基于主成分分析的管理学核心期刊评价研究

针对我国目前科技期刊评价中存在的学科划分不够严谨、指标权重人为选取等问题,以管理学核心期刊为研究对象,提出了基于主成分分析的期刊评价方法,对CNKI文献数据库中19种管理学核心期刊进行了分析和评价,给出期刊排名,并与影响因子及总被引频次的评价结果进行对比,表明了主成分分析方法的可靠性和客观性。     

Unsymmetrical Pyrene‐Fused Phthalocyanine Derivatives: Synthesis,Structure, and Properties

Novel pyrene‐fused unsymmetrical phthalocyanine derivatives 2,3,9,10,16,17‐hexakis(2,6‐dimethylphenoxy)‐22,25‐diaza(2,7‐di‐tert‐butylpyrene)[4,5]phthalocyaninato zinc complex Zn[Pc(Pz‐pyrene)(OC₈H₉)₆] ( 1 ) and 2,3,9,10‐tra(2,6‐dimethylphenoxy)‐15,18,22,25‐traza(2,7‐di‐tert‐butylpyrene)[4,5]phthalocyaninato zinc compound Zn[Pc(Pz‐pyrene)₂(OC₈H₉)₄] ( 2 ) were isolated for the first time. These unsymmetrical pyrene‐fused phthalocyanine derivatives have been characterized by a wide range of spectroscopic and electrochemical methods. In particular, the pyrene‐fused phthalocyanine structure was unambiguously revealed on the basis of single crystal X‐ray diffraction analysis of 1 , representing the first structurally characterized phthalocyanine derivative fused with an aromatic moiety larger than benzene.     

仿生非光滑花纹沟对轮胎抗滑水性能的影响

以205/55R16乘用车轮胎为研究对象,采用计算流体动力学建立了考虑胎面花纹变形的轮胎滑水分析模型;以气-液二相流数值模型分析了轮胎的滑水性能,并将临界滑水速度仿真值与NASA滑水速度预测值及轮胎发生滑水时力平衡下的速度进行对比.在此基础上,引入仿生减阻理念,研究了夹角为60°、高度为0.6mm的仿生对称V形结构对花纹沟排水量和水流阻力的影响,并将其结构特征信息等效移植到接地区轮胎花纹沟底,进行了仿生花纹轮胎的滑水性能分析.结果表明:所建滑水分析模型可用来分析轮胎滑水时的流体运动特性;相对原花纹轮胎,仿生非光滑花纹沟轮胎通过提高接地区花纹沟内水流速度,降低了胎面动水压力,提高了临界滑水速度.     

Identification of the Enzymes Mediating the Maturation of the Seryl-tRNA Synthetase Inhibitor SB-217452 during the Biosynthesis of Albomycins

Albomycin δ₂ is a sulfur-containing sideromycin natural product that shows potent antibacterial activity against clinically important pathogens. The l -serine-thioheptose dipeptide partial structure, known as SB-217452, has been found to be the active seryl-tRNA synthetase inhibitor component of albomycin δ₂. Herein, it is demonstrated that AbmF catalyzes condensation between the 6′-amino-4′-thionucleoside with the d -ribo configuration and seryl-adenylate supplied by the serine adenylation activity of AbmK. Formation of the dipeptide is followed by C3′-epimerization to produce SB-217452 with the d -xylo configuration, which is catalyzed by the radical S-adenosyl-l -methionine enzyme AbmJ. Gene deletion suggests that AbmC is involved in peptide assembly linking SB-217452 with the siderophore moiety. This study establishes how the albomycin biosynthetic machinery generates its antimicrobial component SB-217452.     

Strategies for Improving the Catalytic Performance of 2D Covalent Organic Frameworks for Hydrogen Evolution and Oxygen Evolution Reactions

Hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) have been deemed as clean and sustainable strategies to solve the energy crisis and environmental problems. Various catalysts have been developed to promote the process of HER and OER. Among them, two-dimensional covalent organic frameworks (2D COFs) have received great attention due to their diverse and designable structure. In this minireview, we mainly summarize the diverse linkages of 2D COFs and strategies for enhancing the catalytic performance of 2D COFs for HER and OER, such as introducing active building blocks, metal ions and tailored linkages. Furthermore, a brief outlook for the development directions of COFs in the field of HER and OER is provided, expecting to stimulate new opportunities in future research.     

Numerical simulation and structure optimization of a liquid–vapor separation plate condenser

Journal of Thermal Analysis and Calorimetry - Based on innovative design, a liquid–vapor separation plate condenser with excellent heat transfer performance is invented. It takes less time to...