新型树枝状PNP铬催化剂的合成及催化性能

以1.0代聚酰胺-胺(PAMAM)为配体骨架,氯代二苯基膦为原料,通过取代反应合成了1种含有较大空间位阻的新型树枝状PNP配体,再以Cr Cl3(THF)3为络合试剂,通过络合反应合成树枝状PNP铬催化剂.采用傅里叶变换红外光谱(FTIR)、紫外-可见分光光度计(UV-Vis)、核磁共振波谱(NMR)、电喷雾电离质谱(ESI-MS)和元素分析等手段证实合成的新型树枝状PNP配体及其铬催化剂的结构与理论设计的结构一致.以甲基铝氧烷(MAO)为助催化剂,对乙烯齐聚反应进行了研究,考察了溶剂种类、反应温度、反应压力及Al/Cr摩尔比对该催化剂活性和选择性的影响.结果表明,以甲苯为溶剂,MAO为助催化剂,当反应温度为25℃,反应压力为0.9 MPa,Al/Cr摩尔比为500时,该催化剂的活性高达2.15×105g/(mol Cr·h),催化剂对乙烯三聚、四聚反应的选择性共达到36.76%.     

ICP-MS法测定心可舒片中的微量元素

为建立准确快速测定心可舒片中微量元素含量的方法,对该药生产进行质量控制,并为合理用药提供依据,采用电感耦合等离子体质谱法(ICP-MS),对心可舒片中的21种元素进行了分析。结果表明,心可舒片对心血管病的疗效与其中的微量元素有关。     

高效液相色谱手性固定相法拆分联二萘酚、联二萘酚胺和联二萘胺对映体

在纤维素三(3,5-二甲基苯基氨基甲酸酯)(Ch iralcel OD-H)手性柱上对联二萘酚、联二萘酚胺和联二萘胺对映体的分离作了研究,分别考察了在流动相正己烷中,不同的醇类添加剂及醇类添加剂的浓度以及温度对手性分离的影响,当流动相为正己烷-正丁醇(90∶10,V/V),流速0.5 mL/m in,温度25℃时,联二萘酚、联二萘酚胺和联二萘胺对映体在Ch iralcel OD-H柱上的分离度Rs分别为2.27、2.40和9.28。研究了空间立体结构因素对手性分离的影响,在此基础上对其手性识别机理进行探讨。     

关注手性药物：从“反应停事件”说起

Since the Thalidomide tragedy in the 1960s, the issue of chirality has become increasingly important in the fields of novel drug development and pharmaceutical research. Enantiomers may exhibit different pharmacologic, pharmacokinetic, metabolic, and toxicological activity in living organisms. Recently, chiral High-Performance Liquid Chromatography (HPLC) technology combined with chiroptical spectroscopy has been widely used in separation and analysis of chiral compounds, and will play a critical role in the detection and quality control of chiral pharmaceuticals.     

Hybeanones A and B,Two Highly Modified Polycyclic Polyprenylated Acylphloroglucinols from Hypericum beanii

Hybeanones A and B(1 and 2),two highly oxygenated and rearranged polycyclic polyprenylated acylphloroglucinols(PPAPs),were isolated from the aerial parts of Hypericum beanii.Their structures comprising absolute configurations were elucidated by spectroscopic analysis,single-crystal X-ray diffraction,and quantum chemical calculations.Compounds 1 and 2 are defined by a newly assembled cyclopentanone unit fused to a tricyclic γ-lactone unit via a ketone carbonyl.The breakage of C-1/C-2 linkage via retro-Claisen reaction,attack from C-1 to C-19,and Baeyer-Villiger oxidation at C-1/C-23 bond were presumed to be the key steps in the assembly of 1 and 2.The isolates 1 and 2 showed potential acetylcholinesterase(AchE)inhibitory activities,with IC50 values of 21.34±1.48 and 18.79±2.36μmol/L,respectively.     

我国西南地区生物柴油发展潜力及其主要决定因素

作为生物柴油原料的麻疯树在我国已呈现快速发展态势,但对其未来发展潜力尚缺乏实证研究.目的是通过构建麻疯树生产决策模型,模拟分析不同情景下我国西南地区麻疯树发展潜力.研究结果表明:1)在基准方案下,麻疯树种籽产量与生物柴油产量可以达到320万吨和93万吨,但难以达到预期发展目标.2)影响麻疯树发展潜力的最重要因素是技术进步、产出品(麻疯树种籽)与主要投入品(劳动与肥料)价格,其中技术进步是提升未来麻疯树发展潜力的关键,而麻疯树种籽与肥料等价格取决于能源价格.在发展以麻疯树为原料的生物柴油产业发展战略上,近期国家应把加强优良品种的选育与丰产栽培技术作为重点,未来发展需密切关注能源市场的变化.     

High-resolution Reflection Spectroscopy of Cs D2 Line Studied by High-order-harmonic Detection

In this paper, by numerical analysis the relationship of the modulation broaden index with modulation index using high-order-harmonic detection is investigated. Using the voltage modulation the 2f,4f and 6f harmonic signals about the reflection spectroscopy of 6S1/2(F=4)→6P3/2 transition of the cesium D2 line are also be measured. The experimental results are in good agreement with the theoretical predictions. It is found that narrower line-width can be achieved by higher-harmonic detection than the line-width detected by direct absorption when the modulation index is smaller than 1.81, 2.98 and 4.14 for 2f, 4f, and 6f signals, respectively.     

Crystallographic report: Bis[bis(N,N‐dibenzyldithiocarbamato)zinc(II)](4,4′‐bipyridine)

The centrosymmetric structure of {Zn[S₂CN(CH₂Ph)₂]₂}₂(4,4′‐bipy) features chelating dithiocarbamate ligands so that a trigonal bipyramidal NS₄ coordination geometry for zinc results. Copyright © 2003 John Wiley & Sons, Ltd.     

自适应免疫遗传算法

遗传算法(GA)是基于自然遗传规则随机搜索技术的一种进化算法,但是随着实际结构的大型化和复杂化,它往往出现过早收敛的现象。在研究了算法的编码方式、控制参数和算子操作之后,就其全局收敛性的不足,提出动态自适应策略以改进其性能,在基本遗传算子的基础上,采用了免疫遗传算子和保优策略。其中免疫算子可以防止交叉变异中的个体退化,自适应策略则保持了种群的多样性,以此保证遗传算法尽快收敛到全局最优解,称之为自适应免疫遗传算法(AIGA)。随后以经典的十杆桁架结构优化问题作为例子说明算法的优越性,结果表明AIGA在随机结构优化中计算有效、结果可靠。