高效液相色谱和高效液相色谱—质谱法测定粮食中互隔交链孢霉醇,互隔交…

建立了粮食中互隔交链孢霉醇，互隔交链孢霉醇单甲醚和玉米赤烯酮三个毒素的ＨＰＬＣ定性定量分析法和粒子束ＬＣ－ＭＳ／ＥＩ＾＋鉴定方法，采用反相色谱，以８０％的甲醇水溶液作流动相，这三个毒素在Ｃ１８色谱柱上彼此间均获得较好的分离，方法对粮食中ＡＯＨ，ＡＭＥ两个毒素的回收率均在７９％以上，ＡＯＨ，ＡＭＥ两个毒素的最低检出限为１×１０＾－９ｇ。用所建立方法对１００多个大骨节病病区，非病区的粮食样品进行了检测     

红外光谱法测定端羟基聚丁二烯(HTPB)胶粘体系的固化度

介绍用红外光谱法测定端羟基聚丁二烯（HTPB）胶粘体系固化度的原理及方法，并对端羟基聚丁二烯胶粘体系固化过程进行监控，分析了一定温度下胶粘体系的固化度与固化时间，以及相同固化时间内胶粘体系的固化度与固化温度之间的数学关系。     

分析化学教学的探讨与实践

分析化学是发展和应用各种方法、仪器和策略以获得有关物质在空间和时间方面组成和性质的一门科学。分析理论、方法、仪器和技术的飞跃发展使分析化学正在发展成为一门与数学、物理学、计算机科学、生物学相结合的多学科性的综合性科学。正如 1 991年ＩＵＰＡＣ国际分析科学会议主席Ｅ .Ｎｉｋｉ教授所说 ,2 1世纪是光明还是黑暗取决于人类在能源与资源科学、信息科学、生命科学与环境科学四大领域的进步 ,而取得这些领域进步的关键问题的解决主要依赖于分析科学。　　分析化学课程是一门综合性课程 ,涉及无机、有机、物化、环化、生化等学…     

碱处理法改善Pt／ZSM-5异构化性能

制备了一系列不同条件下碱处理的ZSM-5样品,以调控其酸性和孔道结构. 考察了酸性和孔道结构对Pt/ZSM-5的异构化性能的影响. 样品的晶相、酸性及结构分别通过X射线衍射、 NH3程序升温脱附及N2吸附-脱附表征. 结果表明,缓和的碱处理导致ZSM-5上强酸中心减少,催化剂异构化活性下降; 而苛刻条件下的碱处理使得ZSM-5上强酸中心增加、大量中孔产生及催化剂异构化活性明显提高. 催化剂的异构化活性取决于分子筛上强酸中心的量,与孔道结构无关; 而异构体的分布不仅与孔道结构有关,而且与正己烷转化率密切相关,与分子筛的酸性无关.     

姜黄素类似物合成与体外抗肿瘤活性研究

以芳香醛、4-哌啶酮为原料,Claisen-Schimidt缩合制备3,5-(E)-二亚苄基哌啶-4-酮类化合物.采用MTT法测试目标化合物对人类慢性粒细胞白血病急变细胞K562,人结肠癌细胞SW1 116增殖的抑制活性.化合物1-19的结构经核磁和质谱确证,化合物7、10、11对SW1 116的抑制活性比EF-24强...     

BH分子8个Λ-S态和23个Ω态光谱性质的理论研究

本文利用内收缩多参考组态相互作用方法计算了BH分子8个低电子态(X~1∑~+、a~3∏,A~1∏,b~3∑~-,2~3∏,1~3∑~+,1~5∏~-和1~5∏)和在自旋-轨道耦合效应下所产生的23个Ω态的势能曲线、以及X~1∑_0~+~+,a~3∏_0~+,a~3∏₁,a~3∏₂和A~1∏₁态之间6对跃迁的跃迁偶极矩.为了获得精确的势能曲线,计算中修正了单双电子激发、核价相关效应、相对论效应和基组截断带来的误差.获得的BH分子的光谱和跃迁数据与现有的理论值和实验值符合得很好.计算结果表明:BH分子的A~1∏₁(v’=0-2,J’=1,+)→X~1∑_0~+~+(v"=0-2,J"=1,-)跃迁具有较大的爱因斯坦A系数和加权的吸收振子强度、高度对角化分布的振动分支比,A~1∏₁态具有较短的辐射寿命.另外,a~3∏_0~+和a~3∏₁态对A~1∏₁(v’=0)...     

Exotic electronic states in the world of flat bands:From theory to material

It has long been noticed that special lattices contain single-electron flat bands(FB) without any dispersion. Since the kinetic energy of electrons is quenched in the FB, this highly degenerate energy level becomes an ideal platform to achieve strongly correlated electronic states, such as magnetism, superconductivity, and Wigner crystal. Recently, the FB has attracted increasing interest because of the possibility to go beyond the conventional symmetry-breaking phases towards topologically ordered phases, such as lattice versions of fractional quantum Hall states. This article reviews different aspects of FBs in a nutshell. Starting from the standard band theory, we aim to bridge the frontier of FBs with the textbook solidstate physics. Then, based on concrete examples, we show the common origin of FBs in terms of destructive interference,and discuss various many-body phases associated with such a singular band structure. In the end, we demonstrate real FBs in quantum frustrated materials and organometallic frameworks.     

有初始几何缺陷的壳体弹塑性大变形分析

在等温小变形弹塑性内时本构方程偏量形式的基础上，导出了适用于大位移、小应变分析的弹塑性内时本构方程。并导出了带有初始几何缺陷的非线性弹塑性问题的有限元方程。文中给出的算例表明本方法是可行有效的。     

组合旋转壳体的安定上限分析

对旋转组合壳体的各个子区的位移场进行双三次Ｂ样条插值，同时对子区交界处的广义力向量以单三次Ｂ样条展开，推导出以广义向量表示的组合壳体的平衡方程，然后从Ｂｅｔｉ互换定理和虚功原理出发推导出离散的壳体结构中可能的塑性应变率循环，从而给出了组合壳体安定上限分析的有限元列式，把组合壳体的安定上限分析归结为求解一个数学规划问题，文末给出了算例     

Numerical solution of the unsteady Euler equations for airfoils using approximate boundary conditions

This paper presents an efficient numerical method for solving the unsteady Euler equations on stationary rectilinear grids. Boundary conditions on the surface of an airfoil are implemented by using their first-order expansions on the mean chord line. The method is not restricted to flows with small disturbances since there are no restrictions on the mean angle of attack of the airfoil. The mathematical formulation and the numerical implementation of the wall boundary conditions in a fully implicit time-accurate finite-volume Euler scheme are described. Unsteady transonic flows about an oscillating NACA 0012 airfoil are calculated. Computational results compare well with Euler solutions by the full boundary conditions on a body-fitted curvilinear grid and published experimental data. This study establishes the feasibility for computing unsteady fluid-structure interaction problems, where the use of a stationary rectilinear grid offers substantial advantages in saving computer time and program design since it does not require the generation and implementation of time-dependent body-fitted grids.