全文获取类型
收费全文 | 813篇 |
免费 | 92篇 |
国内免费 | 47篇 |
专业分类
电工技术 | 10篇 |
综合类 | 39篇 |
化学工业 | 13篇 |
金属工艺 | 1篇 |
机械仪表 | 6篇 |
建筑科学 | 17篇 |
矿业工程 | 2篇 |
能源动力 | 1篇 |
轻工业 | 26篇 |
武器工业 | 2篇 |
无线电 | 73篇 |
一般工业技术 | 74篇 |
冶金工业 | 465篇 |
自动化技术 | 223篇 |
出版年
2023年 | 17篇 |
2022年 | 26篇 |
2021年 | 24篇 |
2020年 | 28篇 |
2019年 | 24篇 |
2018年 | 14篇 |
2017年 | 13篇 |
2016年 | 19篇 |
2015年 | 26篇 |
2014年 | 24篇 |
2013年 | 22篇 |
2012年 | 21篇 |
2011年 | 45篇 |
2010年 | 65篇 |
2009年 | 50篇 |
2008年 | 71篇 |
2007年 | 53篇 |
2006年 | 44篇 |
2005年 | 57篇 |
2004年 | 38篇 |
2003年 | 44篇 |
2002年 | 45篇 |
2001年 | 34篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1995年 | 9篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1989年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1979年 | 3篇 |
1971年 | 2篇 |
1968年 | 2篇 |
1966年 | 4篇 |
1965年 | 10篇 |
1964年 | 9篇 |
1963年 | 5篇 |
1962年 | 9篇 |
1961年 | 7篇 |
1960年 | 5篇 |
1959年 | 10篇 |
1958年 | 6篇 |
1957年 | 7篇 |
1956年 | 12篇 |
1955年 | 10篇 |
1954年 | 4篇 |
排序方式: 共有952条查询结果,搜索用时 62 毫秒
21.
The authors investigated whether infants are sensitive to visual event trajectory forms, and whether they are sensitive to the underlying dynamics of trajectory forms. The authors habituated 8-month-old infants to a videotaped event run either forward or reversed in time and then switched them to the same event run in the opposite direction. Infants dishabituated when switched to the event with the novel direction in time, indicating sensitivity to the form of the trajectory. Infants exhibited equivalent habituation rates and looking times for forward and reversed events, thus failing to provide evidence that infants are sensitive to the underlying dynamics. In a partial replication of this first experiment, the same pattern of results was found. Both experiments revealed infant sensitivity to the trajectory forms, but not the underlying dynamics of events. The authors discuss implications for methods used in infant event perception studies. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
22.
Schub? Anna; Schlaghecken Friederike; Meinecke Cristina 《Canadian Metallurgical Quarterly》2001,27(4):919
Although traditionally texture segmentation has been regarded as an automatic, preattentive process, participants confronted with texture segmentation in experimental settings (i.e., with brief presentation time and subsequent masking) are initially unable to perform the task. According to perceptual learning concepts, participants must learn to fine-tune their sensory channels before perception improves under restricted viewing conditions. The present article proposes an alternative perspective that emphasizes the role of the mask. Four experiments showed that the amount of observed learning depends on the structural and temporal homogeneity or heterogeneity of the mask. The authors suggest that learning consists of separating the task-relevant signal stemming from the texture from the task-irrelevant signal of the mask and of ignoring the mask. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
23.
24.
25.
针对纹理防伪标签在光线不足、视力不佳的情况下难以鉴别的问题,提出了一种基于DCT、感知哈希和视觉特征向量的纹理防伪标签鉴别算法.首先通过DCT和感知哈希提取图像的特征向量;然后建立特征数据库,通过特征向量之间的归一化相关系数(NC)实现纹理防伪标签的自动鉴别.实验结果表明,该方法可以有效抵抗常规攻击和几何攻击,可实现自动鉴别技术.与现有的纹理防伪技术相比,该算法可以减小占据的数据库存储空间,具有更好的实用性. 相似文献
26.
Perceptual auditory filter banks such as Bark-scale filter bank are widely used as front-end processing in speech recognition
systems. However, the problem of the design of optimized filter banks that provide higher accuracy in recognition tasks is
still open. Owing to spectral analysis in feature extraction, an adaptive bands filter bank (ABFB) is presented. The design
adopts flexible bandwidths and center frequencies for the frequency responses of the filters and utilizes genetic algorithm
(GA) to optimize the design parameters. The optimization process is realized by combining the front-end filter bank with the
back-end recognition network in the performance evaluation loop. The deployment of ABFB together with zero-crossing peak amplitude
(ZCPA) feature as a front process for radial basis function (RBF) system shows significant improvement in robustness compared
with the Bark-scale filter bank. In ABFB, several sub-bands are still more concentrated toward lower frequency but their exact
locations are determined by the performance rather than the perceptual criteria. For the ease of optimization, only symmetrical
bands are considered here, which still provide satisfactory results. 相似文献
27.
王顺琼 《昆明冶金高等专科学校学报》2009,25(3):67-70
由于工矿企业负荷的感性性质,国家采取“功率因素调整电费”来收取电费,通过分析“功率因素调整电费”的计算方法,说明工矿企业必须要进行无功补偿,提高用电设备的功率因数,从而获得更大的经济效益的重要意义。 相似文献
28.
The location of the egocenter in kinesthetic space was investigated in 4 experiments. Participants, with their eyes closed, adjusted a comparison stimulus after or while touching a standard in a transverse plane at the belly or shoulder level so that they perceived the line joining the comparison and the fixed standard as pointing directly at themselves. The mean location of the intersections of the obtained lines was taken as the location of the egocenter. The main results showed that the location of the kinesthetic egocenter depended on the hand or hands used for touching, the timing of touching, and the distance of the standard from the participant. Implications of these results were discussed in relation to models of the kinesthetic egocenter. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
29.
A class of selective attention models often applied to speech perception is used to study effects of training on the perception of an unfamiliar phonetic contrast. Attention-to-dimension (A2D) models of perceptual learning assume that the dimensions that structure listeners' perceptual space are constant and that learning involves only the reweighting of existing dimensions to emphasize or de-emphasize different sensory dimensions. Multidimensional scaling is used to identify the acoustic-phonetic dimensions listeners use before and after training to recognize the 3 classes of Korean stop consonants. Results suggest that A2D models can account for some observed restructuring of listeners' perceptual space, but listeners also show evidence of directing attention to a previously unattended dimension of phonetic contrast. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
30.
There is increasing evidence that the major source of drawing errors lies in the initial perception of the to-be-drawn object. In four experiments, the authors explore the relation between an artist's susceptibility to perceptual transformations, as measured by a simple shape constancy task, and drawing accuracy. The data reveal a robust negative relation between errors on the shape constancy task and drawing accuracy in general, and specifically the accuracy of the rendering of spatial relations. The data further suggest that the perceptual processes that lead to errors on the shape constancy task occur during the initial encoding of the stimuli. The authors conclude that the shape constancy task likely measures one's ability to overcome constructive perception processes that transform the retinal image into a final percept, and that this ability is necessary for the accurate rendering of objects. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献