拓扑集成指数与TIBO类衍生物构效关系的研究

4H-甲基咪唑苯二氮(?)酮(TIBO)类衍生物是抗爱滋病的一种新药,分子连接性指数是经证明应用广泛、较为成功的一种指数,本文定义并计算了TIBO类衍生物原子的特征值δi,利用量子化学计算方法,建构新的拓扑集成指数G和分子连接性指数mX,基于多元回归技术建立的对TIBO类衍生物药物的油水分配系数,作出精确估算和预测的定量结构-活性相关关系,得到的多元回归方程为:logP=0.782 G-0.1430X 0.2312X-3.829,估算的平均相对误差为2.53%。为了检验模型的稳定性和预测能力,做了留一法交互校验,预测平均相对误差为3.40%。该模型相关系数高,稳定性好,预测能力强。     

Characterization of a Thermostable and Surfactant-Tolerant Chondroitinase B from a Marine Bacterium Microbulbifer sp. ALW1

Chondroitinase plays an important role in structural and functional studies of chondroitin sulfate (CS). In this study, a new member of chondroitinase B of PL6 family, namely ChSase B6, was cloned from marine bacterium Microbulbifer sp. ALW1 and subjected to enzymatic and structural characterization. The recombinant ChSase B6 showed optimum activity at 40 °C and pH 8.0, with enzyme kinetic parameters of K_m and V_max against chondroitin sulfate B (CSB) to be 7.85 µg/mL and 1.21 U/mg, respectively. ChSase B6 demonstrated thermostability under 60 °C for 2 h with about 50% residual activity and good pH stability under 4.0–10.0 for 1 h with above 60% residual activity. In addition, ChSase B6 displayed excellent stability against the surfactants including Tween-20, Tween-80, Trion X-100, and CTAB. The degradation products of ChSase B6-treated CSB exhibited improved antioxidant ability as a hydroxyl radical scavenger. Structural analysis and site-directed mutagenesis suggested that the conserved residues Lys248 and Arg269 were important for the activity of ChSase B6. Characterization, structure, and molecular dynamics simulation of ChSase B6 provided a guide for further tailoring for its industrial application for chondroitin sulfate bioresource development.     

基于正交试验法的平面磨削用量的优选

通过在M7130平面磨床上的试验,采用正交试验方法对平面磨削用量进行分析研究,从而进一步了解平面磨削用量对已加工表面质量的影响规律,及其影响的主次关系,为合理选择平面磨削用量提供可靠的依据.     

喷射成形Al-Zn-Mg-Cu系超高强度铝合金热处理制度的实验研究

研究了喷射成形Al-Zn-Mg-Cu系超高强度铝合金的沉积态和挤压态的组织,对挤压态合金进行了固溶处理和时效处理,得到了时效硬度曲线,并进行了力学性能测试.结果显示:沉积态合金孔隙较多;挤压态合金内存在大量的颗粒,经能谱分析为富铜相;固溶温度达到490℃时,晶界出现熔化现象.时效硬度曲线表明:采用120℃时效,在15~25h之间达到硬度峰值;采用135℃时效,达到硬度峰值的时间与合金的成分有关,随着Zn含量的增加,达到硬度峰值的时间变短,而抗拉强度基本稳定在700MPa左右.     

四川盆西平原区裸土扬尘中Pb、Cd化学形态的生物有效性

为探究四川盆西平原区裸土扬尘中Pb、Cd总质量分数与其生物有效性的规律,在构建的"阳离子型污染物土壤表层运移行为研究系统"内进行模拟起尘试验,对土壤样品进行Pb、Cd模拟污染试验,结果表明:试验条件下,四川盆西平原区裸土扬尘颗粒物中Pb、Cd的总质量分数随着粒径的减小而增大,其中Pb的化学形态以碳酸盐结合态为主(44....     

加强信息资源建设搭建数字化资源平台

文章对华北电网公司数字化图书馆的功能特点、资源建设情况及系统采用的关键技术等进行了简要介绍,从侧面论述了该数字化图书馆信息量大、专业性强、技术先进,是各类专业技术人员、管理人员日常工作中获取科技、管理知识的窗口和渠道。     

China’s Oil and Gas Policy in 2010

China has mapped out and adopted a series of energy policies during the 11th Five-Year Plan period and achieved good results,and thus accomplished the task of saving energy and reducing emissions,sped up energy development and optimized     

Development of High Deformability Pipeline Steel

Based on strain-based design, high deformability X70 high strength pipeline steel with dual-phase microstructure has been developed, which can be laid in the seismic, the cold or the deepwater region. The results illustrated that the developed X70 steel has the stress-strain curve like round house and it shows good anti-transformation characteristic, high uniform deformation(≥10%), enhanced n-value(≥0.10), and the low yield-tensile ratio Y/T(≤0.85). The dual-phase microstructure of ferrite and bainite conta...     

Cobalt-iron cyanide hollow cubes: Three-dimensional self-assembly and magnetic properties

Cobalt-iron cyanide hollow cubes have been synthesized via a poly(vinylpyrrolidone) assisted solvothermal route. A unique formation process: self-assembly followed by Ostwald ripening process, has been put forward to take account for the construction of hollow cubes. The rod-like nanocrystals first assemble as porous cubes via an oriented attachment process. Then, the porous cubes undergo an Ostwald-ripening process, which create interior spaces and result in the formation of hollow cubes. The magnetic property investigation reveals that K_0.22Co_0.58Fe_2.2(CN)₆ hollow cubes exhibit a ferromagnetic behavior.