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排序方式: 共有782条查询结果,搜索用时 31 毫秒
51.
提出了一种基于模块化的LabView的光信号检测方法。基于该方法的实验系统由信号采集和数据处理两大部分组成。信号采集部分通过光电二极管将光强信号转换为电信号,利用放大器(AD620)、数模转换器(ADC0809)、单片机(AT89S51)、电平转换器(MAX232)和计算机(PC)完成对光信号的采集。数据处理部分主要利用LabView软件通过计算机的9针串口从信号采集部分获取数据,并对该数据进行进一步处理,最后输出光信号强度随时间变化的曲线。提出的设计方案充分利用了计算机强大的数据处理能力,不仅最大程度地实现了光信号的自动检测,而且简化了信号检测硬件系统的设计,提升了系统的功能。 相似文献
52.
53.
Dagnachew Birru 《International Journal of Electronics》2013,100(4):437-443
Design considerations for a high-speed CMOS comparator for application in highspeed analogue-to-digital conversion are presented. Extensive simulations show that the comparator designed accordingly operates well above 250MHz clock speed in standard 0.5µm CMOS technology. An accuracy of 5mV and average power consumption of 0.3mW on 3.3V power supply is observed using simulations when it operates at 250MHz. 相似文献
54.
介绍了一种可用于半导体激光器、高速摄影、信号处理以及激光雷达的纳秒脉冲驱动电路。利用晶体 管的雪崩效应,通过两级雪崩晶体管阵列,得到了7 ns、6 A的大电流窄脉冲。并对触发脉冲的获得、电路板的 印制进行了简要的介绍。 相似文献
55.
Laser-beam-induced current (LBIC) is being investigated as an alternative to electrical measurements of individual photodiodes
in a two-dimensional array. This is possible because LBIC only requires two electrical contacts to an array and the two-dimensional
scanning of a focused laser beam across the array to image the entire array. The measured LBIC profiles, obtained from linear
arrays of HgCdTe photodiodes, will be used to study the uniformity of photodiodes in the array and to extract the R0A of the photodiodes. It will be shown that the shape of the LBIC signal is correlated to the electrical performance of the
photodiode, with R0A related to the spreading length of the photodiodes. Linear arrays of n-on-p, mid-wavelength infrared (MWIR) and long wave-length
infrared (LWIR) devices were formed in liquid-phase epitaxy HgCdTe epilayers using a plasma junction-formation technique.
The LBIC profiles were measured on each of the devices at various temperatures. For the MWIR devices, the extracted spreading
length shows no correlation with R0A. However, the LBIC signal does detect nonuniform devices within the array. For the case of the LWIR devices, the spreading
length is extracted as a function of temperature, with the R0A subsequently calculated from the spreading length. The calculated R0A, obtained without requiring contact to each photodiode in the array, agrees well with electrical measurements. Asymmetry
of the LBIC signals for certain devices in the arrays is shown to be a result of localized leakage at the photodiode junction
or from the contact pads through the passivation layers. These results are confirmed by numerical modeling of the device structures. 相似文献
56.
57.
Alan L. Migdall Carsten Winnewisser 《Journal of research of the National Institute of Standards and Technology》1991,96(2):143-146
The effect of optical irradiance on the linearity of a Si photodiode was studied. These results are compared for light modulated at 30 MHz and at dc as the optical irradiance was varied over a 9 decade range. We discuss how these results affect the use of this detector as a heterodyne receiver. As the optical irradiance varied from 10−2 to 10+3 mW/cm2, while maintaining constant total power, the photocurrent was constant to about 1%, but as the power density increased further, the photocurrent increased about 13%. At the highest densities that we could achieve, about 6×107 mW/cm2 there was only slight evidence of the onset of saturation. These results are of importance in our work to use optical heterodyne detection to measure filter transmittances over a wide dynamic range. The results provide guidelines for achieving maximum accuracy when using this particular diode as an optical heterodyne receiver. 相似文献
58.
George Eppeldauer 《Journal of research of the National Institute of Standards and Technology》1998,103(2):153-162
Frequency dependent response characteristics of photocurrent meters using large area, radiometric quality Si photodiodes have been analyzed. The current responsivity, the voltage noise and drift amplification, and the gain and bandwidth of the photocurrent-measuring analog control loop were calculated. The photodiodes were selected for high shunt resistance. The effect of the photodiode junction capacitance on the response characteristics was also analyzed. As a result of photocurrent gain dependent frequency compensations, the noise boosting effect was minimized at the output of the current meter. The loop gain and bandwidth were maximized. High-accuracy photocurrent measurements can be achieved using the described procedures for both dc and modulated optical radiation. 相似文献
59.
T. C. Larason S. S. Bruce C. L. Cromer 《Journal of research of the National Institute of Standards and Technology》1996,101(2):133-140
We describe how the National Institute of Standards and Technology obtains a scale of absolute spectral response from 406 nm to 920 nm. This scale of absolute spectral response is based solely on detector measurements traceable to the NIST High Accuracy Cryogenic Radiometer (HACR). Silicon photodiode light-trapping detectors are used to transfer optical power measurements from the HACR to a monochromator-based facility where routine measurements are performed. The transfer also involves modeling the quantum efficiency (QE) of the silicon photodiode light-trapping detectors. We describe our planned quality system for these measurements that follows ANSI/NCSL Z540-1-1994. A summary of current NIST capabilities based on these measurements is also given. 相似文献
60.