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Synthesis of new chiral 1,2,3,4-tetrahydroisoquinoline β-amino alcohols from L-DOPA

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Chinese Chemical Letters 2008年第11期19卷 1271-1273页

作者： Geng xu zhan Zhu Liu Institute of Materia Medica Peking Union Medical College ＆ Chinese Academy of Medical Science Beijing 100050 China

Four new chiral 1,2,3,4-tetrahydroisoquinoline-derived β-amino alcohols were synthesized from L-DOPA in good yields. The structures of the target compounds were confirmed by ^1H NMR, ^13C NMR and MS.

关键词： β-Amino alcohol Tetrahydroisoquinoline L-DOPA Pictet-Spengler reaction

Synthesis of new chiral 1,2,3,4-tertrahydroisoquinoline β-amino alcohol for asymmetric diethylzinc addition to aryl aldehydes(Ⅰ)

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Chinese Chemical Letters 2009年第12期20卷 1393-1396页

作者： Geng xu zhan Zhu Liu Key Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal Medicine (Peking Union Medical College) Ministry of Education Institute of Materia Medica Peking Union Medical College & Chinese Academy of Medical Sciences Beijing 100050 China

Four new chiral 1,2,3,4-tetrahydroisoquinoline-derived G-amino alcohols were synthesized from commercially available LDOPA. These ligands were evaluated in the asymmetric addition of diethylzinc to benzaldehydes and showed different catalytic activities （up to 86% ee）. The solvent played an important role in the enantioselective process. The transition state models were proposed to explain the reversion of the product configuration.

关键词： β-Amino alcohol Tetrahydroisoquinoline Diethylzinc Asymmetric addition

Subfemtosecond X-ray Pulses Produced Directly by High Harmonic Generation

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Chinese Physics Letters 2000年第7期17卷 491-492页

作者： WANG Ying-song xu Zhi-zhan Laboratory for High Intensity Optics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800

The generation of subfemtosecond pulses in hydrogen-like atoms through high-harmonic generation by using superintense multicycle driver pulses is numerically investigated. It is shown that a single subfemtosecond pulse can be directly generated when the driver pulse is strong enough to deplete the neutral atoms within several optical cycles. The propagation effect is neglected during the numerical examinations.

关键词： femtosecond pulse neglected

Potential Transmission Choice for Internet of Things(IoT):Wireless and Batteryless Communications and Open Problems

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China Communications 2021年第2期18卷 241-249页

作者： zhan xu Guanjie Hu Minzheng Jia Lan Dong School of Information and Communication Engineering and with Key Laboratory of Modern Measurement&Control Technology Ministry of EducationBeijing Information Science&Technology UniversityChina Beijing Key Lab of Transportation Data Analysis and Mining School of Computer and Information TechnologyBeijing Jiaotong UniversityBeijingChina Department of Information Engineering Beijing Polytechnic CollegeBeijingChina

The 5th generation mobile communications aims at connecting everything and future Internet of Things(IoT)will get everything smartly *** realize it,there exist many *** key challenge is the battery problem for small devices,such as sensors or *** backscatter,also referred to as or battery-free backscatter,is a new potential technology to address this *** early and typical type of batteryless backscatter is ambient ***,batteryless backscatter utilizes environmental wireless signals to enable battery-free devices to communicate with each *** devices first harvest energy from ambient wireless signals and then backscatter these signals so as to transmit their own *** paper reviews the current studies about batteryless backscatter,including various backscatter schemes and theoretical works,and then introduces open problems for future research.

关键词： batteryless backscatter battery-free channel state information(CSI) channel estimation multiple antennas signal detection symbiotic communication

Early Permian Sunidyouqi suprasubduction-zone ophiolites in the central Solonker suture zone(Inner Mongolia, China)

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Geoscience Frontiers 2019年第3期10卷 1101-1111页

作者： Guo xu Huichuan Liu Yinglei Li zhan xu Yan Xie School of Earth Sciences China University of Geosciences Inner Mongolia Key Laboratory of Magmatic Mineralization and Ore-Prospecting Geological Survey Institute of Inner Mongolia School of Earth Science and Geological Engineering Sun Yat-Sen University

Different final closing ages have been proposed for the evolution of the Paleo-Asian Ocean(PAO),including Late Silurian, pre-Late Devonian, Early Permian, Late-Permian and Late Permian-Early *** represent fragments of ancient oceanic crust and play an important role in identifying the suture zone and unveiling the evolutionary history of fossil oceans. Our detailed geological, geochemical and geochronological investigations argue for the existence of Early Permian(297 Ma) SSZ type ophiolites in the Sunidyouqi area of central Inner Mongolia, China. The gabbros and basalts show LREE depleted REE patterns and left-leaning primitive mantle-normalized spider diagrams with variable negative Nb-Ta anomalies(Nb~*= 0.24-1.28 and 0.29-0.55, respectively). The Sunidyouqi ophiolites were generated in a mature back-arc basin. The Sunidyouqi ophiolites share the same petrological,geochemical and geochronological characteristics with the other ophiolites along the Solonker suture zone, delineating a Late Paleozoic ocean and arc-trench system. This Late Paleozoic ocean and arc-trench system coincides with a Permian paleobiogeographical boundary, i.e. the boundary between the northern cold climate(Boreal faunal-Angaraland floral realm), and a southern warm climate(Tethys faunal-Cathaysian floral realm). A tectonic scenario was proposed at last for the closure of the SE PAO involving(1) Late Ordovician to Middle Permian continuous southward subduction beneath the northern margin of North China;(2) Carboniferous to Middle Permian continuous northward subduction the forming the Northern Accretionary Orogen;(3) Late Permian final closure of the SE PAO.

关键词： Paieo-Asian Ocean Solonker North China Craton Ophiolite SSZ

Momentum Transfer of an Atom Moving in an Optical Cavity

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Chinese Physics Letters 2001年第8期18卷 1069-1071页

作者： zhanG Jing-Tao xu Zhi-zhan Laboratory for High Intensity Optics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800

When an atom moves in an optical cavity,the total momentum of the atom does not keep *** study a two-level atom moving slowly in an optical cavity,and give the time dependence of its mean *** is found that when the initial momentum of the atom is larger than that of the photon,the mean momentum oscillates around a value less than the initial value,But,if the initial momentum is less than the momentum of the photon,the mean momentum of the atom is greater than its initial value in most time.

关键词： momentum value initial

Distributed antenna wireless communication system coverage design and field trial over higher frequency band

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仪器仪表学报 2016年第S1期37卷 131-138页

作者： xu zhan Liu Jienan Zhou Shidong Chen Xiang Wang Wenqi Beijing Information Science & Technology University University of Georgia Tsinghua University Sun Yat-sen University

This paper aims to examine the architecture design of a distributed antenna based Gbps wireless communication system using the high frequency *** order to analyze the feasibility of the higher frequency band applications,the cumulative distribution of simulated user throughput in a cellular is investigated *** shows that capacity improvement can be obtained using higher operating frequency band,especially in hotspot ***,the architecture of the distributed antenna system(DAS) is introduced to overcome the disadvantages of weak coverage and rank deficient for the traditional multiple-input multiple-output(MIMO) systems using higher frequency bands in line-of-sight(LOS)*** addition,a software-defined-radio(SDR) based Gbps wireless transmission system with scalable hardware architecture is designed and ***,a demo of outdoor DAS coverage for high data throughput application is *** trials show that 1 Gbps data rate and a large coverage in outdoor environments can be achieved over 6.05 *** is proved that the Gbps DAS system at a higher frequency band can be a successful model for future wireless broadband coverage in hotspot scenarios.

关键词： higher frequency band capacity testbed distributed antenna system(DAS)

Study of oxidization of coal–pitch by O_3

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International Journal of Mining Science and Technology 2016年第4期26卷 677-681页

作者： Wang Yaoling Chen Sishun Ding Mingjie xu zhan School of Chemical and Material Engineering Henan University of Urban Construction Department of Light Industry Luohe Vocational Technology College

For the purpose of obtaining small molecular and oxygen-containing aromatic compounds, taking a toluene-extracted coal pitch as the research object, the oxidation of coal-pitch by ozone （03） in formic acid was studied. The coal-pitch sample and the oxidized pitch residue were characterized by elementary analysis and Fourier transform infrared spectroscopy （FTIR）, while the small molecular products were analyzed by a gas chromatography-mass spectrometer （GC-MS）. The results show that the highest oxygen content of oxidized coal pitch had been acquired at a reaction temperature of 50℃C, an 03 flow rate of 6300 mg/h and a reaction time of 4 h. Quite a lot of hydroxyls and carbonyls were introduced into the structure of the oxidized coal-pitch, while the small molecules produced mainly involve nonpolar aro- matic compounds, aromatic anhydride and quinone compounds. It is speculated that the mechanism is direct electrophilic oxidation in which the molecules of 03 directly attack the aromatic ring at its carbon atoms with high electron density, and then generate hydroxyl or carbonyl until the aromatic ring cracks. This study shows that 03 can make the fused aromatic ring of coal-pitch become oxidized and depoly- merized, and hence the ozonization of coal-pitch can be a potential method for obtaining oxygen- containing aromatic compounds.

关键词： Study Coal-pitch Ozone oxidation Depolymerization

Data-Driven Deep Learning for OTFS Detection

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China Communications 2023年第1期20卷 88-101页

作者： Yi Gong Qingyu Li Fanke Meng Xinru Li zhan xu School of Information Communication and Engineering Beijing Information Science and Technology UniversityBeijing 100876China School of Economics and Management Xi’an University of Posts and TelecommunicationsXi’an 710100China Tianjin Yinyuan Information Technology CO. LTD.Tianjin 300202China

Recently,orthogonal time frequency space(OTFS)was presented to alleviate severe Doppler effects in high mobility *** of the current OTFS detection schemes rely on perfect channel state information(CSI).However,in real-life systems,the parameters of channels will constantly change,which are often difficult to capture and *** this paper,we summarize the existing research on OTFS detection based on data-driven deep learning(DL)and propose three new network *** presented three networks include a residual network(ResNet),a dense network(DenseNet),and a residual dense network(RDN)for OTFS *** detection schemes based on data-driven paradigms do not require a model that is easy to handle ***,compared with the existing fully connected-deep neural network(FC-DNN)and standard convolutional neural network(CNN),these three new networks can alleviate the problems of gradient explosion and gradient *** simulation,it is proved that RDN has the best performance among the three proposed schemes due to the combination of shallow and deep *** can solve the issue of performance loss caused by the traditional network not fully utilizing all the hierarchical information.

关键词： data-driven deep learning OTFS detection