全文获取类型
收费全文 | 3069篇 |
免费 | 347篇 |
国内免费 | 285篇 |
专业分类
电工技术 | 329篇 |
综合类 | 252篇 |
化学工业 | 100篇 |
金属工艺 | 40篇 |
机械仪表 | 199篇 |
建筑科学 | 82篇 |
矿业工程 | 19篇 |
能源动力 | 63篇 |
轻工业 | 9篇 |
水利工程 | 27篇 |
石油天然气 | 18篇 |
武器工业 | 21篇 |
无线电 | 168篇 |
一般工业技术 | 327篇 |
冶金工业 | 83篇 |
原子能技术 | 2篇 |
自动化技术 | 1962篇 |
出版年
2024年 | 22篇 |
2023年 | 82篇 |
2022年 | 71篇 |
2021年 | 96篇 |
2020年 | 126篇 |
2019年 | 116篇 |
2018年 | 90篇 |
2017年 | 111篇 |
2016年 | 139篇 |
2015年 | 130篇 |
2014年 | 193篇 |
2013年 | 248篇 |
2012年 | 188篇 |
2011年 | 200篇 |
2010年 | 163篇 |
2009年 | 181篇 |
2008年 | 193篇 |
2007年 | 171篇 |
2006年 | 186篇 |
2005年 | 163篇 |
2004年 | 129篇 |
2003年 | 129篇 |
2002年 | 117篇 |
2001年 | 80篇 |
2000年 | 62篇 |
1999年 | 53篇 |
1998年 | 49篇 |
1997年 | 40篇 |
1996年 | 20篇 |
1995年 | 34篇 |
1994年 | 18篇 |
1993年 | 16篇 |
1992年 | 12篇 |
1991年 | 16篇 |
1990年 | 12篇 |
1989年 | 10篇 |
1988年 | 6篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 8篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有3701条查询结果,搜索用时 223 毫秒
121.
122.
Robust actuator fault isolation and management in constrained uncertain parabolic PDE systems 总被引:1,自引:0,他引:1
Sathyendra Ghantasala Author Vitae Author Vitae 《Automatica》2009,45(10):2368-42
This paper presents a methodology for the design of an integrated robust fault detection and isolation (FDI) and fault-tolerant control (FTC) architecture for distributed parameter systems modeled by nonlinear parabolic Partial Differential Equations (PDEs) with time-varying uncertain variables, actuator constraints and faults. The design is based on an approximate finite-dimensional system that captures the dominant dynamics of the PDE system. Initially, an invertible coordinate transformation-obtained through judicious actuator placement-is used to transform the approximate system into a form where the evolution of each state is excited directly by only one actuator. For each state, a robustly stabilizing bounded feedback controller that achieves an arbitrary degree of asymptotic attenuation of the effect of uncertainty is then synthesized and its constrained stability region is explicitly characterized in terms of the constraints, the actuator locations and the size of the uncertainty. A key idea in the controller synthesis is to shape the fault-free closed-loop response of each state in a prescribed fashion that facilitates the derivation of (1) dedicated FDI residuals and thresholds for each actuator, and (2) an explicit characterization of the state-space regions where FDI can be performed under uncertainty and constraints. A switching law is then derived to orchestrate actuator reconfiguration in a way that preserves robust closed-loop stability following FDI. Precise FDI rules and control reconfiguration criteria that account for model reduction errors are derived for the implementation of the FDI-FTC structure on the distributed parameter system. Finally, the results are demonstrated using a tubular reactor example. 相似文献
123.
Robust predictive control handles constrained systems that are subject to stochastic uncertainty but propagating the effects of uncertainty over a prediction horizon can be computationally expensive and conservative. This paper overcomes these issues through an augmented autonomous prediction formulation, and provides a method of handling probabilistic constraints and ensuring closed loop stability through the use of an extension of the concept of invariance, namely invariance with probability p. 相似文献
124.
This paper presents the retrieval method L-APOM which aims at characterizing the microphysical and optical properties of aerosol plumes from hyperspectral images with high spatial resolution. The inversion process is divided into three steps: estimation of the ground reflectance below the plume, characterization of the standard atmosphere (gases and background aerosols) and estimation of the plume aerosols properties. As using spectral information only is not sufficient to insure uniqueness of solutions, original constraints are added by assuming slow spatial variations of particles properties within the plume. The whole inversion process is validated on a large set of simulated images and reveals to remain accurate even in the worst cases of noise: relative estimation errors of aerosol properties remain between 10% and 20% in most cases. L-APOM is applied on a real AVIRIS hyperspectral image of a biomass burning plume for which in situ measurements are available. Retrieved properties appear globally consistent with measurements. 相似文献
125.
Gil Shklarski Sivan Toledo 《Computer Methods in Applied Mechanics and Engineering》2009,198(37-40):3084-3095
We present a method for computing the null space of finite element models, including models with equality constraints. The method is purely algebraic; it requires access to the element matrices, but not to the geometry or material properties of the model.Theoretical considerations show that under certain conditions, both the amount of computation and the amount of memory required by our method scale linearly with model size; memory scales linearly but computation scales quadratically with the dimension of the null space. Our experiments confirm this: the method scales extremely well on 3-dimensional model problems. In general, large industrial models do not satisfy all the conditions that the theoretical results assume; however, experimentally the method performs well and outperforms an established method on industrial models, including models with many equality constraints.The accuracy of the computed null vectors is acceptable, but the method is usually less accurate than a more naive (and computationally much more expensive) method. 相似文献
126.
Harmonic fields have been shown to provide effective guidance for a number of geometry processing problems. In this paper, we propose a method for fast updating of harmonic fields defined on polygonal meshes, enabling real-time insertion and deletion of constraints. Our approach utilizes the penalty method to enforce constraints in harmonic field computation. It maintains the symmetry of the Laplacian system and takes advantage of fast multi-rank updating and downdating of Cholesky factorization, achieving both speed and numerical stability. We demonstrate how the interactivity induced by fast harmonic field update can be utilized in several applications, including harmonic-guided quadrilateral remeshing, vector field design, interactive geometric detail modeling, and handle-driven shape editing and animation transfer with a dynamic handle set. 相似文献
127.
128.
In this paper, adaptive neural tracking control is proposed for a robotic manipulator with uncertainties in both manipulator dynamics and joint actuator dynamics. The manipulator joints are subject to inequality constraints, i.e., the joint angles are required to remain in some compact sets. Integral barrier Lyapunov functionals (iBLFs) are employed to address the joint space constraints directly without performing an additional mapping to the error space. Neural networks (NNs) are utilised to compensate for the unknown robot dynamics and external force. Adapting parameters are developed to estimate the unknown bounds on NN approximations. By the Lyapunov synthesis, the proposed control can guarantee the semi-global uniform ultimate boundedness of the closed-loop system, and the practical tracking of joint reference trajectory is achieved without the violation of predefined joint space constraints. Simulation results are given to validate the effectiveness of the proposed control scheme. 相似文献
129.
Recently, various autonomous mobile robots have been developed for practical use. To support the coexistence of robots and humans in real environments, we propose a concept named ‘Region with Velocity Constraints (RVC),’ which is set around hazardous areas. RVCs are regions where the velocities of the robot are constrained to predefined values. Inside the RVCs, the robot has to reduce its translational velocity to avoid predicted hazards such as collisions with obstacles, and to reduce its rotational velocity to prevent undesirable motions such as sharp turns. We also propose a motion planning method for navigating the mobile robot in an environment with RVCs based on the Navigation Function and Global Dynamic Window Approach. Our method generates a trajectory satisfying both translational and rotational velocity constraints to be compatible with the surroundings. Moreover, to demonstrate the validity of our method, we performed numerical simulations and experiments. 相似文献
130.
一种基于同类约束的半监督近邻反射传播聚类方法 总被引:1,自引:0,他引:1
以近邻反射传播 (Affinity propagation, AP) 聚类算法为基础, 提出了一种基于同类约束的半监督近邻反射传播聚类方法 (Semi-supervised affinity propagation clustering method with homogeneity constraints, HCSAP).该方法在聚类目标函数中引入同类约束项, 以保证聚类结果与同类集先验信息一致.利用最大和信任传播 (Max-sum belief propagation) 优化过程对目标函数进行求解, 导出同类约束下的吸引度 (Responsibility) 和归属度 (Availability) 的迭代方程.人工数据集和真实数据集上的实验结果表明本文所提方法的有效性. 相似文献