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排序方式: 共有1395条查询结果,搜索用时 15 毫秒
61.
PA Crossey C Eng M Ginalska-Malinowska TW Lennard DC Wheeler BA Ponder ER Maher 《Canadian Metallurgical Quarterly》1995,32(11):885-886
Inherited predisposition to phaeochromocytoma is seen in multiple endocrine neoplasia type 2 syndromes, von Hippel-Lindau (VHL) disease, and neuro-fibromatosis type 1. In addition familial phaeochromocytoma alone has been reported. To investigate the genetic basis for familial phaeochromocytoma alone, we screened three affected kindreds for mutations in the RET proto-oncogene and the VHL tumour suppressor gene. We did not detect MEN 2 associated RET mutations in any family, but missense VHL gene mutations (V155L and R238W) were identified in two kindreds with no clinical evidence of VHL disease. Patients with familial, multiple, or early onset phaeochromocytoma should be investigated for germline VHL and RET gene mutations as the molecular diagnosis of multisystem familial cancer syndromes enables appropriate counselling and screening to be provided. 相似文献
62.
用于结构光分布图采集的图像帧存贮器设计 总被引:1,自引:0,他引:1
设计了一种用于结构光分布图采集的图像帧存贮器(RAM)电路。由于预先对结构光分布进行了硬件细化处理以及大容量存贮芯片的使用,电路设计十分简单。该系统带可作为数字化仪用于各种二值图像的数字化,并可作为计算机和其它外设的输入/输出缓冲设备。 相似文献
63.
This article provides a brief history of dimensionally stable anodes by reviewing innovations in the chlor-alkali industry, electroplating and electrogalvanizing, and electrowinning. These anodes are attractive for numerous reasons (e.g.,.long life and reduced energy consumption), but they must still overcome the hurdle of cost togain wider acceptance for applications in the metallurgical process industries. 相似文献
64.
Jane M. Cavanagh M.Sc. David A. Torvi Ph.D. P. Eng Kamiel S. Gabriel Ph.D. P.Eng. Gary A. Ruff Ph.D. 《Microgravity science and technology》2006,18(2):14-26
To address fire safety concerns associated with the use of flammable fabrics during space travel, an apparatus was designed
to be flown on low-gravity parabolic aircraft flights in order to assess the flammability of cotton and 50% cotton/50% polyester
fabrics, and the resulting skin burn injury that would occur if these fabrics were to ignite. The apparatus, modelled after
a standard fabric flammability test, was also used on the ground for experiments under earth’s gravity. Variables examined
in the tests include gravity level, fabric type, air gap size, and orientation of the fabric. Flame spread rates, heat fluxes,
and skin burn predictions determined from test results were compared under the two gravity levels. The orientation of the
fabric had a large effect on flame spread rates, heat fluxes and predicted skin burn times for tests conducted under earth’s
gravity. Flame spread rates and heat fluxes were highest when the fabric was held in the vertical orientation, which resulted
in the lowest predicted times to produce skin burns. Flame spread rates and heat fluxes were considerably lower in microgravity
than under earth’s gravity, which resulted in longer predicted times to produce skin burns. 相似文献
65.
Optical switching is demonstrated using movable integrated optical waveguides fabricated on silicon-on-insulator substrates. The switching effect is produced by the voltage-controlled micromechanical deflection of the movable waveguides. The dynamic response of the deflection is studied. A contrast ratio of 12 dB of switching is obtained using an applied voltage of less than 10 V. At 20 V, the contrast ratio is about 40 dB 相似文献
66.
Eng L.E. Bacher K. Yuen W. Larson M. Ding G. Harris J.S. Jr Chang-Hasnain C.J. 《Electronics letters》1995,31(7):562-563
The authors demonstrate a spatially chirped emission wavelength in vertical cavity surface emitting laser (VCSEL) arrays grown by molecular beam epitaxy. The wavelength shift is due to a lateral thickness variation in the Al0.2Ga0.8As cavity, which is induced by a substrate temperature profile during growth. A 20 nm shift in lasing wavelength is obtained in a VCSEL array 相似文献
67.
Taewon SeoSchool of Mechanical Eng. Andong National Univ. South KoreaWang Xing-kui Wang Guang-qianDepartment of Hydraulic Eng. Tsinghua Univ. Beijing P.R.China 《水动力学研究与进展(B辑)》1998,(3)
This study condiders spatially developing free shear layers at moderateReynolds numbers that are formed by the merging of two free streams initially separatedby a splitter plate.To study the nonlinear interactions between the two-and three-dimen-sional fundamental and subharmonic modes in the spatially developing shear layer,the se-lected five modes represent the minimum number that needs to be considered.The objec-tive of this study is to investigate the nonlinear effects arising from the interactions be-tween two-and three-dimensional large-scale coherent structures in a free shear layer.Our attention is focused on the energy exchange mechanisms between the various modes,and the effects of the nonlinear evolution of the phases of the interacting modes.It isshown that depending on the initial modal phase angles the downstream growth of theshear layer and the associated local entrainment can be strongly affected by the presence ofthese nonlinear interactions.This high sensitivity of the shear layer growt 相似文献
68.
Eng K. Rangayyan R.M. Bray R.C. Frank C.B. Anscomb L. Veale P. 《IEEE transactions on bio-medical engineering》1992,39(3):296-306
An image analysis technique has been developed to quantitatively describe the fine vascular patterns observed in ligament tissue. The longitudinal orientational distribution and total vessel volume of India-ink-perfused blood vessel segments in normal and healing ligaments were determined. The methods involved special vascular preparation of adult rabbit knee medial collateral ligaments (MCL) by India-ink perfusion. Black and white microscope images of ink-perfused tissue sections were subjected to a thresholding procedure to binarize digitized ligament images, which were then skeletonized and analyzed for directional distribution based on the least-squares technique. Analysis of medial collateral ligaments in New Zealand White rabbits using this method has shown that scarred tissue is more vascular and has a more chaotic angular distribution of blood-vessel segments than normal ligament tissue. 相似文献
69.
M. T. Collins Ph.D. E. J. McConaghy B. Chem. Eng. B.Sc. R. F. Stauffer B.Sc. G. J. Desroches B.Sc. B. D. Krysa B.Sc. 《JOM Journal of the Minerals, Metals and Materials Society》1994,46(4):51-58
The first commercial application of the Sherritt two-stage zinc pressure leach process commenced operation at the Hudson Bay Mining and Smelting Company metallurgical complex in Flin Flon, Manitoba (Canada), on July 2, 1993. The start-up was relatively smooth, and full design rate for the plant was achieved by September 12, 1993. Since that time, zinc extraction in the zinc pressure leach plant has consistently been in excess of 98%, and production has continued to exceed expectations. The successful operation of the Hudson Bay plant represents a significant advancement of zinc processing technology, especially with respect to meeting the environmental challenge faced by zinc plants today. 相似文献
70.
P. Sharrock MA Msc MBA C. Eng MInstMC MIEE 《e & i Elektrotechnik und Informationstechnik》1997,114(5):245-248
This paper introduces LonWorks technology, intrinsic safety and how the two are combined in the IS-78 physical channel which enables networks to be taken into hazardous areas. The capabilities of the physical channel are described, together with some applications in which it has been used. 相似文献