Enhanced brightness and efficiency of organic light-emitting diodes with an LiF in the Alq/sub 3/

Highly efficient and bright organic light-emitting diodes have been realized by inserting a thin insulating lithium fluoride (LiF) layer in the tris-(8-hydroxyquinoline) aluminum (Alq/sub 3/) with conventional organic layers. By comparing the performances of newly devised devices as a function of the position of the LiF in the Alq/sub 3/ layer, the authors propose the optimal position of the LiF in the Alq/sub 3/ layer. Experimental results show that the efficiency and brightness of the newly devised device with LiF in the Alq/sub 3/ layer were seven times higher than that without LiF in the Alq/sub 3/ layer.     

Molecular design,synthesis, and electro‐optic properties of novel Y‐type polyesters with high thermal stability of second harmonic generation

3,4‐Di‐(2′‐hydroxyethoxy)‐4′‐nitrostilbene was prepared and condensed with terephthaloyl chloride, adipoyl chloride, and sebacoyl chloride to yield novel Y‐type polyesters containing NLO‐chromophore dioxynitrostilbenyl groups, which constituted parts of the polymer backbone. Polymers were found soluble in common organic solvents such as acetone and N,N‐dimethylformamide. They showed thermal stability up to 300 °C in thermogravimetric analysis with glass‐transition temperatures obtained from differential scanning calorimetry in the range 110–152 °C. The second harmonic generation (SHG) coefficients (d₃₃) of poled polymer films at a 1064 cm^?1 fundamental wavelength were around 3.51 × 10^?8 esu. The dipole alignment exhibited high thermal stability even at 10 °C higher than the glass‐transition temperature, and there was no SHG decay below 120 °C for one of these polymers due to the partial main‐chain character of polymer structure, which was acceptable for NLO device applications. Copyright © 2005 Society of Chemical Industry     

掺杂Cu的Ni基催化剂用于制备碳纳米管

以共浸渍法制备的Ni-Cu-Al金属复合物为催化剂,甲烷高温裂解合成碳纳米管。考察了Cu含量对Ni-Cu-Al催化剂活性和碳纳米管形貌的影响及焙烧温度和焙烧气氛对Ni-Cu-Al催化剂性能的影响。采用透射电子显微镜对Ni-Cu-Al催化剂和碳纳米管的形貌进行了表征,采用程序升温还原方法考察了Ni-Cu-Al催化剂的还原温度。实验结果表明,在Ni-Al催化剂中加入Cu不仅可提高催化剂的活性、延长催化剂的寿命,还有助于控制生成的碳纳米管的内径。当n(Ni)∶n(Cu)∶n(Al)=75∶15∶10时,Ni-Cu-Al催化剂的BET比表面积最大,为278.18m2/g;活性也最高,在甲烷流量60mL/min、反应温度1023K、反应时间300min的条件下,碳纳米管的收率(以催化剂的质量计)为23.66g。Ni-Cu-Al催化剂的最佳焙烧条件为350℃,氮气气氛。     

基于Matlab的扩频序列相关值的快速算法

文章提出了应用Matlab进行扩频序列相关值快速计算的方法，该方法充分利用Matlab的矩阵计算优势，大大缩短了在扩频序列的研究中对相关值计算所耗费的时间。通过实例讨论了该方法在扩频序列设计和研究中的应用。     

磁共振成像的信噪比：计量方法与影响因素

在临床上研究不同的MRI扫描技术时，必须要用信噪比这个参数来对图像的成像质量进行评价。最大限度地提高信噪比能有效地改善图像质量。本文描述了信噪比的常用计量方法及在临床磁共振成像扫描中选择不同的参数对信噪比的影响。     

车门包边模

介绍了摆动式和滑动式两种车门包边模的结构及工作过程，比较了它们的特点，阐述了制模中要注意的问题。     

溶胀动力学方法测定高分子链结构

本文成功地用溶胀动力学方法测定了交联、线型及支化高分子的溶胀特征曲线，并认为可由这种溶动力学探针技术判别高分子链的结构类型及特征，是一个很有特色的研究方法。     

MPCVD法在氧化铝陶瓷上的金刚石膜沉积及其成核分析

用微波等离子体化学气相沉积（ＭＰＣＶＤ）法在氧化铝陶瓷基片上沉积了金刚石薄膜。实验表明，对基片进行适当的预处理，包括用金刚石研磨膏仔细研磨和沉积前原位沉积一层无定形碳层，可显著提高成核密度；对硅衬底和氧化铝基片上金刚石膜的成核过程进行了对比分析，并提出了提高氧化铝基片上沉积金刚石的成核的措施。