检索结果-南通市图书馆

Highly stereospecific polymerization of isoprene with homogeneous binary Ziegler-Natta catalysts based on NCN-pincer neodymium precursor

在线全文

学校读者我要写书评

暂无评论

Science china chemistry 2010年第8期53卷 1641-1645页

作者： LIU DongTao1,2.CUI DongMei1 & GAO Wei3 1State Key Laboratory of Polymer Physics and chemistry changchun Institute of {2. chemistry,chinese academy of sciences,changchun 13.02.,china 2.raduate University of chinese academy of sciences,Beijing 100039,china 3School of chemistry,Jilin University,changchun 130012.china State Key Laboratory of Polymer Physics and chemistry changchun Institute of applied {2. Chinese Academy of Sciences Changchun China Graduate University of chinese academy of sciences Beijing China School of chemistry Jilin University Changchun China

The aryldiimine NCN-pincer stabilized neodymium dichloride combined with aluminum alkyls established a new type of homogeneous binary neutral Ziegler-Natta catalyst *** system exhibited high activity and high cis-1,4 selectivity for the polymerization of isoprene (Tp=2. °C,98.2.;Tp=-2. °C,> 99%).Such catalytic performances remained under a broad range of polymerization temperatures and monomer-to-neodymium ratios (from 500 to 8000),reaching high number-average molecular weight (Mn=1582.kg/mol) and relatively narrow molecular weight distribution (PDI=1.68),which was,however,influenced by the amount and bulkiness of aluminum *** investigation of the polymerization was performed,which showed the number-average molecular weight of the resultant polyisoprene had an almost linear correlation with the conversion,suggesting,in some degree,the polymerization with this catalytic system was controllable.

关键词： neodymium cis-1 4 selectivity NCN-pincer complex polyisoprene

The Film-forming Behavior on the Interface between Air and Hydrosol of Fe_2._3 Nanoparticles

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2009年第4期24卷 525-527页

作者：曹立新 Institute of Materials sciences and Engineering Ocean University of China changchun Institute of applied {2. Chinese Academy of Science

The film forming behavior on the interface between air and hydrosol of Fe2.3 nanoparticles was investigated by the surface pressure-time isotherms, the surface pressure-trough area isotherms, Brewster angle microscopy and transmission electron microscopy. It is found that the freshly prepared hydrosol of Fe2.3 nanoparticles is not stable. The surface pressure increases with the aging time and finally approaches a constant, and the smaller the concentration is, the smaller the surface pressure is stabilized at and the shorter the time the hydrosol reaching stable needs. The surface pressure also increases with compression until collapsed, and the longer the hydrosol is aged, the higher the collapsing pressure is. A uniform and compact film composed of nanoparticles with an average diameter of about 2.3 nm on the air-hydrosol interface is observed by Brewster angle microscope and transmission electron microscope.

关键词： film interface air and hydrosol Fe2.3 nanoparticles

FEASIBLE STUDY ON THE INTEGRATION SYSTEM FOR THE SPACE MONITORING OF MAJOR EARTHQUAKES AND VOLCANOES IN TERRESTRIAL LAND

在线全文

学校读者我要写书评

暂无评论

chinese Geographical Science 2002年第4期12卷 350-353页

作者： BO Li-qun(changchun Institute of Geography,t he chinese academy of sciences,changchun 130012.P.R.china) changchun Institute of Geography the Chinese Academy of Sciences Changchun P. R. China

With the rapid development of space technology,earth observation tech nology and sky observatory technolo-gy,they have played a more and more im portant part in monitoring and predi cting of earthquakes and volcanoes i n the terres-trial *** recent years,the rela ted agencies have done the experimen ts and researches on monitoring and p redicting of earthquakes and volcanoes in the forewarning period by means of many appr oaches,such as satellite thermal in frared re-mote sensing(TIRS),Global Positioning System(GPS),differential interferometric syn thesis aperture radar(D-INSAR),astronomical time-latitude residual anomaly,and Geographic Information Systems (GIS),etc.A quite large number of re-search foundation has been built in t he fundamental theories and applica tion *** experiments and re searches have shown that these technology is e fficient methods for high frequency crust *** the existed separate scientific forces and results are possibly asse mbled together to form a more complete integration monitoring system wit h the combina-tion of space,sky observation,grou nd,deep geology and macro anomaly,i t will come into a new stage of monitoring and predicting of earthquakes and volca nic eruptions.

关键词： space technology integration system earthquake and volcano

Permselectivity　of　4－Aminophenol，Paracetanol　and　Phenacetin　on　the　Self－Assembled　n－Alkanethiol　Monolayer　Modified　Gold　Electrode

在线全文

学校读者我要写书评

暂无评论

Chemical Research in chinese Universities 1996年第4期12卷 340-347页

作者： Li Jing-hong LIU Zhi-ming DONG Shao-jun and WANG Er-kang(Laboratory of Electroanalytical chemistry,changchun inuitute of {2. chemistry,chinese academy of Science,changchun,13.02.) chinese ACAD SCI CHANGCHUN INST APPL CHEMELECTROANALYT CHEM LABCHANGCHUN 130022PEOPLES R CHINA

The gold electrodes coated by n-alkanethiol with various chain lengths were used to study the permeability of uric acid,ascorbic acid,4-aminophenol,paracetanol and phenacetin by means of linear sweep *** results show that the optimum chain length is n=*** improvements in the selectivity and the stability of the amperometric detection of these compounds in a flow stream were obtained by n-alkanethiol self assembled monolayers modified electrodes based on their differences in the hydrophobicity and the permeability.

关键词： s:Permselectivity Self-assembled monolayer Hydrophobicity Phenacetin.Paracetanol 4-Aminophenol

Syntheses of(C_8H_8)Ln(C_9H_7)·(THF)_2.Ln=Pr,Nd)and crystal structure of(C_8H_8)Pr(C_9H_7)·(THF)_2

在线全文

学校读者我要写书评

暂无评论

chinese Journal of chemistry 1992年第4期10卷 331-336页

作者： WEN,Ke JIN,Zhong-Sheng WEI,Ge-Cheng CHEN,Wen-Qi changchun Institute of applied {2.,chinese academy of sciences,changchun 13.02. changchun Institute of applied {2. Chinese Academy of Sciences Changchun 130022

This paper reports two lanthanide complexes of formula (C_9H_7)Ln(C_8H_8)·(THF)_2.where Ln is Pr or Nd,C_9H_7 is indenyl,and C_8H_8 is cyclooctatetraene (COT).The complexes were prepared by the reaction of LnCl_3 with K(C_9H_7) and K_2.C_8H_8) in THF.(C_9H_7)Pr(C_8H_8)·(THF)_2.crystallizes in THF at - 15℃ in the monoclinic space group P2.1:with unit cell dimensions a=8.446(0),b=10.083(2., c=13.407(3),β=105.48(1)°,V=1100.43(35)~3,Dc=1.52./cm^3 and Z=*** final R value is 0.033,R_w value is 0.030,*** (C_9H_7)Pr(C_8H_8)·(THF)_2.a five-membered ring centroid of C_9H_7,the C_8H_8 ring centroid and the two oxygen atoms from the two THF molecules form a distorted tetrahedral geometry around the metal.

关键词： Syntheses of C8H8)Pr C8H8)Ln C9H7 THF Nd

水资源税改革:基于河北省经验、成效的调研与思考

在线全文

学校读者我要写书评

暂无评论

税务研究 2024年第5期 88-93页

作者：李长春国家税务总局河北省税务局

我国水资源较为紧张,实施水资源税改革对于优化用水结构、恢复生态环境、缓解水资源严峻形势具有重要意义。2.16年7月1日,河北在全国率先实行水资源税改革试点。通过调研河北水资源税改革试点以来的经验做法发现,河北省水资源税改革试... 详细信息

我国水资源较为紧张,实施水资源税改革对于优化用水结构、恢复生态环境、缓解水资源严峻形势具有重要意义。2.16年7月1日,河北在全国率先实行水资源税改革试点。通过调研河北水资源税改革试点以来的经验做法发现,河北省水资源税改革试点取得了用水效率显著提升、地下水超采有效遏制、用水结构持续优化、水资源税收入明显增长等方面的成效。但是,水资源禀赋差异较大、税制设计有待优化、农村征缴极具难度、财政支出难以支撑是制约水资源税全面推广的重要因素。为进一步发挥好水资源税制度的作用,可从全面调研总结、分析评估精深化,合理统筹设计、税制体系科学化,紧密结合实际、税收政策灵活化,积极推进立法、各项规定标准化等四个方面进行完善,助力水资源税全面推广。

关键词：水资源税税收制度税制改革税收政策

The freeze-thaw metallogenic model of regenerated gold placers under cold low temperature conditions

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 1999年第S2期44卷 11-13页

作者： ZHANG Baolin~1, WANG Chunhe~2. WANG Jie~1 and SONG changchun~2.1. Institute of Geology and Geophysics, chinese academy of sciences, Beijing 10002., {2. 2. changchun Institute of Geography, chinese academy of sciences, changchun 13.02., {2. Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China changchun Institute of Geography Chinese Academy of Sciences Changchun 130021 China

LOCATED in the mined-out areas of primary gold placers, the regenerated gold placers in permafrost zonesare a kind of special low temperature deposit formed under modem cold climate conditions. Although theregeneration phenomenon was first discovered in South America, the scale and periodicity of the regeneration are more evident in permafrost environment of Northern Hemisphere.

关键词： regeneration gold placer freeze-thaw model.

BjuIR:A multi-omics database with various tools for accelerating functional genomics research in Brassica juncea

在线全文

学校读者我要写书评

暂无评论

Plant Communications 2024年第8期5卷 96-99页

作者： Linna Zhang Jinyuan Xiao Congyuan Liang Yifan Chen changchun Yu Xinle Zhao Jiawei Li Mingli Yan Qian Yang Hao Chen Zhongsong Liu Zhengjie Wan Zhiquan Yang Qing-Yong Yang National Key Laboratory for Germplasm Innovation and Utilization of Horticultural Crops College of InformaticsHuazhong Agricultural UniversityWuhan 430070China Hubei Key Laboratory of Agricultural Bioinformatics and Hubei Engineering Technology Research Center of Agricultural Big Data College of InformaticsHuazhong Agricultural UniversityWuhan 430070China National Key Laboratory of Crop Genetic Improvement Hubei Hongshan LaboratoryHuazhong Agricultural UniversityWuhan 430070China Yazhouwan National Laboratory Sanya 572025China National Key Laboratory for Germplasm Innovation and Utilization of Horticultural Crops College of Horticulture and Forestry SciencesHuazhong Agricultural UniversityWuhan 430070China Crop Research Institute Hunan Academy of Agricultural SciencesChangsha 410125China College of Agronomy Hunan Agricultural UniversityChangsha 410128China

Dear Editor,Advances in high-throughput omics technologies,along with methodologies for integrating multi-omics datasets,have substantially enhanced the efficiency of identifying candidate genes in breeding(Gusev et al.,2.18;Gupta et al.,2.19).However,this process is often complex and *** address this challenge,databases that integrate extensive data and enable convenient and efficient functional genomics studies are being developed(Ma et al.,2.2.;Yang et al.,2.2.).

关键词： functional integrating convenient

EXTRACTION KINETICS OF YTTRIUM WITH PURIFIED CYANEX 92. FROM NITRATE MEDIUM

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

Acta Metallurgica Sinica(English Letters) 2003年第6期16卷 428-432页

作者： H. Tong, Y.G. Wang, J.H. Lei, D.Q. Li, and P. TangDepartment of applied chemistry, Wuhan University of Technology, Wuhan 430070, {2. Key Laboratory of Rare Earth chemistry and Physics, changchun Institute of applied chemistry, The chinese academy of sciences, changchun 13.02., {2. Dept. of Appl. Chem. Wuhan Univ. of Technol. Wuhan 430070 China Lab. of Rare Earth Chem. and Phys. Changchun Inst. of Appl. Chem. Chinese Acad. of Sci. Changchun 130022 China

Mass transfer and extraction kinetics of yttrium with the purified Cyanex 92. in n-heptane from nitrate medium have been investigated by using a constant interfacial cell with laminar flow at 2.8K. The interfacial adsorption properties of purified Cyanex 92.-heptane-0.2.mol/L (H, Na)NO3 were studied at 2.8K. The experimental results show that the mass transfer is controlled by diffusion and the chemical reactions are carried out in the interfacial zone. The extraction rates of yttrium were measured at different chemical compositions by varying ionic strength, pH values and the purified Cyanex 92. concentrations. The initial extraction rate equations were obtained.

关键词： yttrium Cyanex 92. extraction kinetics interfacial tension