全文获取类型
收费全文 | 14654篇 |
免费 | 2285篇 |
国内免费 | 1409篇 |
专业分类
电工技术 | 1477篇 |
综合类 | 1677篇 |
化学工业 | 809篇 |
金属工艺 | 310篇 |
机械仪表 | 853篇 |
建筑科学 | 951篇 |
矿业工程 | 676篇 |
能源动力 | 314篇 |
轻工业 | 451篇 |
水利工程 | 510篇 |
石油天然气 | 455篇 |
武器工业 | 300篇 |
无线电 | 1984篇 |
一般工业技术 | 1631篇 |
冶金工业 | 605篇 |
原子能技术 | 153篇 |
自动化技术 | 5192篇 |
出版年
2024年 | 34篇 |
2023年 | 163篇 |
2022年 | 371篇 |
2021年 | 473篇 |
2020年 | 529篇 |
2019年 | 450篇 |
2018年 | 475篇 |
2017年 | 587篇 |
2016年 | 642篇 |
2015年 | 771篇 |
2014年 | 967篇 |
2013年 | 1076篇 |
2012年 | 1193篇 |
2011年 | 1187篇 |
2010年 | 991篇 |
2009年 | 956篇 |
2008年 | 984篇 |
2007年 | 1101篇 |
2006年 | 865篇 |
2005年 | 728篇 |
2004年 | 622篇 |
2003年 | 556篇 |
2002年 | 463篇 |
2001年 | 380篇 |
2000年 | 297篇 |
1999年 | 233篇 |
1998年 | 208篇 |
1997年 | 179篇 |
1996年 | 128篇 |
1995年 | 104篇 |
1994年 | 113篇 |
1993年 | 80篇 |
1992年 | 58篇 |
1991年 | 55篇 |
1990年 | 47篇 |
1989年 | 39篇 |
1988年 | 31篇 |
1987年 | 20篇 |
1986年 | 21篇 |
1985年 | 23篇 |
1984年 | 16篇 |
1983年 | 14篇 |
1982年 | 9篇 |
1980年 | 7篇 |
1979年 | 12篇 |
1978年 | 6篇 |
1965年 | 8篇 |
1959年 | 9篇 |
1955年 | 10篇 |
1954年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 688 毫秒
71.
Learning a sequence of target locations when the sequence is uncorrelated with a sequence of responses and target location is not the response dimension (pure perceptual-based sequence learning) was examined. Using probabilistic sequences of target locations, the author shows that such learning can be implicit, is unaffected by distance between target locations, and is mostly limited to first-order transition probabilities. Moreover, the mechanism underlying learning affords processing of information at anticipated target locations and appears to be attention based. Implications for hypotheses of implicit sequence learning are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
72.
73.
实际图像处理中当视场的变化引起目标变形时,固定大小的形态学算子很难达到较好的处理效果。研究了利用距离变换自适应地调整结构元大小的方法,即根据图像的不同位置来调整结构元素的大小,从而实现图像的形态学运算,并由此推导出了快速计算方法,最后测试了这种新算法的有效性。实验结果表明,该算法取得了较为理想的效果。 相似文献
74.
Optimal Locations of Groundwater Extractions in Coastal Aquifers 总被引:1,自引:0,他引:1
A regional water supply management model for coastal aquifers was developed. One of its outcomes is the definition of the
optimized locations for groundwater withdrawal. Such a tool permits the analysis of alternative plans for groundwater extraction
and the sustainable use of water resources in a coastal aquifer subject to saltwater intrusion. The principal components are
the evolutionary optimization and the analytical/numerical simulation models. The optimization technique looks for the best
well locations taking into consideration the economic results and the satisfaction of the societal water demand. However these
two concerns are conditioned by trying to control the saltwater intrusion, i.e., preserving the environmental equilibrium.
The simulation model uses the governing mathematical equations for groundwater movement to find the interface between freshwater
and saltwater. Because of the non-linearity in the system and the possibility of a jumping interface, a security distance
was defined. This is a controlling variable which can be set by the decision makers. The model was applied to a typical case
with interesting results. For example, diagrams showing the relationship between the location of the wells and the security
distance(s) are of importance to the managers. It was also crucial to have an understanding of the tradeoffs between groundwater
withdrawals, positions of the wells from the coast line, and the security distance. The model was also applied to a real case
in order to relate the extractions, distances and artificial recharge (not presented in this paper). 相似文献
75.
76.
77.
本文讨论了格形码距离谱的计算问题,定义了度量空间意义下的广义准正则格形码,对具有Imai与Hirakawa[2]和Ungerboeck[3]定义的典型的时不变网格结构的广义准正则格形码,证明了其距离谱可用全零信息序列对应的码字进行计算。在理论上推广了M.Rouance与D.J.Costelo的结果,解决了非平方欧几里德度量意义下一类TCM信号序列的距离谱计算问题 相似文献
78.
79.
偏最小二乘回归的应变统计模型研究 总被引:1,自引:0,他引:1
在应变监控模型中,各因子之间存在着多重相关性,将会严重影响参数估计、扩大模型误差、破坏模型的稳健性,为了克服多重相关性对模型的干扰.引入了能辨别系统信息与噪声的偏最小二乘回归.研究分析表明,与普通的最小二乘回归相比,偏最小二乘回归模型具有很好的稳定性. 相似文献
80.
He Ping 《电子科学学刊(英文版)》1994,11(4):296-302
The minimum squared Euclidean distance(MSED) of binary multi-h phase codes is presented. The signal segregation degree(SSD) has been put forward to determine MSED of multi-h phase codes. In order to maximize MSED, SSD should be as large as possible. The necessary and sufficient conditions of maximizing
SSD are derived. Finally, SSD and the exact formulae for MSED of binary 2-h phase codes are also presented. 相似文献