全文获取类型
收费全文 | 28021篇 |
免费 | 3909篇 |
国内免费 | 2431篇 |
专业分类
电工技术 | 5045篇 |
综合类 | 2826篇 |
化学工业 | 2127篇 |
金属工艺 | 339篇 |
机械仪表 | 1724篇 |
建筑科学 | 835篇 |
矿业工程 | 605篇 |
能源动力 | 483篇 |
轻工业 | 760篇 |
水利工程 | 331篇 |
石油天然气 | 525篇 |
武器工业 | 604篇 |
无线电 | 7927篇 |
一般工业技术 | 1274篇 |
冶金工业 | 478篇 |
原子能技术 | 183篇 |
自动化技术 | 8295篇 |
出版年
2024年 | 56篇 |
2023年 | 285篇 |
2022年 | 458篇 |
2021年 | 599篇 |
2020年 | 798篇 |
2019年 | 678篇 |
2018年 | 694篇 |
2017年 | 990篇 |
2016年 | 1163篇 |
2015年 | 1335篇 |
2014年 | 1895篇 |
2013年 | 1868篇 |
2012年 | 2454篇 |
2011年 | 2575篇 |
2010年 | 2077篇 |
2009年 | 2013篇 |
2008年 | 2054篇 |
2007年 | 2332篇 |
2006年 | 2006篇 |
2005年 | 1551篇 |
2004年 | 1199篇 |
2003年 | 1042篇 |
2002年 | 753篇 |
2001年 | 659篇 |
2000年 | 508篇 |
1999年 | 410篇 |
1998年 | 321篇 |
1997年 | 265篇 |
1996年 | 266篇 |
1995年 | 227篇 |
1994年 | 177篇 |
1993年 | 139篇 |
1992年 | 107篇 |
1991年 | 86篇 |
1990年 | 67篇 |
1989年 | 61篇 |
1988年 | 39篇 |
1987年 | 24篇 |
1986年 | 18篇 |
1985年 | 20篇 |
1984年 | 26篇 |
1983年 | 17篇 |
1982年 | 7篇 |
1981年 | 15篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1978年 | 8篇 |
1977年 | 5篇 |
1974年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 17 毫秒
101.
102.
设计IIR数字滤波器的遗传优化算法 总被引:2,自引:0,他引:2
提出了IIR数字滤波器设计的遗传优化法。这是一种模拟自然遗传和达尔文进化理论的随机并行优化算法。首先,详细描述了遗传算法并给出了计算步骤,然后将遗传算法用于IIR数字滤波器的优化设计,最后给出了模拟计算结果。 相似文献
103.
104.
本文提出了一种多变量鲁棒自校正解耦间接算法。它采用一种新的正则化和相对死区实现了鲁棒自校正解耦控制。这种方法可以使系统跟踪特性不受死区界和正则化因子的影响。本文还给出了算法的鲁棒性分析和仿真结果。 相似文献
105.
Ben J. A. Kr se Kai M. Compagner Franciscus C. A. Groen 《Robotics and Autonomous Systems》1993,11(3-4):221-230
This paper describes a robust and accurate ultrasonic sensing system for a mobile robot. The system continuously updates a local map of the environment in which obstacles are represented by straight lines or points in a robot centered coordinate frame. The presented algorithms use a Kalman filter for the reduction of the noise in the ultrasonic data and use a systematical error correction (‘bundle correction’) to reduce the uncertainty in obstacle direction. Experiments are carried out in simulation and with a real mobile robot system. Results show that the accuracy with which line parameters can be estimated is in the order of 1 degree for the orientation and about 2 cm for the position. The effect of the bundle correction is significant and maximal when the robot approaches walls under a small angle. 相似文献
106.
Conditions for stability of the extended Kalman filter and their application to the frequency tracking problem 总被引:1,自引:0,他引:1
Barbara F. La Scala Robert R. Bitmead Matthew R. James 《Mathematics of Control, Signals, and Systems (MCSS)》1995,8(1):1-26
The error dynamics of the extended Kalman filter (EKF), employed as an observer for a general nonlinear, stochastic discrete time system, are analyzed. Sufficient conditions for the boundedness of the errors of the EKF are determined. An expression for the bound on the errors is given in terms of the size of the nonlinearities of the system and the error covariance matrices used in the design of the EKF. The results are applied to the design of a stable EKF frequency tracker for a signal with time-varying frequency.This research was supported by the Co-operative Research Centre for Robust and Adaptive Systems ((CR)2 ASys). The authors wish to acknowledge the funding of the activities of (CR)2 ASys by the Australian Commonwealth Government under the Co-operative Research Centre Program. 相似文献
107.
本文对染料激光用调谐器进行了理论分析,提出了同时兼顾调谐灵敏度,输出光强度及输出激光线宽等因素的综合设计方案。 相似文献
108.
José Martínez-Aroza Ramón Román-Roldán 《Multidimensional Systems and Signal Processing》1995,6(1):7-35
A multiresolution analysis of digital gray-level images is presented. A gray-level multi-scale framework is determined from two main assumptions: the gray scale is binary at the finest spatial resolution, and the gray levels of composed regions are obtained additively. In order to interrelate the gray-level histograms of the same image at different resolutions, probabilistic linear models are developed, which are then applied for estimation. Linear-optimization theory is used as a way of constructing such models. A general procedure for image processing is sketched, based on gray-level estimation. A versatile algorithm for nonlinear filtering is derived. Some examples of prospective applications are given.This work was partially supported by grant TIC91-646 from the DGYCIT of the Spanish Government. 相似文献
109.
D.Z.-Y. Ting X. Cartoixà T.C. McGill D.L. Smith J.N. Schulman 《Journal of Computational Electronics》2002,1(1-2):147-151
The Rashba effect resonant tunneling diode is a candidate for achieving spin polarizing under zero magnetic field using only conventional non-magnetic III–V semiconductor heterostructures. We point out the challenges involved based on simple arguments, and offer strategies for overcoming these difficulties. We present modeling results that demonstrate the benefits of the InAs/GaSb/AlSb-based asymmetric resonant interband tunneling diode (a-RITD) for spin filtering applications. 相似文献
110.
Abstract— We have developed a process to fabricate optical components, such as a lens, prism, or diffuser, directly on to a glass substrate. Processes include precision mastering by diamond cutting and multi‐layer photopolymer (2P) molding to realize flat surfaces and the integration of multiple components with an alignment within a few micrometers. 相似文献