稀土纳米磁致冷复合材料

采用急冷快淬，高能球磨及粉末包套包覆轧制方法制备出Ｇｄ－Ｙ，Ｇｄ－Ｚｎ和Ｇｄ－Ｔｈ的纳米固体复合磁致冷材料。实验测试结果表明：与大块状材料相比，纳米固体的居里温度明显降低，比热显著增加：Ｇｄ－Ｔｈ和Ｇｄ－Ｚｎ合金的磁热熵效应有所降低，但Ｇｄ－Ｙ系的磁热熵效应则显著增加。对制备工艺条件及若干影响磁质变熵效应的因素进行了较详细的分析。     

Hepatoprotective and hypolipidemic effects of water-soluble polysaccharidic extract of Pleurotus eryngii

The potential biological functions of Pleurotus eryngii have long been described in Chinese traditional medicine. However, little is known about the bioactive components of P. eryngii and their functions in liver injury and high-fat induced animal models. The present study thoroughly investigated the comprehensive functions of water-soluble polysaccharidic extract of P. eryngii (PEPE) using in vivo mouse models and in vitro biochemistry tests. PEPE could significantly increase the activities of antioxidant enzymes and effectively remove the free radicals in a liver-injury mouse model. Furthermore, in a high-fat-load mouse model, PEPE not only remarkably decreased the lipid levels of total cholesterol, total triglyceride, and low-density lipoprotein cholesterol, but also resulted in an increase in high-density lipoprotein cholesterol. Histopathological observations indicated that PEPE could effectively prevent excessive lipid formation in liver tissue. Our data suggest that PEPE can be used as a valuable functional food additive for hypolipidemic and hepatoprotective treatments.     

浅谈反应进度和摩尔反应和引用单位反应概念

深入讨论了物理化学教学中的热化学部分中经常采用的反应进度和摩尔反应等重要概念,并采用摩尔反应概念时存在的一些问题和解决这些问题的方法。提出引用一种新的概念—单位反应概念,详细介绍单位反应概念并把它代替摩尔反应概念的优点。     

尿基熔体造粒高塔内流场分析

以复混肥造粒过程原理为基础,采用Fluent软件对尿基复混肥高塔造粒过程进行数值模拟。连续相数学描述采用欧拉法,分散相采用拉格朗日法,连续相与分散相进行耦合计算。分析得到造粒塔内空气的温度、速度分布及复混肥颗粒的运动轨迹、空间分布。通过与测试结果对比,证明数值模拟结果可信,方法可行。关键词尿基复混肥高塔造粒数值模拟多相流     

使用自适应RF预失真技术改善放大器线性的研究

RF功率放大器对信号造成的非线性失真会产生邻道干扰，并降低信号质量，因此宽带通信系统对功率放大器的线性提出了严格的要求。本文提出了可以改善功率放大器线性的自适应RF预失真电路的模型，描述了自适应RF预失真的实现过程；介绍了现有的一些自适应预失真技术，具体分析了常用的矩形功函数预失真技术和最小功率自适应方法；通过仿真进一步证明了预失真技术可大大提高RF功率放大器的线性度。     

面向态势评估的一种有效的证据理论合成公式

战场态势评估是指挥决策的基础,如何进行合理的态势评估是C4ISR数据融合系统中的一个重要环节.针对态势评估中的证据在合成过程中的重要程度不同,通过引入证据权重值,提出了一种新的D-S证据理论合成方法.实验表明该方法可提高态势评估中证据合成的合理性与可靠性,能得到更理想的合成结果,更符合实际情形.     

Preparation of vanadium dioxide powders by thermolysis of a precursor at low temperature

A kind of crystal precursor, (NH₄)₅[(VO)₆(CO₃)₄(OH)₉]·10H₂O, less than 12 × 40 m in dimensions was synthesized by reaction of vanadyl dichloride and ammonium hydrocarbonate in solution. The precursor microcrystals were fined to less than 10 m with mean size of about 4 m, by using organic solvents and surfactant in the process of the synthetical technique. Thermolysis of the precursor in a flow of nitrogen gas was investigated by TGA and DTA. The XRD powders patterns for the products from the thermolysis of the precursor show that the VO₂ powder obtained at 350, 365, 380 and 410°C for 30 min were a noncrystalline phase, a monoclinic one named as B phase, a mixed phase of the B and the usual monoclinic A phase, and the pure A phase, respectively. SEM micrographs of VO₂ powders from the fined precursor demonstrated that the particle sizes of these fine powders were less than 2 m. DSC curve of the VO₂ obtained at 450 °C for 30 min from the fined precursor showed that there was an endothermic phase transition at 71 °C.     

基于MATLAB的通信原理实验设计和仿真

提出一种基于MATLAB系统仿真平台的通信原理实验设计与仿真,以实例验证通信原理的理论知识.MATLAB是集数值计算、图形绘制、图像处理及系统仿真等强大功能于一体的科学计算语言.将MATLAB的图形绘制和系统仿真等功能应用于通信原理实验仿真中,通过自己创建的系统来进行实验更能使学生深入理解通信系统工作原理.     

平面镜反射系统用于太阳能节能住宅设计与研究

通过借鉴平面镜的反射原理,达到在太阳能板同等面积、同等气象条件情况下,将更多的太阳光聚集到太阳能电池板上,从而使每块太阳能电池板的工作效率提升甚至翻倍的效果,切实做到节省太阳能电池板的投资,在使用同样数量的太阳能电池板条件下,提高太阳能电池板的实际输出功率,实现太阳能光电一体化住宅节能减排的目标.     

碳化硼基复合材料制备研究进展

碳化硼断裂韧性低、烧结温度高、抗氧化能力差、对金属的稳定性差,限制了其在工程上的进一步应用。综述了碳化硼粉末的成型方法以及碳化硼基复合材料的烧结方法,总结了碳化硼陶瓷的增韧及烧结过程中的氧化行为。