全文获取类型
收费全文 | 3047篇 |
免费 | 241篇 |
国内免费 | 185篇 |
专业分类
电工技术 | 33篇 |
综合类 | 101篇 |
化学工业 | 248篇 |
金属工艺 | 282篇 |
机械仪表 | 328篇 |
建筑科学 | 159篇 |
矿业工程 | 32篇 |
能源动力 | 35篇 |
轻工业 | 77篇 |
水利工程 | 3篇 |
石油天然气 | 22篇 |
武器工业 | 10篇 |
无线电 | 202篇 |
一般工业技术 | 480篇 |
冶金工业 | 123篇 |
原子能技术 | 17篇 |
自动化技术 | 1321篇 |
出版年
2024年 | 5篇 |
2023年 | 42篇 |
2022年 | 47篇 |
2021年 | 70篇 |
2020年 | 97篇 |
2019年 | 74篇 |
2018年 | 70篇 |
2017年 | 76篇 |
2016年 | 92篇 |
2015年 | 123篇 |
2014年 | 151篇 |
2013年 | 176篇 |
2012年 | 162篇 |
2011年 | 254篇 |
2010年 | 147篇 |
2009年 | 208篇 |
2008年 | 214篇 |
2007年 | 214篇 |
2006年 | 181篇 |
2005年 | 150篇 |
2004年 | 132篇 |
2003年 | 164篇 |
2002年 | 103篇 |
2001年 | 80篇 |
2000年 | 71篇 |
1999年 | 70篇 |
1998年 | 53篇 |
1997年 | 40篇 |
1996年 | 34篇 |
1995年 | 38篇 |
1994年 | 24篇 |
1993年 | 17篇 |
1992年 | 18篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 14篇 |
1988年 | 12篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1974年 | 2篇 |
排序方式: 共有3473条查询结果,搜索用时 140 毫秒
1.
3.
Two experiments are reported in which people’s sensory, hedonic, and efficacy expectations associated with pharmaceutical pills of differing colour and shape were assessed. In Experiment 1, 101 participants from the USA viewed online photos of tablets having one of 7 colours and 3 shapes. The participants had to arrange the 21 tablets based on the expectations generated solely by the tablets’ visual properties. The results revealed that the colour of the tablets influenced expected bitterness, expected alertness, and expected efficiency in combating headaches, whereas the shape of the tablets influenced the expected difficulty of swallowing. In Experiment 2, the major findings of Experiment 1 were replicated while using a greater variety of colours, in 358 participants from China, Colombia, and the USA. Importantly, the results revealed some shared expectations across cultures, such as the high expected efficacy of white tablets in combating headaches, or the high expected difficulty of swallowing the diamond-shaped tablets. The results also revealed some differences among the three groups, such as that the colour of the pills influenced how difficult the Chinese participants (but not the other two groups) expected the pills would be to swallow. These findings clearly demonstrate that the differing colours and shapes of pharmaceutical pills set-up significantly different expectations which likely play an important role in terms of people’s subsequent experience. 相似文献
4.
Simulating the psychological experience of human vision,a road extraction model based on the format tower is proposed to extract the road in the high resolution remote sensing image from the perspective of morphology.Firstly,based on the spectral and texture information,the suspected road targets are extracted by using segmentation technology.Then these targets are classified according to their reliability and extract the road targets for each category.Finally,three types of identified road information are verified and merged,and the continuous smooth road extraction results are obtained.Experiments on real high resolution images show that the results are consistent with the visual perception of the human eye,and the overall classification accuracy is higher,indicating that the algorithm is effective and feasible and has good use value. 相似文献
5.
The objective is to have uniformly distributed tangential stresses on the transition profile of a stepped bar subjected to tensile and torsional loading using an axisymmetric boundary element formulation. The transition curve is represented by the Langragian interpolation polynomial with progressive degrees to avoid shape distortion during the optimization procedure. The calculated result is compared with that obtained by fluid dynamics given in the literature. It is seen that the transition curve obtained in this paper is reasonable. 相似文献
6.
A theory is presented that explains how the visual system infers the lightness, opacity, and depth of surfaces from stereoscopic images. It is shown that the polarity and magnitude of image contrast play distinct roles in surface perception, which can be captured by 2 principles of perceptual inference. First, a contrast depth asymmetry principle articulates how the visual system computes the ordinal depth and lightness relationships from the polarity of local, binocularly matched image contrast. Second, a global transmittance anchoring principle expresses how variations in contrast magnitudes are used to infer the presence of transparent surfaces. It is argued that these principles provide a unified explanation of how the visual system computes the 3-D surface structure of opaque and transparent surfaces. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
8.
基于空间矩的灰度边缘亚像元度量精度分析 总被引:7,自引:0,他引:7
灰度图像中边缘定位受采样密度限制,亚像元精度度量方法在需要高精度的应用中受到重视,要想知识到底需要多高的分辨率才能达到定精度指标,就有必要分析特征定位方法的最坏情况的精度,文中用分析和实验的方法给出了基于空间矩的边缘定位方法,对于边缘点,边缘直线以及直边缘区域的最坏情况定位精度分析。分析和讨论的结果不但可以用来确定已知形状位置估计的最大误差,而且还可用于对准的形状几何参数,以获得较高的精度。 相似文献
9.
Measuring shape: ellipticity, rectangularity, and triangularity 总被引:1,自引:0,他引:1
Paul L. Rosin 《Machine Vision and Applications》2003,14(3):172-184
10.