物理实验教学现代化的一个实例

介绍了CCD图像及计算机技术在物理实验教学中的应用,并就大学物理实验教学内容和教学方法的改革进行了初步的探讨     

太赫兹时域光谱及成像技术在农作物品质检测中的应用研究进展

太赫兹辐射以其独特的技术优势,如瞬时性、宽带性、相干性、低能量性、穿透性和吸收性,受到了全世界各国政府、高等院校、科研机构等的高度重视并日趋成为生物医学、材料科学和物理学等领域的新兴研究热点.农作物成分如水分、蛋白、脂肪、淀粉等理论上在太赫兹谱区有较为丰富的吸收;太赫兹波的低辐射特性对农业生物样本检测更为安全;太赫兹波...     

网上技术市场发展模式与运行管理机制--以中国浙江网上技术市场为例

网上技术市场正逐步发展成为技术交易的主要形式.本文以中国浙江网上技术市场为例,从其定位和动力模式两方面探讨了网上技术市场的发展模式,以及从信息资源管理、技术交易管理和市场运作三方面探讨了网上技术市场的运行管理机制.     

基于BP神经网络的焊点自动光学检测

提出了一种新的表面组装焊点的自动光学检测分类方法。采用单层环形光源获取焊点图像,并根据归一化分割曲线方程将焊点图像分成四部分,分别提取其特征。使用BP神经网络将焊点按照锡量多少分成三类:少锡,容许和多锡。实验结果证明该方法分类正确率达到了99.2%,具有较高的实用价值。     

高校学生管理信息系统的设计与实现

本文介绍一个用C语言开发的学生管理信息系统。该系统具有功能齐全、数据安全可靠、操作方便、人机界面友好等特点。文中讨论了实现该系统所用的主要数据结构、系统结构、系统的实现等。     

溅射羽辉与基底夹角对掺氧二硫化钼薄膜光学性质的影响

二硫化钼(MoS₂)在环境中的热稳定性和化学稳定性好,迁移率相对较高,已应用于气体传感器、光电探测器和场效应管等器件的研制。采用氧气辅助技术生长的氧掺杂MoS₂(MoS_2-xO_x)不仅可以调控MoS₂单晶尺寸,还能提高MoS₂单晶光致发光强度。本文采用射频反应磁控溅射技术、自然环境中氧化和热退火工艺,改变溅射羽辉与玻璃基底夹角来制备MoS_2-xO_x薄膜并研究其光学性质。采用X射线光电子能谱分析了样品的元素和价态;扫描电子显微镜观测的结果表明,溅射羽辉与基底成45°(θ=45°)时表面形貌为最优;紫外-可见分光光度计的测试结果表明,随着厚度和氧含量的增加,MoS_2-xO_x薄膜的光学带隙减小;采用COMSOL Multiphysics软件模拟了MoS_2-xO_x薄膜光学透过率,理论和实验结果相吻合。本文的研究结果将为MoS_2-xO_x薄膜在光学领域的应用提供科学参考。     

An effective method for extracting anthocyanins from blueberry based on freeze-ultrasonic thawing technology

The aim of this study was to develop an effective method for extracting anthocyanins from blueberry Vaccinium spp. (ABVS) using freeze-ultrasonic thawing technology (FUTE). Various parameters including freezing time, ultrasonic time, ultrasonic temperature and liquid–solid ratio were optimized by a single-factor design and multiple response surface methodology. The amounts of extracted anthocyanin and cyanidin-3-O-glucoside were measured by UV and HPLC respectively. The maximum yield of anthocyanins was achieved by freezing the samples for 5.43 min in liquid nitrogen at the liquid–solid ratio of 24.07:1 mL/g, followed by ultrasonic thawing at 41.64 °C for 23.56 min. The yield and antioxidant effects of ABVS extracted using FUTE, ultrasound-assisted extraction (UAE) and freeze-thawing extraction (FTE) were compared in order to determine the overall efficacy of FUTE. In addition to the higher content, FUTE extracted ABVS showed greater ability to scavenge DPPH·, ABTS⁺ and superoxide anions, and inhibit lipid peroxidation compared to the ABVS extracted by UAE or FTE. The reducing power of the FUTE-derived ABVS was intermediate between that of the UAE and FTE samples. Taken together, FUTE can rapidly and effectively extract ABVS and retain its antioxidant capacity.     

Application of ultrasonic technology in postharvested fruits and vegetables storage: A review

It has been an important research topic and a serious applicable issue to extend storage time of fruits and vegetables using advanced scientific and effective technology. Among various approaches, ultrasound has been regarded as one of the most pollution-free and effective technical means to significantly improve the preservation of fruits and vegetables. This paper summarizes the application of ultrasonic technology in fruits and vegetables storage in recent years, including removal of pesticide residues and cleaning, sterilization, enzyme inactivation, effect on physico-chemical indexes. Additionally, we also discussed limitations and negative effects of ultrasonic treatment on fruits and vegetables such as damages to tissues and cells. Furthermore, a proper application of ultrasonic technology has been proven to effectively extend the storage period of postharvest fruits and vegetables and maintain the quality. Moreover, the combination of ultrasound and other conventional preservation technologies can further improve the preservation in a coordinate manner and even have a broader application prospect.     

改进的平均源边界节点法模拟平面位势问题

平均源边界节点法ASBNM是一种最近提出的边界型无网格法。该方法仅使用边界节点不涉及任何单元和积分的概念,具有方法简单和程序设计容易等特点。但是,对于依赖于边界积分方程的边界型无网格法,关键问题是如何准确高效地估计影响矩阵的对角元。本文提出直接计算影响矩阵对角元的方法,是已有ASBNM法的改进,将对角元的计算转化为一个纯几何问题,因此适用于任何二维边值问题。数值算例证明了本文方法的有效性和准确性。     

SERS结合快速前处理检测绿茶中毒死蜱农药残留

茶叶是中国的主要经济作物之一,而在茶叶种植过程中存在农药不合理使用及滥用等行为,导致茶叶中存在严重农药残留问题。茶叶中农药残留检测主要采用经典化学实验室方法,存在前处理复杂、耗时长、成本高等缺陷,急需研究茶叶中农药残留的快速检测方法,以监管茶叶市场的质量安全。本论文采用纳米竹炭(NBC)为净化剂快速去除绿茶的色素等基质影响,使用表面增强拉曼光谱(SERS)方法分析绿茶中毒死蜱农药残留,建立绿茶中毒死蜱农药残留的SERS快速检测方法。采用不同NBC用量(0,15,20,25和30 mg)去除茶叶基质,比较不同NBC用量去除基质的净化效果和SERS谱图,得出最优NBC用量,并对前处理方法进行回收率实验,验证前处理方法的可靠性。结果表明,使用20 mg NBC能较好地净化绿茶中的色素等基质影响,前处理方法回收率实验表明,该净化剂用于绿茶中毒死蜱农药残留基质净化是可行的。采用密度泛函理论模拟毒死蜱分子理论拉曼光谱,对比毒死蜱分子理论拉曼光谱和实验拉曼光谱,对其官能团进行谱峰归属,得到定性定量分析绿茶中毒死蜱农药残留的5个特征峰:526,560,674,760和1096 cm-1。在0.28~11.11 mg·kg-1浓度范围内,以1096 cm-1的峰强度建立绿茶中毒死蜱农药残留线性分析方程y=0.0175x+0.9092,决定系数为R 2=0.9863,表明毒死蜱农药浓度与其特征峰强度之间具有良好的线性关系,方法的平均回收率在96.71%~105.24%之间,相对标准偏差(RSD)为2.36%~3.65%。该方法检测绿茶中毒死蜱农药的最低检出浓度约为0.56 mg·kg-1,单个样本检测时间在15 min内完成。研究表明,表面增强拉曼光谱技术结合净化剂前处理方法能快速检测绿茶中的农药残留。