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991.
Herein a water-soluble ‘click’ modified coumarin-based fluorescent probe for hydrogen peroxide is reported. This probe shows significant intensity increases (up to fivefold) in near-green fluorescence upon reaction with hydrogen peroxide, and good selectivity over other reactive oxygen species. 相似文献
992.
This work aimed to classify the categories (produced by different processes) and brands (obtained from different geographical origins) of Chinese soy sauces. Nine variables of physico-chemical properties (density, pH, dry matter, ashes, electric conductivity, amino nitrogen, salt, viscosity and total acidity) of 53 soy sauce samples were measured. The measured data was submitted to such pattern recognition as cluster analysis (CA), principal component analysis (PCA), discrimination partial least squares (DPLS), linear discrimination analysis (LDA) and K-nearest neighbor (KNN) to evaluate the data patterns and the possibility of differentiating Chinese soy sauces between different categories and brands. Two clusters corresponding to the two categories were obtained, and each cluster was divided into three subsets corresponding to three brands by the CA method. The variables for LDA and KNN were selected by the Fisher F-ratio approach. The prediction ability of all classifiers was evaluated by cross-validation. For the three supervised discrimination analyses, LDA and KNN gave 100% predications according to the sample category and brand. 相似文献
993.
Peng Gao Yingying Yu Zhangqin Ni Qiwen Teng 《Central European Journal of Chemistry》2010,8(3):587-593
The equilibrium geometries and electronic structures of a series of SWCNTs doped with a silicon atom were studied by using
density function theory (DFT). The most stable doping site of silicon predicted at B3LYP/6-31G(d,p) level was located near
the boundary of the SWCNTs. The energy gaps of (3,3) C48, (3,3) C60 and (3,3) C72 were respectively decreased by 0.43, 0.25 and 0.14 eV after doping. Based on the B3LYP/6-31G(d) optimized geometries, the
electronic spectra of the doped SWCNTs were computed using the INDO/CIS method. The first UV absorption at 973.9 nm of (5,5)-Si(L)
(C59Si) compared with that at 937.5 nm of (5,5) (C60) was red-shifted. The 13C NMR spectra and nuclear independent chemical shifts (NICS) of the doped SWCNTs were investigated at B3LYP/6-31G(d) level.
The chemical shift at 119.4 of the carbon atom bonded with the silicon atom in (3,3)-Si(L) (C59Si) in comparison with that at 144.1 of the same carbon atom in (3,3) (C60) moved upfield. The tendency of the aromaticity (NICS = −0.1) for (3,3)-Si(H) (C47Si) with respect to that of the anti-aromaticity (NICS = 6.0) for (3,3) (C48) was predicted.
相似文献
994.
Serge Kokot 《中国化学快报》2010,21(2):213-216
<正>High performance liquid chromatographic(HPLC) fingerprints of Cassia seed,a traditional Chinese medicine(TCM),were developed by means of the chromatograms at two wavelengths of 238 and 282 nm.Then,the two data sets were combined into one matrix.The application of principal component analysis(PCA) for this data matrix showed that the samples were clustered into four groups in accordance with the plant sources and preparation procedures.Furthermore,partial least squares(PLS),back propagation artificial neural network(BP-ANN),and radial basis function artificial neural network(RBF-ANN) were effectively applied to predict the category of the four different samples in the test set. 相似文献
995.
Fernández MC Sánchez CC Niño RR Patino JM 《The journal of physical chemistry. B》2006,110(47):24212-24221
In this work we have analyzed the penetration of betalactoglobulin into a monoglyceride monolayer (monopalmitin or monoolein) spread at the air-water interface and its effects on the structural, dilatational, and topographical characteristics of mixed films. Dynamic tensiometry, surface film balance, Brewster angle microscopy (BAM), and surface dilatational rheology have been used, maintaining the temperature constant at 20 degrees C and the pH and ionic strength at 7 and 0.05 M, respectively. The initial surface pressure (mN/m) of the spread monoglyceride monolayer (pii(MONOGLYCERIDE)) at 10, 20, and the collapse point is the variable studied. Beta-lactoglobulin can penetrate into a spread monoglyceride monolayer at every surface pressure. The penetration of beta-lactoglobulin into the monoglyceride monolayer with a more condensed structure, at the collapse point of the monoglyceride, requires monoglyceride molecular loss by collapse and/or desorption. However, the structural, topographical, and dilatational characteristics of monoglyceride penetrated by beta-lactoglobulin mixed monolayers are essentially dominated by the presence of monoglyceride (either monopalmitin or monoolein) in the mixed film. In fact, monoglyceride molecules have the capacity to re-enter the monolayer after expansion and recompression of the mixed monolayer. Thus, monoglyceride molecular loss by collapse and/or desorption is reversible. The topography of the monolayer under dynamic conditions corroborates these conclusions. 相似文献
996.
A canonical Monte Carlo simulation is performed to investigate the microstructure and the electrical double layer (EDL) of polyelectrolytes around macroions in the bulk systems based on the primitive model. We explore the influences of particles size, chain length, and charge density of polyelectrolytes on the microscopic behavior of the macroions-polyelectrolytes systems. The simulation results show that the surface charge density and the chain length of the polyelectrolytes are two key factors that affect the microstructure of polyelectrolytes around the macroions and potential of mean force between the macroions as well as the zeta potential of the spherical EDL constructed by polyelectrolytes. The high surface charge density of a polyelectrolyte leads to the polyelectrolyte acting as a bridge for the aggregation of macroions, causing the presence of the attraction between macroions. The polyelectrolytes with a long chain length present a cooperativity effect for the adsorption of the polyelectrolytes on the surface of the macroions. Furthermore, the two key factors both induce the overcharge of the macroions. The longer the chain length and the higher surface charge density of the polyelectrolytes, the stronger is the overcharge. 相似文献
997.
针对由单个物流服务提供商和集成商组成的物流服务供应链,基于集中化模式、纳什博弈模式和Stackelberg博弈模式三种典型模式,考虑市场需求随机且受服务质量缺陷承诺水平的影响,探讨物流服务供应链的订购与质量缺陷承诺策略问题。通过分析发现:物流服务质量缺陷承诺水平随着市场需求弹性系数的增加而递减,但其受物流服务集成商观测水平的影响却因合作模式不同而变化不一致;集中化模式下的物流服务订购量随着物流服务集成商观测水平或市场需求弹性系数的增大而递减,但在其他两种合作模式下物流服务订购量随着物流服务集成商观测水平或市场需求弹性系数的增加而增加;在三种模式下,物流服务供应链的整体利润随着市场需求弹性系数的增加而递减,但其受物流服务集成商观测水平的影响却因合作模式不同而变化不一致。 相似文献
998.
999.
J. Camarero V. Cros M.J. Capitán J. Álvarez S. Ferrer M.A. Niño J.E. Prieto L. Gómez J. Ferrón A.L. Vázquez de Parga J.M. Gallego J.J. de Miguel R. Miranda 《Applied Physics A: Materials Science & Processing》1999,69(5):553-557
Interlayer diffusion in epitaxial systems with a high energy barrier at the atomic steps – the so-called Ehrlich–Schwoebel
(ES) barrier – is strongly reduced. As a consequence of this, a continuous accumulation of roughness takes place during growth.
This undesirable effect can be corrected by using surfactant agents. We have studied the influence of the ES barrier on the
preparation of epitaxial films on Cu(111), and the surfactant effect of a monolayer of Pb.
Received: 21 April 1999 / Accepted: 17 August 1999 / Published online: 6 October 1999 相似文献
1000.
煤的工业分析至元素分析的BP神经网络预测模型 总被引:8,自引:1,他引:7
以大量煤质分析数据为基础,建立了利用煤工业分析数据( 包括水份、灰份、挥发份及热值) 计算元素分析数据的BP神经网络预测模型,并将该模型与现有经验公式进行了比较,结果表明神经网络模型有很好的推广能力。可以满足工业应用的要求 相似文献