全文获取类型
收费全文 | 567篇 |
免费 | 9篇 |
专业分类
公路运输 | 191篇 |
综合类 | 132篇 |
水路运输 | 135篇 |
铁路运输 | 104篇 |
综合运输 | 14篇 |
出版年
2023年 | 1篇 |
2022年 | 9篇 |
2021年 | 17篇 |
2020年 | 11篇 |
2019年 | 8篇 |
2018年 | 4篇 |
2017年 | 9篇 |
2016年 | 13篇 |
2015年 | 19篇 |
2014年 | 22篇 |
2013年 | 22篇 |
2012年 | 44篇 |
2011年 | 43篇 |
2010年 | 42篇 |
2009年 | 37篇 |
2008年 | 36篇 |
2007年 | 64篇 |
2006年 | 40篇 |
2005年 | 34篇 |
2004年 | 12篇 |
2003年 | 13篇 |
2002年 | 21篇 |
2001年 | 9篇 |
2000年 | 12篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有576条查询结果,搜索用时 15 毫秒
571.
Although progress in face recognition is encouraging, the accuracy rate of face recognition remains to be increased. Since the face image quality has a positive influence on face recognition accuracy, the image enhancement methods are popular in face recognition. Most current image enhancement methods aim at improving visual appearance, but cannot improve recognition accuracy remarkably. In this paper, a feature evaluation operator is designed to overcome this problem. The operator selects patches with the best quality, and then face image is reconstructed with the selected patches. The proposed algorithm is tested on two different face recognition applications. Accuracy is raised after enhancement, and the result proves that the proposed algorithm is effective. 相似文献
572.
The thermal stability of Cu-14Fe and Cu-14Fe-0.07Ag in situ composites is investigated. The evolution of Fe filaments in two composites is analyzed detailedly by annealing at high temperature. The results indicate that the Cu-14Fe in situ composite exhibits two kinds of evolution of Fe filament, the longitudinal splitting of Fe filaments at low temperature (below 600°C) and spheroidization of Fe filaments at high temperature (above 600°C). With the addition of trace Ag, the longitudinal splitting of Fe filaments at low temperature is accelerated, while spheroidization of Fe filaments at high temperature inhibited. The microstructure evolution procedure of Cu-14Fe without and with trace Ag has been modeled. This work would promote the understanding of the microstructure evolution of Cu-Fe in situ composite. 相似文献
573.
指出结点水准网等权替代法进行平差计算的理论依据为序贯平差,在分析结点水准网序贯平差特点的基础上,给出了其逐次平差和精度评定的实现步骤。剖析了计算器中固化统计功能程序的实质,扩展了其应用范围,给出了在实数权情况下各统计功能的含义,结点水准网平差统计功能实现的方法,并通过算例进行了验证。 相似文献
574.
为了保证飞行安全,基于我军现有作战飞机的使用条件,分析现行公路飞机跑道净空规定存在的问题,从公路飞机跑道净空影响因素、净空要求出发,参照现行有关标准、规范的净空规定,提出了公路飞机跑道净空区组成和要求,进行了指标来源分析,为公路飞机跑道的建设和净空保护提供了技术依据. 相似文献
575.
Most existing overlay multicast approaches refuse to consider any network layer support no matter whether it is available or not. This design principle greatly increases the complexity of the routing algorithms and makes the overlay topologies incompatible with the underlying network. To address these issues, topologyaware overlay multicast over IP multicast networks (TOMIMN) was proposed as a novel overlay multicast protocol, which exploits the cooperation between end-hosts and IP multicast routers to construct a topologyaware overlay tree. Through a little modification to protocol independent multicast sparse mode (PIM-SM), a multicast router is able to receive registration from nearby group members and redirect passing-by join requests to them. Due to the multicast router's support, TOMIMN organizes its group members into an overlay multicast tree efficiently, which matches the physical network topology well. 相似文献
576.
作为具有66年历史的老国有企业,一汽锡柴义无反顾地承担起国企的政治责任、经济责任和社会责任,全力以赴打造资源节约型和环境友好型企业。通过节能减排,提前完成了我国“十一五”规划纲要提出的主要污染物排放总量减少10%的指标;通过技术创新,锡柴机环保性能领先国内、接轨国际,使锡柴收获了“中国节能环保型客车发动机最佳制造企业”和“最佳节油型发动机”的美誉。 相似文献