检索结果-南通市图书馆

Observation of the New Heavy Neutron-Rich Isotope ^(238)Th

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 Physics Letters 1999年第8期16卷 555-556页

作者： YUANG Shuang-gui yang wei-fan HE Jian-jun XU Yan-bing MA Tao-tao XIONG sing LI Zong-wei Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000

A new nuclide 238Th was produced via multinucleon transfer reaction by 60 MeV/u 18O ion irradiation of the natural uranium. The thorium was radiochemically separated from the mixture of uranium and reaction products. The growth and decay of 238Pa gamma rays was observed, identifying the 238Pa parent as 238Th. The half-life of 238Th was determined to be 9.4±2.0min.

关键词： products. separated decay

China＇s Trade Deficit,or？COMPOSITION of China＇s Trade Deficit

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

China's Foreign Trade 2010年第12期 22-25页

作者： yang wei fan Gang

China＇s foreign trade in March witnessed a monthly trade deficit according to its national Customs data. It was the first time for China to have a trade deficit after 70 months of continuous trade surplus, since May ... 详细信息

关键词：中国贸易赤字海关对外贸易

Separation of protactinium in the reaction of 60MeV/nucleon ^(18)O ions with natural uranium

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2002年第2期13卷 119-124页

作者： yang wei-fan, YUAN Shuang-Gui, XIAO Yong-Hou, XU Yan-Bing, fanG Ke-Ming (Institute of Modern Physics, the Chinese Academy of Sciences, Lanzhou 730000) Institute of Modern Physics the Chinese Academy of Sciences Lanzhou 730000

The activities of protactinium were produced by the multi-nucleontransfer reactions in bombardment of the natural uranium with 60 MeV/nucleon 1sOions. A simple, relatively fast radiochemical procedure was used for extraction sep-aration of protactinium from the uranium and a variety of reaction products using1-phenyl-3-methyl-4-benzoyl-5-pyrazolone and tri-iso-octylamine as extractants. Theγ ray spectrum of the separated protactinium fractions showed that the protactiniumcould be separated from all of the main impurity elements. The decontaminationfactors of the uranium and the main reaction products produced in the reaction aregiven.

关键词：镤 PMBP提取天然铀

维普期刊数据库

Sharp Isolated Toughness Bound for Fractional(k,m)-Deleted Graphs

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2025年第1期41卷 252-269页

作者： wei GAO wei-fan WANG Yao-jun CHEN School of Mathematics Hohai UniversityNanjing 210098China Department of Mathematics Zhejiang Normal UniversityJinhua 321004China Department of Mathematics Nanjing UniversityNanjing 210093China

A graph G is a fractional(k,m)-deleted graph if removing any m edges from G,the resulting subgraph still admits a fractional *** k≥2 and m≥1 be ***[2m/k]^(*)=[2m/k]if 2m/k is not an integer,and[2m/k]^(*)=[2m/k]-1 if 2m/k is an *** this paper,we prove that G is a fractional(k,m)-deleted graph if δ(G)≥k+m and isolated toughness meets I(G)>{3-1/m,if k=2 and m≥3,k+[2m/k]^(*)m+1-[2m/k]^(*);***,we show that the isolated toughness bound is tight.

关键词： graph isolated toughness fractional k-factor fractional(k,m)-deleted graph

维普期刊数据库

Rapid detection of colored and colorless macroand micro-plastics in complex environment via near-infrared spectroscopy and machine learning

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2025年第1期147卷 512-522页

作者： Hui-Huang Zou Pin-Jing He wei Peng Dong-Ying Lan Hao-yang Xian fan Lü Hua Zhang Institute of Waste Treatment&Reclamation College of Environmental Science and EngineeringTongji UniversityShanghai 200092China Shanghai Institute of Pollution Control and Ecological Security Shanghai 200092China

To better understand the migration behavior of plastic fragments in the environment,development of rapid non-destructive methods for in-situ identification and characterization of plastic fragments is ***,most of the studies had focused only on colored plastic fragments,ignoring colorless plastic fragments and the effects of different environmental media(backgrounds),thus underestimating their *** address this issue,the present study used near-infrared spectroscopy to compare the identification of colored and colorless plastic fragments based on partial least squares-discriminant analysis(PLS-DA),extreme gradient boost,support vector machine and random forest *** effects of polymer color,type,thickness,and background on the plastic fragments classification were ***-DA presented the best and most stable outcome,with higher robustness and lower misclassification *** models frequently misinterpreted colorless plastic fragments and its background when the fragment thickness was less than 0.1mm.A two-stage modeling method,which first distinguishes the plastic types and then identifies colorless plastic fragments that had been misclassified as background,was *** method presented an accuracy higher than 99%in different *** summary,this study developed a novel method for rapid and synchronous identification of colored and colorless plastic fragments under complex environmental backgrounds.

关键词： Colorless microplastics Near-infrared hyperspectral imaging Plastic identification Partial least squares discriminant analysis Machine learning

Gamma Decay of the Lowly Excited States of ^(229)AC

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 Physics Letters 1997年第4期14卷 263-265页

作者： YUAN Shuang-gui yang wei-fan SHEN Shui-fa fanG Ke-ming MOU Wan-tong ZHANG Xue-qian LI Zong-wei Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000

By bombarding the natural thorium targets with 14 MeVneutrons,^(229)Ra was produced through the reaction ^(232)Th(n,α)^(229)*** radium activities were separated from the irradiated targets by coprecipitation with BaC_(12).A total of 18 weak γ rays with energies of 14.5,15.6,18.8,21.8,22.5,44.0,47.5,55.0,63.0,69.6,93.6,94.1,98.5,102.2,104.5,106.1,161.1,and 171.5keV,which could be assigned to the decay of ^(229)Ra,has been observed in the isolated radium fractions employing high-resolution HPGe detectors and γ(x)-γ coincidence methods.A decay scheme of ^(229)Ra based on these observations has been proposed.

关键词： methods. decay coincidence

Identification of a New Isotope ^(186)Hf

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 Physics Letters 1999年第6期16卷 406-407页

作者： yang wei-fan YUAN Shuang-gui XU Yan-bing HE Jian-jun LI Zong-wei MA Tao-tao fanG Ke-min SHEN Shui-fa Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000

The new neutron-rich isotope 186Hf has been produced through a multinucleon transfer reaction by irradiation of natural tungsten targets with 60MeV/u ^(18)O *** ^(186)Hf activities were separated radiochemically from the tungsten and reaction product *** γ-ray singles spectra were measured with a high resolution HPGe *** new isotope ^(186)Hf was identified based on the growth and decay of 737.5 keV γ rays from the β^(-) decay of its daughter ^(186)*** half-life has been determined to be 2.6±1.2 min.

关键词： MeV/u decay

Transtarget residue products of 47 MeV/u 12C ions on 133Cs targets

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 1997年第3期 55-57页

作者： Li Zong wei, yang wei fan and Zhao Zhi Zheng ( Institute of Modern Physics, the Chinese Academy of Sciences,Lanzhou 730000)

Ｔｒａｎｓｔａｒｇｅｔｒｅｓｉｄｕｅｐｒｏｄｕｃｔｓｏｆ４７ＭｅＶ／ｕ１２Ｃｉｏｎｓｏｎ１３３ＣｓｔａｒｇｅｔｓＬｉＺｏｎｇＷｅｉ，ＹａｎｇＷｅｉＦａｎａｎｄＺｈａｏＺｈｉＺｈｅｎｇ（ＩｎｓｔｉｔｕｔｅｏｆＭｏ... 详细信息

Ｔｒａｎｓｔａｒｇｅｔｒｅｓｉｄｕｅｐｒｏｄｕｃｔｓｏｆ４７ＭｅＶ／ｕ１２Ｃｉｏｎｓｏｎ１３３ＣｓｔａｒｇｅｔｓＬｉＺｏｎｇＷｅｉ，ＹａｎｇＷｅｉＦａｎａｎｄＺｈａｏＺｈｉＺｈｅｎｇ（ＩｎｓｔｉｔｕｔｅｏｆＭｏｄｅｒｎＰｈｙｓｉｃｓ，ｔｈｅＣ...

关键词： Transtarget product yields Chemical separation Heavy ion nuclear reaction The most probable mass number Gamma spectra

Radiochemical separation of thorium from ^(18)O inducedreaction with natural uranium

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2001年第2期12卷 81-86页

作者： yang wei-fan, YUAN Shuang-Gui, XIONG Bing, XU Yan-Bing, HE Jian-Jun, PAN Qiang-Yan, MA Tao-Tao Institute of Modern Physics, the Chinese Academy of Sciences, Lanzhou 730000 中科院近代物理所甘肃兰州 730000

A radiochemical procedure used to separate and purify trace concentration thorium produced in heavy ion reaction with uranium targets is presented. The procedure can rapidly yield thorium fraction suitable for gamma-ray spectroscopy studies. The resultant gamma-ray spectra showed that Th was isolated from a large number of elements produced in the reaction, and there were only a few contaminating activities of isotopes of Sc, Cd, In, etc. The decontamination factors for the main reaction products are given.

关键词：钍放射化学分离天然铀

维普期刊数据库