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91.
A correction method is proposed for the quantitative determination of stoichiometric ratios in porous materials by electron microprobe analysis. Analysis of this kind of material is complicated by an imperfect surface that can only be improved to some extent. The correction is based on a linear dependence (different for each element) of the analyses on a sum of weight concentrations of oxides. With this correction it is possible to use analyses affected by the imperfection of the surface with much better confidence compared to common normalisation. An example is presented for a series of ceramic superconductors Bi2.1(SrCa)2.9Cu2O8+. 相似文献
92.
微波消解-火焰原子吸收光谱法测定污泥中铅 总被引:8,自引:0,他引:8
研究了微波消解-火焰原子吸收光谱法测定污泥中铅。应用正交试验设计法确定了微波消解试样的最佳条件。该法与传统敞口消解法测定结果吻合。样品测定结果的相对标准偏差(n=6)为1.5%~4.7%,加标回收率为93.0%-106.2%。该方法省时省酸,减少环境污染,改善了工作环境。 相似文献
93.
对甲醛单分子热反应模拟给出了分子渠道Eckart垒,计算了该渠道在不同温度下的隧道校正因子,研究了分子渠道与游离基渠道间的相互作用,计算了存在反应渠道间相互作用时各渠道的K_(uni)(i)、Ea(i),分子渠道考虑隧道效应,而游离基渠道无隧道效应,计算结果与实验结果一致。 相似文献
94.
一种基于二进小波变换的自适应滤波方法 总被引:3,自引:0,他引:3
根据信号和噪声经小波变换后在不同尺度上有不同的特征,将相邻尺度二进小波变换值的相关量进行归一化处理并与小波变换值比较来判断信号与噪声,以噪声在各尺度的方差作为终止迭代的标准,提出了一种基于二进小波变换小波域选择噪声的自适应滤波方法。研究了模拟信号的去噪过程、半峰宽和信噪比对去噪结果的影响,并对模拟含噪信号和含噪毛细管电泳信号去噪前后的结果进行了比较。实验结果表明:由于该方法具有良好的自适应性和显著的滤波效果,必将得到广泛的应用。 相似文献
95.
96.
Fluorescence has been the preferred choice for data quantification in biomedical microarray formats since their earliest days. As much as the formats have grown and evolved over the years, the methods in optical analysis have become ever more sophisticated and complex in order to produce more and better output. This review will provide an insight into the most common methods and the state-of-the-art of all areas in microarray fluorescence analysis. Starting with an overview on microarray formats with a focus on their demands on the readout, the most common and useful organic fluorescent stains are discussed before proceeding on to other approaches; the use of semiconductor nanocrystals (quantum dots), polymer and silica nanoparticles and fluorescent proteins. Ways to enhance the intrinsically low signal on biochips have become increasingly important as they offer a sound approach towards the detection of low concentration sample content. The three main categories are presented: amplification using DNA, enzymes, and dendrimers. As much diversity as on the microarrays themselves can be found at the detection device. Standard optical microarray detectors, and non-standard methods using fluorescence anisotropy, fluorescence lifetime imaging (FLIM) and fluorescence resonance energy transfer (FRET), and their advantages and disadvantages are discussed. 相似文献
97.
This work describes a hybrid procedure for eliminating major interference sources in aqueous near-infrared (NIR) spectra, that include aqueous influence, noise, and systemic variations irrelevant to concentration. The scheme consists of two parts: extension of wavelet prism (WPe) and orthogonal signal correction (OSC). First, WPe is employed to remove variations due to aqueous absorbance and noise; then OSC is applied to remove systemic spectral variations irrelevant to concentration. Although water possesses strong absorption bands that overshadow and overlap the absorption bands of analytes, along with noise and systematic interference, successful calibration models can be generated by employing the method proposed here. We show that the elimination of major interference sources from the aqueous NIR spectra results in a substantial improvement in the precision of prediction, and reduces the required number of PLS components in the model. In addition, the strategy proposed here can be applied to various analytical data for quantitative purposes as well. 相似文献
98.
99.
Jian-binSong Min-qiaoRen Qing-yongChen Shu-yunWang Qing-xiangZhao Hong-fangZhang 莫志深 《高分子科学》2004,(5):491-496
Based on the X-ray scattering intensity theory and using the approximate expression for the atomic scattering factor, the correction factors for three crystalline peaks and an amorphous peak of Nylon 1212 were calculated and the formula of degree of crystallinity of Nylon 1212 was derived by a graphic multipeak resolution method. The degree of crystallinity calculated from the WAXD method is compatible with those obtained by density and calorimetry methods. 相似文献
100.
Correlated intermolecular interaction components from asymptotically corrected Kohn-Sham orbitals 总被引:1,自引:0,他引:1
SONG Huajie XIAO Heming & DONG Haishan . Department of Chemistry Nanjing University of Science Technology Nanjing China . Institute of Chemical Materials China Academy of Engineering Physics Mianyang China 《中国科学B辑(英文版)》2004,47(6):466-479
In these years there was considerable interest inunderstanding of intermolecular forces in energetic(explosive) systems[1—3]. The supermolecular approach(SM) is widely adopted for calculating ab initio in-termolecular interactions. Nevertheless, it is unable toprovide physically meaningful interaction contribu-tions such as electrostatic, induction, repulsion anddispersion energies. In contrast, the symmetry-adaptedperturbation theory (SAPT)[4—8] has the ability to de-rive these correlated… 相似文献