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51.
WANG Huijun XIONG Chunhua** YAO Caiping . Marine Science & Technology College of Zhejiang Ocean University Zhoushan Zhejiang China . College of Food Science Biotechnology Environmental Engineering Zhejiang Gongshang University Hangzhou China 《Chinese Journal of Reactive Polymers》2004,(Z1)
1. INTRODUCTION The research papers about synthesis characterization and adsorption property of polymeric materials have been reported in recent years [1~8]. Macroporous phosphonic acid resin (PAR) is a novel polymeric material which contains a functional group of [-PO(OH)2]. It has quite a lot of advantages such as high adsorption capacity, easy regeneration and convenient operation. PAR can be effectively used in the adsorption of metal ions. So far, however, there is no report abo… 相似文献
52.
EmmanuelA. Meyer Nicola Donati Marine Guillot W.Bernd Schweizer Franois Diederich Bernhard Stengl Ruth Brenk Klaus Reuter Gerhard Klebe 《Helvetica chimica acta》2006,89(4):573-597
This paper describes the rational design, synthesis, and biological evaluation of a new generation of inhibitors of the bacterial enzyme tRNA‐guanine transglycosylase (TGT), which has been identified as a new target in the fight against bacillary dysentery (Shigellosis). The enzyme catalyzes the exchange of guanine in the anticodon wobble position of tRNA by the modified base preQ1, a guanine derivative, according to a ping‐pong mechanism involving a covalent TGT‐tRNA intermediate (Fig. 2). Based on computer modeling (Fig. 3), lin‐benzoguanine (6‐aminoimidazol[4,5‐g]quinazolin‐8(7H)‐one ( 2 )) was selected as an extended central scaffold, to form up to seven in‐plane intermolecular H‐bonds with the protein while sandwiching between Tyr106 and Met260. Versatile synthetic protocols were developed for the synthesis of 2 , and derivatives with phenyl, benzyl, and 2‐phenylethyl side chains (i.e., 16, 17a , and 12a, 12b, 13, 17 , resp.) to reach into the lipophilic pocket lined by Val282, Val45, and Leu68 (Schemes 1–3). To account for the limited solubility of the new ligands and in consequence of a recently developed detailed understanding of the mechanism of TGT catalysis (Fig. 2), the enzyme kinetic assay was completely redesigned, providing competitive (Kic) and uncompetitive (Kiu) inhibition constants with respect to tRNA binding by TGT. The modifications of the various parameters in the new assay are described in detail. Binding affinities of the new inhibitors were found to be in the single‐digit micromolar range (Kic values, Fig. 8). Decoration of the lin‐benzoguanine scaffold with lipophilic residues only gave a modest improvement in biological activity which was explained on structural grounds with the help of four crystal structures (Fig. 10) obtained by soaking the protein with inhibitors 2 and 12a – 12c . Both biochemical and biostructural analyses reported in this paper provide a fertile basis for the development of more potent future generations of TGT inhibitors. 相似文献
53.
Observation of quantum noise reduction on twin laser beams 总被引:1,自引:0,他引:1
Heidmann A Horowicz RJ Reynaud S Giacobino E Fabre C Camy G 《Physical review letters》1987,59(22):2555-2557
54.
本文简要叙述了微量碳酸盐样品碳,氧稳定同位素测试对于古海洋学研究的重要性,着重介绍了该方法的原理,制样过程以及质谱测量,同时还介绍了微量测试几个方面的试验工作,并对影响微量测试的几种因素进行了探讨。 相似文献
55.
A New Cyclic Bisdesmoside from Tubers of Bolbostemma paniculatum 总被引:2,自引:0,他引:2
HaiFengTANG YangHuaYI ShuYuZHANG PengSUN LingLI DaZhengZHOU 《中国化学快报》2005,16(4):479-482
The structure of tubeimoside V (1), a new cyclic bisdesmoside, isolated from tubers of Bolbostemma paniculatum (Tu Bei Mu), was established by means of 2D NMR spectral and chemical methods. Compound 1 has inter-saccharide chain bridging by a dicrotalic acid to form aunique macrocyclic structure. 相似文献
56.
石墨炉原子吸收法连续测定气溶胶中重金属 总被引:7,自引:0,他引:7
提出了用石墨炉原子吸收法连续测定气溶胶中六种重金属的方法.气溶胶样品经处理后,直接用石墨炉原子吸收法测定其中的铜、钴、镍、镐、铅和铬.其检出限在 1.9×10~(-12)~1.6×10~(-10)g,仪器的精密度(RSD)<6.1%,标准加入回收率为90.4%~106.5%,已用于大批气溶胶样品的测定,结果令人满意. 相似文献
57.
58.
59.
S. Bodeur J. L. Maréchal C. Reynaud D. Bazin I. Nenner 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1990,17(4):291-298
High resolution photoabsorption spectra of HCl and Cl2 have been measured near the chlorineK edge in the 2810–2850 eV photon energy range. Below the ClK edge, the strongest resonance is interpreted as a simple core excitation into the unoccupied σ* valence orbital for both molecules, leading to a markedly repulsive state. Higher resonances due to low lying Rydberg states, are observed in both systems, but with a larger oscillator strength for HCl as compared to Cl2. In Cl2, the σ* orbital is deep enough to avoid any mixing with Rydberg orbitals. In HCl, we observe the dipole forbidden Cl 1s → 4s transition which denotes a strong 4s–4p hybridization. Above the ClK edge, the multiplet features seen for HCl are analysed in terms of double-core-valence excited vacancy states. In Cl2, their counterpart are found very close to the ionization threshold because of the deep σ* orbital and possibly because the excited core and valence electrons originates either from the same atomic site or from different ones. 相似文献
60.
The present study experimentally investigated the near-field flow mixing characteristics of two turbulent jets issuing from equilateral triangular and circular orifice plates into effectively unbounded surroundings,respectively.Planar particle image velocimetry(PIV) was applied to measure the velocity field at the same Reynolds number of Re=50,000,where Re = UeDe /with Ue being the exit bulk velocity and the kinematic viscosity of fluid,D e the equivalent diameters.The instantaneous velocity,mean velocity,Reynolds stresses were obtained.From the mean velocity field,the centreline velocity decay rate and half-velocity width were derived.Comparing the mixing characteristics of the two jets,it is found that the triangular jet has a faster mixing rate than the circular counterpart.The triangular jet entrainments with the ambient fluid at a higher rate in the near field.This is evidenced by a shorter unmixed core,faster Reynolds stress and centreline turbulence intensity growth.The primary coherent structures in the near field are found to break down more rapidly in the triangular jet as compared to the circular jet.Over the entire measurement region,the triangular jet maintained a higher rate of decay and spread.Moreover,all components of Reynolds stress of the triangular jet appear to reach their peaks earlier,and then decay more rapidly than those of the circular jet.In addition,the axis-switching phenomenon is observed in the triangular jet. 相似文献