原子吸收光谱法测定铬元素的最灵敏线

对国内原子吸收文献中记载的原子吸收光谱法测定铬元素的最灵敏线提出了不同观点.文献记载,原子吸收光谱法测定铬元素的最灵敏线为357.9nm,次灵敏线为359.3nm.经过对铬元素进行原子吸收光谱扫描证实,最大吸收峰位置在359.3nm处;次吸收峰位置在357.9nm处.同时,分别在357.9nm和359.3nm处进行校准曲线的测定,359.3nm处所测的有效吸收值和灵敏度均高于357.9nm处的吸收值和灵敏度.结果表明,原子吸收光谱法测定铬元素的最灵敏线应为359.3nm.     

ICP-AES测定镉及镉合金中的杂质元素

采用ICP-AES同时测定镉及镉合金中锌、铅、铁、铜、砷、锑、锡、镍、铋、铊10种杂质元素的含量.各元素的检出限为0.0018-0.030μg/mL,相对标准偏差为1.36％-4.42％,样品加标回收率为90％-110％.测试结果表明,该法是测定镉及镉合金的简单、准确、快速的方法.     

ICP-AES测定宁夏地产骨碎补粉剂及其煎剂中的无机元素

以硝酸-双氧水作为消解体系,采用电热板直接消解法对宁夏地产骨碎补粉剂及其煎剂进行消解,然后用电感耦合等离子体-原子发射光谱法(ICP-AES)测定了K、Ca、Mg、Fe、Zn、Mn等17种元素.回收率在90.0％-110.0％之间,各元素相对标准偏差在0.009％-1.26％之间,具有良好的准确度和精密度.实验结果表明,宁夏地产骨碎补中含有丰富的K、Ca元素,Mg、Fe、Na、Zn、Mn的含量也相对丰富,并且在煎剂中,除铁元素外,其他几种元素的溶出率也较高.骨碎补微量元素含量的测定,为进一步探讨宁夏地产骨碎补粉剂与煎剂与其药性的相关性,及回医骨伤科药进一步开发与研究提供科学依据.     

12C6+离子辐照对阿维链霉菌代谢效应研究

对12C6+ 离子辐照诱变高产阿维链霉菌株ZJAV-Y1-203 和原始菌株ZJAV-A-1 的摇瓶发酵pH 值、菌体浓度、碳源和氮源代谢进行了测定,研究了12C6+ 辐照对阿维链霉菌的代谢效应。在发酵前期(48h),原始菌株发酵液pH 值低于突变菌株;在发酵96~196 h,诱变高产菌株ZJAV-Y1-203 繁殖快,生长旺盛,N的利用率高;菌体浓度大于原始菌株的浓度,且发酵液的pH 稳定,菌体处于代谢相对更稳定期;在发酵144~240 h,诱变高产菌株ZJAV-Y1-203 对糖源消耗低于原始菌株ZJAV-A-1。这些结果表明,12C6+ 离子辐照对阿维链霉菌代谢影响有利于阿维菌素合成。pH value, mycelium concentration, carbon source and nitrogen metabolism in flask fermentation of the mutant high-producing strain ZJAV-Y1-203 and the original strain ZJAV-A1 have been investigated, in order to show the metabolic effect of avermitilis irradiated by ion beam of 12C6. In early stage (48 h) of the fermentation, pH value of the original fermentation was lower than that of the mutant strains. In 96~196 h of fermentation, the nitrogen utilization in the strains ZJAV-Y1-203 was higher than that in the original strains, its reproductive was fast, and its growing was vigorous. The mycelium concentration of ZJAV-Y1-203 was greater than the original strain, and the pH value of fermentation were stable, so its metabolism was relatively more stable. In 144240 h of fermentation, the strain ZJAV-Y1-203 on sugar consumption was less than the original strains. The effect of 12C6 ion irradiation on metabolism of Streptomyces avermitilis is conducive to the synthesis of avermectin.     

重离子束12C6+累进辐照诱变柠檬酸菌株选育研究

应用大剂量重离子束12C6+ 对菌株H3001 进行二次辐照选育,对初选获得的高产柠檬酸菌株进行摇瓶发酵试验及10~ 100 L 中试发酵罐试验,采用酸碱中和法测定发酵液中柠檬酸的含量。结果表明:当二次重离子12C6+剂量为857.8 Gy 时,致死率和正突变率达到最大值,分别为94.5% 和8%。通过摇瓶发酵试验,最终获得一株高产柠檬酸菌株hw317,控制该菌株发酵周期为60 h,柠檬酸酸度能达到19.2±0.2%。Heavy 12C6+ ion beams in various high doses were employed to irradiate H3001 strain for screening Aspergillus niger strain for hyper citric acid production. Three high-yield strains were obtained after shaker fermentation test. Among the three strains, the strain hw317 was implemented shaker fermentation for stability test and 10~100 L pilot fermentation tank for citric acid productive maximization. Acid-base neutralization method was applied to determinate the content of citric acid in fermented liquid. The results showed that: when the secondary heavy ion 12C6+ dose was 857.8 Gy, both of the fatality rate (94.5%) and the positive mutation rate (8%) were highest. Through the shaker fermentation tests and 10 ~ 100 L pilot fermentation test, one strain hw317 was screened and obtained for hyper citric acid production. Consequently, the final citric acid acidity can reach up to 19.2±0.2% with controlling fermentation cycle for 60 h.     

高氢容量硼氢化锂/碳气凝胶复合材料的制备与性质北大核心CSCD

采用"纳米装填"技术和"熔化渗透"工艺成功制备了氢容量在硼氢化锂质量分数80%以上的硼氢化锂/碳气凝胶复合材料。并用扫描电镜、透射电镜、傅里叶红外透射光谱等手段表征了复合材料的结构与性能。发现硼氢化锂填充了碳气凝胶骨架孔隙的90%以上,形成均匀的复合材料。研究了复合材料的形成机制,发现硼氢化锂先进入碳气凝胶骨架的小孔,再逐渐填充大孔。这有利于材料晶粒的细化,提高吸放氢性能,减少结构缺陷。经放氢动力学测试表明,LiBH4/CRF复合材料的放氢速率是文献中LiBH4与活性炭的球磨样品的5倍。     

激光诱导叶绿素荧光寿命的测量及其特性分析

提出了一种用于评估植物生长状况及环境监测的激光诱导叶绿素荧光寿命测量方法. 采用波长355 nm的激光作为光源激发叶绿素荧光, 由光电倍增管接收其荧光信号, 由于被测叶绿素荧光衰减函数与激光脉冲、仪器响应函数卷积在一起, 根据它们的特性, 运用时间分辨测量法分别测得叶绿素荧光及其背景信号, 并结合一种新型解卷积算法可分离出真实的叶绿素荧光衰减函数, 从而获取叶绿素的荧光寿命. 测试结果表明: 该方法能够实现叶绿素荧光寿命的高精度实时监测, 对不同叶绿素含量的溶液荧光寿命进行了测试, 证明叶绿素含量与其荧光寿命具有相关性, 并且拟合了叶绿素含量与荧光寿命的标定曲线. 关键词： 荧光寿命 激光诱导荧光 时间分辨测量法 叶绿素含量     

例说构造几何图形解代数题

在解题过程中,通过对条件和结论的分析,构造辅助元素（它可以是一个图形、一个方程（组）、一个等式、一个函数、一个等价命题等）,架起一座连接条件和结论的桥梁,从而使问题得以解决,达到思维的创新．华罗庚先生曾说过：“数缺形时少直观,形离数时难入微．”利用数形结合的思想,可沟通代数、几何的关系,实现难题巧解。     

数据缺损矩阵低秩分解的正则化方法

数据缺损下矩阵低秩逼近问题出现在许多数据处理分析与应用领域. 由于极高的元素缺损率,数据缺损下的矩阵低秩逼近呈现很大的不适定性, 因而寻求有效的数值算法是一个具有挑战性的课题. 本文系统完整地综述了作者近期在这方面的一些研究进展, 给出了基本模型问题的不适定性理论分析, 提出了两种新颖的正则化方法: 元素约束正则化和引导正则化, 分别适用于中等程度的数据缺损和高度元素缺损的矩阵低秩逼近. 本文同时也介绍了相应快速有效的数值算法. 在一些实际的大规模数值例子中, 这些新的正则化算法均表现出比现有其他方法都好的数值特性.     

Visual perception of textiles using surface and display samples

In this study, 15 parameters representing textile properties are evaluated by the psychophysical method of categorical judgment with samples presented either in a light booth or on a display to investigate human visual perception based on the textural features of textiles. Visual perceptions of textiles can be expressed by the properties of regularity, smoothness, and warmth, which respectively explain the geometric placement rules of primitive elements, depth information, and emotion of textiles. Textiles with large primitive elements have high regularity and coarseness, whereas textiles with subtle primitive elements exhibit randomness and smoothness. Texture analysis results of the surface samples coincide well with those of display samples.