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   18168篇
  免费   2208篇
  国内免费   995篇
电工技术   1135篇
综合类   1243篇
化学工业   2948篇
金属工艺   830篇
机械仪表   894篇
建筑科学   1385篇
矿业工程   352篇
能源动力   434篇
轻工业   2433篇
水利工程   401篇
石油天然气   469篇
武器工业   139篇
无线电   2496篇
一般工业技术   2177篇
冶金工业   951篇
原子能技术   177篇
自动化技术   2907篇
  2024年   144篇
  2023年   410篇
  2022年   793篇
  2021年   1124篇
  2020年   870篇
  2019年   657篇
  2018年   647篇
  2017年   808篇
  2016年   730篇
  2015年   1009篇
  2014年   1190篇
  2013年   1431篇
  2012年   1373篇
  2011年   1507篇
  2010年   1228篇
  2009年   1028篇
  2008年   1048篇
  2007年   930篇
  2006年   822篇
  2005年   600篇
  2004年   386篇
  2003年   334篇
  2002年   351篇
  2001年   314篇
  2000年   208篇
  1999年   171篇
  1998年   220篇
  1997年   154篇
  1996年   112篇
  1995年   97篇
  1994年   74篇
  1993年   74篇
  1992年   61篇
  1991年   57篇
  1990年   44篇
  1989年   54篇
  1988年   29篇
  1987年   32篇
  1986年   23篇
  1985年   18篇
  1984年   12篇
  1983年   23篇
  1982年   23篇
  1981年   19篇
  1980年   26篇
  1979年   18篇
  1977年   13篇
  1976年   23篇
  1975年   9篇
  1972年   9篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
The basic structural units of the genome are nucleotides. A single nucleotide polymorphism (SNP) is a mutation at a single nucleotide position. This paper discusses several major problems in SNP data analysis and review some existing solutions in this work. Generally speaking, a rich set of SNP analysis problems are cast in the signal processing framework. Our objective is to offer a state-of-the art review on this topic from a signal processing viewpoint so that researchers in the signal processing field can grasp the important domain knowledge to overcome the barrier between the two fields  相似文献   
32.
一个安全有效的身份鉴别协议与对应的数字签名方案   总被引:3,自引:0,他引:3  
吴铤  于秀源 《通信学报》2002,23(7):70-75
本文利用二元一次不定方程和Schnorr身份鉴别协议,构造出一个新的身份鉴别协议,该协议在RSA问题和离散对数问题是难解的假设下是安全的,同时给出了所对应的数字签名方案。  相似文献   
33.
同等功率和照射时间条件下,在14只家兔大脑皮质运用伊文思蓝染料和超微结构观察方法进行血脑屏障改变的研究。结果表明:CO_2激光作用十分表浅,且激光作用后的水肿层血脑屏障改变是可逆的。  相似文献   
34.
Laguerre Functional Model has many advantages such as good approximation capability for the variances of system time‐delay, order and other structural parameters, low computational complexity, and the facility of online parameter identification, etc., so this model is suitable for complex industrial process control. A series of successful applications have been gained in linear and non‐linear predictive control fields by the control algorithm based on Laguerre Functional Model, however, former researchers have not systemically brought forward the theoretical analyses of the stability, robustness, and steady‐state performance of this algorithm, which are the keys to guarantee the feasibility of the control algorithm fundamentally. Aimed at this problem, we introduce the principles of the Incremental Mode Linear Laguerre Predictive Control (IMLLPC) algorithm, and then systemically propose the theoretical analyses and proofs of the stability and robustness of the algorithm, in addition, we also put forward the steady‐state performance analysis. At last, the control performances of this algorithm on two different physical industrial plants are presented in detail, and a number of experimental results validate the feasibility and superiority of IMLLPC algorithm. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
35.
Performance analysis of adaptive interleaving for OFDM systems   总被引:7,自引:0,他引:7  
We proposed a novel interleaving technique for orthogonal frequency division multiplexing (OFDM), namely adaptive interleaving, which can break the bursty channel errors more effectively than traditional block interleaving. The technique rearranges the symbols according to instantaneous channel state information of the OFDM subcarriers so as to reduce or minimize the bit error rate (BER) of each OFDM frame. It is well suited to OFDM systems because the channel state information (CSI) values of the whole frame could be estimated at once when transmitted symbols are framed in the frequency dimension. Extensive simulations show that the proposed scheme can greatly improve the performance of the coded modulation systems utilizing block interleaving. Furthermore, we show that the adaptive interleaving out performs any other static interleaving schemes, even in the fast fading channel (with independent fading between symbols). We derived a semi-analytical bound for the BER of the adaptive interleaving scheme under correlated Rayleigh fading channels. Furthermore, we discussed the transmitter-receiver (interleaving pattern) synchronization problem  相似文献   
36.
37.
The basic ideas underlying an Estelle-C compiler, which accepts an Estelle protocol specification and produces a protocol implementation in C, are presented. The implementation of the ISO (International Organization for Standardization) class-2 transparent protocol, using the semiautomatic approach, is discussed. A manual implementation of the protocol is performed and compared to the semiautomatic implementation. The semiautomatic approach to protocol implementation offers several advantages over the conventional manual one, including correctness and modularity in protocol implementation code, conformance to the specification, and reduction in implementation time. Finally, ongoing development of a new Estelle-C compiler is presented  相似文献   
38.
39.
Bench-scale tests were conducted with raw and beneficiated shales in an advanced multi-purpose research reactor. Raw Alabama shale and raw and beneficiated Indiana shales were retorted at 515 °C using hydrogen pressures of 4 and 7 MPa. Shale feed rates were 15 to 34 kg h−1. High oil yields and carbon conversions were achieved in all tests. Oil yield from Alabama shale hydroretorted at 7 MPa was 200% of Fischer assay. Raw and beneficiated Indiana shales hydroretorted at 7 MPa produced oil yields of 170 and 195% of Fischer assay respectively. Total carbon conversions were >70% for all tests conducted at 7 MPa.  相似文献   
40.
李婷 《绝缘材料》2003,36(6):14-16
在实践经验的基础上,分析了我国匝间绝缘短路的主要原因,提出在匝间绝缘的设计,制造工艺及耐压试验等工序采取合理措施,以提高匝间绝缘的可靠性。  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