检索结果-南通市图书馆

Study of Survival Probability of Super Heavy Nuclei

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2003年第2X期40卷 199-202页

作者： WANGNan ZHAOEn-Guang LIWen-Fei lijian-Feng XUHu-Shan ZUOWei LIJun-Qing InstituteofTheoreticalPhysics theChineseAcademyofSciencesBeijing100080China InstituteofModernPhysics theChineseAcademyofSciencesLanzhou730000China CenterofTheoreticalNuclearPhysics NationalLaboratoryofHeavyIonAcceleratorLanzhou730000China

The survival probability of super heavy nuclei produced in cold fusion reactions is studied by using the standard Fermi gas level density formula and analyzed with fission and neutron evaporation characteristics predicted in different theoretical models. The level density formula used in this letter suppresses the ratio of neutron emission width to fission width, Гn/Гf. The dependence of Гn/Гf on the saddle point level density parameter and excitation energy is also investigated.

关键词：超重原子核超重元素幸存可能性裂变宽度中子发射宽度

Sea ice thickness analyses for the Bohai Sea using MODIS thermal infrared imagery

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 Oceanologica Sinica 2016年第7期35卷 96-104页

作者： ZENG Tao SHI lijian MARKO Makynen CHENG Bin ZOU Juhong ZHANG Zhiping National Satellite Ocean Application Service State Oceanic AdministrationBeijing 100081China Key Laboratory of Space Ocean Remote Sensing and Application State Oceanic AdministrationBeijing 100081 China Finnish Meteorological Institute Helsinki FI-00101Finland

Level ice thickness distribution pattern in the Bohai Sea in the winter of 2009-2010 was investigated in this paper using MODIS night-time thermal infrared imagery. The cloud cover in the imagery was masked out manually. Level ice thickness was calculated using MODIS ice surface temperature and an ice surface heat balance equation. Weather forcing data was from the European Centre for Medium-Range Weather Forecasts （ECMWF） analyses. The retrieved ice thickness agreed reasonable well with in situ observations from two off-shore oil platforms. The overall bias and the root mean square error of the MODIS ice thickness are -1.4 cm and 3.9 cm, respectively. The MODIS results under cold conditions （air temperature 〈 -10~C） also agree with the estimated ice growth from Lebedev and Zubov models. The MODIS ice thickness is sensitive to the changes of the sea ice and air temperature, in particular when the sea ice is relatively thin. It is less sensitive to the wind speed. Our method is feasible for the Bohai Sea operational ice thickness analyses during cold freezing seasons.

关键词： sea ice thickness MODIS Bohai Sea ice surface temperature thermal infrared

Synthesis and Characterization of AlPO_4-11 and MAPO-11 Single Crystals

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2004年第2期20卷 131-133页

作者： lijian-jun LIGuo-dong XIChun-yu GUOYing CHENJie-shengt StateKeyLaboratoryofInorganicSynthesisandPreparativeChemistry CollegeofChemistry，JilinUniversityChangchun130023

The preparation of two types of molecular sieves AlPO 4-11 and MAPO-11 is reported. The particle size of the latter is hundreds of microns, about 10 times larger than that of the former. The XRD, IR and DTA spectra have demonstrated that magnesium has been introduced into the framework of AlPO 4-11. The successful preparation of large single crystal of MAPO-11 will open up a new area for the preparation of large molecular sieves crystals in the future. The large MAPO-11 crystal compound is a promising host for the host-guest assembly of composite materials.

关键词： Single crystal MAPO-11 Molecular sieve Host-guest

Properties and Application of Iron-based Shape Memory Alloy

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2005年第2期2卷 69-73页

作者： lijian-chen JiangQing DaiJun KeyLaboratoryofAutomobileMaterials（MinistryofEducation China）JilinUniversityChangchun130022P.R.China ChangchunInstituteofProductQualityInspectionandSupervision Changchun130012P.R.China

The properties of FeMnSiCrNi shape memory alloy were investigated. The results show that the best shape memory effect of Fe14Mn6Si9Cr5Ni alloy is 85%. The transformation amount of the ε→γ transformation is not complete after heating the alloy to 1000 K, As and Af points drop with increased transformation enthalpy (ΔH γ→ε ) by thermal cycling and increased prestrain. The alloy shows also good creep and stress relaxation resistance. In addition, the alloy having a tensile force of 20 kN and a sealing pressure of 6 MPa can satisfy requirements for possible industrial application on pipe joints.

关键词： composite materials Iron-based shape memory alloy shape memory effect application

Effects of Additives on Structure and Properties of Synthesized Cordierite

在线全文

学校读者我要写书评

暂无评论

China's Refractories 2014年第3期23卷 11-14页

作者： MA lijian XU Delong YANG Pan Xi'an University of Architecture and Technology Xi'an 710055 China Hua Qing College Xi'an University of Architecture and Technology Xi'an 710043 China

Cordierite was synthesized using fly ash,sintered magnesia and silica fume as starting materials,ZrO2 and CaF2as additives,drying at（110 ± 5） ℃ for 24 h,and then firing at 1 290 ℃ for 3 h. Effects of type and addition of additives on structure and properties of synthesized cordierite were researched. The compressive strength, water absorption and apparent porosity,shrinkage rate,and bulk density of the specimens were measured,the phase composition was analyzed by XRD,and the specimens were observed by SEM. The results show that：（1） cordierite can be successfully synthesized using fly ash,sintered magnesia and silica fume;（2）CaF2facilitates the sintering,enhancing bulk density and shrinkage rate, but reducing the compressive strength; ZrO2 can promote cordierite synthesis,compacting the structure and increasing the compressive strength;（3） when the ZrO2 addition is 2 mass%,the main crystal phases are hexagonal α-cordierite and orthorhombic β-cordierite,the crystals grow well,and the amount of synthesized cordierite is the highest.

关键词： fly ash cordierite zirconia calciumfluoride

Recent progress on all-small molecule organic solar cells using small-molecule nonfullerene acceptors

在线全文

学校读者我要写书评

暂无评论

InfoMat 2021年第2期3卷 175-200页

作者： Bin Kan Yuanyuan Kan lijian Zuo Xueliang Shi Ke Gao Department of Materials Science and Engineering University of WashingtonSeattleWashington

Recently,solution-processed organic solar cells combining small-molecule donor and nonfullerene acceptor have achieved breakthrough results with the certified efficiency over 15%.These impressive progresses are driven by the concerted efforts of modifying the donor and acceptor materials and optimizing the *** the defined chemical structures and easily tuned properties of small-molecule materials,it is of great necessity and importance to pay more attentions on the topic of all-small molecule organic solar ***,we summarize the recent progress of all-small molecule organic solar cells from the prospect of materials'evolutions and expect to provide some hints for its future *** involved small-molecule donors including oligothiophene-,benzodithiophene-,naphthodithiophene-,and porphyrin-based materials are discussed to illustrate the relationship of chemical structures,properties,and device ***,the small-molecule nonfullerene acceptors in all-small molecules organic solar cells are discussed to highlight their vital ***,we will present the challenges and future of this research area.

关键词： all-small molecule organic solar cells high-performance nonfullerene acceptors small-molecule donors

Sunlight-activated AlFeO_3/TiO_2 photocatalyst

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

Science China Chemistry 2006年第1期49卷 67-74页

作者： YUAN Zhihao WANG Yuhong SUN Yongchang WANG Jing BIE lijian DUAN Yueqing Nanomaterials & Nanotechnology Research Center School of Materials Science & Engineering Tianjin University of Technology Tianjin 300191 China Nanomaterials & Nanotechnology Research Center School of Materials Science & Engineering Tianjin University of Technology Tianjin 300191 China Nanomaterials & Nanotechnology Research Center School of Materials Science & Engineering Tianjin University of Technology Tianjin 300191 China Nanomaterials & Nanotechnology Research Center School of Materials Science & Engineering Tianjin University of Technology Tianjin 300191 China Nanomaterials & Nanotechnology Research Center School of Materials Science & Engineering Tianjin University of Technology Tianjin 300191 China Nanomaterials & Nanotechnology Research Center School of Materials Science & Engineering Tianjin University of Technology Tianjin 300191 China

A nanocomposite photocatalyst composed of AlFeO3 and TiO2 is prepared, and charac-terized through X-ray diffraction. Application of the nanocomposite for the photodegradations of eosin dye and methyl orange gives an improved photoactivity compared with TiO2-only nanomaterials. The optimal concentration of AlFeO3 in the composite is about 1.0 wt% under UV excitation, and 9.0 wt% under sunlight excitation for the improved photoactivity. Furthermore, this nanocomposite is more active for eosin photodegradation if natural sunlight rather than UV is used. This may be due to the reason that adding AlFeO3 nanoparticles into TiO2 matrix can promote the separation of photogener-ated charge carriers, and extend the photoresponse of TiO2 toward visible region, which results in an increase in the solar energy utilization efficiency.

关键词： nanocomposite, photocatalysis, titania, aluminum ferrite.

Pre-existing chromatin accessibility of switchable repressive compartment delineates cell plasticity

在线全文

学校读者我要写书评

暂无评论

National Science Review 2022年第6期9卷 100-113页

作者： Xiaolong Ma Xuan Cao Linying Zhu Ying Li Xuelong Wang Baihua Wu Gang Wei lijian Hui State Key Laboratory of Cell Biology Shanghai Institute of Biochemistry and Cell Biology Center for Excellence in Molecular Cell Science Chinese Academy of Sciences School of Life Science and Technology Shanghai Tech University School of Life Science Hangzhou Institute for Advanced Study University of Chinese Academy of Sciences University of Chinese Academy of Sciences Bio-Research Innovation Center Shanghai Institute of Biochemistry and Cell Biology Institute for Stem Cell and Regeneration Chinese Academy of Sciences CAS Key Laboratory of Computational Biology Shanghai Institute of Nutrition and Health Chinese Academy of SciencesUniversity of Chinese Academy of Sciences

Cell plasticity endows differentiated cells with competence to be reprogrammed to other lineages. Although extrinsic factors driving cell-identity conversion have been extensively characterized, it remains elusive which intrinsic epigenetic attributes, including high-order chromatin organization, delineate cell *** analysing the transcription-factor-induced transdifferentiation from fibroblasts to hepatocytes, we uncovered contiguous compartment-switchable regions(CSRs) as a unique chromatin unit. Specifically,compartment B-to-A CSRs, enriched with hepatic genes, possessed a mosaic status of inactive chromatin and pre-existing and continuous accessibility in fibroblasts. Pre-existing accessibility enhanced the binding of inducible factor Foxa3, which triggered epigenetic activation and chromatin interaction as well as hepatic gene expression. Notably, these changes were restrained within B-to-A CSR boundaries that were defined by CTCF occupancy. Moreover, such chromatin organization and mosaic status were detectable in different cell types and involved in multiple reprogramming processes, suggesting an intrinsic chromatin attribute in understanding cell plasticity.

关键词： cell plasticity intrinsic properties compartment-switchable regions mosaic status pre-existing accessibility hepatic transdifferentiation

Concept Association and Hierarchical Hamming Clustering Model in Text Classification

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural Sciences 2004年第3期9卷 339-342页

作者： SuGui-yang lijian-hua MaYing-hua LiSheng-hong YinZhong-hang SchoolofElectronicEngineering ShanghaiJiaotongUniversityShanghai200030China

We propose two models in this paper. The concept of association model is put forward to obtain the co-occurrence relationships among keywords in the documents and the hierarchical Hamming clustering model is used to reduce the dimensionality of the category feature vector space which can solve the problem of the extremely high dimensionality of the documents' feature space. The results of experiment indicate that it can obtain the co-occurrence relations among key-words in the documents which promote the recall of classification system effectively. The hierarchical Hamming clustering model can reduce the dimensionality of the category feature vector efficiently, the size of the vector space is only about 10% of the primary dimensionality. Key words text classification - concept association - hierarchical clustering - hamming clustering CLC number TN 915. 08 Foundation item: Supporteded by the National 863 Project of China (2001AA142160, 2002AA145090)Biography: Su Gui-yang (1974-), male, Ph. D candidate, research direction: information filter and text classification.

关键词： text classification concept association hierarchical clustering hamming clustering