全文获取类型
收费全文 | 3216篇 |
免费 | 446篇 |
国内免费 | 236篇 |
专业分类
电工技术 | 1084篇 |
技术理论 | 1篇 |
综合类 | 323篇 |
化学工业 | 298篇 |
金属工艺 | 146篇 |
机械仪表 | 205篇 |
建筑科学 | 135篇 |
矿业工程 | 77篇 |
能源动力 | 248篇 |
轻工业 | 49篇 |
水利工程 | 235篇 |
石油天然气 | 141篇 |
武器工业 | 18篇 |
无线电 | 262篇 |
一般工业技术 | 251篇 |
冶金工业 | 138篇 |
原子能技术 | 103篇 |
自动化技术 | 184篇 |
出版年
2024年 | 15篇 |
2023年 | 60篇 |
2022年 | 132篇 |
2021年 | 147篇 |
2020年 | 142篇 |
2019年 | 107篇 |
2018年 | 103篇 |
2017年 | 159篇 |
2016年 | 149篇 |
2015年 | 193篇 |
2014年 | 225篇 |
2013年 | 226篇 |
2012年 | 240篇 |
2011年 | 272篇 |
2010年 | 176篇 |
2009年 | 194篇 |
2008年 | 170篇 |
2007年 | 216篇 |
2006年 | 165篇 |
2005年 | 128篇 |
2004年 | 135篇 |
2003年 | 105篇 |
2002年 | 80篇 |
2001年 | 72篇 |
2000年 | 51篇 |
1999年 | 42篇 |
1998年 | 39篇 |
1997年 | 30篇 |
1996年 | 17篇 |
1995年 | 19篇 |
1994年 | 17篇 |
1993年 | 15篇 |
1992年 | 13篇 |
1991年 | 8篇 |
1990年 | 9篇 |
1989年 | 6篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1961年 | 1篇 |
1960年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有3898条查询结果,搜索用时 15 毫秒
1.
《International Journal of Hydrogen Energy》2022,47(91):38682-38689
A body-centered cubic equiatomic TiZrTaNbAl multi-principal element alloy (MPEA) with elemental fluctuations was investigated to further understand the relationship between the microstructure and hydrogen distribution. In this study, a composition dependence of the hydrogen distribution was observed in the TiZrTaNbAl MPEA. An inhomogeneous electron density distribution of the MPEA was revealed by advanced differential phase-contrast scanning electron microscopy (DPC-STEM) for the first time. The results showed that the electron density has a significant effect on the hydrogen distribution in TiZrTaNbAl MPEAs. This work provides new insight into the design of materials with high hydrogen storage capacity and high hydrogen embrittlement resistance. 相似文献
2.
Yixuan ZHOU Huajie WANG Yi YU Yihang CHEN Rui KE Min XU Chijie XIAO Zhanhui WANG Jiquan LI Xuru DUAN Minyou YE 《等离子体科学和技术》2021,23(7):75105-52
In this article, we present the optical design of a novel diagnostic on the HL-2 A tokamak, i.e. the20-channel edge Lyman-alpha beam emission spectroscopy, which is a promising solution for edge density turbulence research on tokamaks, as it offers the possibility of density fluctuation measurement with a 3.3 mm spatial resolution while maintains a high temporal resolution of1 μs. The optical path, including the reflective collection optics, the high-dispersion spectrometer, and the linear detector array, is carefully optimized to obtain a good image quality and a high throughput. The maximum root mean square radius of the collection optics is 64 μm.The detected photon flux is estimated to be about 10~(11) photons/s/channel. 相似文献
3.
墙体裂缝的成因及防治 总被引:2,自引:2,他引:0
介绍了墙体裂缝的种类,从地基不均匀下沉、温度变化等方面分析了引起墙体裂缝的原因,介绍了墙体裂缝的预防措施和治理措施,以有效控制墙体裂缝的危害程度。 相似文献
4.
5.
从原料与生产工艺过程分析了瓷质势光砖批量色差产生的原因,并提出了相应对策,为生产质量佳化提供一定的参考。 相似文献
6.
7.
The transit time of the coolant, and thus its velocity, has been measured using the temperature fluctuation at the outlet of a reactor core. An impulse response function estimation is introduced, which substitutes the widely used cross-correlation measurement technique. It is shown in theory and practice that the time delay estimation is improved when using the impulse response function instead of the cross-correlation function in parameter estimation. Extremely low velocities (down to 2 cm/sec) have been measured in a natural circulation regime in a research reactor. 相似文献
8.
The effect of the charge fluctuation of dust particles on ion acoustic wave (IAW) excited through ionization instability was investigated. The hydrodynamic equations and linear time-dependent perturbation theory served as the starting point of theory, by which the dispersion relation and growth rate of the IAW were given. By comparing the results with the case of constant dust charges, it was found that the charge fluctuation of dust particles reduces the instability of the wave mode. 相似文献
9.
Ting-Ting Gao Dan Wu Ying-Ling Huang De-Zhong Yao 《中国电子科技》2007,5(3):272-277
A nonlinear method named detrended fluctuation analysis (DFA) was utilized to investigate the scaling behavior of the human electroencephalogram (EEG) in three emotional music conditions (fear, happiness, sadness) and a rest condition (eyes-closed). The results showed that the EEG exhibited scaling behavior in two regions with two scaling exponents β1 and β2 which represented the complexity of higher and lower frequency activity besides α band respectively. As the emotional intensity decreased the value of β1 increased and the value of β2 decreased. The change of β1 was weakly correlated with the 'approach-withdrawal' model of emotion and both of fear and sad music made certain differences compared with the eyes-closed rest condition. The study shows that music is a powerful elicitor of emotion and that using nonlinear method can potentially contribute to the investigation of emotion. 相似文献
10.
尺度目标识别中的若干技术问题 总被引:1,自引:0,他引:1
从工程应用的角度阐述了现代鱼雷常用的尺度目标识别原理,讨论了影响识别距离的若干因素和措施,提出了小尺度模拟靶通过亮点延时算法以弥补尺度不足及其试验技术,试验结果表明,该方法可以获得良好效果。 相似文献