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991.
Svistunenko DA Sharpe MA Nicholls P Wilson MT Cooper CE 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2000,142(2):266-275
A new method of EPR spectral analysis is developed to quantitate overlapping signals. The method requires double integration of a number of spectra containing the signals in different proportions and the subsequent solution of a system of linear equations. The result gives the double integral values of the individual lines, which can then be further used to find the concentrations of all the paramagnetic species present. There is no requirement to deconvolute the whole spectrum into its individual components. The method is employed to quantify different heme species in methemoglobin and metmyoglobin preparations. A significantly greater intensity of the high-spin signal in metmyoglobin, compared to methemoglobin at the same heme concentration, is shown to be due to larger amounts of low-spin forms in methemoglobin. Three low-spin types in methemoglobin and two in metmyoglobin are present in these samples. When their calculated concentrations are added to those of the high-spin forms, the results correspond to the total heme concentrations obtained by optical spectroscopy. 相似文献
992.
Yuko Yamaura Takao Odake Akifumi Suzuki Mamiko Fujii Kiyoshi Nakayama 《Optical Review》2003,10(5):411-414
To understand the optical properties of living tissue in the NIR range, it appeared informative to investigate the scattering properties of high concentration particle suspension. We measured the angular light scattering of aqueous suspension of 3.5 μmφ polystyrene particles contained in a 60 μm thick cuvette up to 50% volume concentration at 805 nm wavelength using a goniophotometer. We found that the discrepancy between the measurement and the Monte Carlo simulation becomes larger with increased concentration, which is attributable to the phase function change as well as the scattering coefficient change. 相似文献
993.
A new method is studied for estimating the hemoglobin concentration and oxygenation of a local blood layer in a human skin tissue model on the basis of visible and near infrared reflectance spectra. This method uses the iterative Monte Carlo technique for a multi-layered skin tissue model. The numerical simulation was performed to investigate the effects of estimation errors for epidermis and dermis layers on the results for the local blood layer. Experiments with skin tissue phantoms were performed to verify the possibility of this method. 相似文献
994.
Quantitative evaluation of TLC by direct photometric scanning is a promising method, in view of the development of cheap microprocessors: soon instruments for digital scanning will be commercialy available. In this paper we describe a multilayer model which seems to be a good approximation for solving the radiation transfer equation in the case of layer models with a gradient in an inward direction. Changes of remitted and transmitted light, in cases where a band lies in different layers, are presented. Examples shown are: the absorbance profile of a chromatographed band in the direction of scanning is approximated to that of an isosceles triangle; the concentration of the band is uniform, e.g. 0.3 A. U.; the concentration of the band is changing from 0 to 2.0 A. U. These results will serve to set up the correct algorithms for digital scanning and simultaneous determination in TLC. 相似文献
995.
Marek Kanter 《Journal of multivariate analysis》1976,6(2):222-236
This paper derives a sharp bound for the probability that a sum of independent symmetric random vectors lies in a symmetric convex set. In one dimension this bound is an improvement of an inequality first proved by Kolmogorov. The subject of multidimensional concentration functions is also treated. 相似文献
996.
针对目前大部分PM2.5预测模型预测效果不稳定、泛化能力不强的现状,以记忆能力较强的循环神经网络(RNN)和特征表达能力较强的卷积神经网络(CNN)为基础,采取Stacking集成策略对两者进行融合,提出了RNN-CNN集成深度学习预测模型。该模型不仅充分利用时间轴上的前后关联信息去预测未来的浓度,而且在不同层次上将自动提取的高维时序数据通用特征用于预测,以保证预测结果的稳定性。最后,对集成之前的RNN、CNN和集成之后的RNN-CNN模型,以2016年中国大陆地区1 466个监测站点的空气质量数据为样本进行实例验证,结果表明,RNN-CNN在PM2.5时间序列预测上的表现明显优于集成之前的RNN和CNN,而且泛化误差更低,在34%站点上的拟合度超过0.97,该模型可用于大范围区域的PM2.5小时浓度预测。 相似文献
997.
Electroluminescence has been excited in the phosphor anthracene doped by 9-vinylanthracene (10−4 mole %) at room temperature (300°K). Variation of light output with voltage is governed by the relationB=B
0 exp [−(C/V
1/2)] as in the case of inorganic phosphors. HereB
0 andC are constants andV is the rms value of the voltage applied to the phosphor. Frequency dependence of the electroluminescence has also been studied
at different voltages of the applied electric field. 相似文献
998.
John J. Morelli David M. Hercules Paul C. Lyons Curtis A. Palmer Janet D. Fletcher 《Mikrochimica acta》1988,96(1-6):105-118
The variation in relative elemental concentrations among a series of coal macerals belonging to the vitrinite maceral group was determined using laser micro mass spectrometry (LAMMS). Variations in Ba, Cr, Ga, Sr, Ti, and V concentrations among the coals were determined using the LAMM A-1000 instrument. LAMMS analysis is not limited to these elements; their selection illustrates the application of the technique. Ba, Cr, Ga, Sr, Ti, and V have minimal site-to-site variance in the vitrinite macerals of the studied coals as measured by LAMMS. The LAMMS data were compared with bulk elemental data obtained by instrumental neutron activation analysis (INAA) and D. C. arc optical emission spectroscopy (DCAS) in order to determine the reliability of the LAMMS data. The complex nature of the ionization phenomena in LAMMS and the lack of standards characterized on a microscale makes obtaining quantitative elemental data within the ionization microvolume difficult; however, we demonstrate that the relative variation of an element among vitrinites from different coal beds in the eastern United States can be observed using LAMMS in a bulk mode by accumulating signal intensities over several microareas of each vitrinite. Our studies indicate gross changes (greater than a factor of 2 to 5 depending on the element) can be monitored when the elemental concentration is significantly above the detection limit.Bulk mode analysis was conducted to evaluate the accuracy of future elemental LAMMS microanalyses. The primary advantage of LAMMS is the inherent spatial resolution, ~ 20m for coal. Two different vitrite bands in the Lower Bakerstown coal bed (CLB-1) were analyzed. The analysis did not establish any certain concentration differences in Ba, Cr, Ga, Sr, Ti, and V between the two bands. 相似文献
999.
Resource partitioning theory claims that Increasing concentration enhances the life chances of specialist organizations. We systematically think through this theory, specify implicit background assumptions, sharpen concepts, and rigorously check the theory's logic. As a result, we increase the theory's explanatory power, and claim—contrary to received opinion'that under certain general conditions, resource partitioning and the proliferation of specialists can take place independently of organizational mass and relative size effects, size localized competition, diversifying consumer tastes, increasing number of dimensions of the resource space, and changing niche widths. Our analysis makes furthermore clear that specialist and generalist strategies are asymmetric, and shows that not concentration enhances the life chances of specialists but economies of scale instead. Under the conditions explicated, we argue that if scale economies come to dominate, the number of organizations in the population increases, regardless of the incumbents' sizes. 相似文献
1000.
The paramagnetism and the ac electrical conductivity of samples of a soot–polyethylene composite have been investigated. It has been established that the EPR line with the gfactor 2.0025 is asymmetric on the metal side of the insulator–metal concentration transition of the composite. It is shown that the asymmetry of the line reflects the appearance of a percolation soot cluster in the samples of the composite. 相似文献