全文获取类型
收费全文 | 149536篇 |
免费 | 19696篇 |
国内免费 | 9617篇 |
专业分类
电工技术 | 54367篇 |
技术理论 | 5篇 |
综合类 | 13021篇 |
化学工业 | 7592篇 |
金属工艺 | 3893篇 |
机械仪表 | 9626篇 |
建筑科学 | 5626篇 |
矿业工程 | 3992篇 |
能源动力 | 10652篇 |
轻工业 | 4688篇 |
水利工程 | 4003篇 |
石油天然气 | 3327篇 |
武器工业 | 1399篇 |
无线电 | 16988篇 |
一般工业技术 | 8171篇 |
冶金工业 | 3502篇 |
原子能技术 | 2373篇 |
自动化技术 | 25624篇 |
出版年
2024年 | 989篇 |
2023年 | 2605篇 |
2022年 | 4697篇 |
2021年 | 5211篇 |
2020年 | 5902篇 |
2019年 | 4899篇 |
2018年 | 4411篇 |
2017年 | 5885篇 |
2016年 | 6377篇 |
2015年 | 7147篇 |
2014年 | 11221篇 |
2013年 | 9803篇 |
2012年 | 12455篇 |
2011年 | 13102篇 |
2010年 | 9347篇 |
2009年 | 9584篇 |
2008年 | 9083篇 |
2007年 | 10452篇 |
2006年 | 9061篇 |
2005年 | 7243篇 |
2004年 | 5894篇 |
2003年 | 4716篇 |
2002年 | 3741篇 |
2001年 | 3175篇 |
2000年 | 2637篇 |
1999年 | 1858篇 |
1998年 | 1391篇 |
1997年 | 1133篇 |
1996年 | 1016篇 |
1995年 | 814篇 |
1994年 | 706篇 |
1993年 | 461篇 |
1992年 | 401篇 |
1991年 | 280篇 |
1990年 | 234篇 |
1989年 | 201篇 |
1988年 | 135篇 |
1987年 | 80篇 |
1986年 | 61篇 |
1985年 | 50篇 |
1984年 | 74篇 |
1983年 | 66篇 |
1982年 | 68篇 |
1981年 | 31篇 |
1980年 | 26篇 |
1979年 | 25篇 |
1978年 | 19篇 |
1977年 | 12篇 |
1959年 | 16篇 |
1951年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
Marcus T. Schmitz Bashir M. Al-Hashimi Petru Eles 《Design Automation for Embedded Systems》2002,6(4):401-424
In this paper, we introduce the LOPOCOS (Low Power Co-synthesis) system, a prototype CAD tool for system level co-design. LOPOCOS targets the design of energy-efficient embedded systems implemented as heterogeneous distributed architectures. In particular, it is designed to solve the specific problems involved in architectures that include dynamic voltage scalable (DVS) processors. The aim of this paper is to demonstrate how LOPOCOS can support the system designer in identifying energy-efficient hardware/software implementations for the desired embedded systems. Hence, highlighting the necessary optimization steps during design space exploration for DVS enable architectures. The optimization steps carried out in LOPOCOS involve component allocation and task/communication mapping as well as scheduling and dynamic voltage scaling. LOPOCOS has the following key features, which contribute to this energy efficiency. During the voltage scaling valuable power profile information of task execution is taken into account, hence, the accuracy of the energy estimation is improved. A combined optimization for scheduling and communication mapping based on genetic algorithm, optimizes simultaneously execution order and communication mapping towards the utilization of the DVS processors and timing behaviour. Furthermore, a separation of task and communication mapping allows a more effective implementation of both task and communication mapping optimizationsteps. Extensive experiments are conducted to demonstrate the efficiency of LOPOCOS. We report up to 38% higher energy reductions compared to previous co-synthesis techniques for DVS systems. The investigations include a real-life example of an optical flow detection algorithm. 相似文献
92.
93.
M. Stolpe K. Svanberg 《International journal for numerical methods in engineering》2003,57(5):723-739
This paper deals with topology optimization of discretized continuum structures. It is shown that a large class of non‐linear 0–1 topology optimization problems, including stress‐ and displacement‐constrained minimum weight problems, can equivalently be modelled as linear mixed 0–1 programs. The modelling approach is applied to some test problems which are solved to global optimality. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
94.
首先对OFDM的发展以及应用做了简要的介绍,然后讨论了当前OFDM研究过程中的两个关键技术问题,最后展望了OFDM的未来发展。 相似文献
95.
96.
S. M. Nikonov I. V. Elkin I. A. Lipatov A. V. Basov A. V. Kapustin A. A. Rovnov 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2007,41(6):351-354
Results of experiments conducted on a large-scale integral PSB-VVéR bench and directed toward investigation of the performance
of new passive safety systems for nuclear plants with a water-cooled power reactor, an additional system for passive flooding
of the active zone, and a system for the passive removal of heat from steam generators are presented.
__________
Translated from élektricheskie Stantsii, No. 9, September 2007, pp. 7–10. 相似文献
97.
简单回顾了国内外在火电机组运行优化领域的研究历程,列举了目前国内外市场上针对火电机组的各种主流运行优化产品的功能特点和应用情况,分析了国外引进产品和国内自主研发产品在中国当前市场环境下各自的优势和劣势。介绍了当前运行优化系统在国内电站机组的应用现状,阐述了国内外运行优化系统在实际应用中存在的问题,并提出了相应的改进意见。对机组运行优化系统的未来发展进行了展望,指出机组运行优化系统将利用先进技术设备和信息平台,与电站管理紧密结合,在日益规范的市场中不断发展完善,为提高电站经济性发挥更大的作用。 相似文献
98.
Understanding how the structure of the unit-cell affects the cryogenic performance of a Si power Metal Oxide Semiconductor Field Effect Transistor (MOSFET) is an important step toward optimizing of the device for cryogenic operations. In this paper, numerical simulations of the Si power Double Diffused MOSFET’ (DMOS) are performed at room temperature and cryogenic temperatures. Physically based models for temperature dependent silicon properties are employed in the simulations. The performances of power DMOS’ with various unit-cell structures are compared at both room temperature and low temperatures. The effect of the cell structure on the on-resistance and breakdown voltage of the device are analyzed. The simulation results suggest that the device optimized for room temperature operation can be further optimized at cryogenic temperatures. 相似文献
99.
Martijn Hendriks Barend van den Nieuwelaar Frits Vaandrager 《International Journal on Software Tools for Technology Transfer (STTT)》2006,8(6):633-647
For a case-study of a wafer scanner from the semiconductor industry it is shown how model checking techniques can be used
to compute (1) a simple yet optimal deadlock avoidance policy, and (2) an infinite schedule that optimizes throughput. in
the absence of errors. Deadlock avoidance is studied based on a simple finite state model using Smv, and for throughput analysis a more detailed timed automaton model has been constructed and analyzed using the Uppaal tool. The Smv and Uppaal models are formally related through the notion of a stuttering bisimulation. The results were obtained within 2 weeks, which
confirms once more that model checking techniques may help to improve the design process of realistic, industrial systems.
Methodologically, the case study is interesting since two models were used to obtain results that could not have been obtained
using only a single model.
Supported by the European Community Project IST-2001-35304 (Ametist), http://ametist.cs.utwente.nl/. 相似文献
100.
基于Agent的分布式查询优化研究 总被引:8,自引:0,他引:8
Internet上异构的软硬件环境以及多种并行机制对分布式查询优化技术提出了新的挑战,文章将分布式人工智能与数据库管理系统两个研究领域相结合,给出了基于Agent的分布式查询优化系统模型,在该系统中,Agent采用了典型的慎思型体系结构,即BDI模.Agent具有信念库,目标库并在此基础上进行学习和推理,多个Agent之间通过协调,协作以及协商以支持分布式数据库系统的动态查询优化和规划的执行,提高系统的查询效率。 相似文献