全文获取类型
收费全文 | 5533篇 |
免费 | 523篇 |
国内免费 | 242篇 |
专业分类
电工技术 | 272篇 |
综合类 | 347篇 |
化学工业 | 936篇 |
金属工艺 | 352篇 |
机械仪表 | 275篇 |
建筑科学 | 352篇 |
矿业工程 | 131篇 |
能源动力 | 160篇 |
轻工业 | 540篇 |
水利工程 | 93篇 |
石油天然气 | 285篇 |
武器工业 | 26篇 |
无线电 | 505篇 |
一般工业技术 | 799篇 |
冶金工业 | 373篇 |
原子能技术 | 87篇 |
自动化技术 | 765篇 |
出版年
2024年 | 23篇 |
2023年 | 78篇 |
2022年 | 151篇 |
2021年 | 241篇 |
2020年 | 178篇 |
2019年 | 130篇 |
2018年 | 200篇 |
2017年 | 202篇 |
2016年 | 181篇 |
2015年 | 214篇 |
2014年 | 262篇 |
2013年 | 366篇 |
2012年 | 360篇 |
2011年 | 449篇 |
2010年 | 293篇 |
2009年 | 328篇 |
2008年 | 317篇 |
2007年 | 270篇 |
2006年 | 280篇 |
2005年 | 236篇 |
2004年 | 158篇 |
2003年 | 155篇 |
2002年 | 123篇 |
2001年 | 86篇 |
2000年 | 126篇 |
1999年 | 147篇 |
1998年 | 148篇 |
1997年 | 117篇 |
1996年 | 74篇 |
1995年 | 87篇 |
1994年 | 67篇 |
1993年 | 39篇 |
1992年 | 26篇 |
1991年 | 29篇 |
1990年 | 13篇 |
1989年 | 9篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 9篇 |
1985年 | 9篇 |
1984年 | 10篇 |
1983年 | 11篇 |
1982年 | 8篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1978年 | 10篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1974年 | 5篇 |
1972年 | 5篇 |
排序方式: 共有6298条查询结果,搜索用时 15 毫秒
1.
2.
Mengru Liu Weihai Zhang Limin Ma 《International Journal of Adaptive Control and Signal Processing》2022,36(1):69-87
The article investigates the finite-time adaptive fuzzy control for a class of nonlinear systems with output constraint and input dead-zone. First, by skillfully combining the barrier Lyapunov function, backstepping design method, and finite-time control theory, a novel adaptive state-feedback tracking controller is constructed, and the output constraint of the nonlinear system is not violated. Second, the fuzzy logic system is used to approximate unknown function in the nonlinear system. Third, the finite-time command filter is introduced to avoid the problem of “complexity explosion” caused by repeated differentiations of the virtual control signal in conventional backstepping control schemes. Meanwhile, a new saturation function is added in the compensating signal for filter error to improve control accuracy. Finally, based on Lyapunov stability analysis, all the signals of the closed-loop are proved to be semi-globally uniformly ultimately bounded, and the tracking error converges to a small neighborhood region of the origin in a finite time. A simulation example is presented to demonstrate the effectiveness for the proposed control scheme. 相似文献
3.
4.
Li Lei Limin Li Shasha Wang Gaoyang Zhao Yoshifumi Oshima Yang Ren Lei Zhao Lihua Jin Yao Wang Chengshan Li Pingxiang Zhang 《Journal of the European Ceramic Society》2018,38(14):4694-4700
Highly (100)-oriented Ce1-x(Y0.2Zr0.8)xOδ (CYZO) films were prepared on biaxially textured NiW substrates by a chemical solution deposition approach using metal inorganic salts as starting materials. It has been found that both the preferential orientation and surface roughness of CYZO films decrease gradually with increasing of the doping percentage of Y3+ and Zr4+ ions. The epitaxial growth relationship of (220)CYZO//(200)NiW and [00?l]CYZO//[001]NiW was demonstrated by XRD texture measurement as well as atomic resolution STEM observation. XRD, Raman and XPS spectra results indicate that Y3+ and Zr4+ ions were indeed introduced into CeO2 lattice to substitute Ce4+ ions and form cubic fluorite CYZO solid solution. Moreover, CeO2 buffer layer can be endowed a strong enough capability to prevent element diffusion through co-doping of yttrium and zirconium, provided that an optimal doping ratio of them is adopted. This will provide a new approach to fabricating strong-barrier single buffer layer for coated conductor. 相似文献
5.
6.
地震多次波压制方法技术应用研究 总被引:4,自引:0,他引:4
辽河盆地西部凹陷地质条件复杂,地震波场中多次波较发育,受其影响,主要目的层反射波干涉现象较严重,有效波难以识别,总体信噪比不高,给构造及岩性解释造成困难。对三维地震资料的处理研究表明,采用预测反褶积、F—K域多次波衰减技术及近道内切法等相结合的方法压制多次波是一种有效的途径。从资料处理效果看,剖面质量明显得到改善,证明该组合去噪技术是切实可行的。 相似文献
7.
8.
Physically based simulation of human hair is a well studied and well known problem. But the “pure” physically based representation of hair (and other animation elements) is not the only concern of the animators, who want to “control” the creation and animation phases of the content. This paper describes a sketch-based tool, with which a user can both create hair models with different styling parameters and produce animations of these created hair models using physically and key frame-based techniques. The model creation and animation production tasks are all performed with direct manipulation techniques in real-time. 相似文献
9.
10.
Nanofiber bundles of Ag2S, Ag2Se, and Ag have been successfully synthesized by making use of Ag2C2O4 template nanofiber bundles, utilizing both anion‐exchange and redox reactions. The obtained bundles were polycrystalline nanofibers composed of nanoparticles in which the precursor morphology was well‐preserved, indicating that Ag2C2O4 nanofiber bundles acted as a general sacrificial template for the synthesis of silver‐based semiconductor and metal nanofibers. Dispersing media and transforming reactants were found to be key factors influencing the chemical transformation in the system. In particular, separate single‐crystalline Ag nanofibers were obtained via a nontemplate route when ascorbic acid was used as a relatively weak reductant. An electrical transfer and switching device was built with the obtained Ag2S and Ag nanofiber bundles, utilizing the unique ion‐conductor nature of Ag2S and revealing their potential applications in electronics. 相似文献