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   41293篇
  免费   4281篇
  国内免费   2813篇
电工技术   2474篇
技术理论   2篇
综合类   3854篇
化学工业   6810篇
金属工艺   3111篇
机械仪表   1789篇
建筑科学   2875篇
矿业工程   1872篇
能源动力   1972篇
轻工业   3191篇
水利工程   1233篇
石油天然气   2487篇
武器工业   576篇
无线电   4101篇
一般工业技术   4432篇
冶金工业   2856篇
原子能技术   1027篇
自动化技术   3725篇
  2024年   146篇
  2023年   545篇
  2022年   1093篇
  2021年   1341篇
  2020年   1467篇
  2019年   1248篇
  2018年   1209篇
  2017年   1589篇
  2016年   1708篇
  2015年   1749篇
  2014年   2654篇
  2013年   2888篇
  2012年   3246篇
  2011年   3275篇
  2010年   2442篇
  2009年   2390篇
  2008年   2136篇
  2007年   2644篇
  2006年   2219篇
  2005年   1937篇
  2004年   1653篇
  2003年   1433篇
  2002年   1210篇
  2001年   1029篇
  2000年   881篇
  1999年   715篇
  1998年   620篇
  1997年   522篇
  1996年   488篇
  1995年   409篇
  1994年   305篇
  1993年   236篇
  1992年   218篇
  1991年   172篇
  1990年   139篇
  1989年   100篇
  1988年   66篇
  1987年   43篇
  1986年   42篇
  1985年   35篇
  1984年   30篇
  1983年   17篇
  1982年   17篇
  1981年   13篇
  1980年   16篇
  1978年   6篇
  1977年   3篇
  1975年   9篇
  1959年   8篇
  1951年   6篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
931.
Network State Estimation and Prediction for Real-Time Traffic Management   总被引:1,自引:0,他引:1  
Advanced Traveler Information Systems (ATIS) and Advanced Traffic Management Systems (ATMS) have the potential to contribute to the solution of the traffic congestion problem. DynaMIT is a real-time system that can be used to generate guidance for travelers. The main principle on which DynaMIT is based is that information should be consistent, and user optimal. Consistency implies that the traffic conditions experienced by the travelers are consistent with the condition assumed in generating the guidance. To generate consistent user optimal information, DynaMIT performs two main functions: state estimation and prediction. A demand simulator and a supply simulator interact to perform these tasks. A case study demonstrates the value of the system.  相似文献   
932.
路由选择的多Agent系统模型   总被引:17,自引:0,他引:17  
董军  潘云鹤 《计算机学报》2000,23(2):221-221,F003
路由选择是曜网的关键技术之一,其优劣直接影响着网络的接通率和负载平衡程度,我国长途电信网的率只有45%左右,链路的利用率又仅为30%~40%,据介绍,若其接通率提高一个百分点,收益可达10亿元,随着业务量的飞速增长,路由选择问题日益突出,文中在分析目前程控交换机使用的路由选择方法的不足的基础上,提出基于多Agent系统和神经网络预测的智能路由策略,介绍系统模型和选择方法,它因良好的分布特性和智能决  相似文献   
933.
无线Ad Hoc网络是一种无中心、自组织的多跳网络,其MAC层的研究是近年来的研究热点。在MAC层的研究中,有一些关键的技术问题有待解决,包括隐藏终端和暴露终端问题,公平性问题,QoS保证,速率自适应等。文章详细论述了每一个问题,并提供了一些解决的思路。  相似文献   
934.
Recently, a convex incremental algorithm (CI-ELM) has been proposed in Huang and Chen (Neurocomputing 70:3056–3062, 2007), which randomly chooses hidden neurons and then analytically determines the output weights connecting with the hidden layer and the output layer. Though hidden neurons are generated randomly, the network constructed by CI-ELM is still based on the principle of universal approximation. The random approximation theory breaks through the limitation of most conventional theories, eliminating the need for tuning hidden neurons. However, due to the random characteristic, some of the neurons contribute little to decrease the residual error, which eventually increase the complexity and computation of neural networks. Thus, CI-ELM cannot precisely give out its convergence rate. Based on Lee’s results (Lee et al., IEEE Trans Inf Theory 42(6):2118–2132, 1996), we first show the convergence rate of a maximum CI-ELM, and then systematically analyze the convergence rate of an enhanced CI-ELM. Different from CI-ELM, the hidden neurons of the two algorithms are chosen by following the maximum or optimality principle under the same structure as CI-ELM. Further, the proof process also demonstrates that our algorithms achieve smaller residual errors than CI-ELM. Since the proposed neural networks remove these “useless” neurons, they improve the efficiency of neural networks. The experimental results on benchmark regression problems will support our conclusions. The work is under the funding of Singapore MOE AcRF Tier 1 grant WBS No: R 252-000-221-112.  相似文献   
935.
936.
改进的RBF神经网络在磨矿指标预测中的应用   总被引:1,自引:0,他引:1  
针对选矿生产过程中磨矿生产率和磨矿浓度、介质填充率和料球比3个指标之间的关系,分析了磨矿生产率对磨矿过程产品质量和工作效率的影响,提出了磨矿过程预测模型,采用了模糊聚类与改进的遗传算法相结合训练RBF神经网络的新方法。仿真结果表明,该模型可以快速准确地预报生产状况,对于企业进行实时生产控制具有较高的实用价值。  相似文献   
937.
An online face recognition system is presented in the paper. To online face recognition system, we should consider the recognition rate, the image compression and image size. In the paper we researched the innovation technologies for face recognition system, including Kernel Principal Component Analysis (Kernel PCA), Delta low-pass wavelet filter, and face recognition algorithm using multiple images. Kernel PCA is derived to classify the characteristics of training images in the database. Delta low-pass wavelet filter is used to reduce the image size. A face recognition algorithm using multiple images is presented to improve the recognition rate. Simulation experiment shows that in the case of packet loss recognition rate is improved highly.  相似文献   
938.
Aihua Li  Yong Shi  Jing He   《Applied Soft Computing》2008,8(3):1259-1265
Cardholders’ behavior prediction is an important issue in credit card portfolio management. As a promising data mining approach, multiple criteria programming (MCLP) has been successfully applied to classify credit cardholders’ behavior into two groups. In order to better control credit risk for financial institutes, this paper proposes three methods based on MCLP to improve the “Bad” catching accuracy rate. One is called MCLP with unbalanced training set selection, the second is called fuzzy linear programming (FLP) method with moving boundary, and the third is called penalized multi criteria linear programming (PMCLP). The experimental examples demonstrate the promising performance of these methods.  相似文献   
939.
We obtain analytically the slip velocity (up to the second order) of shear-thinning fluids inside the periodically corrugated microtube by using the verified fluid model and boundary perturbation method. Our results show that, even the slip length being zero, there is a slip velocity which is proportional to the small amplitude of periodic corrugation, the (referenced) shear rate, the applied forcing, and the orientation or the angle. Our results could be applied to the flow control in microfluidics as well as biofluidics.  相似文献   
940.
Fire fighting work comprises work tasks requiring an energy yield at maximal or close to maximal levels of the individual. Due to the very nature of fire fighting more complex physiological variables are difficult to measure. We measured metabolic and respiratory responses in 15 male, professional fire fighters during simulated work tasks on a test ground. Work time was on the average 22 min with individual components of work tasks lasting 2-4 min. The mean oxygen consumption for the whole exercise (22 min) was 2.75+/-0.29 l/min. The most demanding work task demanded an oxygen uptake of 3.55+/-0.27 l/min. Corresponding values for respiratory minute volumes were 82+/-14 and 102+/-14l/min, respectively. Heart rates averaged 168+/-12 for the whole test and 179+/-13 beats/min for the heaviest work task. Two new classes for classification of intensive and exhausting, short term physical work are proposed for inclusion in ISO8996 and values for relevant parameters are proposed.  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