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本文讨论了分次模范畴等价的两个分次代数的循环同调群之间的关系以及范畴gr-R,GR-R上的分次循环同调的形式. 相似文献
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以双酚A型聚碳酸酯(PC)为基体、苯乙烯-丙烯腈共聚物(SAN)为散射体,通过熔融共混方法制备了同时具备高透光率和高雾度的高散射聚碳酸酯光散射片,研究了SAN含量对光散射片微观结构和光散射性能的影响,发现透光率和雾度同时随着散射体含量增加而提高的现象.研究结果表明,当SAN含量低于30%时,分散相为球形颗粒,颗粒的平均粒径随着SAN含量的增加而增加,而颗粒的数量浓度则随之减小,这使得其透光率和雾度均随着SAN含量的增加而增加,当SAN含量为30%时,透光率和雾度达到最大值,分别为89.1%和91.7%.并结合Mie散射理论解释说明了透光率和雾度同时随着散射体含量的增加而提高的现象.但当SAN含量的进一步增加,分散相颗粒尺寸已远大于光波的波长,不再适用于Mie散射理论,且部分不再呈球形颗粒,使得PC片的透光率和雾度略有降低. 相似文献
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We report a high-power thin Nd:YAG slab laser with slab dimension of 1 × 10 ×60 (mm) partially edgepumped by diode laser arrays. Passive Q-switching is achieved with a Cr^4+ :YAG microchip adopted as the saturable absorber mirror. The pulse duration is around 10 ns while the pulse repetition rate is higher than 10 kHz. The average output power of 70 W is obtained with a slope efficiency of 36%. The diffraction limited beam quality in the thickness direction is obtained by controlling the pump beam diameter inside the slab. The laser head is very compact with size of only 60 × 74×150 (mm). 相似文献
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综述了几种用于监控薄膜外延生长的光学原位实时监测方法的进展。其中光反射差法/光反射各向异性谱(RDS/RAS)和p偏振反射谱(PRS),表面光吸收(SPA),椭偏仪(SE)等。在外延过程中已观测到了薄膜层状外延周期振荡。 相似文献
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使用激光分子束外延 ,在SrTiO3 ( 1 0 0 )单晶衬底上成功生长了一系列c轴取向的 ,具有原子量级控制精度的BaTiO3/SrTiO3超晶格 .利用晶格失配导致的薄膜表面台阶密度的周期性变化 ,讨论了反射式高能电子衍射 (RHEED)强度在BaTiO3 层和SrTiO3 层中的周期性调制 .系统研究了二阶非线性光学极化率同超晶格结构的关系 .实验测量和理论拟合结果表明 ,BaTiO3 /SrTiO3 超晶格的二阶非线性光学极化率显著增强 ,其最大值比BaTi3体单晶提高一个数量级以上 .从应力导致的晶格畸变和极化增强出发 ,讨论了二阶光学非线性增强的物理机制 相似文献
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Thermal stability and data retention of resistive random access memory with HfO_x/ZnO double layers 下载免费PDF全文
As an industry accepted storage scheme, hafnium oxide(HfO_x) based resistive random access memory(RRAM)should further improve its thermal stability and data retention for practical applications. We therefore fabricated RRAMs with HfO_x/ZnO double-layer as the storage medium to study their thermal stability as well as data retention. The HfO_x/ZnO double-layer is capable of reversible bipolar switching under ultralow switching current( 3 μA) with a Schottky emission dominant conduction for the high resistance state and a Poole–Frenkel emission governed conduction for the low resistance state. Compared with a drastically increased switching current at 120℃ for the single HfO_x layer RRAM, the HfO_x/ZnO double-layer exhibits excellent thermal stability and maintains neglectful fluctuations in switching current at high temperatures(up to 180℃), which might be attributed to the increased Schottky barrier height to suppress current at high temperatures. Additionally, the HfO_x/ZnO double-layer exhibits 10-year data retention @85℃ that is helpful for the practical applications in RRAMs. 相似文献
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利用活化气体做氧源,使生长气压比普通脉冲激光沉积方法(PLD)低2~3个数量级,用激光分子束外延在SrTiO3(100)衬底上制备出临界转变温度Tc0=85~87K,临界电流密度Jc≥1×106A/cm2的高质量YBCO超导薄膜.原子力显微镜(AFM)测得表面无明显颗粒,均方根粗糙度约为7.8nm.在这种薄膜基础上制备的Josephson量子干涉器件(DC-SQUID)具有良好的温度循环稳定性. 相似文献