全文获取类型
收费全文 | 461篇 |
免费 | 51篇 |
国内免费 | 20篇 |
专业分类
化学 | 35篇 |
力学 | 94篇 |
综合类 | 5篇 |
数学 | 108篇 |
物理学 | 290篇 |
出版年
2024年 | 1篇 |
2023年 | 22篇 |
2022年 | 17篇 |
2021年 | 24篇 |
2020年 | 17篇 |
2019年 | 9篇 |
2018年 | 10篇 |
2017年 | 11篇 |
2016年 | 10篇 |
2015年 | 12篇 |
2014年 | 45篇 |
2013年 | 31篇 |
2012年 | 71篇 |
2011年 | 61篇 |
2010年 | 29篇 |
2009年 | 35篇 |
2008年 | 27篇 |
2007年 | 19篇 |
2006年 | 21篇 |
2005年 | 16篇 |
2004年 | 2篇 |
2003年 | 8篇 |
2002年 | 6篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 10篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1993年 | 6篇 |
1992年 | 1篇 |
1990年 | 1篇 |
排序方式: 共有532条查询结果,搜索用时 31 毫秒
51.
A master-slave visual surveillance system is composed of one fish-eye panoramic camera and one dynamic pan-tilt-zoom (PTZ) dome camera. In order to make PTZ dome camera zoom into all targets of interest in panoramic image, the fish-eye panoramic camera is fixed inclining towards the gravity direction, which may cause more obvious distortion. This paper proposed a novel method for the distortion correction of captured panoramic image based on the midpoint circle algorithm (MCA). The method uses incremental calculation of decision parameters to determine the pixel positions along a circle circumference, and both of the vertical and horizontal are rectilinearised. Experimental results show that our correction method based on MCA is efficient and effective. In particular, due to its low computational cost, our method can be applied on embedded camera platform without any extra hardware resources. 相似文献
52.
The present work describes the design of three flat superlens structures for acoustic source imaging and explores an active acoustic metamaterial (AAM) to realise such a design. The first two lenses are constructed via the coordinate transform method (CTM), and their constituent materials are anisotropic. The third lens consists of a material that has both a negative density and a negative bulk modulus. In these lenses, the quality of the images is “clear” and sharp; thus, the diffraction limit of classical lenses is overcome. Finally, a multi-control strategy is developed to achieve the desired parameters and to eliminate coupling effects in the AAM. 相似文献
53.
《European Journal of Operational Research》2002,139(3):533-542
We consider a satellite following orbits around the earth in order to take shots corresponding to images requested by various customers. The daily operations of such a satellite consist of defining a feasible and satisfactory shot sequence. This problem involves both combinatorial and multiple criteria difficulties. Indeed, the number of feasible shot sequences grows significantly with the number of images asked for, and the evaluation of a shot sequence is based on several conflicting criteria. We propose to formulate this problem as the selection of a multiple criteria path in a graph without circuit. Our approach for solving this problem involves two stages: generation of efficient paths and selection of a satisfactory path using a multiple criteria interactive procedure. 相似文献
54.
DAI Hong-Yi ZHANG Ming KUANG Le-Man 《理论物理通讯》2008,50(7):73-76
We present a scheme for probabilistic remote preparation of multi-qubit with three-party from a sender to either of two receivers. The quantum channel is composed of a partial entangled tripartite GHZ state. We obtain the successful totM probability of the scheme in the general case and special case, respectively. We also calculate total classical communication cost required in the RSP process with three-party in the general case and special case, respectively. 相似文献
55.
56.
为得到接触爆炸下钢筋混凝土(reinforced concrete,RC)梁的局部破坏模式和毁伤效应,对同一尺寸的RC梁进行了不同装药量的接触爆炸试验研究。试验中采用框架结构中典型工程尺度RC原型梁为研究对象,通过4次爆炸试验,观测了RC梁在不同装药量下的局部破坏模式和破坏特征,分析了装药量对局部毁伤效应的影响。研究结果表明:接触爆炸荷载作用下,RC梁将发生正面成坑、侧面崩落、背面震塌和截面冲切等局部破坏模式,爆坑深度、震塌厚度、表面毁伤面积以及受压区纵筋变形均与装药量立方根近似呈线性增加关系。在试验数据基础上,将RC梁局部毁伤程度划分为轻度毁伤、中度毁伤、重度毁伤和严重毁伤4个等级,采用比例装药量判据进行评估。研究成果可为抗爆结构设计和结构毁伤评估提供理论依据。 相似文献
57.
58.
Fluid Dynamics - To predict the boundary layer transition on swept wings, experimental and numerical researches were conducted to obtained the accurate boundary layer transition front and to... 相似文献
59.
传统的紫外熔石英元件加工方法本身会引入各类制造缺陷,需要后期加工来消除前期加工带来的缺陷,限制了熔石英元件的加工质量和加工效率。针对这些问题,课题组提出了采用磁流变、离子束、保形光顺和流体动压抛光等可控柔体加工技术提升熔石英元件的加工效果,并开展了相关研究。主要介绍了课题组在关键技术上取得的重要进展,包括亚纳米精度表面控形制造技术、纳米精度本征表面控性生成方法、熔石英元件高精度低缺陷组合工艺与设备等一系列关键技术。通过探讨关键技术及其发展现状,为未来紫外熔石英元件高精度低缺陷制造技术的发展提供参考。 相似文献