全文获取类型
收费全文 | 22986篇 |
免费 | 1993篇 |
国内免费 | 1313篇 |
专业分类
电工技术 | 810篇 |
综合类 | 1664篇 |
化学工业 | 3932篇 |
金属工艺 | 914篇 |
机械仪表 | 2728篇 |
建筑科学 | 1111篇 |
矿业工程 | 406篇 |
能源动力 | 1175篇 |
轻工业 | 452篇 |
水利工程 | 395篇 |
石油天然气 | 529篇 |
武器工业 | 592篇 |
无线电 | 1135篇 |
一般工业技术 | 3495篇 |
冶金工业 | 683篇 |
原子能技术 | 352篇 |
自动化技术 | 5919篇 |
出版年
2024年 | 80篇 |
2023年 | 414篇 |
2022年 | 551篇 |
2021年 | 852篇 |
2020年 | 771篇 |
2019年 | 735篇 |
2018年 | 636篇 |
2017年 | 834篇 |
2016年 | 931篇 |
2015年 | 899篇 |
2014年 | 1342篇 |
2013年 | 1535篇 |
2012年 | 1305篇 |
2011年 | 1833篇 |
2010年 | 1122篇 |
2009年 | 1314篇 |
2008年 | 1306篇 |
2007年 | 1412篇 |
2006年 | 1239篇 |
2005年 | 1034篇 |
2004年 | 950篇 |
2003年 | 781篇 |
2002年 | 656篇 |
2001年 | 527篇 |
2000年 | 464篇 |
1999年 | 459篇 |
1998年 | 385篇 |
1997年 | 288篇 |
1996年 | 256篇 |
1995年 | 230篇 |
1994年 | 177篇 |
1993年 | 166篇 |
1992年 | 135篇 |
1991年 | 133篇 |
1990年 | 95篇 |
1989年 | 113篇 |
1988年 | 79篇 |
1987年 | 41篇 |
1986年 | 44篇 |
1985年 | 22篇 |
1984年 | 33篇 |
1983年 | 22篇 |
1982年 | 27篇 |
1981年 | 13篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1959年 | 8篇 |
1956年 | 2篇 |
1955年 | 5篇 |
1951年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
61.
J.R. Red-Horse T.L. Paez 《Computer Methods in Applied Mechanics and Engineering》2008,197(29-32):2578
This article specifies a virtual structural dynamic subsystem and some systems, as well as mathematical models that approximately simulate them. The purpose is to define a setting for model validations conceived by participants in the Sandia National Laboratories Validation Workshop. Some broad guidelines for the model validations are set, as well as a regulatory requirement to be satisfied by the target system. Participants are directed to present techniques for subsystem model validation, to analytically predict whether or not the regulatory requirement will be met, and to estimate the likelihood of accuracy of the prediction. 相似文献
62.
This note presents a stabilizing decentralized model predictive control (MPC) algorithm for nonlinear discrete time systems. No information is assumed to be exchanged between local control laws. The stability proof relies on the inclusion of a contractive constraint in the formulation of the MPC problem. 相似文献
63.
Bingyong Yan Zuohua Tian Songjiao Shi 《International Journal of Electrical Power & Energy Systems》2008,30(5):343-360
In this paper, we propose a novel distributed robust fault detection and identification (RFDI) scheme for a class of nonlinear systems. Firstly, a detection and identification estimator—robust fault tracking approximator (RFTA) is designed for online health monitoring. A novel feature of the RFTA is that it can simultaneously detect and accurately identify the shape and magnitude of the fault and disturbance. Moreover, it takes less online training time compared with the traditional neural network based fault diagnosis schemes. For some distributed systems, a network of distributed estimators is constructed where the RFTA is embedded into each estimator. Then we use consensus filter to filter the outputs of each estimator. One of the most important merits of the consensus filter is that its outputs can dramatically improve the accuracy of fault detection and identification. Next, the stability of the distributed RFDI scheme is rigorously investigated. Finally, two numerical examples are given to illustrate the feasibility and effectiveness of the proposed approach. 相似文献
64.
The present paper studies a feedback regulation problem that arises in at least two different biological applications. The feedback regulation problem under consideration may be interpreted as an adaptive control problem for tuning bifurcation parameters, and it has not been studied in the control literature. The goal of the paper is to formulate this problem and to present some preliminary results. 相似文献
65.
Reset controllers are linear controllers that reset some of their states to zero when their input is zero. We are interested in their feedback connection with linear plants, and in this paper we establish fundamental closed-loop properties including stability and asymptotic tracking. This paper considers more general reset structures than previously considered, allowing for higher-order controllers and partial-state resetting. It gives a testable necessary and sufficient condition for quadratic stability and links it to both uniform bounded-input bounded-state stability and steady-state performance. Unlike previous related research, which includes the study of impulsive differential equations, our stability results require no assumptions on the evolution of reset times. 相似文献
66.
K.D. Do Author Vitae Z.P. Jiang Author Vitae Author Vitae H. Nijmeijer Author Vitae 《Automatica》2004,40(1):117-124
This paper presents a method to design an output-feedback controller that simultaneously solves global asymptotic stabilization and tracking of an underactuated omni-directional intelligent navigator—a spherical underwater vehicle moving in a horizontal plane (i.e. at a constant depth). The vehicle does not have a sway actuator and has only position and orientation measurements available. The control development is based on Lyapunov's direct method, backstepping technique and use of interconnected structure of the vehicle dynamics. Numerical simulations demonstrate the results. 相似文献
67.
68.
Analysis on steady-state and transient heat transfer on a flat plate at the middle of a parallel duct immersed in He II was performed for bath temperatures from 1.8 to 2.1 K at 101.3 kPa. Two-dimensional computer code named SUPER-2D developed by the authors based on the two-fluid model and the theory of mutual friction was used. Steady-state critical heat flux (CHF) and the time lag from the application of a step heat input to λ transition, that is called a lifetime, were obtained numerically for various step heat fluxes and for the channel gaps from 2 to 20 mm. Effect of the gap restriction on the CHF and the lifetime were clarified. The solutions were compared with the experimental data for the ducts with the same structures and the corresponding conditions. They agreed well with the experimental data. The heat transport mechanism in the parallel duct was clarified. 相似文献
69.
Er-Wei Bai Author Vitae 《Automatica》2003,39(9):1521-1530
This paper proposes a frequency domain algorithm for Wiener model identifications based on exploring the fundamental frequency and harmonics generated by the unknown nonlinearity. The convergence of the algorithm is established in the presence of white noise. No a priori knowledge of the structure of the nonlinearity is required and the linear part can be nonparametric. 相似文献
70.
Common sense sometimes predicts events to be likely or unlikely rather than merely possible. We extend methods of qualitative reasoning to predict the relative likelihoods of possible qualitative behaviors by viewing the dynamics of a system as a Markov chain over its transition graph. This involves adding qualitative or quantitative estimates of transition probabilities to each of the transitions and applying the standard theory of Markov chains to distinguish persistent states from transient states and to calculate recurrence times, settling times, and probabilities for ending up in each state. Much of the analysis depends solely on qualitative estimates of transition probabilities, which follow directly from theoretical considerations and which lead to qualitative predictions about entire classes of systems. Quantitative estimates for specific systems are derived empirically and lead to qualitative and quantitative conclusions, most of which are insensitive to small perturbations in the estimated transition probabilities. The algorithms are straightforward and efficient. 相似文献