全文获取类型
收费全文 | 11545篇 |
免费 | 2140篇 |
国内免费 | 1454篇 |
专业分类
电工技术 | 793篇 |
技术理论 | 2篇 |
综合类 | 1209篇 |
化学工业 | 378篇 |
金属工艺 | 245篇 |
机械仪表 | 1260篇 |
建筑科学 | 1556篇 |
矿业工程 | 252篇 |
能源动力 | 182篇 |
轻工业 | 123篇 |
水利工程 | 209篇 |
石油天然气 | 378篇 |
武器工业 | 94篇 |
无线电 | 2217篇 |
一般工业技术 | 908篇 |
冶金工业 | 321篇 |
原子能技术 | 178篇 |
自动化技术 | 4834篇 |
出版年
2024年 | 97篇 |
2023年 | 275篇 |
2022年 | 460篇 |
2021年 | 557篇 |
2020年 | 584篇 |
2019年 | 490篇 |
2018年 | 525篇 |
2017年 | 589篇 |
2016年 | 644篇 |
2015年 | 737篇 |
2014年 | 961篇 |
2013年 | 833篇 |
2012年 | 1029篇 |
2011年 | 987篇 |
2010年 | 786篇 |
2009年 | 760篇 |
2008年 | 658篇 |
2007年 | 749篇 |
2006年 | 658篇 |
2005年 | 563篇 |
2004年 | 410篇 |
2003年 | 363篇 |
2002年 | 322篇 |
2001年 | 220篇 |
2000年 | 183篇 |
1999年 | 141篇 |
1998年 | 114篇 |
1997年 | 71篇 |
1996年 | 63篇 |
1995年 | 48篇 |
1994年 | 45篇 |
1993年 | 54篇 |
1992年 | 23篇 |
1991年 | 27篇 |
1990年 | 20篇 |
1989年 | 26篇 |
1988年 | 16篇 |
1987年 | 12篇 |
1986年 | 10篇 |
1985年 | 7篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1982年 | 1篇 |
1981年 | 5篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1959年 | 2篇 |
1957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
1.
Yasoub Eghbali Mahmoud Ferdosizade Naeiny 《International Journal of Communication Systems》2020,33(14)
In this paper, an off‐grid direction of arrival (DoA) estimation method is proposed for wideband signals. This method is based on the sparse representation (SR) of the array covariance matrix. Similar to the time domain DoA estimation methods, the correlation function of the sources was assumed to be the same and known. A new measurement vector is obtained using the lower‐left triangular elements of the covariance matrix. The DoAs are estimated by quantizing the entire range of continuous angle space into discrete grid points. However, the exact DoAs may be located between two grid points; therefore, this estimation has errors. The accuracy of DoA estimation is improved by the minimization of the difference between the new measurement vector and its estimated values. Simulation results revealed that the proposed method can enhance the DoA estimation accuracy of wideband signals. 相似文献
2.
Anis Zeglaoui Anouar Houmia Maher Mejai Radhouane Aloui 《International Journal of Adaptive Control and Signal Processing》2021,35(9):1842-1859
In compressive sampling theory, the least absolute shrinkage and selection operator (LASSO) is a representative problem. Nevertheless, the non-differentiable constraint impedes the use of Lagrange programming neural networks (LPNNs). We present in this article the -LPNN model, a novel algorithm that tackles the LASSO minimization together with the underlying theory support. First, we design a sequence of smooth constrained optimization problems, by introducing a convenient differentiable approximation to the non-differentiable -norm constraint. Next, we prove that the optimal solutions of the regularized intermediate problems converge to the optimal sparse signal for the LASSO. Then, for every regularized problem from the sequence, the -LPNN dynamic model is derived, and the asymptotic stability of its equilibrium state is established as well. Finally, numerical simulations are carried out to compare the performance of the proposed -LPNN algorithm with both the LASSO-LPNN model and a standard digital method. 相似文献
3.
4.
数模混合仿真中模拟信号的恢复及其误差对整个仿真过程具有重要影响。本文探讨了用零阶保持和一阶保持进行信号恢复的方法,比较了它们的误差及工作特点。特别指出了一阶保持中,由于存在积分器复原时间及数字机操作时间的影响而会带来附加的误差,因此一阶保持方法较难达到其理论的精度。 相似文献
5.
电站锅炉制粉系统的爆炸原因与防范对策 总被引:1,自引:0,他引:1
火力发电厂制粉系统爆炸事故时有发生 ,重大设备损坏 ,造成了严重的经济损失。本文通过分析研究 ,找出制粉系统爆炸的原因 ,从措施上、煤的质量控制上及制粉系统结构改造上提出了防范的对策。 相似文献
6.
H. Luo 《Microsystem Technologies》2006,12(4):324-329
This paper focuses on tracking, reconstruction and motion estimation of a well-defined MEMS optical switch from a microscopic
view. For out-of-view reconstruction, a homography capable of transforming feature points and feature lines between a microscopic
image and a CAD model of the switch is implemented. The homography between two sequential microscopic images is decomposed
and factorized for motion estimation. Optical flow has also been explored to provide rough estimations of rotation centre
and angle. The paper also illustrates motion parameter optimization principles to deal with uncertainty inherent in micro
world. After non-linear optimization, estimation accuracy for rotation angle and rotation centre can reach 0.06° and pixel
level, respectively. 相似文献
7.
8.
本文提出生种新的带限信号的外推方法,该方法能够很好地抑制噪声干扰,且计算复杂性较低,本文给出算法,证明了收敛性,最后给出了误差计算机实验结果。 相似文献
9.
10.
Reconstruction of an original continuous curve and the estimation of its parameters from the digitized version of the curve
is a challenging problem, as quantization always causes some loss of information. In this paper, we have developed a scheme
for reconstruction which is applicable to a class of curves having at the most two parameters. The class of curves for which
the scheme works has also been characterized. We have shown that for one-parameter curves the exact domain of values of the
parameter can be obtained. But in the two-parameter case, only the smallest rectangle containing the domain can be realised.
The distinctive feature of our scheme is that it provides a unified approach to solve the reconstruction and the domain-finding
problem for a class of curves. 相似文献