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991.
掺铬的镁橄榄石晶体连续波可调谐激光器 总被引:2,自引:1,他引:1
本文报道了连续波Nd:YAG激光器泵浦掺铬镁橄榄石(Cr4+:forsterite)晶体获得了连续波可调谐运转,该激光器采用Nd:YAG激光器的1.06μm谱线泵浦Φ5×9mm的Cr4+:forsterite晶体.在吸收泵浦功率为8.7W时,得到1.05W的连续波输出.当在腔内放置色散元件后,其调谐范围是1186nm~1306nm,同时详细研究了输出功率随温度和输出镜透过率的变化特性. 相似文献
992.
热作用下蛋白及全血光学特性变化的实验研究 总被引:8,自引:4,他引:4
利用自行研制的双积分球系统 ,对不同温度 (37℃~ 80℃ )加热后的蛋白及人全血的光学特性参数 (对波长为 6 32 8nm的光而言 )进行了实验研究。结果表明 :热作用下生物样品生理特性的改变可用光学特性参数的变化来描述。不同的热剂量作用下 ,样品形态及结构的改变是不同的 ,相应的光学特性参数 (吸收系数与散射系数 )变化也不同 ;相同热作用下 ,样品成分的不同 ,导致样品光学特性参数的改变也存在差别。光学检测技术可望为热疗的实时无损监测提供一种新的手段。 相似文献
993.
RUAN Ying CAO Chongde & WEI Bingbo Department of Applied Physics Northwestern Polytechnical University Xi’an China 《中国科学G辑(英文版)》2004,47(6):717-728
~~Rapid growth of ternary eutectic un der high undercooling conditions1.Offerman, S.E., Dijk, N.H., Sietsma, J.et al., Grain nucleation and growth during phase transformations, Science, 2002, 298: 1003-1005.
2.Warren, J.A., Langer, J.S., Prediction of dendritic spacings in a directional-solidification experiment, Phys.Rev.E, 1993, 47: 2702-2712.
3.Cao, C.D., Wang, N., Wei, B., Containerless rapid solidification of undercooled Cu-Co peritectic alloys, Science in China, Ser.A, … 相似文献
994.
Guozhen?LuEmail author Juan?J.?Manfredi Bianca?Stroffolini 《Calculus of Variations and Partial Differential Equations》2003,19(1):1-22
Convex functions in Euclidean space can be characterized as universal viscosity subsolutions of all homogeneous fully nonlinear second order elliptic partial differential equations. This is the starting point we have chosen for a theory of convex functions on the Heisenberg group.Received: 5 July 2002, Accepted: 24 October 2002, Published online: 6 June 2003Mathematics Subject Classification (1991):
49L25, 35J70, 35J67, 22E30Guozhen Lu: First author supported by US NSF grant DMS-9970352Juan J. Manfredi: Second author supported by US NSF grant DMS-0100107Bianca Stroffolini: Third author was supported by G.N.A.M.P.A. and by the 2002 projectPartial Differential Equations and Control Theory 相似文献
995.
We use equivariant methods to define and study the orbifold K-theory of an orbifold X. Adapting techniques from equivariant K-theory, we construct a Chern character and exhibit a multiplicative decomposition
for K
*
orb
(X)⊗ℚ, in particular showing that it is additively isomorphic to the orbifold cohomology of X. A number of examples are provided. We then use the theory of projective representations to define the notion of twisted
orbifold K–theory in the presence of discrete torsion. An explicit expression for this is obtained in the case of a global
quotient.
Received: 21 August 2001 / Accepted: 27 January 2003
Published online: 13 May 2003
RID="*"
ID="*" Both authors were partially supported by the NSF
RID="*"
ID="*" Both authors were partially supported by the NSF
Communicated by R.H. Dijkgraaf 相似文献
996.
997.
Spectroscopic study of trypsin, heat and triton X-100-induced denaturation of the chlorophyll-binding protein CP43 总被引:3,自引:0,他引:3
Wang J Shan J Xu Q Ruan X Gong Y Kuang T Zhao N 《Journal of photochemistry and photobiology. B, Biology》2000,58(2-3):136-142
Trypsin-, heat- and Triton X-100-induced denaturation of CP43, the core antenna complex of photosystem II purified from spinach, has been investigated using absorption, fluorescence and circular dichroism spectroscopy. Triton X-100 was found to bring about considerable dissolution of pigments from the protein to the monomeric state in solution and destruction of the interactions among the chlorophyll, carotene and protein. Heat induced significant unfolding of the protein secondary structure and loss of excitonic interactions of the pigments, but no apparent dissolution of the pigments from CP43. Trypsin caused structural changes in the extrinsic part of the protein but no change of the native state of the pigments. Trypsin, heat and Triton X-100 treatments increased the light sensitivity of chlorophyll in CP43 to different extents. The results suggest that the protein and beta-carotene can protect the chlorophyll from light-induced destruction in CP43. 相似文献
998.
利用偏振时间分辨光谱和时间分辨Kerr旋转谱,研究了GaAs中的InAs单层和亚单层的电子自旋动力学.实验发现,在非共振激发条件下,厚度为1/3单层的InAs亚单层中电子自旋弛豫寿命长达3.4ns,而1个单层厚的InAs层的电子自旋寿命只有0.48ns;而在共振激发条件下,亚单层结构中的电子自旋寿命大大减少,只有70ps,单层InAs中电子自旋寿命没有显著变化.分析表明,低温下InAs单层和亚单层结构中,Bir-Aronov-Pikus(BAP)自旋弛豫机理占主导地位.通过改变材料结构特性和激发条件来改变电子空穴的空间相关性,从而达到控制自旋弛豫的目的.
关键词:
InAs亚单层
自旋弛豫
BAP机理 相似文献
999.
用化学镀的方法制备了NiFeCoP/CuBe复合结构丝,研究了其巨磁阻抗特性.结果表明复合结构丝在较低频率的驱动电流下就有明显的磁阻抗效应,当驱动电流频率在20kHz时的磁阻抗效应为40%,最大磁阻抗效应出现的频率在180kHz,为97%.利用复数磁导率和等效电路探讨了该复合丝铁磁层磁化过程的频率特性,复合结构丝的特征弛豫频率在1MHz左右.外加直流磁场抑制畴壁移动,在等效电路中与抵消部分并联电路相关.
关键词:
巨磁阻抗效应
磁导率
弛豫频率
等效电路 相似文献
1000.
Microwave-assisted synthesis and magnetic property of magnetite and hematite nanoparticles 总被引:1,自引:0,他引:1
Nanoparticles of magnetite (Fe3O4) and hematite (α-Fe2O3) have been prepared by a simple microwave heating method using FeCl3, polyethylene glycol and N2H4·H2O. The amount of N2H4·H2O has an effect on the final phase of Fe3O4. The morphology of α-Fe2O3 was affected by the heating method. Crystalline α-Fe2O3 agglomerates were formed immediately at room temperature and most of these nanoparticles within agglomerates show the same
orientation along [110] direction. After microwave heating, ellipsoidal α-Fe2O3 nanoparticles were formed following an oriented attachment mechanism. Both Fe3O4 and α-Fe2O3 nanoparticles exhibit a small hysteresis loop at room temperature. 相似文献