全文获取类型
收费全文 | 2476篇 |
免费 | 155篇 |
国内免费 | 85篇 |
专业分类
电工技术 | 166篇 |
综合类 | 83篇 |
化学工业 | 47篇 |
金属工艺 | 107篇 |
机械仪表 | 367篇 |
建筑科学 | 102篇 |
矿业工程 | 36篇 |
能源动力 | 131篇 |
轻工业 | 16篇 |
水利工程 | 8篇 |
石油天然气 | 41篇 |
武器工业 | 18篇 |
无线电 | 672篇 |
一般工业技术 | 191篇 |
冶金工业 | 22篇 |
原子能技术 | 35篇 |
自动化技术 | 674篇 |
出版年
2024年 | 4篇 |
2023年 | 17篇 |
2022年 | 22篇 |
2021年 | 35篇 |
2020年 | 42篇 |
2019年 | 35篇 |
2018年 | 41篇 |
2017年 | 61篇 |
2016年 | 79篇 |
2015年 | 68篇 |
2014年 | 132篇 |
2013年 | 137篇 |
2012年 | 148篇 |
2011年 | 183篇 |
2010年 | 145篇 |
2009年 | 124篇 |
2008年 | 122篇 |
2007年 | 163篇 |
2006年 | 171篇 |
2005年 | 120篇 |
2004年 | 112篇 |
2003年 | 116篇 |
2002年 | 106篇 |
2001年 | 76篇 |
2000年 | 67篇 |
1999年 | 61篇 |
1998年 | 52篇 |
1997年 | 60篇 |
1996年 | 40篇 |
1995年 | 34篇 |
1994年 | 24篇 |
1993年 | 23篇 |
1992年 | 20篇 |
1991年 | 23篇 |
1990年 | 11篇 |
1989年 | 12篇 |
1988年 | 12篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1978年 | 3篇 |
排序方式: 共有2716条查询结果,搜索用时 31 毫秒
61.
在二级倒立摆稳摆控制中,摆杆的角度信号受到测量噪音污染,通过差分获取角速度时,该噪音被放大,导致稳摆控制器的输出产生较大的随机波动,同时电机作为执行器,也混入了较大的过程噪音.这两种噪音使系统出现较强抖动,既不利于摆杆稳定,也缩短了电机寿命.对此,将稳态卡尔曼滤波器与渐消记忆法结合起来,找到了确定稳态卡尔曼滤波器增益矩阵的有效方法,既克服了模型误差,又满足实时性要求,减小了电机抖动,取得了较好的效果. 相似文献
62.
Due to a lot of robot manipulators application in industry, low noise degree is very important criteria for robot manipulator's joints. In this paper, joint noise problem of a robot manipulator with five joints is investigated both theoretically and experimentally. The investigation is consisted of two steps. First step is to analyze the noise of joints using a hardware and software. The hardware is a part of noise sensors. The second step; according to experimental results, some neural networks are employed for finding robust neural noise analyzer. Five types of neural networks are used to compare each other. From the results, it is noted that the proposed RBFNN gives the best results for analyzing joint noise of the robot manipulator. 相似文献
63.
64.
Guoxian YuAuthor Vitae Hong PengAuthor VitaeJia WeiAuthor Vitae Qianli MaAuthor Vitae 《Neurocomputing》2011,74(4):598-605
Curse of dimensionality is a bothering problem in high dimensional data analysis. To enhance the performances of classification or clustering on these data, their dimensionalities should be reduced beforehand. Locality Preserving Projections (LPP) is a widely used linear dimensionality reduction method. It seeks a subspace in which the neighborhood graph structure of samples is preserved. However, like most dimensionality reduction methods based on graph embedding, LPP is sensitive to noise and outliers, and its effectiveness depends on choosing suitable parameters for constructing the neighborhood graph. Unfortunately, it is difficult to choose effective parameters for LPP. To address these problems, we propose an Enhanced LPP (ELPP) using a similarity metric based on robust path and a Semi-supervised ELPP (SELPP) with pairwise constraints. In comparison with original LPP, our methods are not only robust to noise and outliers, but also less sensitive to parameters selection. Besides, SELPP makes use of pairwise constraints more efficiently than other comparing methods. Experimental results on real world face databases confirm their effectiveness. 相似文献
65.
Subspace sums for extracting non-random data from massive noise 总被引:1,自引:1,他引:0
Anne M. Denton 《Knowledge and Information Systems》2009,20(1):35-62
An algorithm is introduced that distinguishes relevant data points from randomly distributed noise. The algorithm is related
to subspace clustering based on axis-parallel projections, but considers membership in any projected cluster of a given side
length, as opposed to a particular cluster. An aggregate measure is introduced that is based on the total number of points
that are close to the given point in all possible 2
d
projections of a d-dimensional hypercube. No explicit summation over subspaces is required for evaluating this measure. Attribute values are
normalized based on rank order to avoid making assumptions on the distribution of random data. Effectiveness of the algorithm
is demonstrated through comparison with conventional outlier detection on a real microarray data set as well as on time series
subsequence data.
相似文献
Anne M. DentonEmail: |
66.
Joshua R. Ben-Arie Geoffrey J. Hay Ryan P. Powers Guillermo Castilla Benoît St-Onge 《Computers & Geosciences》2009,35(9):1940-1949
LiDAR canopy height models (CHMs) can exhibit unnatural looking holes or pits, i.e., pixels with a much lower digital number than their immediate neighbors. These artifacts may be caused by a combination of factors, from data acquisition to post-processing, that not only result in a noisy appearance to the CHM but may also limit semi-automated tree-crown delineation and lead to errors in biomass estimates. We present a highly effective semi-automated pit filling algorithm that interactively detects data pits based on a simple user-defined threshold, and then fills them with a value derived from their neighborhood. We briefly describe this algorithm and its graphical user interface, and show its result in a LiDAR CHM populated with data pits. This method can be rapidly applied to any CHM with minimal user interaction. Visualization confirms that our method effectively and quickly removes data pits. 相似文献
67.
Effects of additive noise on a series of the periods of oscillations in unidirectionally coupled ring neural networks of ring oscillator type are studied. Kinematical models of the traveling waves of an inconsistency, i.e. the successive same signs in the states of adjacent neurons in the network, are derived. A series of the half periods in the network of N neuron is then expressed by the sum of N sequences of the N-first order autoregressive process, the process with the spectrum of exponential type and the first-order autoregressive process. Noise and the interaction of the inconsistency cause characteristic positive correlations in a series of the half periods of the oscillations. Further, an experiment on an analog circuit of the ring neural oscillator was done and it is shown that correlations in the obtained periods of the oscillations agree with the derived three expressions. 相似文献
68.
基于内容的图像检索方法往往将图片的内容表示成柱状图,根据图片柱状图之间的相似性进行图片的检索。数码图片中包含的噪声使得柱状图变得平滑,从而使图片之间变得更为相似,这增加了返回结果中包含的图片数量。为了进一步提高图片检索的性能,提出了一种对噪声不敏感的柱状图特征描述符,并应用该特征描述符进行图像之间的相似性匹配。首先将图片中的噪声描述为平稳附加高斯白噪声,并给出了相应的柱状图表示;然后通过随机变量的原点矩定义了柱状图的特征描述符,并分析了如何应用特征描述符恢复原始图片的柱状图。在算法的性能验证过程中,将提出的方法与4种相关算法进行比较,应用两个真实的图片数据库的图像检索实验验证了所提方法的有效性。 相似文献
69.
A generalized form of Possibilistic Fuzzy C-Means (PFCM) algorithm (GPFCM) is presented for clustering noisy data. A function of distance is used instead of the distance itself to damp noise contributions. It is shown that when the data are highly noisy, GPFCM finds accurate cluster centers but FCM (Fuzzy C-Means), PCM (Possibilistic C-Means), and PFCM algorithms fail. FCM, PCM, and PFCM yield inaccurate cluster centers when clusters are not of the same size or covariance norm is used, whereas GPFCM performs well for both of the cases even when the data are noisy. It is shown that generalized forms of FCM and PCM (GFCM and GPCM) are also more accurate than FCM and PCM. A measure is defined to evaluate performance of the clustering algorithms. It shows that average error of GPFCM and its simplified forms are about 80% smaller than those of FCM, PCM, and PFCM. However, GPFCM demands higher computational costs due to nonlinear updating equations. Three cluster validity indices are introduced to determine number of clusters in clean and noisy datasets. One of them considers compactness of the clusters; the other considers separation of the clusters, and the third one considers both separation and compactness. Performance of these indices is confirmed to be satisfactory using various examples of noisy datasets. 相似文献
70.
针对传统地球化学数据处理问题,引入Kallman滤波对地球化学数据进行降噪预处理,并对Kalman滤波技术应用于地球化学数据误差校正的可行性进行了系统研究,并以铜绿山1:5万水系中Cu的测量数据为例进行了验证分析,试验结果表明,Kalman滤波技术在对地球化学数据处理方面具有优势,适用于地球化学数据的误差校正。 相似文献