收费全文 | 1512篇 |
免费 | 53篇 |
国内免费 | 7篇 |
电工技术 | 68篇 |
综合类 | 6篇 |
化学工业 | 264篇 |
金属工艺 | 31篇 |
机械仪表 | 45篇 |
建筑科学 | 29篇 |
矿业工程 | 1篇 |
能源动力 | 114篇 |
轻工业 | 122篇 |
水利工程 | 13篇 |
石油天然气 | 13篇 |
武器工业 | 1篇 |
无线电 | 159篇 |
一般工业技术 | 264篇 |
冶金工业 | 196篇 |
原子能技术 | 10篇 |
自动化技术 | 236篇 |
2024年 | 4篇 |
2023年 | 26篇 |
2022年 | 60篇 |
2021年 | 89篇 |
2020年 | 56篇 |
2019年 | 69篇 |
2018年 | 68篇 |
2017年 | 42篇 |
2016年 | 63篇 |
2015年 | 36篇 |
2014年 | 45篇 |
2013年 | 96篇 |
2012年 | 43篇 |
2011年 | 64篇 |
2010年 | 36篇 |
2009年 | 41篇 |
2008年 | 37篇 |
2007年 | 41篇 |
2006年 | 28篇 |
2005年 | 24篇 |
2004年 | 32篇 |
2003年 | 22篇 |
2002年 | 21篇 |
2001年 | 19篇 |
2000年 | 22篇 |
1999年 | 20篇 |
1998年 | 60篇 |
1997年 | 41篇 |
1996年 | 38篇 |
1995年 | 26篇 |
1994年 | 29篇 |
1993年 | 21篇 |
1992年 | 14篇 |
1991年 | 28篇 |
1990年 | 25篇 |
1989年 | 25篇 |
1988年 | 18篇 |
1987年 | 13篇 |
1986年 | 10篇 |
1985年 | 12篇 |
1984年 | 12篇 |
1983年 | 13篇 |
1982年 | 12篇 |
1981年 | 9篇 |
1979年 | 9篇 |
1978年 | 9篇 |
1976年 | 6篇 |
1973年 | 4篇 |
1972年 | 7篇 |
1966年 | 4篇 |
A brain–computer interface (BCI) provides a link between the human brain and a computer. The task of discriminating four classes (left and right hands and feet) of motor imagery movements of a simple limb-based BCI is still challenging because most imaginary movements in the motor cortex have close spatial representations. We aimed to classify binary limb movements, rather than the direction of movement within one limb. We also investigated joint time-frequency methods to improve classification accuracies. Neither of these, to our knowledge, has been investigated previously in BCI. We recorded EEG data from eleven participants, and demonstrated the classification of four classes of simple-limb motor imagery with an accuracy of 91.46% using intrinsic time-scale decomposition and 88.99% using empirical mode decomposition. In binary classifications, we achieved average accuracies of 89.90% when classifying imaginary movements of left hand versus right hand, 93.1% for left hand versus right foot, 94.00% for left hand versus left foot, 83.82% for left foot versus right foot, 97.62% for right hand versus left foot, and 95.11% for right hand versus right foot. The results show that the binary classification performance is slightly better than that of four-class classification. Our results also show that there is no significant difference in terms of spatial distribution between left and right foot motor imagery movements. There is also no difference in classification performances involving left or right foot movement. This work demonstrates that binary and four-class movements of the left and right feet and hands can be classified using recorded EEG signals of the motor cortex, and an intrinsic time-scale decomposition (ITD) feature extraction method can be used for real time brain computer interface.
相似文献Two-dimensional flow of Casson fluid toward an exponentially stretched surface in view of Cattaneo–Christove flux theory is discoursed in current communication. Flow pattern within boundary layer under the effectiveness of magnetic field is also contemplated in the communication. Non-dimensionalized governing expressions are attained through transformation procedure. To anticipate the fascinating features of present work, solution of resulted nonlinear differential system is computed with the collaborated help of shooting scheme and Runge–Kutta method. The influence of involved variables on velocity and temperature fields is scrutinized. Contribution of thermal relaxation is explicitly pointed out. Evaluation of convective heat transfer and friction factor in the fluid flow is visualized through graphs and tables. Additionally, the assurance of present work is affirmed by developing comparison with previous findings in the literature which sets a trade mark for the implementation of numerical approach. It is inferred from the thorough examination of the analysis that present formulation reduces to classical Fourier’s problem by considering \(\varLambda = 0\). Furthermore, decreasing pattern in temperature distribution is depicted in the presence of Cattaneo–Christove flux law as compared to heat transfer due to the Fourier’s law.
相似文献