全文获取类型
收费全文 | 3555篇 |
免费 | 684篇 |
国内免费 | 222篇 |
专业分类
电工技术 | 935篇 |
综合类 | 343篇 |
化学工业 | 104篇 |
金属工艺 | 138篇 |
机械仪表 | 491篇 |
建筑科学 | 164篇 |
矿业工程 | 56篇 |
能源动力 | 72篇 |
轻工业 | 49篇 |
水利工程 | 15篇 |
石油天然气 | 52篇 |
武器工业 | 36篇 |
无线电 | 651篇 |
一般工业技术 | 255篇 |
冶金工业 | 25篇 |
原子能技术 | 51篇 |
自动化技术 | 1024篇 |
出版年
2024年 | 45篇 |
2023年 | 96篇 |
2022年 | 142篇 |
2021年 | 175篇 |
2020年 | 191篇 |
2019年 | 151篇 |
2018年 | 156篇 |
2017年 | 200篇 |
2016年 | 158篇 |
2015年 | 216篇 |
2014年 | 274篇 |
2013年 | 279篇 |
2012年 | 313篇 |
2011年 | 292篇 |
2010年 | 199篇 |
2009年 | 181篇 |
2008年 | 176篇 |
2007年 | 222篇 |
2006年 | 167篇 |
2005年 | 154篇 |
2004年 | 135篇 |
2003年 | 112篇 |
2002年 | 96篇 |
2001年 | 87篇 |
2000年 | 56篇 |
1999年 | 42篇 |
1998年 | 35篇 |
1997年 | 17篇 |
1996年 | 29篇 |
1995年 | 12篇 |
1994年 | 6篇 |
1993年 | 20篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1979年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有4461条查询结果,搜索用时 31 毫秒
1.
To improve the convertibility of reconfigurable manufacturing system (RMS), the concept of delayed reconfigurable manufacturing system (D-RMS) was proposed. RMS and D-RMS are both constructed around part family. However, D-RMS may suffer from ultra-long system problem with unacceptable idle machines using generic RMS part families. Besides, considering the complex basic system structure of D-RMS, machine selection of D-RMS should be addressed, including dedicated machine, flexible machine, and reconfigurable machine. Therefore, a system design method for D-RMS based on part family grouping and machine selection is proposed. Firstly, a part family grouping method is proposed for D-RMS that groups the parts with more former common operations into the same part family. The concept of longest relative position common operation subsequence (LPCS) is proposed. The similarity coefficient among the parts is calculated based on LPCS. The reciprocal value of the operation position of LPCS is adopted as the characteristic value. The average linkage clustering (ALC) algorithm is used to cluster the parts. Secondly, a machine selection method is proposed to complete the system design of D-RMS, including machine selection rules and the dividing point decision model. Finally, a case study is given to implement and verify the proposed system design method for D-RMS. The results show that the proposed system design method is effective, which can group parts with more former common operations into the same part family and select appropriate machine types. 相似文献
2.
某出口型号交流电力机车牵引控制系统要求变流器控制逻辑具备接触器控制、牵引系统数据交互、变流器故障保护、变流器启动自检等功能。针对以上功能,基于MATLAB中的Simulink/Stateflow可视化编程工具进行牵引控制模型的搭建,遵循模块化编程理念,采用较少的程序代码编写实现复杂的逻辑控制模型,生成逻辑清晰的控制功能流程图,进行半实物仿真测试,增强控制模型的可靠性。通过该变流器产品型式试验检验,验证变流器控制逻辑的功能可以满足控制系统的需求。 相似文献
3.
4.
孙耀华 《石油地球物理勘探》2003,38(1):17-21
地震勘探技术应用可以分为以二维地震研究构造为主的地震勘探初级阶段、以地震地层学为主的地震勘探中级阶段、以三维地震油藏静态描述为主的地震勘探高级阶段、以地震储层研究为主的开发地震妆级阶段和以四维地震进行油藏监测为主的开发地震高级阶段。针对5个不同阶段的地质条件和地质任务,选择使用合理的地震勘探技术是有效提高勘探开发效益的重要途径。焉耆盆地的勘探开发体现了以地震勘探为主的思路,在勘探开发过程中重视了针对不同勘探开发阶段和不同的地质 地震技术,因此,在早期勘探开发中取得了很好的经济效益。 相似文献
5.
基于EAI的多层分布式应用与实现 总被引:5,自引:0,他引:5
针对目前大型企业各类应用迅速增加但应用之间缺乏有效通信的问题,采用企业应 用集成(EAI)技术,提出了4层分布式应用体系结构,实现流程自动化和松耦合的应用集成.文中首先从EAI技术和常见解决方案出发,详细阐述了表示层、企业门户、EAI总线层和数据源层的功能及软件结构,并结合电信业务运营支撑系统的实际需求,给出了J2EE平台下的应用实例开发.利用组件和容器的技术构建企业门户,通过工作流和企业Java组件(EJB)技术实现EAI总线,借助资源适配器完成应用之间的互连互通.该系统现已投入实际运行,取得了良好的应用效果. 相似文献
6.
有限冲激响应(FIR)滤波器设计遇到的难题是滤波要进行大量乘法运算,即使是在全定制的专用集成电路中也会导致过大的面积与功耗.对于用硬件实现系数是常量的专用滤波器,可以通过分解系数变为应用加、减和移位而实现乘法.FIR滤波器的复杂性主要由用于系数乘法的加法器/减法器的数量决定.而对于自适应FIR滤波器,大多数场合下可用数字信号处理器(DSP)或CPU通过软件编程的方法来实现,但是对于要求高速运算的场合,VLSI实现是很好的选择.基于这一考虑,可以用符号数的正则表示(CSD)码表示系数, 再利用可重构现场可编程门阵列(FPGA)技术实现.可重构结构的应用,能保证系统的其余部分同时处于运行状态时实现FIR滤波器系数的更新.文中利用CSD码和可重构思想,提出了用FPGA实现自适应FIR滤波器的一种方案. 相似文献
7.
Costas Chaikalis 《Wireless Personal Communications》2007,41(1):77-97
Reconfiguration concept represents reconfigurable functionalities of the radio interface for mobile radio systems. Particularly
for the physical layer, some possible reconfigurable architectures can be identified. We focus on outer interleaving for turbo
codes, which can improve their performance in flat Rayleigh fading environment. The larger the number of columns in the outer
interleaver, the better is the performance, but with the penalty of more complexity and delay. Furthermore, an incorrect choice
of the number of columns can increase the bit and frame error rates. Therefore, it would be advantageous to reconfigure the
outer interleaver in different operating environments with the optimum number of columns. Using two different data frame lengths,
in this contribution simulation results are presented for the four possible outer block interleaver configurations specified
for the 3GPP mobile standard in the case of flat Rayleigh fading channel. It is shown that different operating environments
require an optimum number of columns in terms of bit error rate and frame error rate performance. Finally, frame fade duration
is considered and the effect of the product of the Doppler frequency with the frame duration on the performance for the four
different 3GPP outer block interleaver configurations is discussed.
Costas Chaikalis was born in Athens, Greece, on March 7, 1973. He received the B.Sc. degree in electrical engineering in 1995 from Technological
Educational Institute of Lamia, Greece. He also received the M.Sc. and Ph.D. degrees from Department of Electronics and Telecommunications,
University of Bradford, Bradford, UK in 1999 and 2003, respectively. During his doctoral studies he worked as a Research Assistant
for Mobile Virtual Center of Excellence (Mobile VCE), Terminals Group, UK. Since 2003, he is a lecturer in the Department
of Electrical Engineering, Technological Educational Institute of Lamia, Greece. His research interests are in all areas of
mobile communications but especially in forward error correction coding, reconfigurable (software radio) architectures, cross
layer architectures and DSP applications. 相似文献
8.
9.
本文综述了近睥来国外工具磨床技术的发展现状,介绍了由CNC技术带来的几种新的磨削方法,分析了当代工具磨床典型产品的技术水平。 相似文献
10.
L. V. Chekalov Yu. I. Gromov V. V. Chekalov 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2007,41(3):176-179
Cleaning of TPP flue gases with bag filters capable of pulsed regeneration is examined. A new filtering element with a three-dimensional
filtering material formed from a needle-broached cloth in which the filtration area, as compared with a conventional smooth
bag, is increased by more than two times, is proposed. The design of a new FRMI type of modular filter is also proposed. A
standard series of FRMI filters with a filtration area ranging from 800 to 16,000 m2 is designed for an output more than 1 million m3/h of with respect to cleaned gas. The new bag filter permits dry collection of sulfur oxides from waste gases at TPP operating
on high-sulfur coals. The design of the filter makes it possible to replace filter elements without taking the entire unit
out of service.
__________
Translated from élektricheskie Stantsii, No. 3, March 2007, pp. 43–46. 相似文献