基于分数阶微分的重叠峰分辨方法

根据特定峰信号微分的极值和过零点随着微分阶次的变化而改变, 建立了峰信号的极值和过零点与其相应微分阶次的关系式, 进而得到了两类参数估计器, 利用这些估计器可以估计出Gaussian峰、Lorentzian峰和Tsallis峰信号的特征参数. 首先, 利用分数阶微分器获得特定峰信号的分数阶微分; 其次, 根据峰信号的极值与其微分阶次的关系式和过零点与其微分阶次的关系式, 建立了估计器Ⅰ和估计器Ⅱ; 再利用这些估计器便可以提取峰信号的特征参数; 最后, 用Tsallis峰作为子峰模型对未知重叠峰信号进行分辨. 仿真和实测重叠峰信号的分辨实验表明本方法简单高效.     

二次微分与样条小波自卷积联用分辨重叠伏安峰

本文采用二次微分法寻找重叠峰的各个峰位置，再利用样条小波自卷积（SWSC）方法直接对重叠的伏安峰进行处理，取得了较好的结果。被处理的重叠峰可达到基线分离，且峰位置的相对误差小于3．0％（完全掩盖峰为5．39％），峰面积的相对误差小于2．0％。方法不用于铅（Ⅱ）－铊（Ⅰ）体系的微分脉冲伏安信号处理，取得满意的结果。     

重叠伏安峰的样条卷积法分辨

建立了分辨重叠峰的样条卷积法；利用三阶样条函数构成的峰分辨函数与原信号进行卷积，直接对重叠的伏安峰进行处理，取得了较好的结果；被处理的重叠峰可达到其线分离，且峰位置的相对误差小于3．0％（完全重叠峰为5．4％），峰面积的相对误差小于2．0％；应用于镉（Ⅱ）－铟（Ⅲ）实验体系的微分脉冲伏安信号处理，取得满意的结果。     

离子色谱重叠色谱峰的处理

介绍通过信号微分处理分辨离子色谱中重叠峰的方法。实验将Ｆ＾－、Ｃｌ＾－、Ａｃ＾－、ＮＯ＾－２、ＮＯ＾－３、ＰｈＣＯＯ＾－、山梨酸根和葡萄糖酸根等常见离子分组按一定比例混合,对重叠峰进行微分处理,得到的微分谱图可由峰高定量,收到了较好的效果。     

二阶样条小波卷积法分辨重叠化学信号

首次提出了二阶样条小波卷积分峰法, 通过二阶样条小波与重叠化学信号的卷积运算, 确定出各组分的峰位置和峰宽之比, 再利用样条函数构造峰分辨器, 分辨重叠信号, 同时给出了方法的理论依据, 并对参数的选择进行了讨论. 对大量仿真信号和实验信号的处理实践表明, 分辨后信号可以达到基线分离, 峰位置相对误差小于0.2%, 峰面积相对误差小于4.0%, 即使对于重叠严重的信号, 也能获得满意结果. 该方法可以直接用于含噪音的及多个峰的重叠体系, 是一种分辨重叠信号的有效新方法.     

样条小波变换用于分辨重叠伏安峰的研究

将样条小波变换技术用于分辨重叠的伏安峰 ,以选定的分辨因子作用于样条小波滤波器 ,使之成为峰分辨器 ,用它来直接处理重叠的伏安峰 ,取得了较好的结果 .被处理峰可达到基线分离 ,且峰位置的相对误差小于 3.0 %,峰面积的相对误差小于 5 .0 %,方法简便易行 .讨论了各种影响分峰效果的因素 ,包括不同的分辨因子及样条小波基等 ,并应用于镉 (Ⅱ ) 铟 (Ⅲ )和铅 (Ⅱ ) 铊 (Ⅰ )体系的实验数据的处理以验证该方法     

用于电分析化学重叠信号分辨的样条小波自卷积法

以正弦函数为分辨因子与样条小波滤波器相作用,使其构成样条小波自卷积法的峰分辨器,利用样条小波峰分辨器可以直接分开计算机模拟的不同类型的重叠双峰,分峰前后峰面积和峰位置的相对误差均小于5．0％;将其应用于电分析化学重叠信号的实验数据处理,得到较满意的结果。同时,为样条小波峰分辨器分辨因子提供了新的选择。     

小波分形分析重叠峰信号

用连续小波变换与分形理论相结合的小波分形峰位法对含噪重叠信号峰位置的提取进行了研究, 同时考察了信噪比和分离度对该法提取峰位置的影响; 结果表明 该法是一种提取含噪重叠信号中各单独峰峰位置的有效工具, 即使对于重叠程度和噪声干扰严重的信号也能得到较好的结果; 将其用于 Cd(Ⅱ )和 In(Ⅲ )重叠伏安信号的处理, 峰位置提取的相对误差小于± 1%; 该法具有准确、快捷、简便易行等特点, 发展前景广阔.     

正交投影用于一维重叠色谱峰分辨及背景扣除

对于两组份色谱重叠峰体系,当以小组份色谱峰作为干扰时,本文利用正交投影方法,通过构造正交投影矩阵,利用原始信号及其投影与背景之间的内在关系来确定真实背景,从而将背景干扰予以扣除,使含背景干扰的一维重叠色谱峰得以分辨。模拟研究表明,对于两组份色谱峰重叠体系当以小色谱峰为干扰时本文方法具有很好的分辨效果,对于完全重叠峰,即使其峰分离度为零能得到满意的结果。     

基于非接触式电导信号的土壤速效钾含量检测方法

该文针对土壤中速效钾含量采用传统测定法操作复杂、检测时效滞后的问题,建立了基于非接触式电导检测信号快速检测土壤速效钾含量的分析方法。采用高效毛细管电泳/非接触式电导检测仪获取河南潮土的非接触式电导检测信号,并使用导数法与高斯曲线拟合法相结合进行初步峰谱识别,按条件进行峰值过滤后,引入基于Levenberg-Marquardt(L-M)的高斯分峰拟合算法,实现了单峰和重叠峰的拟合计算,得到高斯峰和相应的特征参数,包括峰位、峰高、半峰宽和峰面积;最后将拟合得到的高斯峰及相应的特征参数表征原始非接触式电导检测信号离子峰谱信息结合偏最小二乘法(PLS),确定特征参数与土壤速效钾含量的关系,建立模型,实现了对土壤中速效钾含量的预测。结果表明,将基于L-M的高斯分峰拟合算法结合偏最小二乘法应用于非接触式电导检测信号测定土壤速效钾含量时具有较高精度,回归模型决定系数(R~2)为0.856 4,相对分析误差(RPD)为2.639,适用于土壤速效钾的快速检测分析。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.