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991.
硅衬底上锗硅合金光波导设计及工艺的优化考虑 总被引:2,自引:0,他引:2
报道用射频加热化学气相沉积法制备Si/GeSi/Si大断面单模脊形光波导中设计和工艺的进一步完善,GeSi合金层中Ge的含量X要满足脊形光波导是单模,光波导的数值,孔径接近单模光纤值,脊高小于临界厚度值等,计算表明兼顾上述三项要求应取x=1~3%,脊的高与宽受大断面及单模的制约。Si的晶体结构使脊的二个腐蚀侧壁是斜坡,为此起始脊宽取5~6μm为宜;腐蚀液,抛光液的选取人保证脊则壁及波导面端的优良镜 相似文献
992.
H. P. Hetherington R. I. Kuzniecky J. W. Pan J. T. Vaughan D. B. Tweig G. M. Pohost 《Magnetic resonance imaging》1995,13(8):1175-1180
Previous spectroscopic imaging studies of temporal lobe epilepsy have used comparisons of metabolite content or ratios to lateralize the seizure focus. Although highly successful, these studies have shown significant variations within each of the groups of healthy subjects and patients. This variation may arise from the natural differences seen in metabolite concentration in gray and white matter, the complex anatomy seen about the hippocampus, and the large voxels typically employed at 1.5 T. Using a 4.1 T whole body system, we have acquired spectroscopic images with 0.5 cc nominal voxels (1 cc after filtering) to evaluate the regional variation in metabolite content of the hippocampus, temporal gray and white matter, midbrain, and cerebellar vermis. Using a threshold value of 0.90 for CR/NAA, a value 90% of all normal hippocampal voxels lay below, we have correctly identified the presence of epileptogenic tissue in patients with unilateral as well as bilateral seizures. By using comparisons to healthy values of the CR/NAA ratio, this method enables the visualization of bilateral disease and provides information on the extent of gray matter involvement. 相似文献
993.
Xing-Bin Pan 《Communications in Mathematical Physics》2002,228(2):327-370
In this paper we study the surface superconductivity phenomenon of type 2 superconductors under applied magnetic fields above
the critical field . We show that, for a cylindrical superconductor of infinite height placed in a homogeneous applied magnetic field, H
e
3, with H lying in between and keeping away from and , superconductivity persists uniformly at a thin sheath surrounding the entire lateral surface of the sample. As the applied
field decreases gradually, superconductivity in the surface sheath becomes strong and develops into a surface superconducting
state, while the interior of the sample remains close to the normal state.
Received: 21 May 2001 / Accepted: 11 February 2002 相似文献
994.
柱层析色谱分离性能优良的新型塑料脱模剂,纯化后得一主要未知组分。用元素分析、红外光谱、核磁共振氢谱研究其结构特征,对其盐酸酸化前后红外光谱吸收峰及核磁带进行了归属分析并确定结构。结果表明,该组分为一表面活性剂N,N-二羟乙基十二烷基胺。这为新型脱模剂的产品开发提供了依据。 相似文献
995.
This paper discusses hydrogen energy and the methods for production of hydrogen. It also provides a review of various materials
which are hydrogen permeable. Previous studies on the proton-conducting ceramics and their properties are summarized. The
principle of proton-conducting solid state fuel cell for conversing the energy of hydrogen containing fuel is described with
a discussion of the advantages of proton-conducting ceramic fuel cells as compared to oxygen-ionic conducting fuel cells.
The paper is concluded with a discussion of the major materials related technical challenges in the development of the proton-conducting
ceramic fuel cells.
Paper presented at the 97th Xiangshan Science Conference on New Solid State Fuel Cells, Xiangshan, Beijing, China, June 14–17,
1998. 相似文献
996.
应用2,3-二氨基萘荧光测定法对36例食管癌患者癌组织与癌旁组织及血清中硒的含量进行了测定。结果表明,癌组织中硒含量平均为1.325±0.81μg/g干重,癌旁组织为0.893±0.68μg/g干重,两者差异显著(P<0.05);血清中硒含量为0.6033±0.0520μmol/L,对照组20例献血员血清为0.8034±0.0650μmol/L,亦有显著性差异(P<0.05)。提示硒在抗肿瘤的过程中有一定作用。 相似文献
997.
998.
999.
1000.
A. Gadea G. de Angelis C. Fahlander M. De Poli E. Farnea Y. Li D.R. Napoli Q. Pan P. Spolaore D. Bazzacco S.M. Lenzi S. Lunardi C.M. Petrache F. Brandolini P. Pavan C. Rossi Alvarez M. Sferrazza P.G. Bizzeti A.M. Bizzeti Sona J. Nyberg M. Lipoglavsek J. Persson J. Cederkäll D. Seweryniak A. Johnson H. Grawe F. Soramel M. Ogawa A. Makishima R. Schubart S. Frauendorf 《Zeitschrift für Physik A Hadrons and Nuclei》1997,358(2):193-194
The structure of 105Sn has been investigated through the 50Cr(58Ni,2pn) reaction at a beam energy of 210 MeV. In addition to an extension of the spherical level scheme, a regular sequence of dipole transitions has been found. The experimental results are in agreement with the prediction of Tilted Axis Cranking calculations, which satisfactorily explain the properties of the band. 相似文献