Efficient Catalyst for Both Suzuki and Heck Cross‐Coupling Reactions: Synthesis and Catalytic Behaviour of Geometry‐ Constrained Iminopyridylpalladium Chlorides

A series of geometry‐constrained iminopyridyl‐palladium chlorides were synthesized and characterized. These phosphine‐free palladium complexes were explored for their catalytic activities in both Suzuki and Heck cross‐coupling reactions, achieving turnover numbers as high as 10⁶ towards various aryl bromides, even those containing various functionalities. In addition, the influence of substituents with steric and electronic factors was reflected by the differences observed in their activities.

     

Enantioselective One‐Pot Reaction: Organocatalyzed Synthesis of Fully Functionalized Oxabicyclo[2.2.2]octanes with Seven Contiguous Stereocenters

An enantioselective one‐pot Michael/Michael/Henry/hemiacetalization reaction between α,β‐unsaturated aldehydes, α‐ketoamides, and nitroalkenes under mild conditions catalyzed by a diarylprolinol silyl ether has been developed. The sequential methodology provides a direct approach to a wide range of fully substituted chiral oxabicyclo[2.2.2]octanes with seven contiguous stereocenters in moderate to excellent yields (up to 99%), high to excellent diastereoselectivities (up to >25:1 dr), and high to excellent enantioselectivities (up to 99% ee).

     

Influences of internal erosion on infiltration and slope stability

Bulletin of Engineering Geology and the Environment - Rainfall-induced slope failures in natural terrains are destructive natural disasters. Transport of fine particles may be induced by the...     

核桃壳活性炭的制备及其对烟酸缓释性能的研究

以二氧化碳(CO2)物理活化法制备了核桃壳活性炭,考察了活化温度、活化时间对核桃壳活性炭得率及烟酸吸附量的影响。以所制备的核桃壳活性炭为烟酸载体,在不同的释放介质(蒸馏水、人工胃液或人工肠液)中进行烟酸释放性能研究。结果表明,人工胃液和人工肠液能促进活性炭对烟酸的释放,其累计释放率分别达到43.96%和47.69%。核桃壳活性炭在3种不同介质中的不同释放阶段的释放过程均符合Higuchi模型。     

房建工程施工技术探讨

房建工程的建设质量是现代社会比较关注的问题,房建工程的质量水平直接关系到其运行安全。施工技术是房建工程的建设基础,有利于提升房建工程的质量。本文对房建工程进行了研究,分析了主要的施工技术。     

安全人机工程学在挖掘机驾驶室中的应用

应用人机工程学原理,针对挖掘机驾驶室.分析挖掘机动臂摆动角度与挖掘机司机视野范围的关系,提出了保证整个施工现场安全的必要条件.并且,分析挖掘机司机所处的特殊工作环境,提出保障司机作业安全的对策措施,确保了司机工作的安全性.     

超分子化合物(C12N2H9)2(C12N2H8)[SW12O40]的合成与结构表征

利用水热法合成了超分子化合物（C12N2H9）2（C12N2H8）[SW12O40],通过元素分析和X射线单晶衍射确定了其晶体结构,该晶体为正交晶系,P2（1）2（1）2（1）空间群,晶胞参数为a=12．0168（3）A^。,b=21．0534（6）A^。,c=22．5820（6）A^。,V=5713．1（3）A^。^3,α=β=γ=90°,Z=4,Dc=3．977mg·m^-3,并通过IR和XRD进行了结构表征,采用热重分析研究了晶体的热稳定性。该化合物由邻菲罗林和Keggin结构[SW12O40]^2-阴离子组成,以氢键自组装成超分子结构化合物。     

HIPS/PPO共混物拉伸和冲击断裂面的电镜观察

研究了高冲击强度聚苯乙烯(HIPS)/聚苯醚(PPO)共混物断面3个特征区的形貌特征及形成机制,分析了它们对材料力学性能的影响。     

武器系统的人机工程研究

运用人机工程的基本知识,综述武器系统中人机工程的重要性及实施方法。武器系统在研制过程中,只有充分综合人-机-环三大要素考虑设计方案。才能使武器系统达到安全、高效和经济的目的。     

中国服装企业库存问题的分析与探讨

从库存的概念及成因入手,分析了我国各类服装企业库存现状及产生原因,并提出解决我国服装企业库存问题的方法及建议.有效的库存能确保物畅其流,提高周转率,提高经济效益.