论二正(异)丙氧基-三嗪的合成

以三聚氯氰为起始原料合成了四种三嗪衍生物,并用红外光谱和质谱分析法对它们进行了表征。产品检测结果表明,四种三嗪衍生物有较高熔点,在常温下不易挥发。     

The meaning of autism: beyond disorder

The incidence of autism spectrum disorders has increased dramatically over the past two decades, yet these disorders are still poorly understood. By considering the viewpoints of autistics themselves, together with evidence from the scientific literature, it becomes clear that autism spectrum disorders are not always the debilitating conditions that they are sometimes portrayed as. In fact, they are often associated with a number of strengths. With a focus on the areas of intelligence, communication, social skills and stereotyped/repetitive behaviours, this article calls into question the idea that autism is a traditional disorder and argues that a new inclusive dialogue on the meaning of autism should be considered.     

Al_（0．3）Ga_（0．7）As／GaAs超晶格在高能高温注入下的晶格损伤

用卢瑟福背散射／沟道技术研究了ＩＭｅＶＳｉ￣＋衬底加温注入Ａｌ_（０．３）Ｇａ_（０．７）Ａｓ／ＧａＡｓ超晶格和作为比较的ＧａＡｓ晶体后晶格的损伤积累与注入剂量的关系。实验结果表明，在注入剂量比较小的情况下，两种晶体都只有很轻微的损伤；动态退火过程的存在抑制了晶格损伤的积累。但在较高的注入剂量下，在几乎无损伤的表面下两种晶体中都形成了损伤埋层，且ＧａＡｓ中损伤峰处的损伤程度和损伤峰的宽度都大于Ａｌ_（０．３）Ｇａ_（０．７）Ａｓ／ＧａＡｓ超晶格中的情形，根据级联碰撞理论分析了晶体中的损伤积累过程，并从化学键相对强度差异的角度定性地解释了ＧａＡｓ和Ａｌ_（０．３）Ｇａ_（０．７）Ａｓ／ＧａＡｓ超晶格实验结果的不同。     

碱土金属钛酸盐和锆酸盐中钐离子的光谱特性

采用高温固相反应法,在空气中合成了Sm3 激活的碱土金属钛酸盐和碱土金属锆酸盐磷光体:MM′O3:Sm3 (M∶Ca,Sr,BaM,:Ti,Zr).结果表明,合成的碱土金属钛酸盐和锆酸盐均为具有确定结构的单一物相,Sm3 在MM′O3中的相对发射强度按Ca→Sr→Ba顺序减弱,可能与碱土金属离子半径和原子的元素电负性有关.     

一种新型扩频信号

从高分辨、抗干扰、低截获角度出发，提出一种新的扩频信号。这种信号是线性调频与非周期伪随机编码信号及线性调频连续波与周期伪随机编码信号组成的一种新型信号。理论分析和大量的计算机模拟结果证明了这种新型扩频信号的有效性。另外，用数字方法实现了这种波形的宽带波形产生器。这种产生器可以产生任意幅度和相位调制的信号。同时给出这种宽带信号用声表面波技术处理的方法。     

非相干硬判决多进制直扩系统的门限选取

首先介绍一种采用非相干硬判决的多进制直扩通信系统的构成和原理，然后推导出一套在高斯白噪背景和窄带干扰下系统的纠错前符号差错率估算公式，并研究最佳门限问题。最后给出一些数值结果并简单总结全文。     

无扩频矩阵知识二维扩频系统的盲同步

针对加性白高斯噪声信道,考虑未知二维扩频矩阵的条件下,提出了一种二维扩频系统的时频同步方法。该方法利用二维扩频矩阵周期性重复的特点,先估计出频率偏差,再通过滑动暂存窗求相关矩阵最大特征值,完成信号的时间同步。计算机仿真结果验证了该方法的有效性。     

阴极发射电流对磁控管性能的影响

利用三维粒子模拟软件,比较研究了在磁控管模拟计算中三种阴极发射方式在电流控制、宏粒子数和计算度上的不同,确定了Beam发射是电流控制的最好发射模式;在固定电子能量的基础上,研究阴极电流发射密度分别为9A/cm 3A/cm~2和7A/cm~2下的输出频谱和模式竞争过程,研究结果表明:选择合适的发射电流大小有利于磁控管频谱噪声抑制．     

Companion animals in families of children with autism spectrum disorder: Lessons learned from caregivers.

Companion animals (i.e., pets) have been increasingly recognized for the roles they play in families, including those with children with Autism Spectrum Disorder (ASD). This cross-sectional study explored the unique functions of companion animals within families with a child with ASD. Phenomenology was used to analyze the responses of participants (N = 338) who responded to a survey offered through the Interactive Autism Network. The study initially focused on dogs; however, the analysis was forced to expand to other species due to the data provided by participants. Seven major themes emerged: bonding and benefits, learning opportunities, barriers, grief, fit (match of family characteristics with those of the companion animal), safety, and alternative animals. Successful fit between companion animals and families was often described as necessary for beneficial functions. Barriers included necessary cost and time, as well as required supervision of interactions to enhance safety of the children and animals.     

Different estimators of the spectral matrix: an empirical comparison testing a new shrinkage estimator

ABSTRACT

In this paper we propose a new non parametric estimator of the spectral matrix of a multivariate stationary stochastic process, with the main goal to locally improve the deficiencies of the smoothed periodogram in terms of mean square error of the estimates. Our estimator is based on a convex linear combination of the frequency averaged periodogram and an estimate of the true mean spectral matrix across frequencies. In a wide simulation study we show that our estimator turns out to be able to markedly improve the frequency averaged periodogram especially at central frequencies.