检索结果-南通市图书馆

Progress in Natural science:materials International 2005年第2期15卷 54-61页

作者： XIA Junhong 1,2, zheng Jinsong 1,2, XU Limei 1,2 and WANG ding1*(1. Institute of Hydrobiology, Chinese Academy of sciences, Wuhan 430072, china 2. Graduate school of the Chinese Academy of sciences, beijing 100039, china) Inst. of Hydrobiology Chinese Acad. of Sciences Wuhan 430072 China Graduate Sch. Chinese Acad. of Sciences Beijing 100039 China

Reproductive behaviors are poorly known for the Yangtze finless porpoise Neophocaena phocaenoides asiaeorientalis. In this study, the parentage of an isolated Yangtze finless porpoise population inhabiting the Yangtze Tian-e-Zhou Baiji National Natural Reserve is determined by analysis of microsatellite loci and mitochondrial DNA (mtDNA) control region sequences, and the porpoise's reproductive behaviors are studied. Overall 4 full parentage assignments and additional 3 single parentage assignments were determined for the population of 23 individuals. The analysis shows that their estimated reproductive cycle is shorter than that reported previously and there probably exists an overlapping between gestation and lactation period. The study also shows that the female does not show fidelity to a particular male for breeding and vice versa, the oldest males did not monopolize mating and the dominance rank could not be so strict for the porpoise society. Moreover, the porpoise's mating pattern and relatedness among candidate parents are discussed here. These results provide important information for making guidelines of management and conservation for this protected population.

关键词： Yangtze finless porpoise isolated population reproductive behavior parentage

Process optimization of reaction of acid leaching residue of asbestos tailing and sodium hydroxide aqueous solution

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

中国科学:技术科学 2010年第4期 462-462页

作者： du gaoxiang 1,3,zheng shuilin 2 & ding hao 1 1 school of materials science and technology,china university of geosciences(beijing),beijing,100083,china 2 school of Chemical and Environment Engineering,china university of Mining and technology(beijing),beijing 100083,china 3 Hebei Qinghe Refractory Group Co.Ltd.,Xingtai 054804,china

Silica is the major component of the acid leaching residue of asbestos *** waterglass solution can be prepared by the reaction of the residue with sodium hydroxide aqueous *** to the high temperature reaction method,this process is environmental friendly and low *** this paper,the reaction process of the residue and the sodium hydroxide aqueous solution is *** optimum reaction process parameters are as follows:the usage of sodium hydroxide is 26.4 g/100 g acid leaching residue,the reaction temperature is 90℃,the reaction time is 1 h,and the ratio of the liquid/solid is *** significance sequence of the process parameters to the alkali leaching reaction effect is the usage of sodium hydroxide>the ratio of the liquid/solid>the reaction time>the reaction *** significance sequence to the leaching ratio of SiO2 is the ratio of the liquid/solid>the usage of sodium hydroxide>the reaction time>the reaction *** significance sequence to the modulus of the sodium silicate is the ratio of the liquid/solid>the usage of sodium hydroxide>the reaction time>the reaction *** the optimum conditions,the leaching ratio of the SiO2 is 77.5%,and the modulus of the sodium silicate is *** XRD analysis result indicates that the major components of the alkali leaching residue are serpentine,talc,quartz and some albite.

关键词： asbestos tailing acid leaching residue sodium hydroxide process optimization

Preparation and Enhanced Daylight-Induced Photo-Catalytic Activity of Transparent C-Doped TiO_2 Thin Films

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Wuhan university of technology(materials science) 2010年第5期25卷 738-742页

作者：白爱英 College of materials science and Engineering Taiyuan University of Technology Xin Zhou Vocational Technical College

The transparent C-doped TiO2 nanostructure films were fabricated on the silicate glass substrates by sol-gel spin-coated method. The as-prepared films were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, UV-visible absorption spectra （UV-vis） and X-ray photoelectron spectroscopy （XPS）. The photocatalytic activity was evaluated via the photocatalytic oxidation of methylene blue in aqueous under daylight irradiation at room temperature. The results show that the daylight-induced photocatalytic activities of the as-prepared films are improved by the C-doping. The calcination temperatures significantly affect the morphology, microstructure and photocatalytic activity of the as-prepared samples. At 723 K, the C-doped TiO2 films exhibit the highest photocatalytic activity due to the synergetic effects of good crystallization, appropriate oxygen vacancies and strong absorption in the near UV and visible-light region.

关键词： C-doped TiO2 films daylight-induced photocatalytic activity spin-coated

维普期刊数据库

The influence of impurity on the critical thickness of the CeO_2 buffer layer for coated conductors

在线全文

学校读者我要写书评

暂无评论

science china(Physics,Mechanics & Astronomy) 2009年第7期52卷 993-996页

作者： PAN Min1, HUANG zheng2, MA HuanFeng2, QIANG WeiRong2, WEI LianFu1, WANG Long2 & Zhao Yong1,3 1 Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of china), Superconductivity R&D Center (SRDC), Southwest Jiaotong university, Chengdu 610031, china 2 school of Physical science and technology, Southwest Jiaotong university, Chengdu 610031, china 3 Superconductivity Research Group, school of materials science and Engineering, university of New South Wale, Sydney, 2052 NSW, Australia Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of china) Superconductivity R&D Center (SRDC) Southwest Jiaotong University Chengdu China school of Physical science and technology Southwest Jiaotong University Chengdu China Superconductivity Research Group School of Materials Science and Engineering University of New South Wale Sydney Australia

The lattice parameters, band structure, density of state and elastic constant of RE-doped CeO2 (RE=Sm, Gd, Dy), the buffer material for coated HTS conductors, are calculated using the plane-wave method with pseudopotentials based on the density functional theory (DFT) of first-principle. The rule and mechanism of the effect of rare earth impurity on the critical thickness of the CeO2 buffer layer are investigated. It is found that, in the range of the calculation, the changes of the lattice volume V and elastic constant E of CeO2 with the impurity are mainly determined by the increased electrons ne of the system. The relationship of the elastic constant E and increased electrons ne is established. It is indicated that the critical thickness of the CeO2 single buffer layer doped with Sm, Gd, and Dy may be enhanced by 22%, 43% and 33%, respectively.

关键词： CeO2 first principle critical thickness elastic constants

维普期刊数据库

Biomineralization of soil with crude soybean urease using different calcium salts

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2024年第5期16卷 1788-1798页

作者： Yajie Weng Junjie zheng Hanjiang Lai Mingjuan Cui Xingzhi ding school of Civil and Hydraulic Engineering Huazhong University of Science and TechnologyWuhan430074China Zijin school of Geology and Mining Fuzhou UniversityFuzhou350108China College of Civil Engineering Fuzhou UniversityFuzhou350116China

Calcium salt is an important contributing factor for calcium-based *** study the effect of calcium salt on soil biomineralization using crude soybean urease,the calcium salts,including the calcium chloride (CaCl_(2)),calcium acetate ((CH_(3)COO)_(2)Ca) and calcium nitrate (Ca(NO_(3))_(2)),were used to prepare the biotreatment solution to carry out the biomineralization tests in this *** series of biomineralization tests in solution and sand column,respectively,were *** electron microscopy (SEM) and X-ray diffraction (XRD) were performed to determine the microscopic characteristics of the precipitated calcium carbonate (CaCO_(3)) *** experimental results indicate that the biomineralization effect is the best for the CaCl2 case,followed by (CH_(3)COO)_(2)Ca,and worst for Ca(NO_(3))_(2) under the test conditions of this study (i.e.1 mol/L of calcium salt-urea).The mechanism for the effect of the calcium salt on the biomineralization of crude soybean urease mainly involves: (1) inhibition of urease activity,and (2) influence on the crystal size and morphology of CaCO_(3).Besides Ca^(2+) ,the anions in solution can inhibit the activity of crude soybean urease,and NO_(3)− has a stronger inhibitory effect on the urease activity compared with both CH_(3)COO^(−) and Cl^(−) .The co-inhibition of Ca^(2+) and NO_(3)− on the activity of urease is the key reason for the worst biomineralization of the Ca(NO_(3))_(2) case in this *** difference in biomineralization between the CaCl_(2) and (CH_(3)COO)_(2) Ca cases is strongly correlated with the crystal morphology of the precipitated CaCO_(3).

关键词： Biomineralization Crude soybean urease Calcium salt Influence mechanism

Identification and Categorization of Horizontally Transferred Genes in Prokaryotic Genomes

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 Biochimica et Biophysica Sinica 2005年第8期37卷 561-566页

作者： Shuo-Yong SHI~1 Xiao-Hui CAI~1 and Da-fu ding~(1,2*) Key Laboratory of Proteomics.Institute of Biochemistry and Cell Biology.Shanghai Institutes for Biological sciences,Chinese Academy of sciences,Graduate school of the Chinese Academy of sciences.Shanghai 200031,china ~2 school of Life science & technology.Shanghai Jiaotong university.Shanghai 200030.china Key Laboratory of Proteomics Institute of Biochemistry and Cell Biology Shanghai Institutes for Biological Sciences Chinese Academy of Sciences Graduate School of the Chinese Academy of SciencesShanghai 200031 China school of Life science & technology Shanghai Jiaotong UniversityShanghai 200030 China

Horizontal gene transfer(HGT),a process through which genomes acquire genetic materialsfrom distantly related organisms,is believed to be one of the major forces in prokaryotic genome ***,systematic investigation is still scarce to clarify two basic issues about HGT:(1) what types ofgenes are transferred:and(2)what influence HGT events over the organization and evolution of ***-scale investigations of these two issues will advance the systematical understanding ofHGT in the context of prokaryotic genome *** investigated 82 genomes,we constructed anHGT database across broad evolutionary *** identified four function categories containing a highproportion of horizontally transferred genes:cell envelope,energy metabolism,regulatory functions,andtransport/binding *** biased function distribution indicates that HGT is not completely random;instead,it is under high selective pressure,required by function restraints in ***,wemapped the transferred genes onto the connectivity structure map of organism-specific pathways listed inKyoto Encyclopedia of Genes and Genomes(KEGG).Our results suggest that recruitment of transferredgenes into pathways is also selectively constrained because of the tuned interaction between original *** organization structures still conserve well through evolution even with the recruitment ofhorizontally transferred ***,in pathways whose organization were significantly affected byHGT events,the operon-like arrangement of transferred genes was found to be *** resultssuggest that operon plays an essential and directional role in the integration of alien genes into pathways.

关键词： genome evolution horizontal gene transfer function and pathway analysis

Effect of Aging on Fracture Toughness and Stress Corrosion Cracking Resistance of Forged 7475 Aluminum Alloy

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Wuhan university of technology(materials science) 2007年第2期22卷 191-195页

作者：李红英 school of materials science and Engineering Central South University

The effects of two-stage aging and retrogression and reaging heat treatment on the fracture toughness and stress corrosion cracking resistance of 7475 alloy were studied. The fracture toughness, conductivity and strength of samples of nine groups under duplex aging conditions and three retrogression and reaging heat treatments were also measured. Incorporating the microstructure and property, we found that when the condition of the first order aging kept identical, the fracture toughness and stress corrosion cracking resistance increase with aging time and the second aging temperature. The optimal treatment conditions are （ 115℃×7h ＋ 185 ℃×13h） among all tested two-stage aging treatments. Although the 7475 alloy treated by RRA method shows the highest strength and its stress corrosion cracking resistance after twenty minutes retrogression can also reach the same level as those by the optimal treatment of （115℃×7h＋ 185℃×13h ）, the fracture toughness is even low.

关键词： 7475 alloy two-stage aging heat treatment RRA treatment fracture toughness stress corrosion

维普期刊数据库

Highly sensitive flexible strain sensor based on the two-dimensional semiconductor tellurium with a negative gauge factor

在线全文

学校读者我要写书评

暂无评论

science china(Information sciences) 2024年第7期67卷 295-304页

作者： Jiarui HE Yusong QU Shengyao CHEN Cong WANG Lena du Xiaoshan du Yuanyuan zheng Guozhong Zhao He TIAN College of Mathematics and Physics Beijing University of Chemical Technology school of Integrated Circuits Tsinghua University Beijing China & The Beijing National Research Center for Information Science and Technology (BNRist)Tsinghua University CAS Center for Excellence in Nanoscience National Center for Nanoscience and Technology &University of Chinese Academy of Sciences beijing Key Lab of Terahertz Spectroscopy and Imaging Key Lab of Terahertz OptoelectronicsMinistry of Education Department of Physics Capital Normal University

Research on flexible strain sensors has advanced rapidly in recent years, with particular attention being devoted to two-dimensional(2D) semiconductor materials owing to their exceptional mechanical and electrical properties that are conducive to sophisticated sensing performance. However, resistive strain sensors based on 2D semiconductor materials typically exhibit positive gauge factors(GF), while materials for strain sensors with a negative GF remain elusive. We have identified a trend of reduction in the band gap of the emerging 2D semiconductor material tellurium(Te) under strain in simulations reported in past research,and have observed a negative GF in the Te-based strain sensor. In this study, we combined Te with a flexible polyethylene terephthalate(PET) substrate to manufacture a flexible strain sensor with a significantly negative GF. The results of tests revealed that the Te-based strain sensor achieved an impressive maximum sensitivity of-139.7 within a small range of bending-induced strain(< 1%). Furthermore, it exhibited excellent linearity and good cyclic stability, and was successfully applied to monitor limb movements. The work here verifies the significant potential for the use of Te-based strain sensors in next-generation flexible electronics.

关键词： 2D semiconductor materials 2D tellurium flexibleelectronics strain sensors negative gauge factor high sensitivity

The precipitation strengthening behavior of Cu-rich phase in Nb contained advanced Fe-Cr-Ni type austenitic heat resistant steel for USC power plant application

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural science:materials International 2012年第3期22卷 175-185页

作者： Cheng-yu Chi a, Hong-yao Yu b, Jian-xin Dong b, Wen-qing Liu c, Shi-chang Cheng d, zheng-dong Liu d, Xi-shan Xie b a school of Metallurgical and Ecological Engineering, university of science & technology beijing, beijing 100083, china b school of materials science and Engineering, university of science & technology beijing, beijing 100083, china c Instrumental Analysis & Research Center, Shanghai university, Shanghai 200444, china d Central Iron and Steel Research Institute, beijing 100081, china school of Metallurgical and Ecological Engineering University of Science & Technology Beijing Beijing 100083 China school of materials science and Engineering University of Science & Technology Beijing Beijing 100083 China Instrumental Analysis & Research Center Shanghai University Shanghai 200444 China Central Iron and Steel Research Institute Beijing 100081 China

Copper has been used as a strengthening element in newly developed Fe-Cr-Ni type austenitic heat resistant steel for inducing Cu-rich phase precipitation to meet high temperature strength requirement for 600 ℃ Ultra Super-Critical (USC) coal fired power plants for many years. However, the precipitation behavior and strengthening mechanism of Cu-rich phase in these advanced austenitic heat resistant steels is still unclear. In order to understand the precipitation strengthening behavior of Cu-rich phase and to promote high strength austenitic heat resistant steel development, 18 Cr9 NiCuNb steel which is a Cu-added Nb contained advanced Fe-Cr-Ni type austenitic heat resistant steel has been selected for this study to be aged at 650 ℃ till to 10,000 h. Micro-hardness and room temperature tensile test were conducted after long-time aging. SEM, TEM, HRTEM and three dimensional atom probe (3DAP) technology accompanying with thermodynamic calculation have been used to investigate the Cu-rich phase precipitation behavior during 650 ℃ aging. The experimental results showed that Cu atoms can quickly concentrate in clusters at very early precipitation stage to form the fine nano-size Cu-rich "segregation areas" within less than 1 h at 650 ℃. With increasing aging time at 650 ℃ Cu atoms continuously concentrate to Cu-rich segregation areas (clusters) and simultaneously other kinds of atoms such as Fe, Cr and Ni diffuse away from Cu-rich segregation areas to austenitic matrix, and finally to complete the transformation from Cu-rich segregation areas to Cu-rich phase. However, there is only Cu atoms concentration but not crystallographic transformation from early stage of Cu-rich clusters forming to the final Cu-rich phase formation. Even the Cu atom becomes the main composed element after 500 h aging at 650 ℃ the Cu-rich phase still keeps coherent relationship with austenitic matrix. According the experimental results in this study, Cu-rich phase precipitation sequence which st

关键词： USC power plant Austenitic heat resistant steel Microstructure Cu-rich phase TEM 3DAP

Nuclear reprogramming: the strategy used in normal development is also used in somatic cell nuclear transfer and parthenogenesis

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Cell Research 2007年第2期17卷 135-150页

作者： Tianlong Gao~(1,*) Junke zheng~(2,*) Fengying Xing~(2,*) Haiyan Fang~2 Feng Sun~1 Ayong Yan~2 Xun Gong~2 Hui ding~3 Fan Tang~2 Hui Z Sheng~2 ~1Program for Graduation Studies,Shanghai Institutes for Biological sciences,Chinese Academy of sciences,Shanghai 200031,china ~2Center for Developmental Biology,Xinhua Hospital,Shanghai Jiao Tong university,school of Medicine,1665 Kong Jiang Road,Shanghai 200092,china ~3school of Animal science and technology,Yangzhou university,Yangzhou 225009,china Program for Graduation Studies Shanghai Institutes for Biological Sciences Chinese Academy of Sciences Shanghai China Center for Developmental Biology Xinhua Hospital Shanghai Jiao Tong University School of Medicine Shanghai China school of Animal science and technology Yangzhou University Yangzhou China

Somatic cell nuclear transfer(SCNT)and parthenogenesis are alternative forms of reproduction and development,building new life cycles on differentiated somatic cell nuclei and duplicated maternal chromatin,*** thepreceding paper(Sun F,et al.,Cell Res 2007;17:117-134.),we showed that an"erase-and-rebuild"strategy is used innormal development to transform the maternal gene expression profile to a zygotic ***,we investigate if the samestrategy also applies to SCNT and *** relationship between chromatin and chromatin factors(CFs)during SCNT and parthenogenesis was examined using immunochemical and GFP-fusion protein *** fromthese studies indicated that soon after nuclear transfer,a majority of CFs dissociated from somatic nuclei and were re-distributed to the cytoplasm of the *** erasure process in oogenesis is recaptured during the initial phase in *** CFs entered pseudo-pronuclei shortly after their *** parthenogenesis,all parthenogenotes underwentnormal oogenesis,and thus had removed most CFs from chromosomes before the initiation of *** CFswere subsequently re-associated with female pronuclei in time and sequence similar to that in fertilized *** these data,we conclude that the"erase-and-rebuild"process observed in normal development also occurs in SCNTand in parthenogenesis,albeit in altered *** process is responsible for transcription reprogramming in ***"erase"process in SCNT is compressed and the efficiency is compromised,which likely contribute tothe developmental defects often observed in nuclear transfer(nt)***,results from this study indicatedthat the cytoplasm of an egg contains most,if not all,essential components for assembling the zygotic program and canassemble them onto appropriate diploid chromatin of distinct origins.

关键词： nuclear reprogramming SCNT parthenogenesis chromatin factors chromatin embryogenesis