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981.
Psychotripine, a trimeric pyrroloindoline derivative with an unprecedented hendecacyclic system bearing a hexahydro-1,3,5-triazine unit, was isolated from the leaves of Psychotria pilifera. The structure was elucidated on the basis of spectroscopic and quantum theory. A possible biogenesis was also postulated. 相似文献
982.
An ultra-high-performance liquid chromatography-electrospray ionization coupled to mass spectrometry method has been developed for determining caseinoglycomacropeptide (CGMP) in infant formulas by selected ion reaction and area monitoring modes. The present study focused on the optimization of sample pretreatment, chromatographic resolution and mass spectrometry parameters. After a simple sample pretreatment, the two genetic variants of caseinoglycomacropeptide, CGMP(A) and CGMP(B), were separated using a BEH300 C(18) column by gradient elution. The established method was extensively validated by determining the linearity (R(2)>0.999), average recovery (95.8-118.4%), inter-day precision (relative standard deviation ≤7.81%) and intra-day precision (relative standard deviation ≤6.99%) based on two scan modes. To further verify the applicability of the method, 21 brands of commercial available infant formulas were analyzed. The results showed that the present method is selective, sensitive and reliable for separating and quantifying two genetic variants (CGMP(A) and CGMP(B)) of caseinoglycomacropeptide in infant formulas with complex matrix. 相似文献
983.
Xu XM Yu C Han JL Li JP El-Sepai F Zhu Y Huang BF Cai ZX Wu HW Ren YP 《Journal of separation science》2011,34(2):210-216
A multi-residue method for the analysis of pesticides in tea was developed by online size exclusion chromatography (SEC)-GC/MS with full scan mode. The sample was fortified with chlorpyrifos-d(10) isotope internal standard and extracted by acetonitrile. After purification by primary secondary amine sorbent and solvent exchange by SEC mobile phase, the sample was detected by online SEC-GC/MS. The purification result of the online system was evaluated by comparing the correlation between Chinese cabbage and tea matrix. The factors for method optimization included sample preparation, matrix effects and the instrument parameters of each online component. Scatter plot was introduced in this study to directly illustrate the results of the condition optimization and matrix effects in the online system. For most of the pesticides, the average recoveries ranged from 70 to 130% and the RSD were below 15%. The feasibility of the application of full scan mode in multi-residue determination of trace amounts of pesticides (LODs below 0.01 mg/kg) in a complex matrix was discussed. 相似文献
984.
A novel electrochemiluminescence (ECL) “sandwich” biosensor has been developed to detect cocaine. The sandwich biosensor was
fabricated on the basis of the fact that a single aptamer could be split into two fragments and the two dissociated parts
could form a folded, associated complex in the presence of targets. One of these (capture probe), which had hexane–thiol at
its 5′-terminus, was immobilized on a gold electrode via thiol–gold binding. The other one (detection probe) was labeled with
the ECL reagent tris(2,2′-bipyridyl)ruthenium(II)-doped silica nanoparticles (RuSiNPs) at its 3′-terminus. Owing to the weak
interaction between the two fragments, the sensor exhibited a low ECL signal in the absence of cocaine. After the target cocaine
had been added to the solution, it induced association of the two fragments and stabilized the associated complexes, leading
to immobilization of RuSiNPs on the electrode surface, and the ECL detected on the electrode surface was enhanced. The enhanced
ECL intensity was directly proportional to the logarithm of the cocaine concentration in the range from 1.0 × 10−9 to1.0 × 10−11 mol/L, with a detection limit of 3.7 × 10−12 mol/L. The biosensor was applied to detect trace amounts of cocaine on banknotes with satisfactory results. 相似文献
985.
We report the preparation of a kind of surface-enhanced Raman scattering (SERS) tags and explore their applications in multifunctional
optical imaging of cancer cells. The proposed nanoparticles (SERS tags) are prepared by connecting dye molecules directly
onto the surfaces of gold nanorods through Au–S or Au–N interactions. The dye molecules are used as Raman reporters, while
gold nanorods are used as enhanced materials due to their localized surface plasmon resonance effect. Multilayered polymers
are further coated onto the surfaces of the nanoparticles to reach better stability and biocompatibility. Gold nanorods with
different aspect ratios and different dye molecules conjugated are compared in order to achieve the diversity of SERS tags
and find out the optimized condition of SERS tags with the highest signal intensity. Our experiments show that the resulting
nanoparticles, which are uptaken by cancer cells, can provide not only dark field cells images but also multiplexing SERS
images. 相似文献
986.
987.
Maomao Cai 《Nonlinear Analysis: Theory, Methods & Applications》2011,74(13):4581-4588
An explicit integro-differential equation formulation is derived for surface ocean waves with finite depth. The equation involves only 2D surface variables. For this equation, we establish the stability and existence of solutions, and explain the effect of depth on surface wave properties. 相似文献
988.
The aim of this paper is to show that a recently proposed technique for eigenstructure assignment of linear time-invariant systems can be extended to solve the corresponding eigenstructure assignment problem for linear parameter-varying systems, whose state-space matrices depend on a set of time-varying parameters that are bounded and available online. In particular, the design of eigenstructure assignment is performed without requiring any conditions on the closed-loop eigenvalues, and provides a simple, complete and analytical parametric approach as well as the most degrees of design freedom for the eigenstructure assignment problem of linear parameter-varying systems. A parameter-varying attitude control system of refueling spacecraft in-orbit is used to demonstrate the usefulness and practicality of the proposed approach. 相似文献
989.
神经元的形态分类和识别 总被引:1,自引:0,他引:1
对神经元特性的认识,最基本问题是神经元的分类.神经元的形态复杂多样,神经元的识别分类问题有相当的困难.对提供的参考数据进行统计分析,将其转化成对应每类神经元的空间形态的指标参数,然后对每个指标进行定性分析和对比分析,确定对各类型神经元细胞识别起关键作用的指标,利用层次分析法、图形截面、几何相似性等分析方法建立神经元的分类模型.分类模型能够将附录提供的神经元进行准确的分类.数据分析采用开源科学计算软件Scilab进行处理,运行环境为Scilab5.2,部分代码采用C#基于VS2008开发. 相似文献
990.
In this paper,we study the complete q-moment convergence of moving average processes under ψ-mixing assumption.The results obtained not only extend some previous known results,but also improve them. 相似文献