水稻叶片色素含量近红外光谱估测模型研究

以不同品种类型和不同施氮水平的水稻(Oryza sativa)叶片近红外光谱信息为基础,运用逐步多元回归法(Stepwise multiple linear regression,SMLR)、主成分回归法(Principal component regression,PCR)、偏最小二乘法(Partial least square,PLS)和BP神经网络法(Back-propagation neural network,BPNN),建立了水稻叶片中叶绿素a(Chl a)、叶绿素b(Chl b)、叶绿素a+b (Chl a+b)和类胡萝卜素(Car)的近红外预测模型.结果显示,利用8000～4000 cm-1波段范围的一阶导数(First derivative,FD)建模效果最佳.其中,基于PLS的预测模型效果最好;4类近红外色素模型的内部交叉验证误差分别为0.251,0.063,0.305和0.073;外部交叉验证的误差RMSEP分别为0.335,0.123,0.302和0.072,表明的预测效果较好.因此,可以基于近红外模型对水稻叶片色素含量进行快速测定.     

叶绿素a和b的二阶导数荧光法测定

本文提出叶绿素a和b的二阶导数荧光分析法。本法以450nm为激发波长。叶绿素b在644nm(正峰)测定,叶绿素a不干扰,测定范围为1—300ppb。叶绿素a在676nm(负峰)测定,叶绿素b在该波长有一弱的正峰应予扣除,测定范围为4—400ppb。此法与分光光度法、同步荧光法同时对照试验,结果基本一致。     

双波长K系数-标准加入-导数分光光度法同时测定钴、镍

1引言双彼长分光光度法通常采用等吸收点法和K系数法，存在灵敏度较低，测量点少而使误差较大的缺点；曾有人提出用双波长标准加入法来提高双波长法的灵敏度，但存在要求具有等吸收点的局限性，操作上也较麻烦．本文将双波长K系数法，标准加入法和导数法三者有机结合，并且独特地同时进行两组分的的标准加入，以一套数据即可完成两组分的同时测定。本方法具有灵敏度高，准确度好，操作简便，适用范围广的优点。2方法原理设样品中有a、b两组分。浓度分别为Ca、Cb，峰值波长对应于λ1、λ2，同时加太浓度为C、C的a、b标准溶液，则波长λ1、…     

用化学计量法—分光光度法测定活体叶片中叶绿素a,b的含量

本文研究了用逐步回归分析法、主成分回归法、偏最小二乘法与人工神经网络法测定活体叶片中叶绿素a、b的含量。活体叶片的光谱由PC微机采集,测定叶绿素a与b的相关系数分别达到0.927～0.958与0.873～0.908;相对标准偏差约5％～9％(叶绿素a 9.4μg/2ml,n=20)。本方法可用于农业研究。     

含硫甲基的芴-苯结构化合物的合成、结构和性能

通过双Suzuki偶联反应一步合成了2种含硫甲基的芴-苯结构化合物2,7-二(4-硫甲基苯基)-9,9-二己基-芴(a)和2,7-二(2,6-二甲基-4-硫甲基苯基)-9,9-二己基-芴(b).紫外-可见和荧光光谱以及分子轨道理论计算表明,位阻较小的化合物a具有更好的共轭性能,其最大紫外-可见吸收波长达到351nm,比两端苯基含4个邻位取代基的化合物b红移了38nm;化合物a的最大荧光发射波长达到410nm,为典型的蓝光化合物,比化合物b红移了43nm.化合物a和b都具有较高的荧光量子产率,分别为59%和65%,在光电材料方面具有潜在的应用前景.     

9,10-二氢苯并[h]香豆素类化合物的双羟化反应研究及酯化产物的合成

报道了在9,10-二氢苯并[h]香豆素类化合物1a,1b的不对称双羟化反应中,除了得到正常的cis-7,8-双羟化产物2a,2b外,还以中等收率(52%和45%)得到了过度氧化产物7-羰基-8-羟基化合物3a,3b,并讨论了氧化剂用量及反应温度对产物分布的影响.双羟化产物2a,2b的ee值通过其樟脑酯化产物4a,4b的1HNMR图谱所示的非对映异构体比例进行了初步推测.过度氧化产物3b及其樟脑酯化产物5b的结构经X射线单晶衍射分析确证     

酸催化α-细辛脑二聚反应及其产物抗癌活性研究

以E-1-(2,4,5-三甲氧基苯基)-2-丙烯(α-细辛脑)为原料,酸催化选择性合成脱碳木脂素类化合物a及二氢化茚类化合物b,其结构经核磁﹑质谱和元素分析表征确认.研究了催化剂种类、反应溶剂和温度等条件对两种化合物产率比的影响,45℃时,HCl为催化剂,乙醇为溶剂,化合物a/b的总收率为98%(a:41%,b:57%);30℃时,AlCl3为催化剂,乙醇为溶剂,化合物a的产率可达75%,没有b生成,对a的选择性为100%;45℃时,以BF3Et2O溶液为催化剂,CH2Cl2为溶剂,化合物a的产率为20%,化合物b的产率可达60%.采用MTT法,分别评价了化合物a/b对四种癌细胞(MCF-7,Bel-7402,A549及Hela)的抑制作用,结果表明:化合物a对MCF-7,Hela(IC50值分别为:120.2,117.3μmol L-1),化合物b则对MCF-7,A549(IC50值分别为:66.1,72.4μmol L-1)显示出比相同条件下5-Fu更好的抗癌抑制活性.同时,研究了a/b浓度﹑作用时间对癌细胞抑制率的影响.     

新型4,4′-双取代-2,2′-二吡啶衍生物的合成及其光学性能

以4,4′-二甲基-2,2′-二联吡啶为原料,经酸化、酰氯化,酯化和缩合反应合成了两个新型的4,4′-双取代-2,2′-二吡啶衍生物—4,4′双(4,5-二苯基嗯唑-2-基)-2,2′-二吡啶(6a)和4,4′-双(4,5-二对甲氧基苯嗯唑-2-基)-2,2′-二毗啶(6b),其结构经1H NMR,IR和MS表征.用UV-Vis和荧光激发光谱测定了6a和6b的光学性能,结果表明,6a和6b的λmax分别为229 nm和238 nm;最大发射波长均为432 nm.     

基于改进免疫遗传算法的近红外光谱变量选择方法

该文在免疫遗传算法（IGA）的基础上,提出一种改进免疫遗传算法（iIGA）用于近红外光谱波长变量的选择。该算法舍去了原算法中固定抗体相似度阈值的思想,取而代之的是抗体相似度阈值自适应,同时引入精英保留策略和贪心算法思想,使得算法朝着正确的方向进行局部性探优。将该算法在玉米的淀粉和蛋白质含量数据集上进行实验测试,建立偏最小二乘（PLS）分析模型,并与IGA、遗传算法（GA）以及全谱方法进行了对比。结果表明,在玉米淀粉含量的预测上,iIGA相较于原IGA算法,预测集均方根误差（RMSEP）从0.312 0降至0.298 0,预测集预测精度提升4.5%;在玉米蛋白质含量的预测上,RMSEP从0.124 4降至0.110 3,预测集预测精度提升11.3%。分别对预测淀粉和蛋白质模型的RMSEP值进行显著性检验,F值分别为165.22和182.05,P值分别为9.5 × 10－23和4.5 × 10－24,P值均小于0.05,因此,iIGA能显著提升模型预测精度。     

基于遗传算法的波长选择方法在绿茶近红外光谱分析模型中的应用

利用遗传算法(GA)提取茶叶的近红外吸收特征波长的方法,研究建立了绿茶水分和氨基酸的近红外分析模型,并对波长选择前后两种成分的模型进行了比较分析。结果表明,经遗传算法波长选择后,简化了分析模型,同时模型的稳健性增强。氨基酸预测集的均方根误差(SEP)减小82.1%,水分预测集的均方根误差减小(SEP)76.6%,它们在波长选择前后对应的分析波长数之比分别为995∶7和1990∶33。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

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.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

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%).     

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.