65 resultados para 920 Biography
em Chinese Academy of Sciences Institutional Repositories Grid Portal
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,601920.:,,19612000,6019200.22;,601820(19612000,)0.52,8219200.42;,100,50,30201.05,1.38,2.02
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Chinese Academy of Sciences [KZCX2-YW-Q1-01, KZCX2-YW-315]; National Natural Science Foundation of China [40625002]
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Detailed investigations on the structural and mechanical properties of the forewing of the cicada were carried out. Measurement of the structures of the wings showed that the thickness of the membrane of each cell and the diameter of each vein were non-uniform in both the longitudinal and transverse directions, and their means were approximately 12.2 and 133.3 mum, respectively. However, the aspect ratios of the wings and the bodies were quite uniform and were approximately equal to 2.98 and 2.13, respectively. Based on the measured thickness, mass and area of the membranes of the cells, the mean density and the mean area density of the wing were approximately 2.3 g cm(-3) and 2.8 x 10(-3) g cm(-2), respectively. In addition, the diameters of the veins of the wings, including the diameters of the holes in the vein of the leading edge, were examined. The mechanical properties of the wing were investigated separately by nanoindentation and tensile testing. The results indicated that the mean Young's modulus, hardness and yield stress of the membranes of the wings were approximately 3.7 Gpa, 0.2 Gpa and 29 Mpa, respectively, and the mean Young's modulus and strength of the veins along the direction of the venation of wings were approximately 1.9 Gpa and 52 Mpa, respectively. Finally, the relevant results were briefly analyzed and discussed, providing a guideline to the biomimetic design of the aerofoil materials of micro air vehicles.
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Multiple refocusing of a tightly focused femtosecond laser due to the dynamic transformation between self-focusing and self-defocusing is employed to provide a novel method to produce quasi-periodic voids in glass. It is found that the diameter or the interval of the periodic voids increases with the increasing pulse energy of the laser. The detailed course for producing periodic voids is discussed by analysing the damaged track induced by the tightly focused femtosecond laser pulses. It is suggested that this periodic structure has potential applications in fabrication of three-dimensional optical devices.
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NdYAG355nm8ns30HzZnO100nmZnOZnO
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Spectral properties of Yb3+/Ni2+ codoped transparent silicate glass ceramics containing LiGa5O8 nanocrystals were investigated. The near-infrared emission intensity of Ni2+ was largely increased with Yb3+ codoping due to Yb3+-> Ni2+ energy transfer. The qualitative calculation of the energy transfer constant Cs-a and rate Ps-a showed that the Yb3+-> Ni2+ energy transfer was much greater than in the opposite direction. Yb3+/Ni2+ codoped glass ceramics with 0.75 mol % Yb2O3 exhibited a near-infrared emission with full width at half maximum of 290 nm and fluorescent lifetime of 920 mu s. The glass ceramics are promising for broadband optical amplification.
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(Rhinopithecus bietz)(2614'N-2920'N,9915'E-9937'E),2600()-4200m();15,1700.,50.,,.,,GISRS,5(1986-2006)Landsat TM,,:1)200613600hm2,4900hm2,3300hm2;2)20(1986-2006),15.5%(2500hm2),58.1%(1 800hm2),17.8%(500hm2);3)75.6%,51.8%(198615.3hm220067.4hm2),54.7%;,ShannonShannon4.0%;4)(r=-1.000),(r=1.000).;.
