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    题名 作者 年代 出处 被引量
1The compositions,sources,and size distribution of the dust storm from China in spring of 2000 and its impact on the global environment显示文摘The average mass concentration of the aerosols in Beijing during the dust storm in the spring of 2000 was -6000 μg · m-3, -30 times as high as that in the non-dust storm days. The enrichment factors of the pollution elements As, Sb and Se were higher than those in the non-dust storm days. This indicated that As, Sb and Se resulted from the pollution sources of those areas, through which the dust storm passed during their long-range transport, in addition to the local pollution sources in Beijing. The enrichment factors of the Pb, Zn, Cd and Cu were much less than those in the non-dust storm days, suggesting that the local pollution sources in Beijing area contributed to them mostly. The enrichment factors of elements Al, Fe, Sc, Mn, Na, Ni, Cr, V and Co were close to 1, showing that these elements originated from crust. The concentration of S in the dust storm was -10 μg · m-3,4 times as high as that in non-dust storm. S in the aerosols resulted from the adsorption of gaseous SO2 and the consequentGuoshun Zhuang Jinghua Guo Hui Yuan Chengyi Zhao 2001Chinese Science Bulletin2001,46,11:44
2A laboratory test of the electrification phenomenon in wind-blown sand flux显示文摘The measured data in the wind-tunnel tests show that the wind-blown sand particles acquired a negative charge when their diameters are smaller than 250 μm and positive charge when their diameters are larger than 500 μm, which confirms Latham’s assumption that the large particles in wind-blown sand flux acquired positive charge while negative charge developed on small ones. In the meanwhile, the measured data also show that the average charge-to-mass ratio for wind-blown sand particles decreases with the increase of the particle diameter and the wind velocity, and increases with the rise of height. The electric field in wind-blown sand flux is mainly formed by the moving charged sand particles. Its direction is vertical to the Earth’s surface and upward, which is opposite to that of the fair-weather field. The electric field increases with wind velocity and height increasing. These experimental results will lay the foundation for developing the theoretical analysis of the electrification phenomenon inNing Huang Xiaojing Zheng 2001Chinese Science Bulletin2001,46,5:16
3Recent progress on ULF wave and its interactions with energetic particles in the inner magnetosphere显示文摘The global distribution properties of Ultra Low Frequency wave (ULF) in the inner magnetospgere and its interactions with energetic particles, such as the wave-particle resonance, modulation, and particle acceleration, are active topics in space physics research. These problems are fundamentally important issues to understand the energy transport from the solar wind into the magnetosphere. In this paper we briefly reviewed the recent research progress on ULF wave and its interactions with energetic particles in the inner magnetosphere; furthermore, we suggested some open questions for future study.Theodore A. FRITZ 2008Science China(Technological Sciences)2008,51,10:16
4Experimental observation of the nano-scale particles in geogas matters and its geological significance显示文摘The geogas collectors showing a geogas anomaly in field geogas prospecting and in simulation tests were selected for the observation under high resolution microscopy. The result demonstrates that the geogas matter is transported in the form of nano scale particles with a size of about \%N\% nm to \%N\%·10 nm, and accumulated into aggregations of 1\2 μm to \%N\%·10 μm, with globular and film shape, and the component of Cu, Zn, Cr, Au, Al, V, Si, Br, Cl, S, Ca, etc. Based on the knowledge of nano science and technique, the mechanism of the geogas prospecting and its significance in geology and mineral prospecting are discussed.童纯菡 李巨初 葛良全 杨凤根 1998Science China Earth Sciences1998,41,3:15
5A random walk with a branching system in random environments显示文摘We consider a branching random walk in random environments, where the particles are reproduced as a branching process with a random environment (in time), and move independently as a random walk on Z with a random environment (in locations). We obtain the asymptotic properties on the position of the rightmost particle at time n, revealing a phase transition phenomenon of the system.Ying-qiu LI Xu LI Quan-sheng LIU 2007Science China Mathematics2007,50,5:13
63DPMD-Arc-based additive manufacturing with titanium powder as raw material显示文摘The study aims to demonstrate the suitability of the 3DPMD for the production of titanium components with and without reinforcing particles in layer-by-layer design. Various demonstrators are prepared and analyzed. The microstructure, the porosity and the hardness values of the different structures are compared with each other through metallographic cross-sections. The uniform distribution of the carbides and the interaction with the matrix was analyzed by SEM and EDX.The miller-test method(ASTM G75-07) was used to determine data for the relative abrasivity of the structures. In summary, 3DPMD offers the possibility to produce titanium structures with and without reinforced particles. Using automated routines, it is possible to generate metal structures using welding robots directly from the CAD drawings. Microstructures and properties are directly related to the process and therefore material-process-property relationships are discussed within this work.Hoefer Kevin Mayr Peter 2019China Welding2019,28,1:12
7Mineralogical characteristics of airborne particles collected in Beijing during a severe Asian dust storm period in spring 2002显示文摘Asian dust storm (ADS) samples were collected on March 20,2002 in Beijing,China. High-resolution field emission scanning electron microscopy with energy dispersive X-ray detector (FESEM-EDX) and X-ray diffraction (XRD) were used to study the morphology,chemical compositions,number-size dis-tributions and mineralogical compositions of ADS particles. The mineral particles were major compo-nents in the ADS samples,accounting for 94% by number. The XRD analysis indicated that the dust particles were dominated by clay (40.3%),and quartz (19.5%),followed by plagioclase (8.4%),calcite (7.5%),K-feldspar (1.5%),hematite (0.9%),pyrite (0.9%),hornblende (0.4%) and gypsum (0.3%),with a certain amount of noncrystalline materials (20.3%). Clay minerals were mainly illite/smectite mixed lay-ers (78%),followed by illite (9%),kaolinite (6%),and chlorite (7%). In addition to these main minerals,FESEM-EDX also detected some trace minerals,such as dolomite,pyrite,thenardite,as well as heavy minerals represented by rutile,ilmenite and apatite. The mineralogical compositions of the 2002-03-20 Asian dust storm and the Saharan dust plumes were similar but the clay mineralogy showed a great distinction,with the illite/smectite mixed layers being common in the Asian dust storm but illite being common in the Saharan dust plumes.SHAO LongYi LI WeiJun YANG ShuShen SHI ZongBo LÜ SenLin 2007Science China Earth Sciences2007,50,6:11
8Magnetization of microorganism cells by sol-gel method显示文摘Microorganism cells could be used as templates during fabrication of magnetic or conductive microstructures in different standard shapes. In this paper, feasibility of magnetizing microorganism cells by sol-gel method, which is to coat cells of Spirulina (a type of natural micro-helical microorganism) with the ferrite (a kind of magnetic material), was discussed and investigated. Then the cell form, components and the phase structure were observed and analyzed using various tools including optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray detector (EDX), transmission electron microscopy (TEM), and X-ray diffraction analysis (XRD). Results showed that spirulina cells could be coated with ferrite after the sol-gel process, with the shape of natural helixes well kept, that the components of different sampling points on the surface layer were consistent and the thickness of layer was uniform, and that the type of the surface ferrite layer formed was cubic Fe3O4. It was also observed that there were nano-particles yielded in the cells and certain deposit on the walls between cells. The kinetics of the cell magnetization technology by sol-gel was also discussed.CHEN Bo ZHAN TianZhuo LIAN ZhiYang ZHANG DeYuan 2008Science China(Technological Sciences)2008,51,5:11
9Relationship of particle stimulated nucleation,recrystallization and mechanical properties responding to Fe and Si contents in hot-extruded 7055 aluminum alloys显示文摘The variations of coarse intermetallic particles in hot-extruded 7055 aluminum alloys with 0.041 wt%Fe and 0.024 wt%Si increasing to 0.272 wt%Fe and 0.134 wt%Si were investigated.The particle stimulated nucleation(PSN)behaviors for different kind of coarse particles were detailly analyzed by EBSD.Moreover,the effect of PSN responding to Fe and Si contents on recrystallization and tensile properties of 7055 alloys was evaluated.With increasing Fe and Si contents,the size and number density of coarseη/S particles are reduced,while the number densities of coarse Al7Cu2 Fe and Mg2Si particles are both increased and the coarse Al7Cu2 Fe particles transform from rod-like to irregular.More PSN recrystallized grains with predominant orientations deviated from the extruded fiber textures are stimulated by the irregular Al7Cu2 Fe and Mg2Si particles,because a higher degree of local non-uniform deformation is produced.The rod-like Al7Cu2 Fe particles cause the greatest degree of local non-uniform deformation owing to the largest aspect ratio,but the shape also restricts the area of particle deformation zone(PDZ)resulting in fewer PSN recrystallized grains.The irregularη/S particles give rise to the lowest degree of local non-uniform deformation and fewest PSN recrystallized grains with the major orientations close to the extruded fiber textures.Consequently,despite the number and size of coarseη/S particles are reduced,the proportion of high angle grain boundaries(HAGBs)is increased and the extruded fiber textures are weakened with Fe and Si contents increasing,because of the increased Al7Cu2 Fe and Mg2Si particles.The strength is slightly declined by the weakened<111>//ED(extrusion direction)fiber texture,while the elongation is reduced for a larger number of coarse particles and more HAGBs with higher Fe and Si contents.Huan She Da Shu Anping Dong Jun Wang Baode Sun Hongchang Lai 2019Journal of Materials Science & Technology2019,35,11:10
10Particles carried by ascending gas flow at the Tongchanghe copper mine,Guizhou Province,China显示文摘We collected and analyzed, using transmission electron microscopy, the particles carried by ascending gas flow in soil above the concealed orebody of the Tongchanghe copper mine, Guizhou Province. Particles of native copper, native copper-iron alloy, and native chromium-iron-copper alloy particles in the ascending gas flow were first discovered. Commonly, they were aggre- gations of relatively small particles. Individual particles within aggregations were subcircular, elliptical, regularly polygonal, or elongate and from 5 to 40 nm in size. The aggregations were subcircular or elliptical and 20-150 nm in size. Chloride, oxide, sulfate, and hydroxide particles containing ore-forming metals in the ascending gas flow were also discovered. The elements of the particles were commonly in a high valence state, suggesting that they were formed in a near-surface oxidizing environment. Discovery of the particles extracted from the ascending gas flow above the Tongchanghe copper mineprovided a powerful tool for exploration for deep concealed orebodies. Our study also showed that native copper, native copper-iron alloys, native chromium-iron-copper alloys, as well as chloride, oxide, sulfate, and hydroxide compounds containing ore-forming metals can be transported in particle form by ascending gas flow below the Earth's surface.Cao JianJin Liu Chang Xiong ZhiHua Qin TingRong 2010Science China Earth Sciences2010,53,11:9
11Development of an integrated model system to simulate transport and fate of oil spills in seas显示文摘A three-dimensional integrated model is developed for simulating transport and final fate of oil spills in seas.The model contains two main modules,flow and transport-fate modules.The flow module uses an unstructured finite-volume wave-ocean coupling model.Using unstructured meshes provides great flexibility for modeling the flow in complex geometries of tidal creeks,barriers and islands.In the transport-fate module the oil dispersion is solved using a particle-tracking method.Horizontal diffusion is simulated using random walk techniques in a Monte Carlo framework,whereas the vertical diffusion process is solved on the basis of the Langeven equation.The model simulates the most significant processes that affect the motion of oil particles,such as advection,surface spreading,evaporation,dissolution,emulsification and turbulent diffusion as well as the interaction of the oil particles with the shoreline,sedimentation and the temporal variations of oil viscosity,density and surface tension.The model simulates either continuous or instantaneous oil spills,and also other toxic matter.This model has been applied to simulate the oil spill accident in the Bohai Sea.In comparison with the observations,the numerical results indicate that the model is reasonably accurate.WANG JinHua & SHEN YongMing State Key Laboratory of Coastal and Offshore Engineering,Dalian University of Technology,Dalian 116023,China 2010Science China(Technological Sciences)2010,53,9:9
12蒸汽相变促进可溶PM_(2.5)凝结增长的数值分析显示文摘为利用蒸汽相变原理促进氨法脱硫系统排放细颗粒物(PM2.5)的脱除,建立多分散颗粒的凝结增长动力学模型,利用数值模拟方法研究了可溶硫酸铵颗粒的凝结增长规律,并将典型粒径可溶与不可溶颗粒的凝结增长过程进行对比分析.结果表明:不同粒径硫酸铵颗粒的增长速率相近,等温系统的凝结增长效果优于绝热系统;对于同一初始粒径分布下的可溶和不可溶颗粒,微米尺度可溶颗粒的增长速率始终大于不可溶颗粒,亚微米尺度可溶颗粒的增长速率先大于而后小于不可溶颗粒,使得二者的增长曲线存在一个交叉点;蒸汽饱和度增大能显著促进硫酸铵颗粒的增长;等温系统中温度对硫酸铵颗粒的增长影响显著,绝热系统中温度的影响较弱.温高森 凡凤仙 2014中国环境科学2014,34,5:9
13Mechanical and thermal properties of sodium silicate treated moso bamboo particles reinforced PVC composites显示文摘The main objective of this research was to study the potential of sodium silicate modification on moso bamboo particles as reinforcements for thermoplastic. Moso bamboo particles were modified with sodium silicate aqueous solutions (of 0.5%, 1%, 2%, 5% and 10% concentrations). The mechanical properties of sodium silicate treated moso bamboo particles reinforced PVC composites (BPPC) were calculated and compared with raw bamboo particles filled samples. The thermal characteristics of the BPPC were studied to investigate the feasibility of sodium silicate treatment on moso bamboo particles. The particle morphology and BPPC microstructure were investigated by scanning electron microscopy. Results showed that the tensile strength and modulus of elasticity of the BPPC increased before the concentration of sodium silicate solution reached 5% and got their maximum values of 15.72 MPa and 2956.80 MPa, respectively at 5% concentration. The modulus of rupture obtained the maximum value of 27.73 MPa at 2% concentration. The mechanical curve decreased as the concentration of solution went higher. Differential scanning calorimetric analysis illustrated that the sodium silicate solution treated BPPC possesses a better compatibility. More uniform dispersion of moso bamboo particles in PVC matrix was obtained after the sodium silicate treatment. Hence, the sodium silicate was a feasible and competitive agent of creating moso bamboo particles reinforced PVC composites.WANG Hui, SHENG KuiChuan*, CHEN Jie, MAO HaiLiang & QIAN XiangQun School of Biosystems Engineering and Food Science,Zhejiang University, Hangzhou 310029, China 2010Science China(Technological Sciences)2010,53,11:9
14Synthesis of MnZn Ferrite Nanoscale Particles by Hydrothermal Method显示文摘Hydrothermal method was used to synthesize nanoscale particles of MnZn ferrites. The crystallites were characterized by XRD, TEM and SEM. The effects of the reaction time, temperature and additives on the product were investigated. Crystallization process would be carried out above 160 ℃ for 5 h or more, higher temperature can reduce the reaction time. Additives were used to remove impurities such as Fe 2O 3, ZnMnO 3.10~15 nm pure slightly agglomerated MnZn ferrite crystallites with a narrow grain size distribution were obtained.GU Ying-ying SANG Shang-bin HUANG Ke-long LIU Jian-shen 2000Journal of Central South University2000,12,1:9
15Drawdown mechanism of light particles in baffled stirred tank for the KR desulphurization process显示文摘To improve the efficiency of the desulfurization process, the drawdown mechanism of light particles in stirred tank is studied in this paper. For both up and down pumping modes, the just drawdown speeds(Njd) of floating particles in transformative Kanbara Reactor(KR) are measured in one and four baffled stirred tanks experimentally. Then numerical simulations with standard k-ε model coupled with volume of fluid model(VOF) and discrete phase model(DPM) are conducted to analyze the flow field at the just drawdown speed Njd. The torques on the impeller obtained from experiments and simulations agree well with each other, which indicates the validity of our numerical simulations. Based on the simulations, three main drawdown mechanisms for floating particles, the axial circulation, turbulent fluctuation and largescale eddies, are analyzed. It's found that the axial circulation dominates the drawdown process at small submergence(S = 1/4 T and 1/3 T) and the large-scale eddies play a major role at large submergence(S = 2/3 T and 3/4 T). Besides, the turbulent fluctuation affects the drawdown process significantly for up pumping mode at small submergence(S = 1/4 T and 1/3 T) and for down pumping mode at large submergence(S = 2/3 T and 3/4 T). This paper helps to provide a more comprehensive understanding of the KR desulphurizer drawdown process in the baffled stirred tank.Meng Li Yangbo Tan Jianglong Sun De Xie Zeng Liu 2019Chinese Journal of Chemical Engineering2019,27,2:8
16Effects of Niaoduqing Particles(尿毒清颗粒)on Delaying Progression of Renal Dysfunction:A Post-trial,Open-Label,Follow-up Study显示文摘Objective: To follow up the participants of the randomized clinical trial 'Efficacy and Safety of Niaoduqing Particles(尿毒清颗粒) for Delaying Moderate-to-Severe Renal Dysfunction', and assess the long-term effects of Niaoduqing Particles on delaying the progression of renal dysfunction. Methods: Participants, who had previously been randomly assigned to receive Niaoduqing Particles or placebo for 24 weeks(146 cases in each group), were invited to follow-up and all were administered Niaoduqing Particles 5 g thrice daily and 10 g before bedtime for 24 weeks. The primary endpoints were changes in baseline serum creatinine(Scr) and estimated glomerular filtration rate(e GFR) after completion of the open-label treatment period. Results: After the double-blind period, the median(interquartile range) changes in Scr were 1.1(–13.0–24.1) and 11.7(–2.6–42.9) μmol/L for the Niaoduqing Particle and placebo groups, respectively(P=0.008), and the median changes in e GFRs were –0.2(–4.3–2.7) and –2.21(–5.7–0.8) mL·min^(-1)·1.73 m^(-2), respectively(P=0.016). There were significant differences in the double-blind period changes in renal function between groups. After the open-label period, the median changes in Scr were 9.0(–10.0–41.9) and 17.5(–6.0–50.0) μmol/L for the Niaoduqing Particle and placebo groups according to baseline grouping, respectively(P=0.214), and the median changes in eGFRs were –2.3(–6.4–1.9) and –3.7(–7.5–1.1) mL·min^(-1)·1.73 m^(-2), respectively(P=0.134). There were no statistical differences in the open-label period changes in renal function between groups. The eGFR reduction of participants who accepted Niaoduqing Particle treatment for 48 weeks was projected to 2.5 m L·min^(-1)·1.73 m(-2) per year. Conclusions: Niaoduqing Particles appear to have long-term efficacy for patients with moderate-to-severe renal dysfunction. Although there was no statistical difference, the early use of Niaoduqing Paticles seems to ameliorate the worsening of renal function.ZHENG Ying WANG Nian-song LIU Yu-ning HE Li-qun JIAN Gui-hua LIU Xu-sheng NI Zhao-hui CHENG Xiao-hong LIN Hong-li ZHOU Wen-hua WANG Ya-ping FANG Jing-ai HE Ya-ni YANG Hong-tao ZHAO Li-juan DING Han-lu WANG Li-hua YU Ren-huan LI Wen-ge YE Zhi-ming GUO Wang ZHAN Yong-li MAO Hui-juan HU Zhao YAO Chen CAI Guang-yan CHEN Xiang-mei 2019Chinese Journal of Integrative Medicine2019,25,3:7
17Effect of Transcatheter Embolization by Autologous Fat Particles in the Treatment of Coronary Artery Perforation During Percutaneous Coronary Intervention显示文摘Background: Coronary artery perforation (CAP) is a rare but severe complication of percutaneous coronary intervention (PCI). The aim of our study was to evaluate the effect and safety oftranscatheter embolization by autologous fat particles in the treatment of CAP. Methods: Once the CAP was confirmed, a little autologous subcutaneous fatty tissue was obtained from the groin of the patient and then was made into 1 mm × 1 mm fat particles. The perforated vessel was embolized by fat particles via a micro-catheter. There were eight patients undergoing transcatheter embolization by autologous fat particles in the treatment of CAP during PCI in Peking University Third Hospital from February 2009 to June 2014, and the clinical data of these patients were collected and analyzed retrospectively. Results: The lesion morphology of the patients was classified based on the American College of Cardiology/American Heart Association Task Force classification, there were one patient with Class B2 lesion and seven patients with Class C lesions (there were five patients with chronic total occlusion lesions). According to the Ellis classification of CAP, there were six patients with Class Ⅱ perforations and two patients with Class III perforations. The causes of perforation included that seven patients induced by guide wire and one patient by balloon predilation. Three patients had pericardial effusion. All of the eight patients with CAP underwent transcatheter embolization by autologous fat particles. Coronary angiography confirmed that all of them were embolized successfully. There was no severe complication after the procedure. The coronary angiography of one patient at 1 week and another patient at 2 years after the embolization showed that the embolized arteries had recanalized. The median follow-up time was 20.3 months (8.8-50.2 months), the event-free survival rate was 100%. Conclusions: Transcatheter embolization by autologous fat particles was an effective, safe, cheap, and easy way to treat the perforation of small vessels during PCI.Li-Yun He Jiang-Li Han Li-Jun Guo Fu-Chun Zhang Ming Cui Wei Gao 2015Chinese Medical Journal2015,,6:7
18Laser induced TiC particle reinforced composite layer on Ti6Al4V and their microstructural characteristics显示文摘An in situ synthesized TiC particle reinforced composite layer on Ti6Al4V were fabricated by laser induced reaction of the pre placed mixed powders of Ti and Cr 3C 2. The microstructure of the composite layer was strongly related to the composition of original powders and also the laser processing parameters. Under certain processing parameters, the matrix of the composite layer was transferred from dual α + β to single phase β with increasing Cr 3C 2 content in the original powder mixture. The TiC particles were fine and uniformly dispersed in the matrix. Furthermore, the fine TiC particles show excellent compatibility with the matrix, thus offering good wear performance.张松 吴维 王茂才 董世运 2000中国有色金属学会会刊:英文版2000,10,1:7
19Ultra low frequency waves impact on radiation belt energetic particles显示文摘One of the most fundamental important issues in the space physics is to understand how solar wind energy transports into the inner magnetosphere.Ultra low frequency(ULF)wave in the magnetosphere and its impact on energetic particles,such as the wave-particle resonance,modulation,and particle acceleration,are extremely important topics in the Earth’s radiation belt dynamics and solar wind― magnetospheric coupling.In this review,we briefly introduce the recent advances on ULF waves study. Further,we will explore the density structures and ion compositions around the plasmaspheric boundary layer(PBL)and discuss its possible relation to the ULF waves.ZONG QiuGang HAO YongQiang WANG YongFu 2009Science China(Technological Sciences)2009,52,12:7
20PREPARATION OF WATERBORNE ULTRAFINE PARTICLES OF EPOXY RESIN BY PHASE INVERSION TECHNIQUE显示文摘Werborne ultrafine particles of epoxy resin were prepared by phase inversion tech-nique. The results of SEM revealed that the particles diameter was in the range of 50to 100 nm and the effects on amount of water required at phase inversion point were alsodisc?d.杨振忠 许元泽:王胜杰 俞浩 蔡维真 1997Chinese Journal of Polymer Science1997,15,1:6
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