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   32249篇
  免费   3089篇
  国内免费   1489篇
电工技术   2278篇
技术理论   1篇
综合类   2029篇
化学工业   5478篇
金属工艺   1800篇
机械仪表   2027篇
建筑科学   2546篇
矿业工程   989篇
能源动力   877篇
轻工业   2418篇
水利工程   586篇
石油天然气   1673篇
武器工业   271篇
无线电   3964篇
一般工业技术   4101篇
冶金工业   1369篇
原子能技术   413篇
自动化技术   4007篇
  2024年   180篇
  2023年   652篇
  2022年   1289篇
  2021年   1533篇
  2020年   1201篇
  2019年   976篇
  2018年   1086篇
  2017年   1213篇
  2016年   991篇
  2015年   1377篇
  2014年   1740篇
  2013年   1908篇
  2012年   2074篇
  2011年   2145篇
  2010年   1819篇
  2009年   1824篇
  2008年   1792篇
  2007年   1568篇
  2006年   1641篇
  2005年   1334篇
  2004年   877篇
  2003年   888篇
  2002年   830篇
  2001年   733篇
  2000年   743篇
  1999年   801篇
  1998年   643篇
  1997年   552篇
  1996年   477篇
  1995年   433篇
  1994年   322篇
  1993年   248篇
  1992年   231篇
  1991年   147篇
  1990年   126篇
  1989年   115篇
  1988年   83篇
  1987年   52篇
  1986年   30篇
  1985年   36篇
  1984年   18篇
  1983年   21篇
  1982年   23篇
  1981年   7篇
  1980年   11篇
  1979年   6篇
  1978年   6篇
  1977年   7篇
  1975年   3篇
  1951年   4篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
本文运用一典型的人工神经网络模型─“反向传播”模型,对高氧化态(Ⅱ─Ⅳ)三核金属簇合物的构型分布进行了分析,得到了较好的分类、预报结果为化合物结构分析提供了新的工具。  相似文献   
3.
In this paper, we extend the original work on multiresolution learning for neural networks, and present new developments on the multiresolution learning paradigm. The contributions of this paper include: (1) proposing a new concept and method of adjustable neural activation functions in multiresolution learning to improve neural network learning efficacy and generalization performance for signal predictions; (2) providing new insightful explanations for the multiresolution learning paradigm from a multiresolution optimization perspective; (3) exploring underlying ideas why the multiresolution learning scheme associated with adjustable activation functions would be more appropriate for the multiresolution learning paradigm; and (4) providing rigorous validations to evaluate the multiresolution learning paradigm with adjustable activation functions and comparing it with the schemes of multiresolution learning with fixed activation functions and traditional learning. This paper presents systematically new analytical and experimental results on the multiresolution learning approach for training an individual neural network model, demonstrates our integral solution on neural network learning efficacy, and illustrates the significant improvements on neural networks' generalization performance and robustness for nonlinear signal predictions.  相似文献   
4.
TiO2 hybrid molecular imprinted polymer (MIP) for ethofumesate using methacrylic acid (MAA) as the functional monomer and silane coupling agent 3-(trimethoxysilyl) propylmethacrylate (KH570) as organic–inorganic connective bridge was synthesized via photo-excitation method. Hydrogen bond was proved to act between MAA and ethofumesate for pre- and post-polymerization binding properties as testified by UV spectrometric method. KH570 modified TiO2 nanoparticles were prepared via sonochemical reaction, which can accelerate hydrolysis, increase collision chance for the reactive system and improve the dispersion of the nanoparticles. Scanning electron microscope (SEM), transmission electron microscope (TEM), binding and the adsorption kinetics experiments as well as thermogravimetric analysis (TGA) were employed for characterization. The results indicated that the hybrid MIP revealed a larger surface area and more ordered imprinting cavities with improved thermal stability compared to organic-only MIP. Furthermore, faster adsorption kinetics and enhancive adsorption capacity were achieved, which made it promising in chemical sensor applications.  相似文献   
5.
A theoretical construction of one-to-many (OTM) and many-to-one (MTO) chaos synchronization communications using semiconductor lasers is presented. One center laser provides strong injections (strong link) to other side lasers, and the side lasers also provide weak injections (weak link) to the center one. Simulation results show that the side lasers synchronize with the center laser through injection-locking. In addition, messages transmitted via the strong links or the weak links experience strong chaos pass filtering, enabling us to realize OTM and MTO communications.  相似文献   
6.
7.
Evolving artificial neural network ensembles   总被引:3,自引:0,他引:3  
Using a coordinated group of simple solvers to tackle a complex problem is not an entirely new idea. Its root could be traced back hundreds of years ago when ancient Chinese suggested a team approach to problem solving. For a long time, engineers have used the divide-and-conquer strategy to decompose a complex problem into simpler sub-problems and then solve them by a group of solvers. However, knowing the best way to divide a complex problem into simpler ones relies heavily on the available domain knowledge. It is often a manual process by an experienced engineer. There have been few automatic divide-and-conquer methods reported in the literature. Fortunately, evolutionary computation provides some of the interesting avenues to automatic divide-and-conquer methods. An in-depth study of such methods reveals that there is a deep underlying connection between evolutionary computation and ANN ensembles. Ideas in one area can be usefully transferred into another in producing effective algorithms. For example, using speciation to create and maintain diversity had inspired the development of negative correlation learning for ANN ensembles, and an in-depth study of diversity in ensembles. This paper will review some of the recent work in evolutionary approaches to designing ANN ensembles.  相似文献   
8.
A clinical case control study to identify prognostic factors present at hospital admission associated with early sequelae and fatal outcome of acute Japanese encephalitis (JE) was carried out in Gusi county, Henan Province, central China from June to September 1991. A total of 70 patients with laboratory-confirmed acute JE were studied, of whom 3 cases died and 33 cases had neurological or psychiatric sequelae at the end of three months follow-up. The results showed that acute JE at younger age, with higher body temperature, high white cell count in CSF, and deep coma present at hospital admission were markers for unfavorable outcomes (sequelae or fatal). A history of the vaccination was not correlated with the early sequelae and fatal outcome of the disease. The paper suggests that early diagnosis and treatment and universal JE vaccination for all susceptible populations are keys for decreasing incidence of sequelae and fatal outcome of acute JE.  相似文献   
9.
本文概括地介绍了我国自70年代以来伺服元件的生产发展状况、元件的性能特点和应用情况,并分析了今后发展的趋势。  相似文献   
10.
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