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991.
992.
遥控雷达光纤传输系统 总被引:2,自引:1,他引:1
介绍了作者研制成功并已实用化的遥控雷达光传输设备。该设备采用PFM调制及数字调制技术来完成雷达信号传输,设备稳定可靠,具有很高的性能价格比。 相似文献
993.
Jutta M. Ellermann Joel D. Siegal John P. Strupp Timothy J. Ebner Kâmil Ugurbil 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1998,131(2):272-285
The dorsal stream is a dominant visuomotor pathway that connects the striate and extrastriate cortices to posterior parietal areas. In turn, the posterior parietal areas send projections to the frontal primary motor and premotor areas. This cortical pathway is hypothesized to be involved in the transformation of a visual input into the appropriate motor output. In this study we used functional magnetic resonance imaging (fMRI) of the entire brain to determine the patterns of activation that occurred while subjects performed a visually guided motor task. In nine human subjects, fMRI data were acquired on a 4-T whole-body MR system equipped with a head gradient coil and a birdcage RF coil using aT*2-weighted EPI sequence. Functional activation was determined for three different tasks: (1) a visuomotor task consisting of moving a cursor on a screen with a joystick in relation to various targets, (2) a hand movement task consisting of moving the joystick without visual input, and (3) a eye movement task consisting of moving the eyes alone without visual input. Blood oxygenation level-dependent (BOLD) contrast-based activation maps of each subject were generated using period cross-correlation statistics. Subsequently, each subject's brain was normalized to Talairach coordinates, and the individual maps were compared on a pixel by pixel basis. Significantly activated pixels common to at least four out of six subjects were retained to construct the final functional image. The pattern of activation during visually guided movements was consistent with the flow of information from striate and extrastriate visual areas, to the posterior parietal complex, and then to frontal motor areas. The extensive activation of this network and the reproducibility among subjects is consistent with a role for the dorsal stream in transforming visual information into motor behavior. Also extensively activated were the medial and lateral cerebellar structures, implicating the cortico–ponto–cerebellar pathway in visually guided movements. Thalamic activation, particularly of the pulvinar, suggests that this nucleus is an important subcortical target of the dorsal stream. 相似文献
994.
本文对GaAs衬底边缘照射微带型线型光控微波开关进行了开关的结构参数设计,对开关的插入损耗和隔离度进行分析计算,并进一步讨论了频率响应及其光脉冲能量对开关隔离度的影响。 相似文献
995.
Asao Arai 《Journal of Geometry and Physics》1993,11(1-4):465-490
Infinite dimensional analysis is developed on an abstract Boson-Fermion Fock space. A general class of Dirac operators acting there is introduced and properties of them are investigated. An index theorem for the Dirac operators is established in terms of a path integral on a loop space. It is shown that the abstract formalism presented here gives a mathematical unification for some models of supersymmetric quantum field theory. 相似文献
996.
997.
本文在Sobolev空间中讨论残差泛函J(u)的概念及性质,论证了残差泛函J(u)的弱紧性、强制性和下半连续性及凸性条件.根据临界点理论在Sobolev空间中建立起该残差泛函的极值原理,给出J(u)=0极小值存在定理.此外还证明了等价定理和J(R_n(c))=0的五种等价形式. 相似文献
998.
E. E. Sinaiskii 《Functional Analysis and Its Applications》2002,36(4):324-327
Two constructions of translation continuous functionals on the space of bounded continuous functions on a locally compact group are introduced and the properties of these functionals related to the notion of support of a functional are considered. 相似文献
999.
使用四甲氧基硅烷(TMOS)和二甲基二甲氧基硅烷(DiMe-DMOS)为共先驱体,采用溶胶-凝胶的有机掺杂,制备对pH具有宽程响应的敏感膜。详细考察了包埋溴酚蓝和溴酚绿的敏感膜对pH的响应值、响应时间、泄漏和可逆性等响应性能指标,并进行了溴酚蓝和溴酚绿在水相与膜内吸收光谱的研究。 相似文献
1000.