全文获取类型
收费全文 | 10711篇 |
免费 | 851篇 |
国内免费 | 99篇 |
专业分类
电工技术 | 211篇 |
综合类 | 44篇 |
化学工业 | 2946篇 |
金属工艺 | 239篇 |
机械仪表 | 422篇 |
建筑科学 | 383篇 |
矿业工程 | 21篇 |
能源动力 | 691篇 |
轻工业 | 1024篇 |
水利工程 | 195篇 |
石油天然气 | 163篇 |
武器工业 | 5篇 |
无线电 | 1123篇 |
一般工业技术 | 1844篇 |
冶金工业 | 309篇 |
原子能技术 | 74篇 |
自动化技术 | 1967篇 |
出版年
2024年 | 45篇 |
2023年 | 207篇 |
2022年 | 376篇 |
2021年 | 663篇 |
2020年 | 586篇 |
2019年 | 724篇 |
2018年 | 830篇 |
2017年 | 769篇 |
2016年 | 772篇 |
2015年 | 459篇 |
2014年 | 754篇 |
2013年 | 1132篇 |
2012年 | 715篇 |
2011年 | 796篇 |
2010年 | 539篇 |
2009年 | 455篇 |
2008年 | 280篇 |
2007年 | 230篇 |
2006年 | 184篇 |
2005年 | 130篇 |
2004年 | 117篇 |
2003年 | 81篇 |
2002年 | 77篇 |
2001年 | 57篇 |
2000年 | 38篇 |
1999年 | 42篇 |
1998年 | 60篇 |
1997年 | 31篇 |
1996年 | 48篇 |
1995年 | 36篇 |
1994年 | 23篇 |
1993年 | 23篇 |
1992年 | 23篇 |
1991年 | 36篇 |
1990年 | 25篇 |
1989年 | 24篇 |
1988年 | 21篇 |
1987年 | 20篇 |
1986年 | 25篇 |
1985年 | 26篇 |
1984年 | 23篇 |
1983年 | 25篇 |
1982年 | 19篇 |
1981年 | 18篇 |
1980年 | 14篇 |
1979年 | 17篇 |
1978年 | 10篇 |
1977年 | 14篇 |
1976年 | 10篇 |
1973年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
In this paper, a direct self‐structured adaptive fuzzy control is introduced for the class of nonlinear systems with unknown dynamic models. Control is accomplished by an adaptive fuzzy system with a fixed number of rules and adaptive membership functions. The reference signal and state errors are used to tune the membership functions and update them instantaneously. The Lyapunov synthesis method is also used to guarantee the stability of the closed loop system. The proposed control scheme is applied to an inverted pendulum and a magnetic levitation system, and its effectiveness is shown via simulation. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society 相似文献
62.
Shima Eshaghi Hamed Kharrati Mohammad Ali Badamchizadeh Iraj Hasanzadeh 《International Journal of Control, Automation and Systems》2012,10(3):574-581
In this paper a hybrid control strategy is presented based on Dynamic Matrix Control (DMC) and feedback linearization methods for designing a predictive controller of five bar linkage manipulator as a MIMO system (two inputs and two outputs). Analyzing the internal dynamic of robot shows the open loop system is unstable and non-minimum phase, so in order to apply the predictive controller, special modifications are needed. These modifications on non-minimum phase behavior are performed using feedback linearization procedure based on state space realization. The design objective is to track a desirable set point as well as time varying trajectories as a command references with globally asymptotical stabilization. The proposed controller is applied to nonlinear fully coupled model of the typical five bar linkage manipulator with non-minimum phase behavior. Simulation results show that the proposed controller has good efficiency. The step responses of system with and without feedback linearization process illustrated that the mentioned modification for stabilizing is performed properly. After applying the proposed predictive controller, the joint angle of robot tracks the reference input while another input acts as the disturbance and vice versa. 相似文献
63.
Prof. Dr. S. Darwish Dr. M. W. Khalil Dr. M. A. Abdel Rahim Porf. Dr. I. A. Ammar 《Materialwissenschaft und Werkstofftechnik》1989,20(9):299-308
A study on the value metal character of Zr in 0.1 M solutions of H2SO4, HNO3, and H3PO4 has been performed using the anode potential as the primary variable in galvanostatic, potentiostatic, and capacity measurements. A method of surface pre-treatment, which suppresses both O2 evolution and metal dissolution, has been described. Kinetic parameters of oxide growth have been calculated. The results indicate that:
- (i) the high field approximation is applicable following an exponential law, and
- (ii) the height and activation distance of the energy barrier for ion transport through the oxide phase (Verwey model) are the same three acids.
64.
Open Forum
Cheep! Cheep! 相似文献65.
66.
In this paper a hybrid finite element method is applied in evaluation of the stress intensity factors K
I
and K
II
of unidirectional fiber reinforced composites. In order to satisfy the stress singularity at the crack tip a singular super-element based on a modified complementary energy principle is developed. The stress and displacement fields in the super-element are expressed in terms of polynomials of two complex variables 1 and 2 in the transformed -plane. The stiffness matrix of the super-element was determined by using a line integral along the boundary of the super-element. The displacement vector was expressed in terms of the element nodal displacement vector {q} and a properly selected shape function defined along the element boundary.Numerical results for K
I
and K
II
of glass-epoxy and graphite-epoxy unidirectional composites with cracks along the diameter of a circular cut out as well as elliptical cut outs were evaluated
Résumé On applique, dans la présente étude, une méthode d'éléments finis hybrides à l'évaluation des facteurs d'intensité de contrainte KI et KII pour des composites renforcés de fibres unidirectionnelles. Pour tenir compte de la singularité de la contrainte à l'extrémité de la fissure, on développe un super élément singulier en se basant sur un principe modifié d'énergie complémentaire. Les champs de contraintes et de déplacements dans le super-élément sont exprimés sous forme polynormale de deux variables complexes 1, et 2 dans le plan de la transformée. La matrice de rigidité du super élément est, quant à elle, définie en utilisant une intégrale linéaire le long du contour de l'élément. Le vecteur de déplacement est exprimé par un vecteur (9) de déplacement nodal de l'élément, et par une fonction de forme appropriée, définie le long du contour de l'élément.On évalue les résultats numériques pour KI et KII, correspondant à des composites à fibres unidirection-nelles de types verre-epoxy et graphite-epoxy, oú des fissures se situeraient sur le diamètre de découpes circulaires et elliptiques相似文献
67.
Azizli Mohammad Javad Barghamadi Mohammad Rezaeeparto Katayoon Mokhtary Masoud Parham Somayeh Darabi Mehdi Joker 《Iranian Polymer Journal》2021,30(10):1001-1018
Iranian Polymer Journal - Effects of graphene oxide (GO) on various properties of rubber hybrid nanocomposites based on PVMQ/XNBR-g-GMA/XNBR (phenyl-vinyl-methyl-polysiloxane/carboxylated nitrile... 相似文献
68.
Esmat Koohsaryan Mansoor Anbia Mohammad Sepehrian Mohammad Maghsoodlu 《Journal of surfactants and detergents》2021,24(1):85-97
This study reports the preparation of hierarchical NaP zeolite with the aim of obtaining a non-phosphate detergent builder as an alternative for environmental remediation from eutrophication phenomenon. Hierarchically structured NaP zeolite was easily synthesized hydrothermally and under different syntheses conditions. Samples were characterized using several standard techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, and N2 adsorption–desorption analysis. Three powder detergents were prepared by mixing main components such as linear alkylbenzene sulfonate, sodium sulfate, sodium silicate, and sodium carbonate as well as different amounts of as-synthesized zeolite and sodium tripolyphosphate in the detergent formulation as potential detergency builders. Some different detergency tests as pH value, water insolubility, foam height, moisture content, alcohol insolubility, and surface tension measurement were carried out for all synthetic detergent samples and two commercial ones. The results demonstrated that the high cleaning performance of the powders was obtained as using eco-friendly zeolite builders in comparison with phosphate-based commercial and synthetic detergent samples. 相似文献
69.
This paper aims to provide a systematic and comprehensive survey of state-of-the-art machine learning techniques and their potential applications in IoT-integrated power systems. 相似文献
70.
Mohammadi Hossein Mohammadi Mohammad Amiri Iraj Sadegh Hosseinghadiry Mahdiar 《SILICON》2021,13(3):747-755
Silicon - In this paper, a new structure: triple work function metal gate SOI MESFET, intended for integration into the deep-submicron CMOS technology, is proposed. The gate of the device consists... 相似文献