全文获取类型
收费全文 | 237365篇 |
免费 | 18302篇 |
国内免费 | 13621篇 |
专业分类
电工技术 | 34448篇 |
技术理论 | 23篇 |
综合类 | 23739篇 |
化学工业 | 11255篇 |
金属工艺 | 7358篇 |
机械仪表 | 18729篇 |
建筑科学 | 26642篇 |
矿业工程 | 9859篇 |
能源动力 | 6430篇 |
轻工业 | 6321篇 |
水利工程 | 9314篇 |
石油天然气 | 7219篇 |
武器工业 | 2922篇 |
无线电 | 18335篇 |
一般工业技术 | 11242篇 |
冶金工业 | 12404篇 |
原子能技术 | 1624篇 |
自动化技术 | 61424篇 |
出版年
2024年 | 812篇 |
2023年 | 2361篇 |
2022年 | 3972篇 |
2021年 | 5105篇 |
2020年 | 6047篇 |
2019年 | 4615篇 |
2018年 | 4154篇 |
2017年 | 6066篇 |
2016年 | 6932篇 |
2015年 | 7696篇 |
2014年 | 16781篇 |
2013年 | 14096篇 |
2012年 | 17194篇 |
2011年 | 18531篇 |
2010年 | 14014篇 |
2009年 | 14643篇 |
2008年 | 14621篇 |
2007年 | 17984篇 |
2006年 | 15949篇 |
2005年 | 13868篇 |
2004年 | 11632篇 |
2003年 | 10308篇 |
2002年 | 8259篇 |
2001年 | 6617篇 |
2000年 | 5553篇 |
1999年 | 4385篇 |
1998年 | 3278篇 |
1997年 | 2802篇 |
1996年 | 2222篇 |
1995年 | 1823篇 |
1994年 | 1517篇 |
1993年 | 1096篇 |
1992年 | 850篇 |
1991年 | 650篇 |
1990年 | 478篇 |
1989年 | 456篇 |
1988年 | 329篇 |
1987年 | 186篇 |
1986年 | 175篇 |
1985年 | 176篇 |
1984年 | 217篇 |
1983年 | 191篇 |
1982年 | 132篇 |
1981年 | 96篇 |
1980年 | 63篇 |
1979年 | 76篇 |
1978年 | 52篇 |
1977年 | 62篇 |
1964年 | 18篇 |
1959年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
81.
In this paper, we proposed a robust discrete-time controller. This control system, which is derived from the idea of the normalized plant, does not include plant parameters. Thus, we obtain a control system independent of plant parameters and that has the same structure as a conventional optimal servo control system. Simulation and experimental results show that the proposed method is fairly robust to plant parameter variations and external disturbances. 相似文献
82.
按照管道加工工艺的不同,管道可分为内径控制管和外径控制管。通过热轧工艺生产的外径控制无缝钢管,可满足火力发电厂汽水系统中绝大部分管道的使用要求。对于超(超)临界机组的主蒸汽和高温再热蒸汽管道采用的P91/P92材质的大口径厚壁无缝钢管,由于对材料性能和加工工艺有特殊要求,因此宜采用内径控制管。 相似文献
83.
As well-known disturbance rejection methods, active disturbance rejection control and disturbance observer-based control can effectively improve the control performances of complex systems in the presence of disturbances. However, the accurate rejection of multiple disturbances for control systems of practical engineering, for example, the attitude control system of flexible spacecraft, is still a bottleneck problem. In order to further improve the anti-disturbance capability and reduce the conservativeness, this paper proposes a novel enhanced anti-disturbance control law for the attitude control system of flexible spacecraft by combining active disturbance rejection control and disturbance observer-based control in a unified framework. More specifically, the disturbance from flexible vibration is described by an uncertain exogenous system based on the partially known information including elastic damping ratios and modal frequencies. The disturbance observer-based control is utilized to estimate and thereby reject this disturbance. On the other hand, the other disturbances such as external environmental disturbance and complex model nonlinearity are merged into a equivalent disturbance with bounded derivative, which is compensated by using the active disturbance rejection control law. Stability and robustness analysis are carried out for the disturbance observer and extended state observer. Finally, simulation results of low-earth-orbit flexible satellite are presented to verify the effectiveness of proposed methods. 相似文献
84.
The objective of this paper is to review and document the mine fleet management systems’ models and algorithms. The purpose is to understand the algorithms behind the fleet management systems and the proposed academic solutions in this area to identify any gaps in the current literature and to open up opportunities to establish research questions that need to be addressed in an integrated simulation and optimisation operational planning research framework. In this paper, we review industrial fleet management systems and the main academic algorithms behind such systems. The fleet management systems are divided into three subsequently related problems to review: shortest path, production optimisation and real-time dispatching. Finally, the limitations of current algorithms for fleet management systems are documented in terms of mining practice feasibility and optimality of the solution on large-scale problems. The results of this literature review enable us to evaluate the logical links between major components of an integrated simulation and optimisation operational planning framework with current theory of fleet management systems. 相似文献
85.
Debadyuti Das 《国际生产研究杂志》2018,56(17):5776-5794
The present work is an attempt to investigate the adoption of sustainable supply chain management (SSCM) practices amongst manufacturing and process based organisations in India and its impact on organisational performance encompassing all three dimensions of sustainability. SSCM practices conceived in the present study include environmental management practices (EMP), socially inclusive practices for employees (SPE), socially inclusive practices for community (SPC), operations practices (OP) and supply chain integration (SCI) which were treated as exogenous variables. Organisational performance considered in this study includes five dimensions, namely environmental performance (EPR), employee-centred social performance (ESP), community-centred social performance (CSP), operations performance (OPR) and competitiveness, which were regarded as endogenous variables. The analysis was carried out with the help of structural equation modelling considering natural logarithm of manpower as a control variable. Few major findings are mentioned. EMP does not have any significant association with OPR, nor does it result in competitiveness. However, when jointly mediated through both EPR and OPR, EMP leads to competitiveness. SPC has significant negative association with competitiveness, when only direct relationship is considered. However, indirect relationship between SPC and competitiveness shows significant positive association when mediated through CSP. The resultant total effect between SPC and competitiveness turns out to be insignificant. Further, OPR fully mediates the relationship between OP and competitiveness. Managerial implications of the findings are discussed. 相似文献
86.
The present paper concerns the induction of stable sustained oscillation in feedback-linearizable single-input affine nonlinear dynamical systems via continuous-time state feedback control. The proposed application-oriented control approach is based on the conception of a state feedback controller that ensures the tracking of a limit cycle characterized in terms of the feedback-linearized system. Boundedness and convergence of the closed-loop trajectories are established following the Lyapunov theoretical framework and applying LaSalle׳s stability principle. The proposed approach is demonstrated with computer-simulated control experiments, showing that it ensures the convergence of the state trajectories of the controlled system to a designed limit cycle and that the methodology can, in principle, be applied to any single input feedback linearizable system. 相似文献
87.
Seong‐Hee Kim 《Quality and Reliability Engineering International》2015,31(6):923-934
We present a distribution‐free tabular cumulative sum chart for monitoring the variability of an autocorrelated process. A quantity known as the asymptotic variance parameter is employed as a measure of the variability, and a distribution‐free tabular cumulative sum chart is applied to variance estimates calculated from batches of nonoverlapping samples. The proposed chart is applicable to a stationary process with a general marginal distribution and a general autocorrelation structure. It also determines control limits analytically without trial‐and‐error simulations. The performance of the proposed chart is tested on stationary processes with both normal and nonnormal marginals with various autocorrelation structures. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
88.
This article presents a new approach for solving the Optimal Control Problem (OCP) of linear time-delay systems with a quadratic cost functional. The proposed method can also be used for designing optimal control time-delay systems with disturbance. In this study, the Variational Iteration Method (VIM) is employed to convert the original Time-Delay Optimal Control Problem (TDOCP) into a sequence of nonhomogeneous linear two-point boundary value problems (TPBVPs). The optimal control law obtained consists of an accurate linear feedback term and a nonlinear compensation term which is the limit of an adjoint vector sequence. The feedback term is determined by solving Riccati matrix differential equation. By using the finite-step iteration of a nonlinear compensation sequence, we can obtain a suboptimal control law. Finally, Illustrative examples are included to demonstrate the validity and applicability of the technique. 相似文献
89.
Rui
Zhang Junmin Li Jianmin Jiao 《International Journal of Adaptive Control and Signal Processing》2020,34(7):919-936
This article investigates an adaptive fuzzy tracking control problem for a class of nontriangular form systems with asymmetric time-varying full state constraints. Unknown functions are approximated by the fuzzy logic systems. A domination approach is employed to tackle the nontriangular form structure. Time-varying asymmetric barrier Lyapunov functions (ABLFs) are adopted to ensure full-state constraints satisfaction. Based on the backstepping technique and time-varying ABLFs, an adaptive controller is proposed and guarantees that all the signals in the closed-loop system are ultimately bounded and the time-varying full state constraints are met. Simulation examples are presented to further demonstrate the effectiveness of the proposed approach. 相似文献
90.