检索结果-南通市图书馆

Ni-catalyzed cross-electrophile alkyl-alkyl coupling reactions

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2025年

作者： Li-Xu You Lan Tian Chun-Ling Guo Shun-Xi Li yu-Cheng liu yu-Long Li Wei Shu College of Chemistry and Environmental Engineering Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan Sichuan University of Science and Engineering Guangming Advanced Research Institute Shenzhen Grubbs Institute Department of Chemistry and Guangdong Provincial Key Laboratory of Catalysis Southern University of Science and Technology

Introducing saturated carbon-carbon bonds into organic molecules significantly increases the three-dimensional configuration,thus altering the physical and chemical properties as well as the functions of molecules. Transition-metal-catalyzed carboncarbon cross-couplings represent one of the most straightforward, efficient and modular alternatives to build saturation in a single step. However, the efficient construction of alkyl-alkyl bonds remains a formidable challenge due to the precise manipulation of multiple alkyl metallic intermediates as well as associated competitive side reactions and selectivity control. Over the past years, Ni-catalyzed cross-coupling under reductive conditions has gained more and more attention for alkyl-alkyl crosscoupling partially attributing to the low-valent state of metal centers under reducing conditions, which suppresses the competitive β-hydride elimination process, thus facilitating the formation of alkyl-alkyl bonds. In this review, the initiative and progress of Ni-catalyzed cross-electrophile alkyl-alkyl cross-coupling, including the efforts in racemic and enantioselective formation of alkyl-alkyl bonds, have been summarized and discussed. Moreover, the challenges and further opportunities in this area have also been discussed.

关键词：

Insufficient MIRO1 contributes to declined oocyte quality during reproductive aging

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China Life Sciences 2025年

作者： Zhen-Nan Pan hao-Lin Zhang Kun-Huan Zhang Jia-Qian Ju Jing-Cai liu Shao-Chen Sun College of Animal Science and Technology Nanjing Agricultural University Reproductive Medicine Centre The Affiliated Yantai Yuhuangding Hospital of Qingdao University

Mitochondrial Rho-GTPase 1 (MIRO1) is an outer mitochondrial membrane protein which regulates mitochondrial transport and mitophagy in mitosis. In present study, we reported the crucial roles of MIRO1 in mammalian oocyte meiosis and its potential relationship with aging. We found that MIRO1 expressed in mouse and porcine oocytes, and its expression decreased in aged mice. MIRO1 deficiency caused the failure of meiotic resumption and polar body extrusion in both mouse and porcine oocytes, which could be rescued by exogenous MIRO1supplementation. Mass spectrometry data indicated that MIRO1 associated with several cytoskeleton and cell cycle-related proteins, and MIRO1 regulated motor protein Dynein for microtubule-organizing centers (MTOCs) dynamics at germinal vesicle (GV) stage, which determined meiotic resumption. Furthermore, we found that MIRO1 regulated Aurora A and kinesin family member 11 (KIF11) for meiotic spindle assembly in oocytes. Besides, MIRO1 associated with several mitochondria-related proteins dynamic-related protein 1 (DRP1),Parkin and lysosomal-associated membrane protein 2 (LAMP2) for mitochondrial dynamics and mitophagy during oocyte meiosis. Taken together, our results suggested that MIRO1 played pivotal roles in meiotic resumption, spindle assembly and mitochondrial function in mouse and porcine oocytes, and its insufficiency might contribute to the oocyte maturation defects during aging.

关键词：

Atmospheric reductive catalytic fractionation of lignocellulose integrated with one-pot catalytic conversion of carbohydrate yielding valuable lignin monomers and platform chemicals from corn straw

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Green Energy & Environment 2025年第1期10卷 161-172页

作者： Meng-Ying liu Zhe-Hui Zhang Xue-Qi Wang Qian Sun Chen Zhang yu Li Zhuohua Sun Katalin Barta Feng Peng Tong-Qi yuan State Key Laboratory of Efficient Production of Forest Resources Beijing Forestry UniversityBeijing100083China Beijing Key Laboratory of Lignocellulosic Chemistry Beijing Forestry UniversityBeijing100083China Department of Chemistry Organic and Bioorganic ChemistryUniversity of GrazHeinrichstrasse 28/II8010 GrazAustria

Developing a cost-effective and environmentally friendly process for the production of valuable chemicals from abundant herbal biomass receives great attentions in recent ***,taking advantage of the“lignin first”strategy,corn straw is converted to valuable chemicals including lignin monomers,furfural and 5-methoxymethylfurfural via a two steps *** key of this research lies in the development of a green and low-cost catalytic process utilizing magnetic Raney Ni catalyst and high boiling point ethylene *** utilization of neat ethylene glycol as the sole slovent under atmospheric conditions obviates the need for additional additives,thereby facilitating the entire process to be conducted in glass flasks and rendering it highly convenient for scaling *** the initial step,depolymerization of corn straw lignin resulted in a monomer yield of 18.1 wt%.Subsequently,in a dimethyl carbonate system,the carbohydrate component underwent complete conversion in a one-pot process,yielding furfural and 5-methoxymethylfurfural as the primary products with an impressive yield of 47.7%.

关键词： Atmospheric reductive catalytic fractionation Corn straw Ethylene glycol Raney Ni 5-Methoxymethylfurfural

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

山洪灾害预警系统远程运行维护技术研究

中国防汛抗旱 2017年第2期27卷 47-50页

作者：刘超虞邦义马浩刘怀利安徽省(水利部淮河水利委员会)水利科学研究院合肥233088

目前全国县级山洪灾害防治非工程措施项目已全部完成,补充完善项目(2013—2015)正在全面实施,如何做好已建系统和补充完善系统后期运行维护工作,已成为各级水行政主管部门亟待研究解决的一项重要工作。从项目建设特点出发,提出了采用远... 详细信息

目前全国县级山洪灾害防治非工程措施项目已全部完成,补充完善项目(2013—2015)正在全面实施,如何做好已建系统和补充完善系统后期运行维护工作,已成为各级水行政主管部门亟待研究解决的一项重要工作。从项目建设特点出发,提出了采用远程监测的方式实现山洪灾害防治非工程措施项目的运行维护思路,希望通过信息化的手段做到山洪灾害防治的省级统一维护、统一管理,使整个系统能够正常运行,发挥应有的作用。

关键词：山洪灾害非工程措施远程监测运行维护

维普期刊数据库

Temperature-insensitive micro-displacement sensor with spindle-shaped structure single mode fiber

在线全文

学校读者我要写书评

暂无评论

Optoelectronics Letters 2025年

作者： ZHANG Weihua MU Jinlin WANG hao WANG Dong yu haozheng TAO Yipeng Engineering Research Center of Optoelectronic Devices and Communication Technology，Ministry of Education， Tianjin Key Laboratory of Film Electronic and Communication Devices， School of Integrated Circuit Science and Engineering， Tianjin University of Technology Engineering Infrastructure Department，Autonomous Driving Department Xiaomi EV Company Ltd

A temperature-insensitive micro-displacement sensor based on a spindle-shaped single mode fiber (SMF) is presented and demonstrated. The SMF is bent into a balloon-shaped SMF and burned into a spindle-shaped SMF by a flame. Due to the bending of the fiber， part of the incident light leaks from the fiber core into the fiber cladding， which excites higher order cladding modes. Therefore， modal interference occurs. The experimental results show that the maximum sensitivity of the sensors is -203 pm/μm when micro-displacement varies from 0 to 80 μm. The sensors are insensitive to temperature in the range of 20-70℃. In addition， the sensors have the advantages of simple structure， low cost， small volume， high sensitivity and stability， which can be widely used in numerous high-precision industrial measurements and civil engineering structure monitoring fields.

关键词：

Inter‑Skeleton Conductive Routes Tuning Multifunctional Conductive Foam for Electromagnetic Interference Shielding,Sensing and Thermal Management

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Nano-Micro Letters 2025年第3期17卷 19-36页

作者： Xufeng Li Chunyan Chen Zhenyang Li Peng Yi Haihan Zou Gao Deng Ming Fang Junzhe He Xin Sun Ronghai yu Jianglan Shui Caofeng Pan Xiaofang liu School of Materials Science and Engineering Beihang UniversityBeijing 100191People’s Republic of China Institute of Atomic Manufacturing Beihang UniversityBeijing 100191People’s Republic of China Tianmushan Laboratory Xixi Octagon CityYuhang DistrictHangzhou 310023People’s Republic of China Science and Technology On Electromagnetic Scattering Laboratory Beijing Institute of Environmental FeaturesBeijing 100854People’s Republic of China

Conductive polymer foam(CPF)with excellent compressibility and variable resistance has promising applications in electromagnetic interference(EMI)shielding and other integrated functions for wearable ***,its insufficient change amplitude of resistance with compressive strain generally leads to a degradation of shielding performance during ***,an innovative loading strategy of conductive materials on polymer foam is proposed to significantly increase the contact probability and contact area of conductive components under *** inter-skeleton conductive films are constructed by loading alginate-decorated magnetic liquid metal on the polymethacrylate films hanged between the foam skeleton(denoted as AMLM-PM foam).Traditional point contact between conductive skeletons under compression is upgraded to planar contact between conductive ***,the resistance change of AMLM-PM reaches four orders of magnitude under ***,the inter-skeleton conductive films can improve the mechanical strength of foam,prevent the leakage of liquid metal and increase the scattering area of EM ***-PM foam has strain-adaptive EMI shielding performance and shows compression-enhanced shielding effectiveness,solving the problem of traditional CPFs upon *** upgrade of resistance response also enables foam to achieve sensitive pressure sensing over a wide pressure range and compression-regulated Joule heating function.

关键词： Inter-skeleton conductive films Conductive polymer foam Liquid metal Electromagnetic interference shielding

维普期刊数据库

在线全文

学校读者我要写书评

暂无评论

生物质光发酵制氢技术研究进展

现代化工 2025年第1期45卷 56-61页

作者：屈皓李玉霞刘玉香太原理工大学环境科学与工程学院山西太原030001 晋中学院化学化工系山西晋中030619

回顾了生物质光发酵制氢的最新研究进展,对生物质预处理技术、制氢过程优化和工艺整合进行了总结分析,在此基础上,从提升制氢效率同时降低能耗方面对生物质光发酵制氢技术的未来发展做出展望。

关键词：生物质制氢光发酵制氢生物质预处理过程优化

维普期刊数据库

在线全文

学校读者我要写书评

暂无评论

日本加入联合国始末

史学集刊 2025年第1期 133-144页

作者：刘子玉温州大学人文学院浙江温州325035

1952年6月日本正式提交入联申请时,联合国受美苏冷战等因素影响,难以通过规范的单独审议程序吸纳新成员。苏联提出共产主义阵营与西方阵营的申请国可以同时入联的“一揽子方案”,但遭到美国的强烈反对。1953年,联合国大会认为应以普适... 详细信息

1952年6月日本正式提交入联申请时,联合国受美苏冷战等因素影响,难以通过规范的单独审议程序吸纳新成员。苏联提出共产主义阵营与西方阵营的申请国可以同时入联的“一揽子方案”,但遭到美国的强烈反对。1953年,联合国大会认为应以普适性原则为基础,通过政治妥协打破入联僵局,尽早吸纳日本等国加入联合国。1955年,加拿大提出日本与蒙古等18个国家同时入联的方案,因中国台湾当局反对蒙古入联而失败。苏联随机应变,提出排除日蒙两国的“16国入联方案”,并顺利通过安理会与联合国大会审议,日本入联再度受挫。1956年10月,日苏恢复邦交,苏联承诺支持日本入联。1956年12月,日本正式加入联合国。1952—1956年间,日本入联进程深受美苏冷战及联合国职能与内部权力关系变化的影响,日本政府的外交努力难以发挥有效作用。

关键词：日本入联美苏冷战联合国大会

A reduction scheme of PAPR in CO-OFDM system using time-delay neural networks

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Optoelectronics Letters 2025年

作者： TONG Zhengrong liu Zhihong WANG hao ZHANG Weihua ZHANG Tianhao JIA Qiqi Tianjin Key Laboratory of Thin Film Electronics and Communication Devices， Engineering Research Center for Optoelectronic Devices and Communication Technology of the Ministry of Education， School of Integrated Circuit Science and Engineering， Tianjin University of Technology

An iterative partial transmission sequence （IPTS） cascading time-delay neural network （TDNN） scheme is proposed to reduce peak-to-average power ratio （PAPR） in the coherent optical orthogonal frequency division multiplexing （CO-OFDM） systems. The IPTS algorithm further reduces computational complexity based on the partial transmission sequence （PTS） algorithm. TDNN is trained by the iterative clipping filtering （ICF） method. Simulation results show that the proposed scheme achieves a PAPR reduction of 5.84 dB when complementary cumulative distribution function （CCDF） is 10-4and an extra transmission distance of 200 km for 10-3bit error rate （BER） compared to the original signals.

关键词：