检索结果-南通市图书馆

Populations of Bright X-ray Sources in the Starburst Galaxies NGC 4038/4039

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

Chinese Journal of Astronomy and Astrophysics 2007年第3期7卷 389-396页

作者： Xi-wei liu Xiang-dong li Department of Astronomy Nanjing University Nanjing 210093

Assuming a naive star formation history, we construct synthetic X-ray source populations, using a population synthesis code, for comparison with the observed X-ray luminosity function （XLF） of the interacting galaxies NGC 4038/4039. We have included highand intermediate-mass X-ray binaries, young rotation-powered pulsars and fallback disk-fed black holes in modeling the bright X-ray sources detected. We find that the majority of the X-ray sources are likely to be intermediate-mass X-ray binaries, but for typical binary evolu- tion parameters, the predicted XLF seems to be steeper than observed. We note that the shape of the XLFs depends critically on the existence of XLF break for young populations, and suggest super-Eddington accretion luminosities or the existence of intermediate-mass black holes to account for the high luminosity end and the slope of the XLF in NGC 4038/4039.

关键词： binaries close - galaxies individual (NGC 4038/4039) - stars evolution -X-ray binaries

Diverse strategic approaches en route to Taxol total synthesis

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2022年第12期33卷 4957-4968页

作者： Zexian li Jianfeng Zheng wei-dong Z.li Sichuan Engineering Research Center for Biomimetic Synthesis of Natural Drugs School of Life Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China

Taxol is one of the most famous diterpenoid natural products used in clinical cancer *** and its analogues are popular synthetic targets and have attracted worldwide attention over the past *** research efforts have already been made and ten groups have achieved the total synthesis of Taxol since *** mini-review summarized the recent highlights of divergent strategic approaches towards the chemical synthesis of Taxol's carbocyclic framework bearing a bridged eight-membered ring.

关键词： Taxol Total synthesis Biomimetic synthesis linear strategy Convergent strategy

Unexpected Grob-type fragmentation of vinylogous β-silyloxy-cyclobutanone into γ-lactone

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2017年第5期28卷 968-970页

作者： Xiang Wu wei-dong Z.li School of Chemistry and Chemical Engineering Hefei University of Technology Innovative Drug Research Centre Chongqing University

An unusual formal oxy transposition of vinylogous β-silyloxy-cyclobutanone 1（a 1,5-difunctionalized substrate） under mild acidic conditions（aqueous HF in CH3CN at 0℃） to the decalinic y-lactone 2 was described.A... 详细信息

关键词： Grob fragmentation Vinylogous β-silyloxy-cyclobutanone Decalinic γ-lactone Oxy transposition Intramolecular γ-lactonization

Current–phase relations of a ring-trapped Bose–Einstein condensate with a weak link

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2019年第1期28卷 218-222页

作者： Xiu-Rong Zhang wei-dong li Institute of Theoretical Physics and Department of Physics State Key Laboratory of Quantum Optics and Quantum Optics DevicesCollaborative Innovation Center of Extreme OpticsShanxi UniversityTaiyuan 030006China

The current–phase relations of a ring-trapped Bose–Einstein condensate interrupted by a rotating rectangular barrier are extensively investigated with an analytical solution. A current–phase diagram, single and multi-valued relation, is presented with a rescaled barrier height and width. Our results show that the finite size makes the current–phase relation deviate a little bit from the cosine form for the soliton solution in the limit of a vanishing barrier, and the periodic boundary condition selects only the plane wave solution in the case of high barrier. The reason for multi-valued current–phase relation is given by investigating the behavior of soliton solution.

关键词： ring-trapped Bose–Einstein condensate weak link current–phase relation analytical solution

Radar target recognition based on micro-Doppler effect

在线全文

学校读者我要写书评

暂无评论

Optoelectronics Letters 2008年第6期4卷 456-459页

作者： dong wei-guang li Yan-jun College of Astronautics Northwestern Polytechnical University Xi ＇an 710072 China

Mechanical vibration of target structures will modulate the phase function of radar backscattering,and will induce the frequency modulation of returned signals from the target. It generates a side bands of the target body Doppler frequency shift,which is helpful for target recognition. Based on this,a micro-Doppler atomic storehouse is built for the target recognition,and four kinds of common classifiers are used separately to perform the classified recognition. The simulation experimental results show that this method has high recognition rate above 90%.

关键词：雷达目标显微多普勒效应信息处理后向散射

Prediction of blast furnace gas generation based on data quality improvement strategy

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2023年第5期30卷 864-874页

作者： Shu-han liu Wen-qiang Sun wei-dong li Bing-zhen Jin Department of Energy Engineering School of MetallurgyNortheastern UniversityShenyang 110819LiaoningChina State Environmental Protection Key Laboratory of Eco-Industry(Northeastern University) Ministry of Ecology and EnvironmentShenyang 110819LiaoningChina State Key Laboratory of Metal Material for Marine Equipment and Application Anshan 114009LiaoningChina Ansteel Iron and Steel Research Institute Ansteel Group Corporation LimitedAnshan 114009LiaoningChina General Heavy Section Mill Angang Steel Company LimitedAnshan 114021LiaoningChina

The real-time energy flow data obtained in industrial production processes are usually of low *** is difficult to accurately predict the short-term energy flow profile by using these field data,which diminishes the effect of industrial big data and artificial intelligence in industrial energy *** real-time data of blast furnace gas(BFG)generation collected in iron and steel sites are also of low *** order to tackle this problem,a three-stage data quality improvement strategy was proposed to predict the BFG *** the first stage,correlation principle was used to test the sample *** the second stage,the original sample set was rectified and *** the third stage,Kalman filter was employed to eliminate the noise of the updated sample *** method was verified by autoregressive integrated moving average model,back propagation neural network model and long short-term memory *** results show that the prediction model based on the proposed three-stage data quality improvement method performs *** short-term memory model has the best prediction performance,with a mean absolute error of 17.85 m3/min,a mean absolute percentage error of 0.21%,and an R squared of 95.17%.

关键词： Blast furnace gas Iron and steel industry Data quality improvement Artificial intelligence Gas generation prediction

Vertical Price Transmission in the China's Layer Industry Chain:an Application of FDL Approach

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

Agricultural Sciences in China 2011年第11期10卷 1812-1823页

作者： XU Shi-wei dong Xiao-xia li Zhe-min li Gan-qiong Key Laboratory of Digital Agricultural Early-Warning Technology Ministry of Agriculture~Agricultural Information Institute ChineseAcademy of Agricultural Sciences Beijing 100081 P.R.China

This paper examines the vertical price relationship between upstream and downstream products in China＇s layer industry chain by estimating elasticity coefficients of the price transmission. We use cointegration tests, error correction models and finite distributed lag models to analyze vertical price shifts between corn, layer feed, egg-laying chicken and egg prices. With monthly data from 1994 to 2010, our results show that various prices in China＇s layer industry chain are well integrated. In addition, our results indicate that both long-run and short-run price relationships between upstream and downstream products in layer industry chain exist and the long-run equilibrium, to a certain extent, may eliminate the short-run dynamics price deviation. We also found that the influence of corn and feed prices on egg prices is still more remarkable than egg-laying chicken prices. Our findings imply that governments should pay more attention to corn and layer feed prices in order to stabilize egg prices under the conditions of market integration.

关键词： finite distributed lag model vertical price transmission layer industry chain China

Dienone-phenol Rearrangement of C-9 Oxygenated Decalinic Dienone and Analogs through B-Ring Cleavage

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2003年第7期14卷 689-692页

作者： Jing Chun CHEN Gang ZHOU wei dong li Yu lin li National Laboratory of Applied Organic Chemistry and Institute of Organic Chemistry Lanzhou UniversityLanzhou 730000

Dehydrogenation of 9-hydroxy decalinic enones and analogs with DDQ resulted in a formal dienone-phenol type rearrangement via B-ring cleavage, while the corresponding dienone acetates underwent base-catalyzed formal d... 详细信息

关键词： Dienone-phenol rearrangement decalinic dienone dehydrogenation DDQ.

Time Dependence of Entropy Flux and Entropy Production of a Dissipative Dynamical System Driven by Non-Gaussian Noise

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2008年第6期49卷 1561-1566页

作者： GUO Yong-Feng XU wei li dong-Xi XIE Wen-Xian Department of Applied Mathematics Northwestern Polytechnical University Xi＇an 710072 China

A stochastic dissipative dynamical system driven by non-Gaussian noise is investigated. A general approximate Fokker-Planck equation of the system is derived through a path-integral approach. Based on the definition of Shannon＇s information entropy, the exact time dependence of entropy flux and entropy production of the system is calculated both in the absence and in the presence of non-equilibrium constraint. The present calculation can be used to interpret the interplay of the dissipative constant and non-Gaussian noise on the entropy flux and entropy production.

关键词： information entropy entropy flux and entropy production non-Gaussian noise Fokker-Planck equation