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71.
Gaussian process (GP) models form an emerging methodology for modelling nonlinear dynamic systems which tries to overcome certain limitations inherent to traditional methods such as e.g. neural networks (ANN) or local model networks (LMN).The GP model seems promising for three reasons. First, less training parameters are needed to parameterize the model. Second, the variance of the model's output depending on data positioning is obtained. Third, prior knowledge, e.g. in the form of linear local models can be included into the model. In this paper the focus is on GP with incorporated local models as the approach which could replace local models network.Much of the effort up to now has been spent on the development of the methodology of the GP model with included local models, while no application and practical validation has yet been carried out. The aim of this paper is therefore twofold. The first aim is to present the methodology of the GP model identification with emphasis on the inclusion of the prior knowledge in the form of linear local models. The second aim is to demonstrate practically the use of the method on two higher order dynamical systems, one based on simulation and one based on measurement data. 相似文献
72.
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
73.
Eitan Altman 《Discrete Event Dynamic Systems》2009,19(1):115-136
We consider in this paper a class of vector valued processes that have the form Y
n + 1 = A
n
( Y
n
) + B
n
. B
n
is assumed to be stationary ergodic and A
n
is assumed to have a divisibility property. This class includes linear stochastic difference equations as well as multi-type
branching processes (with a discrete or with a continuous state space). We derive explicit expressions for the probability
distribution as well as for the two first moments of state vectors at the stationary regime. We then apply this approach to
derive two formalisms to describe the infinite server queue. The first is based on a branching process approach adapted to
phase type service time distributions. The second is based on a linear stochastic difference equation and is adapted to independent
and generally distributed service times with bounded support. In both cases we allow for generally distributed arrival process
(not necessarily i.i.d. nor Markovian).
Eitan Altman Since 1990, Dr. Altman has been a researcher at INRIA (National research institute in informatics and control) in Sophia-Antipolis, France. He has served on the editorial boards of several scientific journals: WINET, COMNET, JDEDS, SIAM (SICON), Stochastic Models, and Journal of Economy Dynamic and Control (JEDC). Has been plenary speaker, (co)chairman of the program committee and general chair of various international conferences. Has received the best paper award in several conferences. His main interests are application of control, game theory and bio-inspired paradigms to networking. 相似文献
Eitan AltmanEmail: |
Eitan Altman Since 1990, Dr. Altman has been a researcher at INRIA (National research institute in informatics and control) in Sophia-Antipolis, France. He has served on the editorial boards of several scientific journals: WINET, COMNET, JDEDS, SIAM (SICON), Stochastic Models, and Journal of Economy Dynamic and Control (JEDC). Has been plenary speaker, (co)chairman of the program committee and general chair of various international conferences. Has received the best paper award in several conferences. His main interests are application of control, game theory and bio-inspired paradigms to networking. 相似文献
74.
75.
This paper is concerned with partial-information mixed optimal stochastic continuous–singular control problem for mean-field stochastic differential equation driven by Teugels martingales and an independent Brownian motion, where the Teugels martingales are a family of pairwise strongly orthonormal martingales associated with Lévy processes. The control variable has two components; the first being absolutely continuous, and the second singular. Partial-information necessary and sufficient conditions of optimal continuous–singular control for these mean-field models are investigated. As an illustration, this paper studies a partial-information linear quadratic control problem of mean-field type involving continuous–singular control. 相似文献
76.
77.
本文提供了一种检测操作系统中死锁的方法.该方法包含三个步骤:(1)通过检测进程加锁与解锁是否匹配来获得锁的持有者;(2)从异常进程中筛选出锁的等待者;(3)通过检查锁的持有者与等待者是否会形成循环等待图来判定死锁.通过实验发现,该方法对系统性能的影响小于l%,而且不需要修改内核源码和源程序. 相似文献
78.
Creating coordinated multiagent policies in environments with uncertainty is a challenging problem, which can be greatly simplified if the coordination needs are known to be limited to specific parts of the state space. In this work, we explore how such local interactions can simplify coordination in multiagent systems. We focus on problems in which the interaction between the agents is sparse and contribute a new decision-theoretic model for decentralized sparse-interaction multiagent systems, Dec-SIMDPs, that explicitly distinguishes the situations in which the agents in the team must coordinate from those in which they can act independently. We relate our new model to other existing models such as MMDPs and Dec-MDPs. We then propose a solution method that takes advantage of the particular structure of Dec-SIMDPs and provide theoretical error bounds on the quality of the obtained solution. Finally, we show a reinforcement learning algorithm in which independent agents learn both individual policies and when and how to coordinate. We illustrate the application of the algorithms throughout the paper in several multiagent navigation scenarios. 相似文献
79.
Yoshito Ohta Author vitae 《Automatica》2011,47(5):1001-1006
This paper studies the system transformation using generalized orthonormal basis functions that include the Laguerre basis as a special case. The transformation of the deterministic systems is studied in the literature, which is called the Hambo transform. The aim of the paper is to develop a transformation theory for stochastic systems. The paper establishes the equivalence of continuous and transformed-discrete-time stochastic systems in terms of solutions. The method is applied to the continuous-time system identification problem. It is shown that using the transformed signals the PO-MOESP subspace identification algorithm yields consistent estimates for system matrices. An example is included to illustrate the efficacy of the proposed identification method, and to make a comparison with the method using the Laguerre filter. 相似文献
80.
Fractional advection–dispersion equation (FADE) is a generalization of the classical ADE in which the first order time derivative and first and second order space derivatives are replaced by Caputo derivatives of orders 0<α?1, 0<β?1 and 1<γ?2, respectively. We use Caputo definition to avoid (i) mass balance error, (ii) hyper-singular improper integral, (iii) non-zero derivative of constant, and (iv) fractional derivative involved in the initial condition which is often ill-defined. We present an analytic algorithm to solve FADE based on homotopy analysis method (HAM) which has the advantage of controlling the region and rate of convergence of the solution series via the auxiliary parameter ? over the variational iteration method (VIM) and homotopy perturbation method (HPM). We find that the proposed method converges to the numerical/exact solution of the ADE as the fractional orders α, β, γ tend to their integral values. Numerical examples are given to illustrate the proposed algorithm. Example 5 describes the intermediate process between advection and dispersion via Caputo fractional derivative. 相似文献