全文获取类型
收费全文 | 73篇 |
免费 | 0篇 |
专业分类
公路运输 | 37篇 |
综合类 | 6篇 |
水路运输 | 9篇 |
铁路运输 | 12篇 |
综合运输 | 9篇 |
出版年
2022年 | 2篇 |
2021年 | 1篇 |
2020年 | 4篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2015年 | 5篇 |
2014年 | 2篇 |
2013年 | 6篇 |
2012年 | 3篇 |
2011年 | 4篇 |
2010年 | 2篇 |
2009年 | 3篇 |
2008年 | 3篇 |
2007年 | 7篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2004年 | 2篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 1篇 |
排序方式: 共有73条查询结果,搜索用时 31 毫秒
31.
Coastal and marine areas provide vital services to support the economic, cultural, recreational, and ecological needs of human communities, but sustaining these benefits necessitates a balance between growing and often competing uses and activities. Minimizing coastal zone conflict and reducing human-induced impacts to ecological resources requires access to consistent spatial information on the distribution and condition of marine resources. Seafloor mapping provides a detailed and reliable spatial template on the structure of the seafloor that has become a core data need for many resource management strategies. The absence of detailed maps of the seafloor hinders the effectiveness of priority setting in marine policy, regulatory processes, and marine stewardship. For large management areas, the relatively high cost of seafloor mapping and limited management budgets requires careful spatial prioritization. In order to address this problem, a consensus based approach, aided by decision-support tools, and participatory geographic information systems (GIS), was implemented in Long Island Sound to spatially prioritize locations, define additional data collection efforts needed, and identify products needed to inform decision-making. The methodology developed has utility for other states and regions in need of spatially prioritizing activities for coastal planning, and organizations charged with providing geospatial services to communities with broad informational needs. 相似文献
32.
文章结合某城市桥梁声屏障设计实例,针对该桥两侧敏感点的分布情况,选择合适类型的声屏障,并通过科学的声学计算,从结构、排水、景观三个方面进行了声屏障设计,对类似项目的声屏障设计有一定的借鉴意义。 相似文献
33.
文章对柴油机的故障表象与诊断技术进行了综合分析,结合理论与实践列出了在柴油机故障诊断中的异常声响发生的部位、异响表象特征和故障基本原因,并以实例阐述了柴油机声响异常辨识在故障诊断中的应用,介绍了该故障诊断技术的发展应用前景。 相似文献
34.
35.
Classically, one mean vehicle representative of each category is used by both static and dynamic traffic noise prediction models. The spectrum associated with this mean vehicle is determined from a linear statistical regression analysis based on measurement campaigns on a track or in situ. However, the variability of individual vehicle emissions can influence predictions and hinder comparison between static and dynamic models. In order to estimate the induced bias, statistical analysis of the distributions of sound power levels emitted by the individual passage of vehicles during 82 measurement campaigns was carried out. The results show that 92% of the residual regression distributions are Gaussian and that standard deviations can reach 3.6 dBA. The value of the proposed correction term for this case study could reach 1.4 dBA for light vehicles and 1.2 dBA for heavy vehicles. This analysis also shows that the variability in sound power levels and thus the corresponding corrections are higher at the lowest speeds that correspond to urban driving conditions. 相似文献
36.
水泥混凝土的振动搅拌技术 总被引:1,自引:0,他引:1
水泥混凝土的振动搅拌效益显著.这里以独联体、美国、日本等国已有的几种振动搅拌装置为例,就其工作原理、结构、性能指标等方面作了重点介绍,以促使这项技术尽快在我国得以应用. 相似文献
37.
38.
车辆及发动机噪声声音品质的研究与发展 总被引:12,自引:0,他引:12
综述了近年来国际上对车辆及发动机噪声声音品质的研究现状,主要论及了对声音品质的描述,主观评价及改善声音品质为目的车辆及发动机的设计和开发研究工作。 相似文献
39.
40.