全文获取类型
收费全文 | 54174篇 |
免费 | 5343篇 |
国内免费 | 2634篇 |
专业分类
电工技术 | 3495篇 |
技术理论 | 4篇 |
综合类 | 3668篇 |
化学工业 | 8599篇 |
金属工艺 | 3261篇 |
机械仪表 | 3712篇 |
建筑科学 | 4221篇 |
矿业工程 | 1733篇 |
能源动力 | 1693篇 |
轻工业 | 3905篇 |
水利工程 | 1158篇 |
石油天然气 | 2850篇 |
武器工业 | 558篇 |
无线电 | 6140篇 |
一般工业技术 | 6434篇 |
冶金工业 | 2573篇 |
原子能技术 | 814篇 |
自动化技术 | 7333篇 |
出版年
2024年 | 138篇 |
2023年 | 921篇 |
2022年 | 1528篇 |
2021年 | 2297篇 |
2020年 | 1760篇 |
2019年 | 1548篇 |
2018年 | 1731篇 |
2017年 | 1833篇 |
2016年 | 1735篇 |
2015年 | 2306篇 |
2014年 | 2889篇 |
2013年 | 3400篇 |
2012年 | 3932篇 |
2011年 | 4127篇 |
2010年 | 3599篇 |
2009年 | 3466篇 |
2008年 | 3269篇 |
2007年 | 3054篇 |
2006年 | 2893篇 |
2005年 | 2432篇 |
2004年 | 1827篇 |
2003年 | 1658篇 |
2002年 | 1733篇 |
2001年 | 1509篇 |
2000年 | 1204篇 |
1999年 | 1177篇 |
1998年 | 801篇 |
1997年 | 634篇 |
1996年 | 578篇 |
1995年 | 514篇 |
1994年 | 372篇 |
1993年 | 313篇 |
1992年 | 243篇 |
1991年 | 176篇 |
1990年 | 135篇 |
1989年 | 89篇 |
1988年 | 99篇 |
1987年 | 44篇 |
1986年 | 57篇 |
1985年 | 26篇 |
1984年 | 22篇 |
1983年 | 11篇 |
1982年 | 13篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 10篇 |
1977年 | 7篇 |
1975年 | 5篇 |
1970年 | 6篇 |
1951年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 906 毫秒
51.
52.
53.
Jianhuai Dong Zhixuan Dong 《International Journal of Adaptive Control and Signal Processing》2020,34(10):1466-1482
This article studies the optimal filtering and control for wireless networked control systems (WNCSs). In WNCSs, packets may be lost in both control and feedback channels and user datagram protocol is usually used to improve the performance of the real-time control. Relevant literature indicates that the conventional optimal filtering for such a system cannot be applied in practice due to the complex calculation with Gaussian mixtures. This paper proposes a novel scheme to realize the optimal filtering and the linear quadratic Gaussian control for WNCSs, in which the controlled node performs a local estimation and the remote-control node performs the final estimation and control, and a synchronization of two estimators is guaranteed by a communication mechanism. An optimal filtering algorithm is developed, the stability condition of the filtering error covariance is obtained, optimal finite-horizon and infinite-horizon control are derived, and the stability of the closed-loop control system is proved. Numerical simulations show the validity and feasibility of the theoretical results. 相似文献
54.
This paper considers a novel distributed iterative learning consensus control algorithm based on neural networks for the control of heterogeneous nonlinear multiagent systems. The system's unknown nonlinear function is approximated by suitable neural networks; the approximation error is countered by a robust term in the control. Two types of control algorithms, both of which utilize distributed learning laws, are provided to achieve consensus. In the provided control algorithms, the desired reference is considered to be an unknown factor and then estimated using the associated learning laws. The consensus convergence is proven by the composite energy function method. A numerical simulation is ultimately presented to demonstrate the efficacy of the proposed control schemes. 相似文献
55.
56.
Tuntun Wang Dr. Sitansu Sekhar Nanda Dr. Georgia C. Papaefthymiou Prof. Dong Kee Yi 《Chembiochem : a European journal of chemical biology》2020,21(9):1254-1264
The extracellular matrix (ECM) is a macromolecular network that can provide biochemical and structural support for cell adhesion and formation. It regulates cell behavior by influencing biochemical and physical cues. It is a dynamic structure whose components are modified, degraded, or deposited during connective tissue development, giving tissues strength and structural integrity. The physical properties of the natural ECM environment control the design of naturally or synthetically derived biomaterials to guide cell function in tissue engineering. Tissue engineering is an important field that explores physical cues of the ECM to produce new viable tissue for medical applications, such as in organ transplant and organ recovery. Understanding how the ECM exerts physical effects on cell behavior, when cells are seeded in synthetic ECM scaffolds, is of utmost importance. Herein we review recent findings in this area that report on cell behaviors in a variety of ECMs with different physical properties, i.e., topology, geometry, dimensionality, stiffness, and tension. 相似文献
57.
Chun Dong Hyun Rhim Geun Bae Youn Min Hye Deviana Deviana Lee Ji Eun Park Ji Chan Jeong Heondo 《Topics in Catalysis》2020,63(9-10):793-809
Topics in Catalysis - Fischer–Tropsch synthesis (FTS) is a promising way to produce clean liquid fuels and high value-added chemicals from low-value carbon-containing resources such as coal,... 相似文献
58.
地应力是影响巷道稳定性的重要因素之一。文章结合王庄煤矿+540采区实际工程地质条件,基于矩形巷道应力现场测试数据,对矩形巷道周围的应力变化进行了分析。并基于FLAC 3D和DDA数值模拟软件,分析了矩形巷道尺寸对围岩应力的影响,以及三维地应力水平对矩形巷道的稳定性。结果表明,在一定范围内,地应力侧压比λ与巷道顶板位移成正比,而超出这一范围,顶板位移随着λ值的增大反而减少。 相似文献
60.
Wenjie Wu Yan Liu Dong Liu Wenxing Chen Zhaoyi Song Ximin Wang Yamin Zheng Ning Lu Chunxia Wang Junjie Mao Yadong Li 《Nano Research》2021,14(4):998-1003
The demand for high-performance non-precious-metal electrocatalysts to replace the noble metal-based catalysts for oxygen reduction reaction(ORR)is intensively increasing.Herein,single-atomic copper sites supported on N-doped three-dimensional hierarchically porous carbon catalyst(Cu1/NC)was prepared by coordination pyrolysis strategy.Remarkably,the Cu1/NC-900 catalyst not only exhibits excellent ORR performance with a half-wave potential of 0.894 V(vs.RHE)in alkaline media,outperforming those of commercial Pt/C(0.851 V)and Cu nanoparticles anchored on N-doped porous carbon(CuNPs/NC-900),but also demonstrates high stability and methanol tolerance.Moreover,the Cu1/NC-900 based Zn-air battery exhibits higher power density,rechargeability and cyclic stability than the one based on Pt/C.Both experimental and theoretical investigations demonstrated that the excellent performance of the as-obtained Cu1/NC-900 could be attributed to the synergistic effect between copper coordinated by three N atoms active sites and the neighbouring carbon defect,resulting in elevated Cu d-band centers of Cu atoms and facilitating intermediate desorption for ORR process.This study may lead towards the development of highly efficient non-noble metal catalysts for applications in electrochemical energy conversion. 相似文献