首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   423749篇
  免费   6690篇
  国内免费   1378篇
电工技术   6556篇
综合类   2743篇
化学工业   68193篇
金属工艺   17843篇
机械仪表   12735篇
建筑科学   11005篇
矿业工程   2615篇
能源动力   9228篇
轻工业   37830篇
水利工程   4788篇
石油天然气   7672篇
武器工业   30篇
无线电   43230篇
一般工业技术   82396篇
冶金工业   62946篇
原子能技术   8154篇
自动化技术   53853篇
  2021年   3624篇
  2020年   2686篇
  2019年   3091篇
  2018年   19022篇
  2017年   17841篇
  2016年   15187篇
  2015年   4684篇
  2014年   6545篇
  2013年   16066篇
  2012年   12744篇
  2011年   21466篇
  2010年   17968篇
  2009年   16432篇
  2008年   17911篇
  2007年   18498篇
  2006年   9888篇
  2005年   10051篇
  2004年   9202篇
  2003年   8875篇
  2002年   8305篇
  2001年   7484篇
  2000年   7141篇
  1999年   7133篇
  1998年   17789篇
  1997年   12995篇
  1996年   9992篇
  1995年   7436篇
  1994年   6692篇
  1993年   6517篇
  1992年   4794篇
  1991年   4765篇
  1990年   4515篇
  1989年   4564篇
  1988年   4484篇
  1987年   3836篇
  1986年   3815篇
  1985年   4519篇
  1984年   4263篇
  1983年   3865篇
  1982年   3646篇
  1981年   3844篇
  1980年   3674篇
  1979年   3554篇
  1978年   3611篇
  1977年   4236篇
  1976年   5620篇
  1975年   3314篇
  1974年   3122篇
  1973年   3182篇
  1972年   2710篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
Brambilla  G. 《Electronics letters》2002,38(17):954-956
The use of gratings written in tin-doped silica fibres as a thermometer for high-temperature applications is described. Measurements up to ~800°C show a significant advantage over conventional fibre gratings. A considerable blue-shift has been observed at high temperatures. If corrections for blue-shift are taken into account, the errors are smaller than ~2°C  相似文献   
92.
Exact pairwise error probability of space-time codes   总被引:9,自引:0,他引:9  
We describe a simple technique for the numerical calculation, within any desired degree of accuracy, of the pairwise error probability (PEP) of space-time codes over fading channels. This method applies also to the calculation of E[Q(√ξ)] for any nonnegative random variable ξ whose moment-generating function Φξ(s)=E[exp(-sξ)] is known. Its application to the multiple antenna independent Rayleigh-fading channel and to the Rayleigh block fading channel is discussed, and illustrated by two simple examples  相似文献   
93.
94.
95.
A method is given for calculating the monitoring reliability parameters (MRP) for an engineering system with allowance for the drift in the measurement error of the means of measurement (MM). The approach is based on introducing a biased MM error distribution into the traditional formulas for the conditional probabilities of spurious and unobserved failure. The bias at the center of the distribution is determined by the systematic error at the given instant. An example is given to illustrate the performance in MRP calculation.Translated from Izmeritel'naya Tekhnika, No. 1, pp. 12–13, January, 1994.  相似文献   
96.
97.
This paper presents a high-speed, small-area circuit specifically designed to identify the levels in the read out operation of a flash multilevel memory. The circuit is based on the analog computation of the Euclidean distance between the current read out from a memory cell and the reference currents that represent the different logic levels. An experimental version of the circuit has been integrated in a standard double-metal 0.7-μm CMOS process with a die area of only 140×100 μm2. Operating under a 5-V power supply, this circuit identifies the read-out current of a memory cell, and associates it with the appropriate logic level in 9 ns  相似文献   
98.
A modification to the `shape-invariant' sinusoidal speech model is proposed, whereby the phases of the component sinewaves used for the excitation are made to add coherently at each glottal closure. Applied to pitch and time-scale modification, higher quality synthetic speech is produced when large changes are required  相似文献   
99.
The authors report the design of a new current-mode A/D converter, based on a modified successive-approximations model, in 1.2 μm CMOS technology. The proposed circuit is characterised by good accuracy and fast dynamic performance, low power consumption and small occupation area. SPICE simulations allow the design approach to be validated and the electrical performance of the ADC to be predicted  相似文献   
100.
In four-color fluorescence-based automated DNA sequencing, a 4×4 filter matrix parameterizes the relationship between the dye-intensity signals of interest and the data collected by an optical imaging system. The filter matrix is important because the estimated DNA sequence is based on the dye intensities that can only be recovered via inversion of the matrix. Here, the authors present a calibration method for the estimation of the columns of this matrix, using data generated through a special experiment in which DNA samples are labeled with only one fluorescent dye at a time. Simulations and applications of the method to real data are provided, with promising results  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号