全文获取类型
收费全文 | 17492篇 |
免费 | 2345篇 |
国内免费 | 1575篇 |
专业分类
电工技术 | 1341篇 |
综合类 | 2134篇 |
化学工业 | 384篇 |
金属工艺 | 229篇 |
机械仪表 | 857篇 |
建筑科学 | 733篇 |
矿业工程 | 359篇 |
能源动力 | 266篇 |
轻工业 | 296篇 |
水利工程 | 211篇 |
石油天然气 | 274篇 |
武器工业 | 195篇 |
无线电 | 6036篇 |
一般工业技术 | 825篇 |
冶金工业 | 357篇 |
原子能技术 | 81篇 |
自动化技术 | 6834篇 |
出版年
2024年 | 42篇 |
2023年 | 152篇 |
2022年 | 267篇 |
2021年 | 342篇 |
2020年 | 421篇 |
2019年 | 387篇 |
2018年 | 360篇 |
2017年 | 484篇 |
2016年 | 567篇 |
2015年 | 619篇 |
2014年 | 1006篇 |
2013年 | 999篇 |
2012年 | 1229篇 |
2011年 | 1283篇 |
2010年 | 1082篇 |
2009年 | 1113篇 |
2008年 | 1271篇 |
2007年 | 1420篇 |
2006年 | 1309篇 |
2005年 | 1153篇 |
2004年 | 1003篇 |
2003年 | 890篇 |
2002年 | 782篇 |
2001年 | 649篇 |
2000年 | 530篇 |
1999年 | 414篇 |
1998年 | 333篇 |
1997年 | 308篇 |
1996年 | 219篇 |
1995年 | 208篇 |
1994年 | 139篇 |
1993年 | 110篇 |
1992年 | 68篇 |
1991年 | 58篇 |
1990年 | 43篇 |
1989年 | 19篇 |
1988年 | 24篇 |
1987年 | 13篇 |
1986年 | 12篇 |
1985年 | 21篇 |
1984年 | 8篇 |
1983年 | 10篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1965年 | 2篇 |
1963年 | 4篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
101.
提出了ERP编码的原则,介绍了常见的四种编码方法:顺序码、分类码、结构码和组合码.最后结合实例介绍了编码系统中各模块的设计。 相似文献
102.
103.
氨合成塔出口氨含量偏低原因分析及对策 总被引:1,自引:0,他引:1
阐述UHDE合成塔运行现状 ,分析氨净值达不到设计值的原因 ,提出相应的解决措施 相似文献
104.
The unity gain buffer will be good to design high frequency SCF if its resistiveeffects can be eliminated,and therefore the whole parasitic sensitivities will greatly be reduced.On the basis of this concept,a novel parasitic tolerant SC DTE(differential transconductanceelement)is proposed.SC floating inductor and integrator fit for high frequency applications areformed by the DTE.The computer simulation and experiment on a third order elliptic LP filterverify its validity. 相似文献
105.
106.
107.
Multiple forms of a symbol-digit substitution task were used to provide a componential analysis of age differences in coding task performance. The results demonstrated age differences in feature encoding, memory, and visual search. A 2nd experiment was conducted with young adults to investigate a sensory deficit as a locus of age differences. The spatial contrast sensitivity deficit of older adults was simulated on forms by applying a digital filter. Persons in the age-simulated contrast condition performed worse than those in the normal contrast condition. The stimulus degradation effect was linked to visual search speed. The study illustrates the utility of componential analysis and offers direct support for the hypothesis that sensory deficits affect performance on tasks used to assess intelligence (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
108.
Multi-User MIMO Mobile CDMA Uplink System Employing Turbo Coding and Joint Detection Through a Multipath Rayleigh Fading Channel 总被引:1,自引:1,他引:0
Yasmine A. Fahmy Hebat-Allah M. Mourad Emad K. Al-Hussaini 《Wireless Personal Communications》2006,38(3):325-341
In this paper, a generalized multiple-input multiple-output (MIMO) antenna system that can be fitted to the uplink of a wireless communication system is considered for the general case of multi-user. At the transmitter, the information bits are Turbo coded, then interleaved and passed through a serial-to-parallel converter. The channel is assumed bad urban suffering from multipath Rayleigh fading resulting in inter-symbol and multiple access interferences (ISI and MAI). At the front-end of the receiver, a number of receiving antennas are used followed by a joint multi-user estimator based on the Minimum Mean Square Error Block Linear Equalizer (MMSE-BLE).Computer simulations demonstrate a significant performance improvement in both single user and multi-user cases.This paper depends in parts on that presented at the 11th European Wireless Conference, Cyprus, Nicosia, pp. 187–192, April 2005.
Yasmine A. Fahmy was born in Guiza, Egypt, on June 4, 1976. She received the B.Sc., M.Sc. and Ph.D. degrees in Communication and Electronics engineering from Cairo University, Egypt on 1999, 2001 and 2005 respectively. She is presently an assistant professor at Cairo University, Egypt. Her current field of interest is wireless communication and channel estimation.
Hebat-Allah M. Mourad received her B.Sc., M. Sc. and Ph.D. degrees in electrical communication engineering from Cairo University, Egypt, in 1983, 1987 and 1994 respectively. Since 1983, she has been with the Department of Electronics and Communications, Faculty of Engineering, Cairo University, and is currently associate professor there. Her research interests include optical fiber communications, mobile and satellite communications.
Emad K. Al-Hussaini received his B.Sc degree in Electrical Communication Engineering from Ain-Shams University, Cairo, Egypt, in 1964 and his M.Sc and Ph.D. degrees from Cairo University, Giza, Egypt, in 1974 and 1977, respectively. From 1964 to 1970, he was with the General Egyptian Aeroorganization. Since 1970, he has been with the Department of Electronics and Communications, Faculty of Engineering, Cairo University, and is currently professor there. He was a research fellow at Imperial College, London, UK, and at the Moore School of Electrical Engineering, University of Pennsylvania, Philadelphia, PA, USA, in the academic years 1976/1977 and 1981/1982, respectively. In 1990, he received the Egyptian national encouragement award for outstanding engineering research. He has written several papers for technical international journals and conferences. His research interests include signal processing, fading channel communication, modulation, and cellular mobile radio systems. Dr Al-Hussaini is a senior member of IEEE. He is listed in Marquis Whos Who in the World and in the IBC (International Biographical Center, Cambridge) for outstanding people of the 20th century. 相似文献
109.
The present situations of waste refrigerators recycling and disposing were analyzed. Three key technologies of layout design
of recycling plants of waste refrigerators were presented as follows: 1) establishment of recycling process of waste refrigerators;
2) the general plane layout of recycling plants; 3) the detailed layout of workshops of recycling plants. The focus of the
three key technologies is to tackle the problem of the detailed layout of workshops of the recycling plants. By adopting Petri
net, the model of logistics system of workshops was established and then optimized, and finally the detailed layout chart
of recycling plants was gained. By adopting E-factory, the recycling plants were simulated. The results show that the method
mentioned is effective.
Foundation item: Project(50375044) supported by the National Natural Science Foundation of China 相似文献
110.
Allen M. Johnson Michael A. Schoenfelder David J. Lebold 《Quality and Reliability Engineering International》1993,9(1):55-62
The Rainbow net simulation technique is applied to modelling the impact of system load and fault handling on the availability of a fault-tolerant multiprocessor architecture. Rainbow nets are described along with the motivation for creating this modelling technique. A Rainbow net fault-handling model is created for the fault-tolerant multiprocessor architecture and the topology is shown to remain constant in size, independent of the number of processor, memory and I/O elements configured in the system. Simulation is performed with a varying load in terms of the number of active jobs the system must support. Results are given showing how the fault-tolerant capability varies with load. Two new metrics for evaluating fault tolerance are introduced; namely full fault-tolerability and partial fault-tolerability. They are based on simple observations in the model. 相似文献