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101.
102.
根据C.F.KURTH和G.S.MOSCHYTZ的采用z域四口等效电路对开关电容网络进行双口分析的理论,以现场可编程模拟阵列FPAA实现的PID控制器为例,建立用于频域仿真的SPICE模型,从而方便地用SPICE软件对PID校正后的整个控制系统的稳定性进行仿真分析。 相似文献
103.
104.
Two types of GaAs/AlGaAs quantum dot arrays with different dot size are fabricated by dry etching and dry-wet etching. PL spectra of the quantum dot arrays at low temperature show the blue shifts due to the quantization confinement effects, and the blue-shift increases with the decrease of the dot size. It is also found that wet chemical etching can reduce the surface damage caused by high-energy ion etching and improve the optical characteristics of the quantum dot arrays. 相似文献
105.
本文给出了在电尺寸很大的理想导体光滑凸表面上,无限小磁矩或电矩在空间产生的电磁场的近似渐近解,利用该解可以准确有效地计算凸表面上天线间的互耦。此解中,表面塌沿Keller的表面射线路经传播,且在阴影边界过渡区域,包括对于源的邻城,它们仍然一致适用。除此之外,在给出的解中,通过一个系数T/K给出了关于表面场的表面射线绕曲的影响,其中,T表示表面射线的绕曲,K表示射线方向上的表面曲率。该解是由简单的典型问题的近似解导出的。给出了圆柱面和圆锥面上裂缝间互耦的数字结果,它与实验结果相吻合。 相似文献
106.
J. Anthony Murphy Rachael Padman 《International Journal of Infrared and Millimeter Waves》1988,9(8):667-704
In this paper we consider the maximization of the throughput of a single large antenna, for two possible array configurations: focal plane imaging arrays and aperture plane phased arrays. We discuss trade-offs between the two types of array in terms of field of view, sampling efficiency and time to map, a source. We also discuss limits on the number of feed elements in an imaging array imposed by the deterioration in aperture efficiency off-axis. 相似文献
107.
128×128elementPtSiinfraredCCDimagesensorYANGJiade;LIUJungang;LIZuojin;YANGYasheng(ChongqingOptoelectrouicsResearchInstitute,Y... 相似文献
108.
A medium access control (MAC) protocol (NULLHOC) for ad hoc networks of nodes with antenna arrays is presented. The antenna
array is used for transmit and receive beamforming with the purpose of increasing spatial reuse by directing nulls at active
transmitters and receivers in the neighborhood. In contrast to previous work with directional antennas, our approach is applicable
to multipath channels, such as occur indoors or in other rich scattering environments. The MAC protocol is designed to support
the control information exchange needed to direct nulls toward other users involved in existing communication sessions. Knowledge
of the channel coefficients between a transmitter or receiver and its neighbors is used to design transmit or receive beamformer
weights that implement the requisite nulling. Simulations are used to demonstrate the improvements in throughput and transmit
powers that are obtained in this approach relative to the IEEE 802.11 MAC protocol. We also analyze the effects of channel
estimation errors on our protocol and propose a simple modification of the basic (NULLHOC) protocol to minimize their impact.
This work was supported in part by National Science Foundation grants ECS-9979408 and ANI-9980526. Any opinions, findings
and conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect
the views of the funding agencies. 相似文献
109.
The fabrication of a hierarchically structured Ni(OH)2 monolayer hollow‐sphere array with the shell composed of building blocks of nanoflakelets is demonstrated based on a colloidal monolayer and electrochemical deposition. The morphology can be easily controlled by the colloidal monolayer and deposition parameters. Importantly, such monolayer hollow‐sphere array shows a morphology‐ and size‐dependent tunable optical transmission stop band. This stop band can be easily tuned from 455–1855 nm by changing the size of the hollow spheres between 1000 and 4500 nm, and also fine‐adjusted by changing the deposition time. The array exhibits a nearly incident‐angle‐independent position of the stop band that 3D photonic crystals do not possess. This structure may have potential applications in optical devices, photonic crystals, and sensors for gas detection. 相似文献
110.
With the progress of the railway technology, the railway transportation is becoming more efficient, intelligent and faster. High speed trains, as a major part of the railway transportation, are engaged with passenger's safety, and therefore the reliability issue is very important in such vital systems. In this paper, a dependable speed controller core based on FPGA has been developed for high speed trains. To improve the reliability and mitigate single upset faults on basic speed controller, this paper proposes a new effective method which is based on hardware redundancy. In the proposed Hybrid Dual Duplex Redundancy (HDDR) method, the original controller is quadruplicated and correct values are voted through the comparator and error detection unit. We have analyzed the proposed system with Reliability, Availability, Mean time to failure and Security (RAMS) theory in order to evaluate the effectiveness of proposed scheme. Theoretical analysis shows that the Mean Time To Failure (MTTF) of the proposed system is 2.5 times better than the traditional Triple Modular Redundancy (TMR). Furthermore, the fault injection experimental results reveal that the capability of tolerating Single Event Upsets (SEUs) in the proposed method increases up to 7.5 times with respect to a regular speed controller. 相似文献