全文获取类型
收费全文 | 18844篇 |
免费 | 2721篇 |
国内免费 | 2234篇 |
专业分类
电工技术 | 1804篇 |
综合类 | 2957篇 |
化学工业 | 908篇 |
金属工艺 | 284篇 |
机械仪表 | 1334篇 |
建筑科学 | 1846篇 |
矿业工程 | 206篇 |
能源动力 | 414篇 |
轻工业 | 170篇 |
水利工程 | 443篇 |
石油天然气 | 283篇 |
武器工业 | 231篇 |
无线电 | 2599篇 |
一般工业技术 | 2697篇 |
冶金工业 | 141篇 |
原子能技术 | 114篇 |
自动化技术 | 7368篇 |
出版年
2024年 | 107篇 |
2023年 | 277篇 |
2022年 | 351篇 |
2021年 | 410篇 |
2020年 | 651篇 |
2019年 | 615篇 |
2018年 | 605篇 |
2017年 | 782篇 |
2016年 | 875篇 |
2015年 | 779篇 |
2014年 | 1017篇 |
2013年 | 1509篇 |
2012年 | 1398篇 |
2011年 | 1360篇 |
2010年 | 1034篇 |
2009年 | 1143篇 |
2008年 | 1177篇 |
2007年 | 1356篇 |
2006年 | 1134篇 |
2005年 | 1058篇 |
2004年 | 857篇 |
2003年 | 765篇 |
2002年 | 622篇 |
2001年 | 626篇 |
2000年 | 599篇 |
1999年 | 448篇 |
1998年 | 369篇 |
1997年 | 388篇 |
1996年 | 284篇 |
1995年 | 247篇 |
1994年 | 206篇 |
1993年 | 151篇 |
1992年 | 140篇 |
1991年 | 106篇 |
1990年 | 79篇 |
1989年 | 61篇 |
1988年 | 38篇 |
1987年 | 16篇 |
1986年 | 22篇 |
1985年 | 13篇 |
1984年 | 24篇 |
1983年 | 8篇 |
1982年 | 19篇 |
1981年 | 12篇 |
1980年 | 18篇 |
1979年 | 15篇 |
1978年 | 12篇 |
1977年 | 11篇 |
1959年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
The object of study is nonlinear stationary controlled system of ordinary differential equations with constant disturbance in the right part. The problem of constructing the synthesising control function providing the transfer of this system from the initial state to the origin is considered. The sufficiently simple for numerical implementation algorithm of solution of the above-mentioned problem is obtained. It is shown that for local null controllability of the considered system, it is sufficient that the conditions of the Kalman's type were satisfied. In addition, the estimates restricting the choice of initial conditions and external disturbances under which the transfer is guaranteed are obtained. The main idea of the method of construction of the desired control function consists in reducing the original problem to stabilisation of a special kind linear non-stationary system and solving the Cauchy problem for an auxiliary system of ordinary differential equations closed by stabilising control. The simplicity of the realisation of this algorithm is determined by the construction of the auxiliary system and its stabilisation that could be obtained by analytical methods. The effectiveness of the method is illustrated by solving the problem of crane control and its numerical simulation. 相似文献
12.
This paper presents a control design for the one‐phase Stefan problem under actuator delay via a backstepping method. The Stefan problem represents a liquid‐solid phase change phenomenon which describes the time evolution of a material's temperature profile and the interface position. The actuator delay is modeled by a first‐order hyperbolic partial differential equation (PDE), resulting in a cascaded transport‐diffusion PDE system defined on a time‐varying spatial domain described by an ordinary differential equation (ODE). Two nonlinear backstepping transformations are utilized for the control design. The setpoint restriction is given to guarantee a physical constraint on the proposed controller for the melting process. This constraint ensures the exponential convergence of the moving interface to a setpoint and the exponential stability of the temperature equilibrium profile and the delayed controller in the norm. Furthermore, robustness analysis with respect to the delay mismatch between the plant and the controller is studied, which provides analogous results to the exact compensation by restricting the control gain. 相似文献
13.
Tong
Ma 《International Journal of Adaptive Control and Signal Processing》2020,34(9):1162-1181
A filtered adaptive constrained sampled-data controller for uncertain multivariable nonlinear systems in the presence of various constraints is synthesized in this paper. A piecewise constant adaptive law drives that estimation error dynamics to zero at each sampling time instant yields adaptive parameters. The filtered control scheme consists of two components. Based on an estimation/cancellation strategy, a disturbance rejection control law is designed to compensate the nonlinear uncertainties within the bandwidth of low-pass filters, whereas a constraint violation avoidance control law is designed to solve an online constrained optimization problem. Although a reduced sampling time helps to minimize the estimation error caused by the neglect of unknowns, the resulting aggressive signals put more restrictions on the control law. Greater sacrifice of tracking performance is required to satisfy the constraints. The constraints violation avoidance control law is in favor of a larger sampling time. Sufficient conditions are given to guarantee the stability of the closed-loop system with the sampled-data controller, where the input/output signals are held constant over the sampling period. Numerical examples are provided to validate the theoretical results, comparisons between the constrained sampled-data controller and unconstrained adaptive controller with the implementation of different sampling times are carried out. 相似文献
14.
Hashim A.
Hashim 《国际强度与非线性控制杂志
》2020,30(10):3848-3870
》2020,30(10):3848-3870
This paper introduces two novel nonlinear stochastic attitude estimators developed on the Special Orthogonal Group with the tracking error of the normalized Euclidean distance meeting predefined transient and steady‐state characteristics. The tracking error is confined to initially start within a predetermined large set such that the transient performance is guaranteed to obey dynamically reducing boundaries and decrease smoothly and asymptotically to the origin in probability from almost any initial condition. The proposed estimators produce accurate attitude estimates with remarkable convergence properties using measurements obtained from low‐cost inertial measurement units. The estimators proposed in continuous form are complemented by their discrete versions for the implementation purposes. The simulation results illustrate the effectiveness and robustness of the proposed estimators against uncertain measurements and large initialization error, whether in continuous or discrete form. 相似文献
15.
This paper proposes an original method for obtaining analytical approximations of the invariant probability density function of multi-dimensional Hamiltonian dissipative dynamic systems under Gaussian white noise excitations, with linear non-conservative parts and nonlinear conservative parts. The method is based on an exact result and a heuristic argument. Its pertinence is attested by numerical tests. 相似文献
16.
An analysis is made of the characteristic features and problems of the optimal processing of the results of measurements in the case of a random observation function utilizing a nonlinear Kalman filter. A method is proposed for increasing the convergence domain of the filter with additional processing of measurements in the frequency domain. 相似文献
17.
18.
19.
一种实现最佳用户检测的非线性优化神经网络 总被引:2,自引:0,他引:2
本文提出并讨论了实现码分多址(CDMA)系统上最佳多用户检测(MUD)的一种神经网络方法。该方法通过将最佳多用户检测视为非线性优化组合问题,利用神经网络能有效求解非线性优化问题的优势,导出了一种非线性优化神经网络来实现最佳多用户检测,理论分析和计算机模拟表明,所提出的神经网络具有可实时应用的动态性能和较传统方法优越得多的误码率性能和抗多址干扰的性能。 相似文献
20.
精细功能陶瓷的若干发展趋势 总被引:5,自引:1,他引:4
概括了分析自90年代初以来精细功能陶瓷的发展趋势,提出了一些相关的研究领域。 相似文献