检索结果-南通市图书馆

Pressure-induced crystallite breaking in La_(0.7)Sr_(0.3)Mn_(0.9)Fe_(0.1)O_3 nanosolids

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 1998年第6期43卷 458-461页

作者： ZHENG Fanlei 1, 2. SUI Yu 1, 3, XU Dapeng 1 and SU Wenhui 1, 4 1. Department of physics, Jilin University, Changchun 13002., china 2. Changchun Institute of physics, chinese academy of sciences, Changchun 13002., china 3. Institute of Metal R Department of physics Jilin University Changchun Chinas Changchun Institute of physics Chinese Academy of Sciences Changchun China Institute of Metal Research Chinese Academy of Sciences Shenyang China international center for {2. physics Chinese Academy of Sceinces Shenyang China center for Condensed Matter and Radiation physics CCAST (World Lab.) Beijing China

In the compacting process of the La 0.7Sr 0.3Mn 0.9Fe 0.1O 3 nanosolids under the pressure range of 0.0-4.5 GPa, the apparent pressure-induced crystallite breaking phenomenon in these nanosolids was observed. With increasing pressure up to 4.5 GPa, the average grain size decreases by 46% while the magnetization of nanosolids decrease by 40% and their coercive increases by 35%. This kind of breaking has a close relation to the existence of oxygen deficiency in La 0.7Sr 0.3Mn 0.9Fe 0.1O 3 nanoparticles. A simple and convenient method for preparing the bulk nanosolids with a large number of clean interfaces has been suggested.

关键词： nanosolid pressure-induced breaking high pressure.

Synthesis and characterization of nanocrystalline Ni produced by cryomilling in liquid nitrogen

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2007年第2期26卷 147-151页

作者： YANG Bin FAN Jianzhong HAO Bin TIAN Xiaofeng CHENG Junsheng ZHANG Jishan State Key Laboratory for Advanced Metals and materials University of Science and Technology Beijing Beijing 100083 China international Centre for materials {2. Chinese Academy of Sciences Shenyang 110016 China National Engineering and Technology Research center for Nonferrous Metals Composites General Research Institute for Nonferrous Metals Beijing 100088 China

NanocrystaUine Ni powders were successfully fabricated by mechanically milling at cryogenic temperature （cryomilling） with 1 wt.%Y2.3 particles. The experimental results have shown that the Ni grain size is reduced to 2. nm after 2.h of cryomilling in the presence of the Y2.3 particles. The cryomiUed Ni/Y2.3 powders can maintain their nanocrystalline structure up to 900℃, or 62. of the melting point of Ni. A bulk nanocrystalline Ni/Y2.3 material with a thermally stable grain size of approximately 100 nm was produced by cryomilling, cold isostatic pressing, followed by hot isostatic pressing. The microhardness of bulk nanocrystalline Ni/1wt.%Y2.3 is 315 DPH, which is two times as high as that of conventional Ni.

关键词： nanocrystalline mechanical milling nickel characterization

Comparative study on the effect of integrin αvβ3 on secretion of matrix metalloproteinases in human normal and carcinoma trophoblasts

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:materials international 2005年第11期15卷 982-987页

作者： BAI Suxia, FU Yayuan, KONG Gang and WANG Yanling (State Key Laboratory of Reproductive Biology, Institute of Zoology, chinese academy of sciences, Beijing 100080, china The Second Hospital of {2. Medicine College, shenyang 110003, china) State Key Laboratory of Reproductive Biology Institute of Zoology Chinese Academy of Sciences Beijing 100080 China. The Second Hospital of chinese Medicine College Shenyang 110003 China

The invasion of cytotrophoblast cells into the maternal endometrium during embryonic implantation is very similar to the metastasis of carcinoma cells. However, the significant difference is that the former is a highly controlled process. In this report, the effects of integnn αvβ3 on the secretion of matrix metalloproteinase (MMP) were compared between normal cytotrophoblast cells and chorio-carcinoma cells by RT-PCR, gelatin zymography and immunocytochemistry. The results reveal that both normal cytotrophobiast cells and choriocarcinoma cells can express integrin αvβ3. The secretion of MMPs in normal cytotrophoblast cells is up-regulated by anti-αvβ3 antibody, whereas, decreased in choriocarcmoma cells. It was suggested that αvβ3 can modulate the expression of MMPs in trophoblasts, and this action is carried out through distinct mechanisms in normal and carcinoma cytotrophoblast cells.

关键词： cytotrophoblast cells choriocarcinoma cells integrfn αvβ3 matrix metalloproteinase.

Stabilization effects of third element on CaCu5 type derivatives of rare-earth transition-metal intermetallics

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 2002年第2期 3-12页

作者： LIANG Jingkui, LIU Quanlin, HUANG Feng, RAO Guanghui and CHEN Xiaolong( Institute of physics and center for Condensed Matter physics, chinese academy of sciences, Beijing 100080, china international center of Material physics, chinese academy of sciences, shenyang 110015, china)

Part of the results of the key project "Search for novel rare-earth functional materials" supported by the National Natural Science Foundation of china is reviewed. In combination with reports in literature, the effects of the third element M on the formation and stability of La2.Co, M)17, R(Fe, M)12.and R3(Fe, M)2. intermetallic compounds are discussed by considering mixing enthalpy of M with rare-earth, Fe and Co, and atomic radius, electronegativity and electronic configurations, etc. It is concluded that the mixing enthalpy and atomic radius dominate the preferential sites and the minimum amount of M required to stabilize a structure, which ultimately affect the magnetic properties of a compound prominently. This review should provide some heuristic hints for exploiting novel rare-earth transition metal functional materials and for improving their performance.

关键词： La2.Co M)17 R(Fe M)12 Rs(Fe M)2. crystal structure magnetic properties.

Diagnostic analysis of mesoscale rainstorms in the Jiang-Huai valley of china with convective vorticity vector

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 2007年第5期17卷 559-568页

作者： Cui Xiaopeng, Gao Shouting and Li Xiaofan (Laboratory of Cloud-Precipitation physics and Severe Storms (LACS), Institute of Atmospheric physics,{2., Beijing 10002., china Joint center for Satellite Data Assimilation and NOAA/NESDIS/center for Satellite Applications and Research, Camp Springs, Maryland, USA) [a]Laboratory of Cloud-Precipitation physics and Severe Storms (LACS) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China [b]Joint center for Satellite Data Assimilation and NOAA/NESDIS/center for Satellite Applications and ResearchCamp Springs Maryland USA

By the vector product of absolute vorticity vectors and equivalent potential temperature gradients, a new vector, convec-tive vorticity vector (CVV) is readdressed after Gao et al., and is applied to the study of the development and movement of mesoscale rainstorms in the Jiang-Huai valley of china by using high-resolution simulation data with PSU/NCAR MM5 briefly. The results show that the CVV, especially its vertical component which is closely related to interactions between vertical secondary circulations and horizontal equivalent potential temperature gradients, may be a good tracer and diagnostic tool in the study of mesoscale rainstorms in the Jiang-Huai valley of china. And the main physical processes responsible for the variations of the vertical component of the CVV are discussed briefly based on its tendency equation proposed in this article.

关键词： convective vorticity vector mesoscale rainstorms tendency equations.

A Model of Dynamic Recrystallization in Alloys during High Strain Plastic Deformation

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 materials Science & Technology 1999年第5期15卷 435-438页

作者： Qiang LI and Yongbo XU(State Key Laboratory for Fatigue and Fracture of materials, Institute of Metal Research, chinese academy of sciences,{2. 110015, china) To whom correspondence should be addressed Present address: Analysis Cener, School of Mater State Key Laboratory for Fatigue and Fracture of materials Institute of Metal Research Chinese Academy of Sciences Shenyang 110015 China Analysis Cener School of Materials Tianjin University Tianjin 300072 China international center of {2. physics Chinese Academy of Sciences Shenyang 110015 China Laboratory for Non-linear Mechanics of Continuous Media Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China

Recrystallized grains, less than 2.0 nm in diameter were observed in heavily shear zones of a high strength low alloy steel and a Ni-based alloy, and Also grain refinement, less than 3 μm in diameter was made in high purity aluminum by ECAE at ambient temperature. The experimental results showed that high strain rate and large deformation could induce dynamic *** on dislocation dynamics and grain orientation change enhanced by plastic deformation,a model for the recrystallization process is developed. The model is used to explain the ultra fine grains which are formed at a temperature still much lower than that for the conventional recrystallization

关键词： Figure A Model of Dynamic Recrystallization in Alloys during High Strain Plastic Deformation

Recent progress in fingerprint recognition

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:materials international 2006年第3期16卷 231-240页

作者： TIAN Jie, CHEN Xinjian, ZHANG Yangyang, YANG Xin, HE Yuliang, LI Liang, XIE Weihua and ZHENG Zhipeng (center for Biometrics and Security Research, Key Laboratory of Complex Systems and Intelligence Science, Institute of Automation, chinese academy of sciences, Beijing 100080,{2. Graduate School of the chinese academy of sciences, Beijing 100080,{2.) [a]center for Biometrics and Security Research Key Laboratory of Complex Systems and Intelligence Science Institute of Automation Chinese Academy of Sciences Beijing China [b]Graduate School of the chinese academy of sciences Beijing China

Fingerprint recognition has been increasingly used to realize personal identification in civilian' s daily life, such as ID card, fingerprints hard disk and so on. Great improvement has been achieved in the on-line fingerprint sensing technology and automatic fingerprint recognition algorithms. Various fingerprint recognition techniques, including fingerprint acquisition, classification, enhancement and matching, are highly improved. This paper overviews recent advances in fingerprint recognition and summarizes the algorithm proposed for every step with special focuses on the enhancement of low-quality fingerprints and the matching of the distorted fingerprint images. Both issues are believed to be significant and challenging tasks. In addition, we also discuss the common evaluation for the fingerprint recognition algorithm of the Fingerprint Verification Competition 2.04 (FVC2.04) and the Fingerprint Vendor Technology Evaluation 2.03 (FpVTE2.03), based on which we could measure the performance of the recognition algorithm objectively and uniformly.

关键词： biometrics fingerprint enhancement matching minutia image registration similarity measures.

Contribution of cloud condensate to surface rainfall process

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 2006年第9期16卷 967-973页

作者： ZHOU Yushu , GUI Xiaopeng and LI Xiaofan ( Institute of Atmospheric physics, chinese academy of sciences, Beijing 10002.,{2. Joint center for Satellite Data Assimilation and NOAA/NESDIS/Office of Research and Applications Camp Springs, Maryland, USA) [a]chinese academy of {2. Institute of Atmospheric Physics Beijing China [b]Joint center for Satellite Data Assimilation and NOAA/NESDIS/Office of Research and Applications Camp Springs Maryland USA

Contribution of cloud condensate to surface rainfall processes is investigated in a life span of tropical convection based on hourly data from a two-dimensional cloud resolving simulation. The model is forced by the large-scale vertical velocity, zonal wind and horizontal advections obtained from tropical ocean global atmosphere coupled ocean-atmosphere response experiment (TOGA COARE). The results show that during the genesis, development, and decay of tropical convection, calculations with water vapor overestimate surface rain rate, and cloud condensate plays an important role in correcting overestimation in surface rain rates. The analysis is carried out in deep convective clouds and anvil clouds during the development of tropical convection. The surface rain rates calculated with water vapor in deep convective clouds and anvil clouds have similar magnitudes, the large surface rain rate appears in deep convective clouds due to the consumption of water hydrometeors whereas the small surface rain rate occurs in anvil clouds because of the gain of ice hydrometeors. Further analysis of the grid data shows that the surface rain rates calculated with water vapor and with cloud condensate are negatively correlated with the correlation coefficient of - 0.85, and the surface rain rate calculated with cloud condensate is mainly contributed to the water hydrometeors in the tropical deep convective regime.

关键词： cloud condensate surface rain rate cloud resolving simulation.

Identification of weed species with hyperaccumulative characteristics of heavy metals

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 2004年第6期 33-41页

作者： WEI Shuhe 1,2.and ZHOU Qixing 1,2. *(1. Key Laboratory of Terrestrial Ecological Process,Institute of Applied Ecology,chinese academy of {2.,shenyang 110016,china 2. Graduate School of the chinese academy of sciences,Beijing 100039,china) Key Laboratory of Terrestrial Ecological Process Institute of Applied Ecology Chinese Academy of Sciences Shenyang 110016China Graduate School of the chinese academy of sciences Beijing 100039 China

In order to promote the effective and economic remediation of soils contaminated with single Cd and Cd combined with Pb,Cu and Zn,a field-screening study on weed hyperaccumulators was carried out on the basis of field pot-culture experiments used to determine characteristics of weed plants enduring and accumulating heavy metals. In this study,54 weed species belonging to 2. families from agricultural fields of the Shengyang suburbs were tested. The results showed that Taraxacum mongolicum,Solanum nigrum and Conyza canadensis could strongly tolerate single Cd and Cd-Pb-Cu-Zn combined pollution,had high Cd-accumulative ability,and generally possessed basic characteristics of hyperaccumulators. Because there are synergic and antagonistic effects among Cd,Pb,Cu and Zn,single-factor pollution tests should be done as well as combined pollution tests during the identification of hyperaccumulators to ensure the efficiency of phytoremediation and the practical significance of hyperaccumulators identified. The field pot-culture experiment should be a new tentative method to screen out accumulative and tolerant species in view of its obvious advantages such as simple operation,low cost,and easy identification of investigated plants.

关键词： contaminated soil phytoremediation hyperaccumulative characteristic weed heavy metal cadmium.