全文获取类型
收费全文 | 671篇 |
免费 | 28篇 |
专业分类
公路运输 | 105篇 |
综合类 | 301篇 |
水路运输 | 192篇 |
铁路运输 | 50篇 |
综合运输 | 51篇 |
出版年
2023年 | 4篇 |
2022年 | 3篇 |
2021年 | 12篇 |
2020年 | 12篇 |
2019年 | 17篇 |
2018年 | 6篇 |
2017年 | 19篇 |
2016年 | 17篇 |
2015年 | 29篇 |
2014年 | 42篇 |
2013年 | 31篇 |
2012年 | 47篇 |
2011年 | 43篇 |
2010年 | 46篇 |
2009年 | 44篇 |
2008年 | 35篇 |
2007年 | 52篇 |
2006年 | 67篇 |
2005年 | 39篇 |
2004年 | 30篇 |
2003年 | 16篇 |
2002年 | 10篇 |
2001年 | 16篇 |
2000年 | 13篇 |
1999年 | 7篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1985年 | 2篇 |
排序方式: 共有699条查询结果,搜索用时 453 毫秒
451.
十字路口黄灯时间及困境区域的数学模型研究 总被引:1,自引:0,他引:1
城市交通十字路口是冲突交通流汇聚的节点,安全问题十分突出,黄灯在交通信号系统中起着非常重要的作用,黄灯时间的长短设置直接影响城市交通的状况.建立保守黄灯时间数学模型,通过逐步修订,建立了更符合实际情况的有效黄灯时间的数学模型,并在城市道路十字路口黄灯时间确定为4s的情况下,对安全停车距离进行了分析,指出困境区域的存在性与进行深入研究的必要性. 相似文献
452.
为了揭示二次交通事故的演变特性,预防二次交通事故的发生,在描述Duffing振子模型的基础上,分析二次交通事故的混沌特性,并建立混沌模型.在仿真环境下,改变模型参数值,得到系统出现周期振荡状态和混沌状态的系统结构条件,并绘制出相平面图和根轨迹图.实例分析结果表明,Duffing振子模型可用于二次交通事故演变过程分析,仿真结果为采取有效的二次交通事故预防措施提供了理论依据. 相似文献
453.
将特征正交分解(Proper Orthogonal Decomposition,POD)应用于二维非饱和土壤水流方程通常的有限元格式,将其简化为一个计算量少但具有足够高精度的POD有限元格式,并给出POD有限元解的误差估计.数值例子表明:POD有限元解能有效地表达土壤水流的运动特征,保证了POD有限元解和通常有限元解误差足够小,而且POD有限元格式有较少的自由度,比通常的有限元格式大大节省了计算量和内存容量,从而验证POD方法的有效性. 相似文献
454.
This paper investigates the impact of a variety of travel information types on the quality of travel choices. Choice quality
is measured by comparing observed choices made under conditions of incomplete knowledge with predicted choice probabilities
under complete knowledge. Furthermore, the potential impact of travel information is considered along multiple attribute-dimensions
of alternatives, rather than in terms of travel time reductions only. Data is obtained from a choice experiment in a multimodal
travel simulator in combination with a web-based mode-choice experiment. A Structural Equation Model is estimated to test
a series of hypothesized direct and indirect relations between a traveler’s knowledge levels, information acquisition behavior
and the resulting travel-choice quality. The estimation results support the hypothesized relations, which provides evidence
of validity and applicability of the developed measure of travel-choice quality. Furthermore, found relations in general provide
some careful support for the often expected impact of information on the quality of travel choices. The effects are largest
for information services that generate previously unknown alternatives, and lowest for services that provide warnings in case
of high travel times only.
Caspar Chorus holds a PhD in Technical Sciences (cum laude) from Delft University of Technology, and is currently an Assistant Professor at Eindhoven University of Technology’s Urban Planning Group. His general interests include traveler behavior research / decision making under knowledge limitations / discrete choice analysis. Theo Arentze received a Ph.D. in Decision Support Systems for urban planning from the Eindhoven University of Technology. He is now an Associate Professor at the Urban Planning Group at the same university. His main fields of expertise and current research interests are decision support systems, activity-based modeling, discrete choice modeling, knowledge discovery and learning-based systems with applications in urban and transport planning. Harry Timmermans received a Ph.D. in Spatial Sciences from the University of Nijmegen. He is Chair of the Urban Planning Group and Director of the European Institute of Retailing and Consumer Services. His main fields of expertise concern behavioral modeling, consumer studies and computer systems in a variety of application contexts including transportation. 相似文献
Caspar G. ChorusEmail: |
Caspar Chorus holds a PhD in Technical Sciences (cum laude) from Delft University of Technology, and is currently an Assistant Professor at Eindhoven University of Technology’s Urban Planning Group. His general interests include traveler behavior research / decision making under knowledge limitations / discrete choice analysis. Theo Arentze received a Ph.D. in Decision Support Systems for urban planning from the Eindhoven University of Technology. He is now an Associate Professor at the Urban Planning Group at the same university. His main fields of expertise and current research interests are decision support systems, activity-based modeling, discrete choice modeling, knowledge discovery and learning-based systems with applications in urban and transport planning. Harry Timmermans received a Ph.D. in Spatial Sciences from the University of Nijmegen. He is Chair of the Urban Planning Group and Director of the European Institute of Retailing and Consumer Services. His main fields of expertise concern behavioral modeling, consumer studies and computer systems in a variety of application contexts including transportation. 相似文献
455.
CFD在潜艇外形方案比较中的应用 总被引:5,自引:0,他引:5
以水滴型潜艇为母型进行改造,提出了新型椭圆截面和碟形截面的潜艇外形设计.水滴型潜艇的型值选用"大青花鱼"号的简化型值,在船长与排水量不变的条件下通过改变截面形状给出了后两种新艇型的型值,建立了计算模型.采用有限体积法求解不可压缩的雷诺平均(RANS)方程数值模拟了三种艇体周围的粘性流场,通过对三者的粘性绕流和阻力性能的比较,给出了三种方案各自的优缺点. 相似文献
456.
457.
458.
459.
460.