全文获取类型
收费全文 | 54512篇 |
免费 | 9173篇 |
国内免费 | 5647篇 |
专业分类
电工技术 | 4992篇 |
技术理论 | 2篇 |
综合类 | 4683篇 |
化学工业 | 2392篇 |
金属工艺 | 2164篇 |
机械仪表 | 3936篇 |
建筑科学 | 2309篇 |
矿业工程 | 1033篇 |
能源动力 | 476篇 |
轻工业 | 4571篇 |
水利工程 | 549篇 |
石油天然气 | 1186篇 |
武器工业 | 826篇 |
无线电 | 12062篇 |
一般工业技术 | 3979篇 |
冶金工业 | 1297篇 |
原子能技术 | 554篇 |
自动化技术 | 22321篇 |
出版年
2024年 | 583篇 |
2023年 | 1646篇 |
2022年 | 2625篇 |
2021年 | 2875篇 |
2020年 | 2805篇 |
2019年 | 2165篇 |
2018年 | 1811篇 |
2017年 | 2355篇 |
2016年 | 2501篇 |
2015年 | 2807篇 |
2014年 | 4342篇 |
2013年 | 3735篇 |
2012年 | 4571篇 |
2011年 | 4762篇 |
2010年 | 3587篇 |
2009年 | 3537篇 |
2008年 | 3536篇 |
2007年 | 3889篇 |
2006年 | 3160篇 |
2005年 | 2631篇 |
2004年 | 1980篇 |
2003年 | 1647篇 |
2002年 | 1222篇 |
2001年 | 867篇 |
2000年 | 732篇 |
1999年 | 552篇 |
1998年 | 462篇 |
1997年 | 351篇 |
1996年 | 318篇 |
1995年 | 231篇 |
1994年 | 165篇 |
1993年 | 149篇 |
1992年 | 147篇 |
1991年 | 117篇 |
1990年 | 90篇 |
1989年 | 57篇 |
1988年 | 53篇 |
1987年 | 31篇 |
1986年 | 35篇 |
1985年 | 27篇 |
1984年 | 32篇 |
1983年 | 24篇 |
1982年 | 19篇 |
1981年 | 21篇 |
1980年 | 23篇 |
1979年 | 9篇 |
1978年 | 9篇 |
1976年 | 5篇 |
1975年 | 6篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
71.
Chia-Jung Pai Author Vitae Author Vitae Yu-Ming Liang Author Vitae Author Vitae Sei-Wang Chen Author Vitae 《Pattern recognition》2004,37(5):1025-1034
This paper presents a system that can perform pedestrian detection and tracking using vision-based techniques. A very important issue in the field of intelligent transportation system is to prevent pedestrians from being hit by vehicles. Recently, a great number of vision-based techniques have been proposed for this purpose. In this paper, we propose a vision-based method, which combines the use of a pedestrian model as well as the walking rhythm of pedestrians to detect and track walking pedestrians. Through integrating some spatial and temporal information grabbed by a vision system, we are able to develop a reliable system that can be used to prevent traffic accidents happened at crossroads. In addition, the proposed system can deal with the occlusion problem. Experimental results obtained by executing some real world cases have demonstrated that the proposed system is indeed superb. 相似文献
72.
V. Rodin Author Vitae A. Benzinou Author VitaeAuthor Vitae P. Ballet Author VitaeAuthor Vitae J. Tisseau Author VitaeAuthor Vitae 《Pattern recognition》2004,37(4):631-645
In this article, we present a parallel image processing system based on the concept of reactive agents. Our system lies in the oRis language, which allows to describe finely and simply the agents’ behaviors to detect image features. We also present a method of segmentation using a multi-agent system, and two biological applications made with oRis. The stopping of this multi-agent system is implemented through a technique issued from immunology: the apoptosis. 相似文献
73.
Kernel Spectral Matched Filter for Hyperspectral Imagery 总被引:1,自引:0,他引:1
In this paper a kernel-based nonlinear spectral matched filter is introduced for target detection in hyperspectral imagery,
which is implemented by using the ideas in kernel-based learning theory. A spectral matched filter is defined in a feature
space of high dimensionality, which is implicitly generated by a nonlinear mapping associated with a kernel function. A kernel
version of the matched filter is derived by expressing the spectral matched filter in terms of the vector dot products form
and replacing each dot product with a kernel function using the so called kernel trick property of the Mercer kernels. The proposed kernel spectral matched filter is equivalent to a nonlinear matched filter in the original input space,
which is capable of generating nonlinear decision boundaries. The kernel version of the linear spectral matched filter is
implemented and simulation results on hyperspectral imagery show that the kernel spectral matched filter outperforms the conventional
linear matched filter. 相似文献
74.
应用功率控制、波束赋形和多用户检测可以有效地消除和减少CDMA系统中的干扰。本文结合波束赋形和多用户检测的特性,提出一种应用波束赋形增益和多用户相关矩阵的解相关算法。基于算法的复杂性,提出一种区分聚集用户进行多用户检测的的算法。由于波束赋形能够消减主瓣波束之外的多用户干扰,对聚集移动台采用解相关检测达到减少运算量和消除多用户干扰的目的。对算法进行了仿真分析,证明了本算法的优越性。 相似文献
75.
Abstract: This paper presents a novelty detection-based technique to identify core material properties of honeycombs and cellular structures. A numerical model (finite element) representing full scale and/or reduced size of the cellular solid is used to generate transmissibilities between topological homologous points at cells in different locations. In order to make the procedure robust against noise, these transmissibilities are artificially corrupted. This step is representative of a series of experimentally obtained measurements which automatically return information relating to the size and shape of data noise along with the mean measurement. The next stage, both in this paper and in the proposal for the experimental approach, is to generate several further sets of transmissibilities from the finite element model; the only difference being that the core material properties are altered from the original values. A novelty detection framework is then adopted to find a similarity measure between each of these 'test' transmissibilities and the original set thereby identifying the material properties. Although this work is concerned with identifying only one material property, the methodology extends to identifying several properties. 相似文献
76.
We study the stressed state of an inhomogeneous welded joint containing an interlayer of a more high-strength material under the action of tensile loads. It is assumed that the contact boundary has a cracklike defect. We deduce analytic dependences of the fracture load on the mechanical inhomogeneity of the joint, thickness of the interlayer, and depth of the defect. The maximum depth of the defect to which the joint is insensitive is established. The proposed theoretical results are innovative and agree with the experimental data obtained for specimens cut out from a pipe of 14KhGS steel. 相似文献
77.
电梯门机控制系统的运行曲线设计 总被引:1,自引:0,他引:1
为了实现电梯轿厢门的开门和关门快速且平稳地运行,介绍了一种基于高性能微型机的门机控制系统结构和门位移的检测原理,以门位移量作为控制系统的反馈量,对门机运行速度进行了分区设计。在高速附近的变化区,门机速度匀速变化时,进行了门机开门和关门控制曲线的计算,推导出运行位移与门机速度具有二次曲线的关系,进而对微型机控制的软件流程进行了设计,达到了门机高低速运行的平稳过渡。最后,给出了实际运行系统的主电路电压波形。 相似文献
78.
新型超微晶软磁合金FePCCuMoSi微观结构缺陷的正电子湮没研究 总被引:1,自引:0,他引:1
用正电子湮没方法研究了新型超微晶软磁合金的微观结构缺陷,样品选用的是在不同温度下退火的Fe81P12C3Cu1Mo0.5Si2.5合金,结果表明,合金的微观结构构陷大小,密度随退火温度有规律地变化,这种现象可能与非晶的晶化过程有关。 相似文献
79.
讨论了粉末静电涂装中出现的涂层抗冲击试验缺陷,通过设计实验寻找造成该缺陷的原因,揭示了产生涂层起皱和脱离基材的原因是钢板与磷化液之间的匹配性差。通过提高磷化液的游离酸酸度解决了该问题。从理论上推出了游离酸与附着力之间可能的关系:游离酸影响磷化膜与基材的结合力,或影响形成的磷化膜的形态。 相似文献
80.
针对汽车锻件拉杆固定支架在生产过程中产生的裂纹、折叠、表面脱碳等多种形式缺陷,从锻件生产工艺过程的各工序来分析其可能产生的缺陷,并重点就裂纹、折叠、表面脱碳等缺陷产生的原因及其解决方法进行探讨,从而进一步完善生产工艺,改善锻件质量. 相似文献