全文获取类型
收费全文 | 64446篇 |
免费 | 12744篇 |
国内免费 | 8643篇 |
专业分类
电工技术 | 8024篇 |
技术理论 | 1篇 |
综合类 | 8465篇 |
化学工业 | 1288篇 |
金属工艺 | 1218篇 |
机械仪表 | 5159篇 |
建筑科学 | 1165篇 |
矿业工程 | 912篇 |
能源动力 | 1354篇 |
轻工业 | 638篇 |
水利工程 | 1074篇 |
石油天然气 | 762篇 |
武器工业 | 1172篇 |
无线电 | 11741篇 |
一般工业技术 | 3979篇 |
冶金工业 | 379篇 |
原子能技术 | 260篇 |
自动化技术 | 38242篇 |
出版年
2024年 | 203篇 |
2023年 | 1135篇 |
2022年 | 2275篇 |
2021年 | 2428篇 |
2020年 | 2695篇 |
2019年 | 2254篇 |
2018年 | 2239篇 |
2017年 | 2628篇 |
2016年 | 3047篇 |
2015年 | 3671篇 |
2014年 | 4729篇 |
2013年 | 4506篇 |
2012年 | 5719篇 |
2011年 | 5956篇 |
2010年 | 4865篇 |
2009年 | 4987篇 |
2008年 | 5250篇 |
2007年 | 5685篇 |
2006年 | 4457篇 |
2005年 | 3649篇 |
2004年 | 2931篇 |
2003年 | 2316篇 |
2002年 | 1706篇 |
2001年 | 1327篇 |
2000年 | 1122篇 |
1999年 | 870篇 |
1998年 | 687篇 |
1997年 | 550篇 |
1996年 | 420篇 |
1995年 | 297篇 |
1994年 | 257篇 |
1993年 | 193篇 |
1992年 | 188篇 |
1991年 | 88篇 |
1990年 | 122篇 |
1989年 | 80篇 |
1988年 | 57篇 |
1987年 | 21篇 |
1986年 | 30篇 |
1985年 | 30篇 |
1984年 | 22篇 |
1983年 | 22篇 |
1982年 | 24篇 |
1981年 | 13篇 |
1980年 | 20篇 |
1979年 | 9篇 |
1978年 | 10篇 |
1977年 | 8篇 |
1975年 | 9篇 |
1959年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 24 毫秒
991.
The learning speed of an adaptive algorithm can be improved by properly constraining the cost function of the adaptive algorithm. In this work, a noise-constrained least mean fourth (NCLMF) adaptive algorithm is proposed. The NCLMF algorithm is obtained by constraining the cost function of the standard LMF algorithm to the fourth-order moment of the additive noise. The NCLMF algorithm can be seen as a variable step-size LMF algorithm. The main aim of this work is to derive the NCLMF adaptive algorithm, analyze its convergence behavior, and assess its performance in different noise environments. Furthermore, the analysis of the proposed NCLMF algorithm is carried out using the concept of energy conservation. Finally, a number of simulation results are carried out to corroborate the theoretical findings, and as expected, improved performance is obtained through the use of this technique over the traditional LMF algorithm. 相似文献
992.
In this paper, several simple and efficient sign based normalized adaptive filters, which are computationally superior having multiplier free weight update loops are used for cancelation of noise in electrocardiographic (ECG) signals. The proposed implementation is suitable for applications such as biotelemetry, where large signal to noise ratios with less computational complexity are required. These schemes mostly employ simple addition, shift operations and achieve considerable speed up over the other least mean square (LMS) based realizations. Simulation studies shows that the proposed realization gives better performance compared to existing realizations in terms of signal to noise ratio and computational complexity. 相似文献
993.
Anisotropic diffusion for noise removal of band pass signals 总被引:1,自引:0,他引:1
Sasan Mahmoodi 《Signal processing》2011,91(5):1298-1307
A noise removal method for band pass signals based on the anisotropic diffusion algorithm originally put forward by Perona and Malik is proposed in this paper. The anisotropic smoothing algorithm proposed here is for band pass signals modulated with a constant carrier frequency. A partial differential equation to smooth band pass noisy signals is derived. The propagator of this differential equation is also analytically calculated in this paper. An appropriate linear operator is then considered here for such band pass signals to form an anisotropic diffusion algorithm. The algorithm proposed here demonstrates better performance for band pass noisy signals containing discontinuities in comparison with the traditional Perona-Malik (PM) algorithm and is robust in the presence of excessive noise with SNR less than unity. 相似文献
994.
Sambhu Nath PradhanAuthor Vitae M. Tilak KumarAuthor Vitae 《Integration, the VLSI Journal》2011,44(3):175-184
Power-gating turns off the power supply of a portion of the circuit completely, resulting in total elimination of power consumption for that part. However, it also necessitates that the sub-circuit to be activated should be charged for some time before its activation. This critical issue can influence the decomposition of a finite state machine (FSM) for its power gated implementation. In this paper we have presented a power-gating method that integrates FSM partitioning with state encoding, thus providing a total solution to the problem of power-aware FSM synthesis. It shows better results, in terms of dynamic and leakage power consumption, compared to the existing techniques reported in the literature. 相似文献
995.
Chenjian RanZili Deng 《Signal processing》2011,91(8):2028-2041
For the multisensor multi-channel autoregressive moving average (ARMA) signal with white measurement noises and a common disturbance measurement white noise, when the model parameters and the noise variances are all unknown, a multi-stage information fusion identification method is presented, where the consistent fused estimates of the model parameters and noise variances are obtained by the multi-dimension recursive instrumental variable (RIV) algorithm, correlation method and Gevers-Wouters algorithm with a dead band. Substituting these estimates into the optimal distributed measurement fusion Kalman signal estimator, a self-tuning distributed measurement fusion Kalman signal estimator is presented. Its convergence is proved by the dynamic error system analysis (DESA) method, so that it has asymptotical global optimality. In order to reduce computational load, a fast recursive inversion algorithm for a high-dimension matrix is presented by the inversion formula of partitioned matrix. Especially, when the process and measurement noise variance matrices are all diagonal matrices, the inversion formula of a high-dimension matrix is presented, which extends the formula of the inverse of Pei-Radman matrix. Applying the proposed inversion algorithm, the computation of the fused measurement and fused noise variance is simplified and their computational burden is reduced. A simulation example shows effectiveness of the proposed method. 相似文献
996.
This paper proposes a novel phishing web image segmentation algorithm which based on improving spectral clustering. Firstly, we construct a set of points which are composed of spatial lo-cation pixels and gray levels from a given image. Secondly, the data is clustered in spectral space of the similar matrix of the set points, in order to avoid the drawbacks of K-means algorithm in the con-ventional spectral clustering method that is sensitive to initial clustering centroids and convergence to local optimal solution, we introduce the clone operator, Cauthy mutation to enlarge the scale of clustering centers, quantum-inspired evolutionary algorithm to find the global optimal clustering centroids. Compared with phishing web image segmentation based on K-means, experimental results show that the segmentation performance of our method gains much improvement. Moreover, our method can convergence to global optimal solution and is better in accuracy of phishing web seg-mentation. 相似文献
997.
Feature selection (FS) is a process to select features which are more informative.It is one of the important steps in knowledge discovery.The problem is that not all features are important.Some of the features may be redundant,and others may be irrelevant and noisy.The conventional supervised FS methods evaluate various feature subsets using an evaluation function or metric to select only those features which are related to the decision classes of the data under consideration.However,for many data mining applications,decision class labels are often unknown or incomplete,thus indicating the significance of unsupervised feature selection.However,in unsupervised learning,decision class labels are not provided.In this paper,we propose a new unsupervised quick reduct (QR) algorithm using rough set theory.The quality of the reduced data is measured by the classification performance and it is evaluated using WEKA classifier tool.The method is compared with existing supervised methods and the result demonstrates the efficiency of the proposed algorithm. 相似文献
998.
相移数字散斑剪切干涉技术可以提高检测精度,利用该方法对圆形铝板试件进行测量。为了实现全场相位的精确求解,运用等四步相移Carré算法定量计算相位。将该非接触测量技术与弹性力学理论分析相结合,对四周固支,中心受集中载荷试件的离面位移导数进行测量与分析,另外采用有限元方法进行模拟。最后将实验结果分别和理论结果、有限元结果进... 相似文献
999.
1000.