全文获取类型
收费全文 | 32176篇 |
免费 | 3913篇 |
国内免费 | 2242篇 |
专业分类
电工技术 | 6429篇 |
技术理论 | 1篇 |
综合类 | 3764篇 |
化学工业 | 685篇 |
金属工艺 | 1323篇 |
机械仪表 | 4803篇 |
建筑科学 | 942篇 |
矿业工程 | 794篇 |
能源动力 | 534篇 |
轻工业 | 334篇 |
水利工程 | 641篇 |
石油天然气 | 522篇 |
武器工业 | 720篇 |
无线电 | 6743篇 |
一般工业技术 | 2513篇 |
冶金工业 | 671篇 |
原子能技术 | 238篇 |
自动化技术 | 6674篇 |
出版年
2024年 | 119篇 |
2023年 | 399篇 |
2022年 | 708篇 |
2021年 | 788篇 |
2020年 | 914篇 |
2019年 | 703篇 |
2018年 | 773篇 |
2017年 | 1116篇 |
2016年 | 1287篇 |
2015年 | 1497篇 |
2014年 | 2037篇 |
2013年 | 1823篇 |
2012年 | 2548篇 |
2011年 | 2669篇 |
2010年 | 2008篇 |
2009年 | 2092篇 |
2008年 | 2025篇 |
2007年 | 2513篇 |
2006年 | 2186篇 |
2005年 | 1721篇 |
2004年 | 1367篇 |
2003年 | 1274篇 |
2002年 | 1006篇 |
2001年 | 866篇 |
2000年 | 753篇 |
1999年 | 599篇 |
1998年 | 439篇 |
1997年 | 392篇 |
1996年 | 359篇 |
1995年 | 279篇 |
1994年 | 244篇 |
1993年 | 183篇 |
1992年 | 130篇 |
1991年 | 96篇 |
1990年 | 81篇 |
1989年 | 83篇 |
1988年 | 64篇 |
1987年 | 31篇 |
1986年 | 16篇 |
1985年 | 21篇 |
1984年 | 21篇 |
1983年 | 12篇 |
1982年 | 12篇 |
1981年 | 16篇 |
1980年 | 11篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1977年 | 10篇 |
1976年 | 4篇 |
1956年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
In asynchronous transfer mode (ATM) networks, fixed length cells of 53 bytes are transmitted. A cell may be discarded during transmission due to buffer overflow or a detection of errors. Cell discarding seriously degrades transmission quality. The quality degradation can be reduced by employing efficient forward error control (FEC) to recover discarded cells. In this paper, we present the design and implementation of decoding equipment for FEC in ATM networks based on a single parity check (SPC) product code using very‐large‐scale integration (VLSI) technology. FEC allows the destination to reconstruct missing data cells by using redundant parity cells that the source adds to each block of data cells. The functionality of the design has been tested using the Model Sim 5.7cXE Simulation Package. The design has been implemented for a 5 ° 5 matrix of data cells in a Virtex‐E XCV 3200E FG1156 device. The simulation and synthesis results show that the decoding function can be completed in 81 clock cycles with an optimum clock of 56.8 MHz. A test bench was written to study the performance of the decoder, and the results are presented. 相似文献
52.
53.
54.
Neuroimaging experiments have shown that prefrontal regions of the brain, which have the most age-related volume loss, are also the regions most likely to be more active in older adults than in younger adults. In an attempt to solve this puzzle, P. M. Greenwood (see record 2007-15625-001) has proposed a cascade that flows from age-related atrophy in the brain to changed processing strategies that result in plastic changes in regions adjacent and contralateral to the atrophic areas, culminating in greater functional activity. This hypothesis should stimulate research into these mechanisms and hopefully will ultimately inform researchers' ability to rehabilitate cognitive disorders in the elderly. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
55.
ZHU Liye FANG Yuan ZHANG Weidong 《机械工程学报(英文版)》2008,21(1):91-93
According to a type of normal nonlinear system, an indirect adaptive fuzzy (IAF) controller has been applied to those systems where no accurate mathematical models of the systems under control are available. To satisfy with system performance, an indirect accelerated adaptive fuzzy (IAAF) controller is proposed, and its general form is presented. The general form IAAF controller ensures necessary control criteria and system's global stability using Lyapunov Theorem. It has been proved that the close-loop system error converges to a small neighborhood of equilibrium point. The optimal IAAF controller is derived to guarantee the process's shortest settling time. Simulation results indicate the IAAF controller make the system more stable, accurate, and fast. 相似文献
56.
57.
58.
D. Roy 《International journal for numerical methods in engineering》2004,61(5):764-790
Sample pathwise numerical integration of noise-driven engineering dynamical systems cannot generally be performed beyond a limited level of accuracy, especially when the noise processes are modelled using (filtered) white noises. Recently, a locally transversal linearization (LTL) strategy has been proposed by the author (Proc Roy Soc London A 2001; 457 :539–566) for direct integration of deterministic and stochastic non-linear dynamical systems. The present effort is focussed on a host of extensions along with detailed theoretical error analyses of the linearization approach, especially as applied to problems in non-linear stochastic engineering dynamics. Thus, to begin with, estimates of local and global error orders in the basic LTL scheme are obtained separately for the displacement and velocity vectors when the system is driven either by a set of additive noises or by an arbitrary combination of (independently evolving) additive and multiplicative noises. Following this, a new family of higher-order LTL schemes is proposed in order to improve upon the basic LTL method and the associated error orders are established. A stepwise implementation of the lower- and higher-order versions of the LTL method, along with certain computational aspects, is also outlined. The proposed schemes are numerically illustrated, to a limited extent, for a single degree-of-freedom (SDOF) and a two degree-of-freedom (TDOF) non-linear engineering systems under additive and/or multiplicative white noise excitations. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
59.
A. Yu. Luchka 《Cybernetics and Systems Analysis》2003,39(6):880-888
A modified variational-gradient method is proposed and substantiated for quasilinear operator equations in a Hilbert space. 相似文献
60.
SIMADYN D控制器应用于动态无功补偿,标志武钢动态无功补偿控制实现数字化突破。提高了系统的可靠性、调节精度和动态指标。 相似文献