全文获取类型
收费全文 | 400319篇 |
免费 | 3989篇 |
国内免费 | 1400篇 |
专业分类
电工技术 | 7163篇 |
综合类 | 367篇 |
化学工业 | 60462篇 |
金属工艺 | 19865篇 |
机械仪表 | 12430篇 |
建筑科学 | 9048篇 |
矿业工程 | 2350篇 |
能源动力 | 8682篇 |
轻工业 | 31824篇 |
水利工程 | 4422篇 |
石油天然气 | 9946篇 |
武器工业 | 15篇 |
无线电 | 43965篇 |
一般工业技术 | 80625篇 |
冶金工业 | 75489篇 |
原子能技术 | 10557篇 |
自动化技术 | 28498篇 |
出版年
2021年 | 3018篇 |
2019年 | 2911篇 |
2018年 | 5157篇 |
2017年 | 5196篇 |
2016年 | 5668篇 |
2015年 | 3497篇 |
2014年 | 5967篇 |
2013年 | 16667篇 |
2012年 | 9420篇 |
2011年 | 12790篇 |
2010年 | 10390篇 |
2009年 | 11485篇 |
2008年 | 12053篇 |
2007年 | 12081篇 |
2006年 | 10782篇 |
2005年 | 9928篇 |
2004年 | 9540篇 |
2003年 | 9471篇 |
2002年 | 9368篇 |
2001年 | 9514篇 |
2000年 | 8868篇 |
1999年 | 9302篇 |
1998年 | 22544篇 |
1997年 | 16047篇 |
1996年 | 12296篇 |
1995年 | 9251篇 |
1994年 | 8200篇 |
1993年 | 8195篇 |
1992年 | 6164篇 |
1991年 | 6152篇 |
1990年 | 5860篇 |
1989年 | 5697篇 |
1988年 | 5604篇 |
1987年 | 4990篇 |
1986年 | 4975篇 |
1985年 | 5585篇 |
1984年 | 5168篇 |
1983年 | 4780篇 |
1982年 | 4426篇 |
1981年 | 4683篇 |
1980年 | 4412篇 |
1979年 | 4468篇 |
1978年 | 4590篇 |
1977年 | 5161篇 |
1976年 | 7110篇 |
1975年 | 4079篇 |
1974年 | 4044篇 |
1973年 | 4081篇 |
1972年 | 3564篇 |
1971年 | 3192篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
We have designed, developed, and tested a very promising thermal image analysis method for polygraph testing. The method achieved a correct classification rate of CCR= 84% on the test population to our avail. This method, once refined, can serve as an additional channel for increasing the reliability and accuracy of traditional polygraph examination. We extract subtle facial temperature fluctuation patterns through nonlinear heat transfer modeling. The modeling transforms raw thermal data to blood flow rate information. Then, we use the slope of the average periorbital blood flow rate as the feature of a binary classification scheme. The results come to support our previous laboratory findings about the importance of periorbital blood flow in anxious states. 相似文献
92.
93.
This letter further discusses the difference between different definitions of voltage unbalance. Contrary to an earlier letter (see P. Pillay et al., ibid., vol.5, p.50-1, 2001), it is concluded that different definitions may give significantly different results. The two IEEE definitions that were not discussed in the earlier letter give different results and both deviate significantly from the true value (ratio of negative, and positive-sequence voltage) when a zero-sequence component is present. 相似文献
94.
95.
96.
A. M. Pristrem N. I. Danilovich V. A. Labunov 《Journal of Engineering Physics and Thermophysics》1987,53(6):1464-1472
By using integral transform methods, an approach is developed to the solution of a problem on the temprature distribution in multilayer structures heated by cw scanning laser radiation, with phase transitions in the layers taken into account.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 53, No. 6, pp. 1000–1010, December, 1987. 相似文献
97.
The carrier sense multiple access with collision detection (CSMA-CD) protocol cannot be applied directly to radio channels because of the difficulty in sensing remote carrier in the presence of local transmission. Only recently, a new protocol called the CSMA with timesplit collision detection (CSMA-TCD) was introduced to overcome this problem on radio channels. This paper presents an extension of the CSMA-TCD protocol, called CSMA-TCD with multitone tree search (CSMA-TCD-MTTS). In CSMA-TCD, a preamble is transmitted before data transmission. For CSMA-TCD-MTTS, the preamble is modulated with one out ofN tones. In case of a collision, a resolution algorithm splits the terminals involved into anN -degree tree according to the tone chosen. This paper presents the throughput and approximate delay analysis of the CSMA-TCD-MTTS protocol. 相似文献
98.
Incremental transmission loss analysis has been used for decades, but recent interest in its application to loss allocation calls for new in-depth results. This paper demonstrates that, for incremental methods to be applied correctly in loss allocation, it is first necessary to specify the load distribution and loss supply strategies. Incremental loss allocation among bus power injections is shown to be arbitrary and, therefore, open to challenge as discriminatory. Loss allocation is possible among incremental loads and/or generators, but the proportion of the total losses assigned to either one is arbitrary. Unique, nonarbitrary incremental loss allocations are however possible among the "equivalent" incremental bilateral exchanges between generators and loads. From these basic components it is possible then to calculate the allocation among generators or loads in any specified proportion. The main results, although developed initially for small increments, are extended to large variations. Finally, a general incremental loss allocation algorithm is developed and tested 相似文献
99.
Aluminum and magnesium alloys are the base structural materials in aircraft and spacecraft engineering. The main stages of the development and introduction of light alloys are described. 相似文献
100.
In this paper, the authors present the results of experiments which clearly demonstrate a technical basis confirming that the carrier frequency harmonics data can be used for diagnostics relative to motor stator insulation degradation. 相似文献