全文获取类型
收费全文 | 3223篇 |
免费 | 154篇 |
专业分类
公路运输 | 730篇 |
综合类 | 879篇 |
水路运输 | 953篇 |
铁路运输 | 579篇 |
综合运输 | 236篇 |
出版年
2024年 | 7篇 |
2023年 | 21篇 |
2022年 | 60篇 |
2021年 | 96篇 |
2020年 | 132篇 |
2019年 | 85篇 |
2018年 | 68篇 |
2017年 | 83篇 |
2016年 | 90篇 |
2015年 | 137篇 |
2014年 | 268篇 |
2013年 | 186篇 |
2012年 | 254篇 |
2011年 | 301篇 |
2010年 | 240篇 |
2009年 | 210篇 |
2008年 | 196篇 |
2007年 | 219篇 |
2006年 | 202篇 |
2005年 | 131篇 |
2004年 | 85篇 |
2003年 | 74篇 |
2002年 | 53篇 |
2001年 | 31篇 |
2000年 | 33篇 |
1999年 | 24篇 |
1998年 | 15篇 |
1997年 | 16篇 |
1996年 | 10篇 |
1995年 | 7篇 |
1994年 | 3篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 9篇 |
1989年 | 6篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1984年 | 2篇 |
排序方式: 共有3377条查询结果,搜索用时 937 毫秒
531.
Kwasi Appeaning Addo 《Coastal management》2013,41(6):555-567
Relative sea-level rise will affect vulnerable coastal communities globally. Quantifying this effect on the coastal environment and infrastructure provides critical information that enables coastal managers to develop sustainable mitigation and adaptation measures. Modeling applications have enabled the past, present, and future trends in shoreline morphology to be investigated in detail. Predictive numerical models depend largely on the reliability of the input data. This article reports on using the Soft Cliff and Platform Erosion (SCAPE) numerical model to simulate future shoreline evolution trend in the central Accra coast in Ghana. The model input parameters include historic shoreline recession rates, wave data, tidal data, bathymetry, beach volume, beach topography, historic relative sea-level rise rates, and the shoreline orientation. The data fed the SCAPE numerical model which simulated the emergence of soft rock shore profiles over timescale of decades to centuries, to project future positions of the central Accra shoreline for the next 100 years under different scenarios of climate change. Simulated future shoreline positions overlaid on a 2005 orthophoto map of Accra enabled vulnerable areas and infrastructure at risk to be identified. It emerged that a highly populated community in central Accra will be inundated by 2065, while the Rivera beach resort will be eroded from 2035. A natural fish landing site in Osu (suburb in Accra) will be lost from 2045. The study has demonstrated that considerable ecological, economic, social, and national losses should be expected within the next century. Shoreline change management options should be explored to help mitigate the expected impact of the sea-level rise. 相似文献
532.
The paper explores the role of stakeholder collaboration in the adoption of innovations as part of the environmental and sustainability agenda of port gateways. We do this through a comparative assessment of the port of Vancouver, British Columbia, and the twin ports of Los Angeles and Long Beach, California. An inductive research approach is used to identify and assess the initiation and implementation process behind exemplary innovations. Innovation includes new technologies and processes for handling and moving cargo, mechanisms for planning and policy making, as well as financing, implementing, upgrading, managing and operating infrastructure systems. A relatively new arena for competition on the basis of innovation concerns environmental performance. The conceptual framework and empirical evidence suggest that while there may be intense demand for and supply of innovation in port gateways, the complex dynamics of the logistics chain are such that successful innovation requires conscious involvement and collaboration of stakeholders. 相似文献
533.
534.
由于梅山本岛土地资源紧张,为了实现梅山规划区块功能,初步考虑在梅山本岛东部围垦以建设梅山通用航
空产业基地等基础设施。采用MIKE 21 HD水动力模型对梅山水道封堵前提下5个不同围垦方案实施后对梅山岛海域的流场
情况进行了数值模拟,并对比围垦实施前后潮流场变化情况,对各方案进行初步比选。从模拟结果可以看出,规划梅东围
垦工程的建设不会改变大范围整体海域的流场结构。总体而言,梅东围垦方案一围垦范围最小,受其影响的范围也相对较
小,而方案5由于未封堵扑蛇山与梅山间汊道,因此其对穿山南作业区的影响程度要小于其他各封堵汊道的方案。 相似文献
535.
采用BISAR3软件从路面力学的角度研究了不同干湿状态下的路基对沥青路面的力学响应,采用路基回弹模量和层间连接状态两个参数来分析路表弯沉、各层面的正应力和剪应力的变化情况。结果表明:路基干湿状态对沥青路面结构的力学变化有很大影响,尤其是路面弯沉和基层层底拉应力,剪应力也有一定影响。 相似文献
536.
Hui Shan Loh 《Maritime Policy and Management》2013,40(4):436-455
ABSTRACTIn the contemporary port business environment, port resilience is of paramount importance for supply chain continuity. A result of the increased integration of ports into supply chains is ports’ potential to supply chain disruptions. This paper introduces a PSCD management model that incorporates the application of risk management, business continuity management, and quality management theories with the purpose of increasing port resilience such that supply chain continuity is enhanced. To validate this model, primary data were collected from samples of port operators and port authorities and analyzed using structural equation modeling with AMOS 22.0. The results indicate that managing PSCD using the management model contributes positively to the identification of internal and external opportunities and through that to port’s resilience of internal operations. This, in turn, positively influences port’s financial health and market reputation. The management model has several managerial and academic implications as it offers meaningful insights on policy development as well as theory building. 相似文献
537.
为了提高出行诱导路径搜索的效率和优度,提出了一种基于道路功能以及交通状态划分的路网二次分层模型,模型从道路的功能角度进行路网的初分层,从道路交通状态角度,通过设定的交通状态阂值进行路网的次分层,建立的路网二次分层模型从宏观方面反映路网的结构,从微观方面反映路网运行的交通参数;利用路网二次分层模型所划分的各层路网之间的协同,借助限制区域的A‘算法进行最优路径的“三段巡径”过程。实例表明该算法实用、高效,有助于搜索得到最优出行路径。 相似文献
538.
文章阐述了二维教学动画的内涵及其特点,从认知负荷的三种角度分析了影响二维教学动画中的认知负荷影响因素,提出了有效控制二维教学动画的认知负荷的设计原则,并在此基础上进行了案例分析,为二维教学动画的设计提供了参考。 相似文献
539.
Yaser E. Hawas 《运输规划与技术》2013,36(2-3):289-309
Abstract This paper reviews the main modules of an integrated system for incident management in real-time, -sim. A core to such a system is a microscopic simulator with extended abilities to model the temporal and spatial evolution of specified non-recurrent traffic conditions. The paper reviews the mathematical formulation of the car-following and lane-changing modules. The model is validated using a simulation-based approach. Concluding comments on the general validation process of the model are provided. The paper finally presents a sample of the accident patterns replicated by the model together with their implications for real world validation. 相似文献
540.