全自动电位滴定法测定锂电池原料碳酸锂中主成分的含量

采用全自动电位滴定法测定锂电池原料碳酸锂中主成分的含量,用盐酸标准溶液进行滴定,考虑自动电位滴定仪的灵敏性和准确度,通过多次对比实验,确定了仪器的最佳工作参数、滴定剂浓度和样品称样量等滴定条件;对两个不同品位试样分别进行了11次平行测定,相对标准偏差(RSD)均小于1％.在碳酸锂试样中加入基准物质无水碳酸钠进行碳酸根的...     

Enantioselective Diels–Alder reactions with left-handed G-quadruplex DNA-based catalysts

Since the discovery of left-handed G-quadruplex(L-G4)structure formed by natural DNA,there has been a growing interest in its potential functions.This study uti...     

二维导电金属有机骨架材料

金属有机骨架(MOFs)是由金属离子或簇与有机配体以配位键组装而成的晶态多孔材料,其高的孔隙率及功能可设计性使其广泛应用于各种领域.然而,传统MOFs多数电导率非常低,这严重制约了其在电学相关领域的发展.近年来,导电金属有机骨架尤其是二维导电金属有机骨架(2D ECMOFs)材料因其结构中独特的π-π堆积及π-d共轭作...     

制备型高效液相色谱在天然产物分离中的应用

制备型高效液相色谱法在天然产物的分离纯化中得到广泛应用。从制备型高效液相色谱法的技术分类及其在天然产物研究中的实际应用方面对目前国内外制备型高效液相色谱技术研究现状进行了综述,对其发展动态进行了展望。     

甲基丙烯酸3—磺酸钾丙酯—苯乙烯共聚物与N,N,N—三甲基十六烷基化铵相 …

两亲分子由于具有自组装性质,如表面活性剂分子自组装形成胶束,囊泡,天然的磷脂分子自组装形成脂质体,继而参于生物膜的形成,这是大家所熟悉的．高分子两亲分子尤其是两亲性两嵌段高分子具有自组装性质,并形成规整性好的聚集体［１～３］．聚电介质表面活性剂体系...     

Recent progress in copper catalyzed asymmetric Henry reaction

Henry reaction is one of the most classical reactions to construct synthetically useful product nitro alcohol, which as a privileged skeleton is widely distributed in various pharmaceuticals. This review summarizes the recent progress of copper-catalyzed asymmetric Henry reaction from 2011 to 2016. The significant progress that has been made in this area will be highlighted and some of challenges that the author believes may be hindering further progress will be revealed.     

微量热法研究过氧化氢酶底物抑制动力学

过氧化氢酶是需氧生物体内抗氧化酶系的重要组分。过氧化氢酶催化过氧化氢分解是一个两底物酶促反应,依照Chance提出的机理,反应速率方程具有一级反应方程的形式。此反应在高浓度底物存在的情况下,表现出明显的不可逆底物抑制。本研究用热动力学方法研究了这一反应,提出了一种不可逆底物抑制机理,并应用该机理求出了相关动力学参数。在310.15K,pH=7.0时k0=9.6×10^5L·mol^-1^·s^-1,k1/k2=2.9×10^6。实验结果证明此机理正确有效。     

A novel fluorescent probe for formaldehyde based-on monomer-excimer conversion and its imaging in live cells

A novel fluorescent probe was developed for formaldehyde, which can be synthesized by one-step Buchwald–Hartwig reaction. When hydrazino-group of probe reacted with formaldehyde, hydrophobic reaction product aggregates into nanoparticles and results in the blue fluorescence due to the monomer-excimer effect. With enough sensitivity, high selectivity, good stability in physiological pH range and excellent biocompatibility, this probe can image formaldehyde in living cells.     

A coumarin based highly selective fluorescent chemosensor for sequential recognition of Cu2+ and PPi

In this study, we have successfully synthesized a new coumarin based fluorescent chemosensor 1, in which tren and quinolone are introduced as receptors for sequential recognition of Cu²⁺ and PPi. The structure of chemosensor 1 was characterized by ¹H NMR, ¹³C NMR and ESI-HR-MS. Sensor 1 showed an obvious “on-off” fluorescence quenching response toward Cu²⁺, and the quenching efficiency reached a maximum of 99.6% with the addition of 20 equiv. of Cu²⁺. The 1-Cu²⁺ complex showed an “off-on” fluorescence enhancement response toward PPi over many competitive anions, especially HPO₄^2? and H₂PO₄^?. The detection limit of sensor 1 was 1.9?×?10^?6?M to Cu²⁺ and 5.96?×?10^?8?M to PPi. In addition, sensor 1 showed a 1:1 binding stoichiometry to Cu²⁺ and sensor 1-Cu²⁺ showed a 2: 1 binding stoichiometry to PPi in CH₃CN/HEPES buffer medium (9:1 v/v, pH?=?7.4). The stable pH range of sensor 1 to Cu²⁺ and 1-Cu²⁺ to PPi was from 4 to 8.     

Local Multilevel Method on Adaptively Refined Meshes for Elliptic Problems with Smooth Complex Coefficients

In this paper, a local multilevel algorithm is investigated for solving linear systems arising from adaptive finite element approximations of second order elliptic problems with smooth complex coefficients. It is shown that the abstract theory for local multilevel algorithm can also be applied to elliptic problems whose dominant coefficient is complex valued. Assuming that the coarsest mesh size is sufficiently small, we prove that this algorithm with Gauss-Seidel smoother is convergent and optimal on the adaptively refined meshes generated by the newest vertex bisection algorithm. Numerical experiments are reported to confirm the theoretical analysis.