共查询到20条相似文献,搜索用时 62 毫秒
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利用圆柱体在自制圆弧轨道上的弱阻尼运动测量阻尼因数.通过Tracker视频分析软件对阻尼运动视频进行分析,得到运动曲线,并利用Origin软件对运动曲线进行拟合,根据拟合曲线方程得到阻尼因数的测量值.本实验可对阻尼因数的测量提供参考. 相似文献
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基于分段硬化曲线的X射线CT射束硬化校正方法 总被引:1,自引:0,他引:1
研究了X射线CT射束硬化的形成机理,分析了射束硬化校正的常用方法,建立了以投影灰度为自变量的射束硬化校正模型,从而降低了射束硬化校正的计算难度。分析了采用多项式拟合射束硬化曲线的优缺点,提出一种基于多项式的分段硬化曲线表达新方法。该方法首先采用过原点的多项式曲线拟合硬化数据,然后通过所得多项式曲线的曲率变化,判断该曲线在拟合区间两端是否出现振荡,并对振荡部分的多项式曲线采用幂函数曲线进行替换,同时保证各段曲线在连接点处C1连续(曲线的C1连续定义为, 两条曲线交于一点且在交点处的一阶导数相等)。计算机CT仿真实验结果表明,该方法对理想CT图像和含噪CT图像的射束硬化校正,均表现出良好的稳定性,并可基本消除射束硬化造成的伪影。 相似文献
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基于高通量微弱荧光快速检测的高分辨熔解曲线分析仪 总被引:1,自引:1,他引:0
高分辨熔解(HRM)曲线分析技术是近年发展起来的一种用于基因突变检测和单核苷酸多态性(SNP)分析的新方法,它通过实时监测PCR产物升温过程中双链DNA饱和染料的荧光强度变化来分析核酸序列的微小差异。根据HRM分析仪对荧光检测的时间和灵敏度需求,提出基于光开关阵列的多路高速荧光激发和检测模块实现高通量的微弱荧光快速检测;并根据HRM荧光数据特点,对原始荧光曲线进行滤波、基线探测、归一化和对温度微分等处理,从熔解曲线两端的线形区域自动提取基线作为归一化的标准,可以在不损失曲线形态特征信息的情况下获得更为精确的熔解温度,从而实现不同基因型熔解曲线的快速、准确识别。 相似文献
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食用花卉中Fe含量及其形态分析 总被引:4,自引:1,他引:3
采用SpectroAA 1 0 (Varian)原子吸收分光光度计对食用花卉中Fe含量进行了分析 ,结果表明 ,花卉中Fe含量较高。并对菊花、芙蓉花、金银花中七种形态进行了测定 ,得出了微量元素Fe的提取率、残留率和浸留比等形态分析参数 ,结果表明 ,三种花卉中Fe总提取率 ,浸留比几种参数均较接近 ,说明花卉中Fe结合形式比较类似。三种花卉中的Fe头煎提取率均比二煎提取率高 ,头煎浸留比均比二煎浸留比高 ,但三种花卉中Fe的提取均未超过总量的一半 ,说明食用花卉中Fe不易被水溶解出来 ,可溶性态较少 ,多为不溶性有机态。回收实验结果表明 ,方法的回收率在 96 5 %~ 1 0 3 2 %之间 ,RSD在 1 2 %~ 3 1 %之间 ,表明方法可行。 相似文献
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E. R. Bauminger T. C. Iancu G. Link A. Pinson C. Hershko 《Hyperfine Interactions》1987,33(1-4):249-262
In order to characterize the nature of iron deposits associated with iron overload in heart cells, Mössbauer spectroscopy and ultrastructural studies were performed in iron loaded heart cell cultures obtained from newborn rats grown in a medium containing 20 μg iron/ml. Maximal uptake of iron after 24 hrs was about 15%. Not more than 20% of the iron in these cells was stored in ferritin and the rest was found in smaller trivalent iron aggregates. With time there was a shift from smaller to larger aggregates. In chase samples there was only a very limited spontaneous release of iron from heart cells. Desferrioxamine, an iron chelating drug, removed a major part of the smaller aggregates, but did not remove ferritin iron. 相似文献
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Iron and its complexes in silicon 总被引:3,自引:0,他引:3
A.A. Istratov H. Hieslmair E.R. Weber 《Applied Physics A: Materials Science & Processing》1999,69(1):13-44
This article is the first in a series of two reviews on the properties of iron in silicon. It offers a comprehensive summary
of the current state of understanding of fundamental physical properties of iron and its complexes in silicon. The first section
of this review discusses the position of iron in the silicon lattice and the electrical properties of interstitial iron. Updated
expressions for the solubility and the diffusivity of iron in silicon are presented, and possible explanations for conflicting
experimental data obtained by different groups are discussed. The second section of the article considers the electrical and
the structural properties of complexes of interstitial iron with shallow acceptors (boron, aluminum, indium, gallium, and
thallium), shallow donors (phosphorus and arsenic) and other impurities (gold, silver, platinum, palladium, zinc, sulfur,
oxygen, carbon, and hydrogen). Special attention is paid to the kinetics of iron pairing with shallow acceptors, the dissociation
of these pairs, and the metastability of iron–acceptor pairs. The parameters of iron-related defects in silicon are summarized
in tables that include more than 30 complexes of iron as detected by electron paramagnetic resonance (EPR) and almost 20 energy
levels in the band gap associated with iron. The data presented in this review illustrate the enormous complexing activity
of iron, which is attributed to the partial or complete (depending on the temperature and the conductivity type) ionization
of iron as well as the high diffusivity of iron in silicon. It is shown that studies of iron in silicon require exceptional
cleanliness of experimental facilities and highly reproducible diffusion and temperature ramping (quenching) procedures. Properties
of iron that are not yet completely understood and need further research are outlined.
Received: 14 December 1998 / Accepted: 22 February 1999 / Published online: 26 May 1999 相似文献
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The concentration of iron in Substantia nigra, the part of the brain which is involved in Parkinson disease, has been found by Mössbauer spectroscopy (MS) to be ~ 160 μg/g wet tissue and ~ 670 μg/g dry weight, both in control and Parkinson samples. All the iron observed by MS in these samples is ferritin-like iron. In several blood diseases, large amounts of ferritin-like iron have been observed in red blood cells. Desferral removed iron from serum, but not from red blood cells. The iron compound in the malarial pigment of human blood infected by P. falciparum was found to be hemin-like, whereas the pigment iron in rats infected by P. berghei was different from any known iron porphyrin. 相似文献
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一种共沉淀分离基体铝的方法用于拟薄水铝石的火焰原子吸收光谱法测定。该法将拟薄水铝石的试样溶液在指示剂存在下调至pH13左右,用过氧化氢溶液氧化,在镁离子存在下生成Fe(OH)3-Mg(OH)2共沉淀,用硝酸(5+95)溶解后用火焰原子吸收光谱法测定。多次测定的相对标准偏差在0.88%—1.47%,样品的加标回收率在88.2%—104.9%之间。该法可用于拟薄水铝石中铁含量≥0.0005%的测定。 相似文献
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研究了光电光谱仪测定生铁中钛的方法 ,确定了最佳分析条件以及其他元素的干扰 ,本法测定生铁中的钛 ,具有良好的准确度和精密度 ,结果令人满意。 相似文献
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羟胺浸提-可见分光光度法测定土壤无定形铁 总被引:1,自引:0,他引:1
采用羟胺浸提-可见分光光度法测定了土壤无定形铁。与草酸-草酸铵浸提法相比,羟胺浸提法排除磁性铁矿物的干扰,克服了原方法实验结果偏高的缺点。该法相对标准偏差RSD<2.0%,回收率为97.5%~101.5%,实验的精密度稍好于草酸-草酸铵法,且具有快速、简便、显色时间短等特点。同时进行了土壤厌氧恒温培养实验,结果显示铁还原启动期、快速期和稳定期的还原速率分别为0.030~0.053 g·d-1·kg-1,0.186~0.333 g·d-1·kg-1和0.015~0.030 g·d-1·kg-1。回归分析结果表明,羟胺浸提法测定结果与土壤培养实验中测得的快速期铁还原速率显著相关(r=0.990 7,p<0.01),说明在浸提土壤无定形铁的过程中,羟胺法比草酸-草酸铵法具有更好的选择性。 相似文献