全文获取类型
收费全文 | 22426篇 |
免费 | 3751篇 |
国内免费 | 3109篇 |
专业分类
电工技术 | 3558篇 |
综合类 | 2610篇 |
化学工业 | 688篇 |
金属工艺 | 1394篇 |
机械仪表 | 1657篇 |
建筑科学 | 452篇 |
矿业工程 | 329篇 |
能源动力 | 288篇 |
轻工业 | 417篇 |
水利工程 | 233篇 |
石油天然气 | 368篇 |
武器工业 | 420篇 |
无线电 | 4302篇 |
一般工业技术 | 1560篇 |
冶金工业 | 1651篇 |
原子能技术 | 55篇 |
自动化技术 | 9304篇 |
出版年
2024年 | 199篇 |
2023年 | 532篇 |
2022年 | 719篇 |
2021年 | 761篇 |
2020年 | 980篇 |
2019年 | 889篇 |
2018年 | 832篇 |
2017年 | 967篇 |
2016年 | 1018篇 |
2015年 | 1135篇 |
2014年 | 1555篇 |
2013年 | 1699篇 |
2012年 | 1855篇 |
2011年 | 1945篇 |
2010年 | 1482篇 |
2009年 | 1456篇 |
2008年 | 1445篇 |
2007年 | 1567篇 |
2006年 | 1407篇 |
2005年 | 1151篇 |
2004年 | 928篇 |
2003年 | 820篇 |
2002年 | 652篇 |
2001年 | 568篇 |
2000年 | 499篇 |
1999年 | 395篇 |
1998年 | 340篇 |
1997年 | 274篇 |
1996年 | 252篇 |
1995年 | 198篇 |
1994年 | 145篇 |
1993年 | 138篇 |
1992年 | 129篇 |
1991年 | 84篇 |
1990年 | 70篇 |
1989年 | 51篇 |
1988年 | 43篇 |
1987年 | 14篇 |
1986年 | 9篇 |
1985年 | 6篇 |
1984年 | 18篇 |
1983年 | 12篇 |
1982年 | 10篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1960年 | 3篇 |
1958年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
The notions of dynamical synchronization and adaptive dynamical synchronization problems are introduced. The algorithm solving adaptive synchronization problem for a subclass of Lurie systems with exciting input is proposed. The performance and potentialities of proposed solutions are demonstrated by two examples related to formation control and self‐organization of swarm systems. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
22.
An effective system control method is presented for applying a three‐phase current‐source PWM converter with a deadbeat controller to active power filters (APFs). In the shunt‐type configuration, the APF is controlled such that the current drawn by the APF from the utility is equal to the current harmonics and reactive current required for the load. To attain the time‐optimal response of the APF supply current, a two‐dimensional deadbeat control scheme is applied to APF current control. Furthermore, in order to cancel both the delay in the two‐dimensional deadbeat control scheme and the delay in DSP control strategy, an Adaptive Line Enhancer (ALE) is introduced in order to predict the desired value three sampling periods ahead. ALE has another function of bringing robustness to the deadbeat control system. Due to the ALE, settling time is made short in a transient state. On the other hand, total harmonic distortion (THD) of source currents can be minimized compared to the case where ideal identification of the controlled system can be made. The experimental results obtained from the DSP‐based APF are also reported. The compensating ability of this APF is very high in accuracy and responsiveness although the modulation frequency is rather low. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(1): 50–61, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20014 相似文献
23.
构筑企业级信息系统安全体系 总被引:1,自引:0,他引:1
滕铁军 《网络安全技术与应用》2004,(7):36-38
本文以跨地区公司为例,探讨企业级信息系统安全体系的构筑,所述的原则和做法可以实现在外部网-内部网-主机-用户体系上,形成多道防线,使企业计算机网络具有相当程度的安全性,从而达到企业信息系统的安全目标。 相似文献
24.
Carsten Carstensen Kerstin Weinberg 《International journal for numerical methods in engineering》2003,56(15):2313-2330
Adaptive algorithms are important tools for efficient finite‐element mesh design. In this paper, an error controlled adaptive mesh‐refining algorithm is proposed for a non‐conforming low‐order finite‐element method for the Reissner–Mindlin plate model. The algorithm is controlled by a reliable and efficient residual‐based a posteriori error estimate, which is robust with respect to the plate's thickness. Numerical evidence for this and the efficiency of the new algorithm is provided in the sense that non‐optimal convergence rates are optimally improved in our numerical experiments. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
25.
Christine Di Massimo Paul A. Lant Aidan Saunders Gary A. Montague Ming T. Tham A. Julian Morris 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1992,53(3):265-277
The last decade has seen the development of a number of approaches for estimating those variables which are difficult to measure on-line in industrial process situations. Whilst a range of techniques is available, a common element is the use of process knowledge in the form of a system model. In the case of bioprocess systems, although a large range of models has been presented in the literature, their use in estimation schemes on an industrial scale has been limited. A number of reasons can be identified for their low level of utilisation. Of particular significance is the uncertainty which exists in quantifying system performance and the process-model mismatch which inevitably results. The level of ‘pre-defined model’ uncertainty, together with the knowledge gained during the course of the fermentation, serves to dictate estimator structure. The paper considers a range of estimation strategies and contrasts, through industrial applications, their performance characteristics and utility. 相似文献
26.
27.
本文讨论了一种带有参考通道的自适应话音消噪滤波器原理,该滤波器采用最小均方差(心幅)算法。将此滤波器应用于复杂噪音背景的话音信号提取,能很好地抑制背景噪声,从而获得清晰的话音信号。 相似文献
28.
29.
Rinkenauer Gerhard; Osman Allen; Ulrich Rolf; Müller-Gethmann Hiltraut; Mattes Stefan 《Canadian Metallurgical Quarterly》2004,133(2):261
Lateralized readiness potentials (LRPs) were used to determine the stage(s) of reaction time (RT) responsible for speed-accuracy trade-offs (SATs). Speeded decisions based on several types of information were examined in 3 experiments, involving, respectively, a line discrimination task, lexical decisions, and an Erikson flanker task. Three levels of SAT were obtained in each experiment by adjusting response deadlines with an adaptive tracking algorithm. Speed stress affected the duration of RT stages both before and after the start of the LRP in all experiments. The latter effect cannot be explained by guessing strategies, by variations in response force, or as an indirect consequence of the pre-LRP effect. Contrary to most models, it suggests that SAT can occur at a late postdecisional stage. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
30.