全文获取类型
收费全文 | 289675篇 |
免费 | 77590篇 |
国内免费 | 49487篇 |
专业分类
电工技术 | 33850篇 |
技术理论 | 9篇 |
综合类 | 27681篇 |
化学工业 | 41753篇 |
金属工艺 | 30235篇 |
机械仪表 | 13617篇 |
建筑科学 | 20150篇 |
矿业工程 | 16367篇 |
能源动力 | 11536篇 |
轻工业 | 27566篇 |
水利工程 | 8969篇 |
石油天然气 | 19741篇 |
武器工业 | 4460篇 |
无线电 | 40708篇 |
一般工业技术 | 42830篇 |
冶金工业 | 12090篇 |
原子能技术 | 2360篇 |
自动化技术 | 62830篇 |
出版年
2024年 | 3110篇 |
2023年 | 6141篇 |
2022年 | 7952篇 |
2021年 | 9791篇 |
2020年 | 11848篇 |
2019年 | 20688篇 |
2018年 | 22571篇 |
2017年 | 24072篇 |
2016年 | 23301篇 |
2015年 | 23294篇 |
2014年 | 23141篇 |
2013年 | 23256篇 |
2012年 | 22775篇 |
2011年 | 20042篇 |
2010年 | 17841篇 |
2009年 | 14488篇 |
2008年 | 12463篇 |
2007年 | 11567篇 |
2006年 | 10848篇 |
2005年 | 9779篇 |
2004年 | 10913篇 |
2003年 | 9280篇 |
2002年 | 8772篇 |
2001年 | 7704篇 |
2000年 | 7361篇 |
1999年 | 7511篇 |
1998年 | 6629篇 |
1997年 | 5768篇 |
1996年 | 5520篇 |
1995年 | 5211篇 |
1994年 | 4241篇 |
1993年 | 3670篇 |
1992年 | 3381篇 |
1991年 | 2453篇 |
1990年 | 1944篇 |
1989年 | 1746篇 |
1988年 | 1349篇 |
1987年 | 511篇 |
1986年 | 440篇 |
1985年 | 326篇 |
1984年 | 220篇 |
1983年 | 161篇 |
1982年 | 204篇 |
1981年 | 184篇 |
1980年 | 131篇 |
1976年 | 233篇 |
1975年 | 208篇 |
1972年 | 237篇 |
1971年 | 127篇 |
1960年 | 205篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Juan Ding Yong He Shenhe Fu Xiangsheng Xie Haowen Liang Jianying Zhou 《Journal of the Society for Information Display》2022,30(2):159-167
Illumination is essential for modern life as colorful world is perceived by human visionary system. Display technology has been developing rapidly in recent decades, and the basic principle is related to the way that the image is illuminated and light is emanated. Traditional illumination is provided by different types of light sources, and the display image is visible in large viewing space until the emanating light decays to zero. This work proposes and demonstrates a novel illumination scheme for a display in which the displaying images are visible only in specific spatial regions. The directional backlight ensures the image propagating to specific direction while imaging visibility can be controlled to terminate abruptly at certain distance from the display screen while exerting no influence to nearby regions. The working principle for such an illumination scheme is the use of the modulated coherent directional backlight through an axicon lens. It is shown that the illumination scheme can robustly deliver carried image information to the designated viewing region. This new illumination scheme has many advantages over conventional illumination, including its usage for personal display, very lower energy consumption, as well as minimizing light hazard pollution. 相似文献
42.
43.
With the emergence of large-scale knowledge base, how to use triple information to generate natural questions is a key technology in question answering systems. The traditional way of generating questions require a lot of manual intervention and produce lots of noise. To solve these problems, we propose a joint model based on semi-automated model and End-to-End neural network to automatically generate questions. The semi-automated model can generate question templates and real questions combining the knowledge base and center graph. The End-to-End neural network directly sends the knowledge base and real questions to BiLSTM network. Meanwhile, the attention mechanism is utilized in the decoding layer, which makes the triples and generated questions more relevant. Finally, the experimental results on SimpleQuestions demonstrate the effectiveness of the proposed approach. 相似文献
44.
45.
Because of heat amount is different from peripheral to central of friction welding interface, which is leaded to vary the characterizations along that interface. Current study, respectively, focused on the effect of different friction pressure on micro-structural and mechanical properties of that friction welding joint interface. Presently, these friction pressures are 110, 130, 150 and 170 MPa while kept all other conditions constant. The effects of different friction pressure on welding interface characterization were investigated by EDX, SEM, tensile, compression, impact and hardness tests. The tensile tests carried out on the standardized test piece with diameter 6 mm and 8 mm, thus, compression tests were extracted from the positions of 0°, 45° 90° with test specimen of 4 mm diameter and 6.5 mm length at weld center. Whereas, the impact test pieces were picked up in two positions, the first one is symmetrical, which it obtained to the respect of the rotation axis and the interface, on the other hand, the second one is non-symmetrical with the axis of rotation and symmetrical to the interface, for making the notch head coincide with the center of the welded joint, The obtained results showed that with reducing of friction pressure will present lack of bonding increasing from peripheral toward the welding center, which will responsible on reducing of the mechanical properties such as tensile, compression and impact strength. 相似文献
46.
47.
目的研究蛋类礼盒包装结构的缓冲性能。方法以蛋类尺寸为基础,建立可发性聚乙烯(expandable polyethylene. EPE)缓冲单元结构和组合结构,进行静态仿真分析和实验验证,比较结构在形状、叠合层数、组合形式等参数变化时的载荷与位移。结果结构层数变化相同时,单元结构的极限载荷从143N增加到236 N,组合结构的极限载荷从224 N增加到476 N,均呈近线性增长。结论蛋类礼盒包装中,组合结构的承载能力优于单元结构,通过单元结构的组合,可满足不同蛋类的包装要求。 相似文献
48.
49.
50.
Science China Technological Sciences - Accurate modelling of lithium ion batteries is crucial for battery management in electric vehicles. Recent studies have revealed the fractional order nature... 相似文献