Magnetostratigraphic dating of mammalian fossils in Junggar Basin；northwest China

IEECAS SKLLQG

开发生产长效碳酸氢铵增强小氮肥企业活力

<正>市场经济的发展使碳铵企业陷入了困境首先,从产品本身来讲,碳铵的化学性质不稳定,含氮量只有17%,氮素利用率低(25%左右),肥效期短(35～45天),

Sensing H2O2 with layer-by-layer assembled Fe3O4-PDDA nanocomposite film

It was found that Fe3O4 nanoparticles (Fe3O4 NPs) possess intrinsic enzyme mimetic activity similar to that found in natural peroxidase. Here, we applied Fe3O4 NPs to the construction of efficient electrochemical sensor to detect the concentration of hydrogen peroxide. The sensor was fabricated with layer-by-layer assembly of Fe3O4 NPs and poly(diallyldimethylammonium chloride) (PDDA) through the electrostatic interaction, and the multilayer film was characterized with UV-vis absorption spectra, atomic force microscopy, and cyclic voltammetry.

含分子内氢键的苯硫酚在水相中的Michael加成反应

苯硫酚的巯基是一个较强的亲核基团 [1] ,对 α,β-不饱和双键的 Michael加成反应已有报道 [2～ 4 ] .但是当巯基的邻位存在与其形成氢键的基团时 ,如果按文献条件进行反应 ,或者反应无法进行 [5,6 ] ,或者要使用反应条件苛刻的丁基锂 [6 ] ,或者使用吡啶等毒性较大的反应溶剂 [2～ 9] ,而且产率较低 .本文选择了饱和碳酸氢钠水溶液 /n-四丁基硫酸氢铵的反应条件 ,探讨了该类化合物在此条件下的 Michael加成反应 .以 3个含分子内氢键的苯硫酚 (邻羟基苯硫酚、邻氨基苯硫酚和邻羧基苯硫酚 )为起始物 ,对丙烯酸乙酯和丙烯腈进行了 Michael加成反应 .本方法的特点在于不使用特殊的有机溶剂 ,反应在水相[10～ 12 ] 中进行 ;反应速度快 ,收率高 ,无巯基偶联 [13] 副产物生成 .反应式如 Scheme1所示 .RSH1 a— 1 c+ OONa HCO3,H2 On-Bu4 N HSO4RSOO2 a— 2 cRSH1 a— 1 c+ NC Na HCO3,H2 On-Bu4 N HSO4RSCN3 a— 3 ca. R =OH;b. R =N H2 ;c. R...

Correlation analysis of the structures and stability constants of gadolinium(III) complexes

To simplify the abstraction of descriptors, for the correlation analysis of the stability constants of gadolinium(III) complexes and their ligand structures, aiming at gadolinium(III) complexes, we only considered the ligands and ignored the common parts of the structures, i.e., the metal ions. Quantum-chemical descriptors and topological indices were calculated to describe the structures of the ligands. Multiple regression analysis and neural networks were applied to construct the models between the ligands and the stability constants of gadolinium(III) complexes and satisfactory results were obtained.

Determination of ascorbic acid by flow injection chemiluminescence suppression method

chemiluminescence suppression method for the determination of ascorbic acid based on Luminol-KIO4-H2O2-ascorbic acid system was established. The linear range for ascorbic acid is 1.0 x 10(-7) similar to 1.0 x 10(-5) mol/L and the detection limit is 6.0 x 10(-8) mol/L. The relative standard deviation (n = 11) is 1.0% for 8.0 x 10(-7) mol/L ascorbic acid. The method has been used to determine the content of ascorbic acid in tablets and injections with satisfactory results.

流动注射化学发光抑制法测定抗坏血酸

基于抗坏血酸对Ｌｕｍｉｎｏｌ－ＫＩＯ４－Ｈ２Ｏ２体系化学发光反应的抑制作用，建立了化学发光抑制快速测定抗坏血酸的新方法。该方法线性范围为 １．０ × １０－７～ １．０ × １０－５ ｍｏｌ／Ｌ，检出限为６．０× １０－８ｍｏｌ／Ｌ，对８．０× １０－７ｍｏｌ／Ｌ抗坏血酸 １１次平行测定的相对标准偏差为 １．０％。用于维生素Ｃ片剂及注射液中抗坏血酸含量的测定，结果令人满意。

Local chain motions in a dilute solution of phenolphthalein poly(ether sulfone)

C-13 and H-1 relaxation times were measured as a function of temperature in two magnetic fields for dilute solutions of phenolphthalein poly(ether sulfone) (PES-C) in deuterated chloroform. The spin-lattice relaxation times were interpreted in terms of segmental motion characterized by the sharp cutoff model of Jones and Stockmayer (J. S. model). The phenyl group rotation is treated as a stochastic diffusion by the J. S. model. The restricted butterfly motion of the phenyl group attached to the cardo ring in PES-C is mentioned but is not discussed in detail in this work. Correlation times for the segmental motion are in the picosecond range which indicates the high flexibility of PES-C chains. The correlation time for the phenyl group internal rotation is similar to that of the segmental motion. The temperature dependence of these motions is weak. The apparent activation energy of the motions considered is less than 10 kJ/mol. The simulating results for PES are also reasonable considering the differences in structure compared with PES-C. The correlation times and the apparent activation energy obtained using the J. S. model for the main chain motion of PES-C are the same as those obtained using the damped orientational diffusion model and the conformational jump model.

Studies on structure-property relationship between color reagents and contrast of their color reactions with cerium by topological indices

In this paper, three topological indices A(m1), A(m2) and A(m3) have been applied to multivariate analysis in structure property relationship studies. The topological indices oi fourty-three asymmetrical phosphono bisazo derivatives of chromotropic acid have been calculated, The structure-property relationship between color reagents and contrast of color reactions with cerium has been studied by A, indices and structure selective factors, Good results have been obtained.