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排序方式: 共有3798条查询结果,搜索用时 31 毫秒
991.
Liang-Liang Wang Qiu-Long Zhang Yang Wang Yan Liu Jiao Lin Fan Xie Liang Xu 《Chemical science》2021,12(25):8698
Introduction of artificial metal–ligand base pairs can enrich the structural diversity and functional controllability of nucleic acids. In this work, we revealed a novel approach by placing a ligand-type nucleoside as an independent toehold to control DNA strand-displacement reactions based on metal–ligand complexation. This metal-mediated artificial base pair could initiate strand invasion similar to the natural toehold DNA, but exhibited flexible controllability to manipulate the dynamics of strand displacement that was only governed by its intrinsic coordination properties. External factors that influence the intrinsic properties of metal–ligand complexation, including metal species, metal concentrations and pH conditions, could be utilized to regulate the strand dynamics. Reversible control of DNA strand-displacement reactions was also achieved through combination of the metal-mediated artificial base pair with the conventional toehold-mediated strand exchange by cyclical treatments of the metal ion and the chelating reagent. Unlike previous studies of embedded metal-mediated base pairs within natural base pairs, this metal–ligand complexation is not integrated into the nucleic acid structure, but functions as an independent toehold to regulate strand displacement, which would open a new door for the development of versatile dynamic DNA nanotechnologies.This metal-mediated artificial base pair can function as an independent toehold based on metal–ligand coordination and exhibit flexible and reversible controllability to manipulate the dynamics of strand displacement. 相似文献
992.
Enzyme-catalyzed reaction of o-phenylenediamine (OPD)-Hz02-horseradish peroxidase (HRP) voltammetric enzyme-linked immunoassay system has been studied in detail with electrochemical
analysis, high performance liquid chromatography (HPLC), ultraviolet/visible (UV/Vis) spectroscopy, infrared (IR) spectroscopy
and nuclear magnetic resonance (NMR) spectroscopy. The pure product of H202 oxidizing OPD catalyzed by HRP was prepared with chemical method. The experimental results of voltammetry and HPLC indicate
that only one product of enzyme-catalyzed reaction has been obtained under the selected enzyme-catalyzed reaction conditions.
Identifications by UV/ Vis spectrum, IR spectrum and13C NMR spectrum show that the product is 2,3-diaminophenazine. The processes of the enzyme-catalyzed reaction and the electroreduction
of the product of the enzyme-catalyzed reaction are described.
Project supported by the National Natural Science Foundation of China 相似文献
993.
A fluorescence quenching method for the determination of vanadium (V) based on the vanadium- catalyzed oxidation of rhodamine
6G (R6G) with periodate in the presence of ethylenediaminetetraacetic acid disodium salt (EDTA) in sulfuric acid medium is
described. The fluorescence was measured with excitation and emission wavelengths of 525 and 555 nm, respectively. The calibration
graph for vanadium (V) had linear ranges of 3.0 × 10−9–1.5 × 10−8 mol/l and 1.5 × 10−8–4.0 × 10−8 mol/l, respectively. The detection limit was 1.7 × 10−9 mol/l. The proposed method was successfully applied to the determination of vanadium (V) in river water, rain water and cast
iron samples.
Received June 29, 2001 Revision October 9, 2001 相似文献
994.
Type 2 diabetes mellitus (T2DM) is a noteworthy worldwide public health problem. It represents a complex metabolic disorder, mainly characterized as hyperglycemia and lipid dysfunction. The gut microbiota dysbiosis has been proposed to play a role in the development of diabetes. Recently, there has been considerable interest in the use of medicine food homology (MFH) and functional food herbs (FF) to ameliorate diabetes and lead to a natural and healthy life. Hence, this review compiles some reports and findings to demonstrate that the practical use of the MFH/FF can modulate the homoeostasis of gut microbiota, thereby ameliorating the development of T2DM. The results provided useful data to support further investigation of the functional basis and application of MFH/FF to treat T2DM through maintaining intestinal homeostasis. 相似文献
995.
996.
Armin de Meijere Vladimir Chaplinski Harald Winsel Mikhael A. Kusnetsov Paul Rademacher Roland Boese Thomas Haumann Marit Traetteberg Paul von R. Schleyer Tosja Zywietz Haijun Jiao Pascal Merstetter Fabian Gerson 《Angewandte Chemie (International ed. in English)》1999,38(16):2430-2433
A surprisingly high first vertical ionization energy (8.44 eV) and an unusually high oxidation potential are exibited by tricyclopropylamine ( 1 )—in sharp contrast to triisopropylamine. These are attributed to the near-tetrahedral geometry of 1 at the N atom and the perpendicular orientation—with respect to the N-orbital axis—of the cyclopropyl groups. γ-Irradiation of 1 led to the radical cation 1 .+, which, in accord with computations, has a planar C3h-symmetrical structure. The EPR-spectroscopic and computational results disclose a dramatic, previously not reported, conformational change on going from 1 to 1 .+. 相似文献
997.
998.
999.
针对界面追踪方法中拉格朗日方法和欧拉--拉格朗日方法计算效率低、不适用大变形、不能应用于三维数值计算模型等问题,研究了一种效率高、界面清晰、适用于三维模型的计算气液两相界面迁移特性的欧拉运动界面追踪方法,该方法将"米"状相邻单元Youngs方法用于运动界面重构,将Youngs-VOF和水平集通过几何方法耦合,提高运动界面精度,克服了VOF和水平集方法存在的缺陷,避免了利用高阶导数本身的稳定性去求解水平集对流方程和距离函数方程."米"状相邻单元Youngs方法避免了数值耗散、数值色散性以及非线性效应引起的捕捉界面模糊的情况.Youngs-VOF耦合水平集方法既保证了计算界面时的稳定性,与拉格朗日方法相比又提高了计算效率.利用Youngs-VOF耦合水平集方法与VOF方法对单个气泡在水中上升过程数值计算与实验对比并对经典剪切流场中圆形运动界面模型的数值计算,验证了Youngs-VOF耦合水平集方法的有效性并比VOF方法捕捉界面更清晰、锐利;通过对溃坝--自由表面流动过程数值计算并与实验进行对比,验证了Youngs-VOF耦合水平集方法的稳定性以及对三维数值模型的适用性. 相似文献
1000.
采用溶胶-凝胶法,通过改变前驱液中酒石酸加入量制备了不同粒径尺寸的铁酸铋(BiFeO3,BFO)颗粒材料.利用XRD、SEM、UV-Vis、PL、铁电综合测试仪等手段对样品进行表征,探讨分析了颗粒材料尺寸变化对BFO光催化活性的影响及机理.研究表明,产物均为菱形钙钛矿相BFO颗粒态晶体材料;其粒径尺寸随酒石酸加入量的增加而减小;BFO颗粒尺寸减小导致材料BFO可见光吸收阈值波长蓝移,光催化活性提高;在可见光源照射150 min条件下,BFO(粒径尺寸为80 nm)对MB降解效率达到75.7;,其光催化效率大约是BFO(粒径尺寸为600 nm)3倍,这主要是因为较小粒径的BFO具有高的比表面积(6.472 m2/g). 相似文献