全文获取类型
收费全文 | 20775篇 |
免费 | 2455篇 |
国内免费 | 1367篇 |
专业分类
电工技术 | 4665篇 |
技术理论 | 1篇 |
综合类 | 2488篇 |
化学工业 | 1734篇 |
金属工艺 | 620篇 |
机械仪表 | 1404篇 |
建筑科学 | 1704篇 |
矿业工程 | 933篇 |
能源动力 | 1099篇 |
轻工业 | 1362篇 |
水利工程 | 982篇 |
石油天然气 | 1634篇 |
武器工业 | 242篇 |
无线电 | 1346篇 |
一般工业技术 | 1710篇 |
冶金工业 | 644篇 |
原子能技术 | 379篇 |
自动化技术 | 1650篇 |
出版年
2024年 | 78篇 |
2023年 | 290篇 |
2022年 | 484篇 |
2021年 | 622篇 |
2020年 | 664篇 |
2019年 | 554篇 |
2018年 | 518篇 |
2017年 | 699篇 |
2016年 | 767篇 |
2015年 | 786篇 |
2014年 | 1182篇 |
2013年 | 1235篇 |
2012年 | 1462篇 |
2011年 | 1521篇 |
2010年 | 1079篇 |
2009年 | 1195篇 |
2008年 | 1136篇 |
2007年 | 1489篇 |
2006年 | 1354篇 |
2005年 | 1189篇 |
2004年 | 945篇 |
2003年 | 874篇 |
2002年 | 716篇 |
2001年 | 642篇 |
2000年 | 576篇 |
1999年 | 486篇 |
1998年 | 369篇 |
1997年 | 331篇 |
1996年 | 284篇 |
1995年 | 246篇 |
1994年 | 164篇 |
1993年 | 136篇 |
1992年 | 110篇 |
1991年 | 93篇 |
1990年 | 73篇 |
1989年 | 73篇 |
1988年 | 57篇 |
1987年 | 28篇 |
1986年 | 17篇 |
1985年 | 15篇 |
1984年 | 8篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1959年 | 7篇 |
1956年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
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
2.
腐蚀阴极尖端的新方法 总被引:1,自引:0,他引:1
给出一种腐蚀阴极尖端的新方法,使得对阴极常用金属材料(W,Mo,Ir,Ta等)制作的阴极尖端的腐蚀效果明显,针尖对称性和重复性都很好,成品率和质量都有所提高. 相似文献
3.
Ying Tan 《The Journal of VLSI Signal Processing》2002,32(1-2):45-54
In this paper, we propose a new approach for signal detection in wireless digital communications based on the neural network with transient chaos and time-varying gain (NNTCTG), and give a concrete model of the signal detector after appropriate transformations and mappings. It is well known that the problem of the maximum likelihood signal detection can be described as a complex optimization problem that has so many local optima that conventional Hopfield-type neural networks fail to solve. By refraining from the serious local optima problem of Hopfield-type neural networks, the NNTCTG makes use of the time-varying parameters of the recurrent neural network to control the evolving behavior of the network so that the network undergoes the transition from chaotic behavior to gradient convergence. It has richer and more flexible dynamics rather than conventional neural networks only with point attractors, so that it can be expected to have much ability to search for globally optimal or near-optimal solutions. After going through a transiently inverse-bifurcation process, the NNTCTG can approach the global optimum or the neighborhood of global optimum of our problem. Simulation experiments have been performed to show the effectiveness and validation of the proposed neural network based method for the signal detection in digital communications. 相似文献
4.
Masami Ikeda Susumu Fukumoto Hiroshi Takao Shinya Ohtsuka Eiichi Haginomori Masayuki Hikita 《Electrical Engineering in Japan》2002,141(4):16-24
This paper describes the dielectric breakdown characteristics of oil and oil‐impregnated paper for very fast transient (VFT) voltages. Blumlein circuits generate VFT voltages of 60 and 300 ns in a pulse width that simulates disconnecting switching surges in gas‐insulated switch gears. We measured the breakdown voltages of needle‐to‐plane, plane‐to‐plane oil gaps and several pieces of paper between plane electrodes for VFT and lightning impulse voltages. The measured data were formulated in V‐t characteristics and Weibull probability distributions. The inclination n of V‐t characteristics of insulating paper is 150, which is less than n = 13.7 of the plane‐to‐plane oil gap in the VFT time range. The shape parameters of Weibull distribution obtained in this study show that the scattering of breakdown voltages of paper is much less than that of oil. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(4): 16–24, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10043 相似文献
5.
Xuejun Xie Siying Zhang 《International Journal of Adaptive Control and Signal Processing》2002,16(1):39-59
This paper considers the adaptive pole‐placement control problem for system (1) with unmodelled dynamics ηn dominated by a small constant ε multiplied by a quantity independent of ε but tending to infinity as the past input, output, and noise grow. Using bounded external excitation and randomly varying truncation techniques, we give a design method of adaptive pole‐placement controller. It is shown that the closed‐loop system is globally stable, the estimation error for the parameter contained in the modelled part is of order ε, and the closed‐loop system under the adaptive pole‐placement control law is suboptimal in the sense of $$\mathop{\lim\sup}\limits_{{n\to\infty }}{1\over n}\mathop{\sum}\limits_{i=0}^n{\left({A^{*}(z)y_{n}‐L(z)C(z)w_{n}‐B(z)R(z)y_{n}^{*}}\right)^{2}{\leq}O({\varepsilon}^{2})+\gamma^{2}\mathop{\sum}\limits_{j=1}^q{b_{j}^{2}}}$$\nopagenumbers\end while the SPR condition used usually in other papers is replaced by a stability condition. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
6.
对韶钢炼铁厂4号高炉炉况和操作上存在的问题进行了分析,主要原因是原材料质量较差,精料水平低,同时,高炉操作不能完全适应原材料条件.按照上稳下活工艺的原则,采取合理鼓风动能、活跃炉缸工作状态、稳定热制度、合理中部冷却强度、炉顶小高压操作以及使用上部调节手段等一系列措施,使高炉的炉况顺行得到了较大的改善,各项主要技术经济指标取得相应的进步.2001年利用系数达3.024 t/m3·d,焦比达441 kg/t. 相似文献
7.
8.
9.
Sorin Manolache Petru Eles Zebo Peng 《International journal of parallel programming》2007,35(2):125-156
As feature sizes shrink, transient failures of on-chip network links become a critical problem. At the same time, many applications
require guarantees on both message arrival probability and response time. We address the problem of transient link failures
by means of temporally and spatially redundant transmission of messages, such that designer-imposed message arrival probabilities
are guaranteed. Response time minimisation is achieved by a heuristic that statically assigns multiple copies of each message
to network links, intelligently combining temporal and spatial redundancy. Concerns regarding energy consumption are addressed
in two ways. First, we reduce the total amount of transmitted messages, and, second, we minimise the application response
time such that the resulted time slack can be exploited for energy savings through voltage reduction. The advantages of the
proposed approach are guaranteed message arrival probability and guaranteed worst case application response time. 相似文献
10.
Wilhelm Heinrichs 《Journal of scientific computing》1991,6(1):1-19
We introduce a stabilized treatment of spectral methods. The condition number of the spectral systems is highly improved. Elliptic and biharmonic problems are considered. Suitable interpolants in the case of inhomogeneous Dirichlet boundary conditions are presented. For a direct solver the improvements with respect to rounding error propagation are numerically demonstrated. 相似文献