varies in the range of 10 to 105 with the increase of the incident wavelength in the visible light range. In addition, the optical power is also found to affect the memristive characteristics of the device. All of these can be attributed to the modulation of the potential barrier by abundant surface states of nanowires and the illumination influences on the carrier concentrations in nanowires. 相似文献
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Crystal growth,spectroscopic characteristics,and Judd–Ofelt analysis of Dy:Lu_2O_3 for yellow laser
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Dy:Lu_2O_3 was grown by the float-zone(Fz) method. According to the absorption spectrum, the Judd–Ofelt(JO) parameters ?_2, ?_4, and ?_6 were calculated to be 4.86 × 10~(-20) cm~2, 2.02 × 10~(-20) cm~2, and 1.76 × 10~(-20) cm~2, respectively.The emission cross-section at 574 nm corresponding to the ~4F6_(9/2)→~6H_(13/2) transition was calculated to be 0.53 × 10~(-20) cm~2.The yellow(~4F_(9/2)→~6H_(13/2) transition) to blue(~4F_(9/2)→~6H_(15/2) transition) intensity ratio ranges up to 12.9. The fluorescence lifetime of the ~4F_(9/2) energy level was measured to be 112.1 μs. These results reveal that Dy:Lu_2O_3 is a promising material for use in yellow lasers. 相似文献
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非线性最小二乘拟合法(NLLSF)和MontCarlo法相结合建立电化学体系数学模型,克服了各自不足,集二者优点于一体,不仅计算迭代速度快,而且计算结果与实验值较吻合。 相似文献
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采用双高纯锗探头符合的正电子湮没技术测量了Finemet合金各组元以及在350℃、380℃和400℃下退火(10分钟)的Finemet非晶薄带的多普勒展宽谱,对Finemet合金热处理过程中元素核外电子间的相互作用进行了研究。结果表明,Finemet合金淬火态商谱(参照样品为硅)的谱峰比纯金属元素Fe、Cu、Nb的谱峰要低,Fe和Nb之间存在着3d-4d轨道键合作用。随着退火温度的升高,Fe原子的3d电子与Nb原子的4d电子之间的轨道键合作用增强,商谱的谱峰降低,Cu原子易在表面富集,而Nb原子则在非晶薄带中富Fe区域里重新分布。 相似文献
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采用射频磁控溅射法,采用不同的溅射压强将同一掺钛氧化锌靶材在普通玻璃衬底上溅射出八个TZO(掺钛氧化锌)薄膜样品,测试其微结构和光电性能,分析其薄膜性能与溅射压强之间的微观机理,从而获得制备性能优越的TZO薄膜所需的最佳溅射压强.结果表明:所有样品均为具有c轴择优取向的六角铅锌矿多晶纳米薄膜;溅射压强对薄膜微结构和光电性能有显著的影响;溅射功率为150 W,氩气流量为25 sccm,衬底温度为150℃,压强为0.5 Pa时制备的薄膜光电性能较好,具有较大晶粒尺寸,在可见光区(400 ~ 760 nm)有较高的平均透过率达91.48;,较低电阻率4.13×10-4 Ω·cm,较高的载流子浓度和较大迁移率. 相似文献