首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   4499篇
  免费   148篇
公路运输   1696篇
综合类   998篇
水路运输   966篇
铁路运输   918篇
综合运输   69篇
  2024年   13篇
  2023年   32篇
  2022年   80篇
  2021年   130篇
  2020年   197篇
  2019年   75篇
  2018年   36篇
  2017年   68篇
  2016年   67篇
  2015年   145篇
  2014年   309篇
  2013年   257篇
  2012年   440篇
  2011年   402篇
  2010年   284篇
  2009年   298篇
  2008年   309篇
  2007年   453篇
  2006年   403篇
  2005年   216篇
  2004年   102篇
  2003年   83篇
  2002年   61篇
  2001年   39篇
  2000年   25篇
  1999年   12篇
  1998年   7篇
  1997年   17篇
  1996年   19篇
  1995年   5篇
  1994年   8篇
  1993年   7篇
  1992年   10篇
  1991年   8篇
  1990年   12篇
  1989年   7篇
  1988年   4篇
  1987年   2篇
  1986年   1篇
  1985年   2篇
  1984年   2篇
排序方式: 共有4647条查询结果,搜索用时 15 毫秒
71.
介绍了京沪高铁工程中,吊运梁机的加高技术改造背景,从工程进度、工程成本方面分析了改造的实施步骤,改造后压杆和整体的稳定性,及改造过程中的安全重点、技术重点等.为今后的类似技术改造提供经验及依据.  相似文献   
72.
运用填充理论进行钢渣的级配和石灰、粉煤灰最佳比例的研究,通过对不同级配、不同二灰掺配比例的混合料路用性能比较,提出了一种最佳比例的二灰稳定钢渣混合料,其钢渣构成承重骨架,二灰密实地填充于其空隙中并裹覆其表面.用电镜等手段对其进行了微观分析;用抗压强度和回弹模量评价其力学性能.此项研究对利用钢渣铺路具有一定的借鉴作用.  相似文献   
73.
在设计盛行“以人为本”的观念下,本文探讨了动画创作领域有关人之本体的几个问题。第一:解读动画创作中“受众”与“受众相关者”,阐释两者在人本观构建中的的重要性。第二:论文进而讨论了受众与受众相关者发生关系的形式。第三:探讨了在何种“生态环境”的特定条件下,动画才能更好的实现“以人为本”的基本原则。  相似文献   
74.
75.
简述国内外钢-混结合梁桥的发展及分类,对钢-混结合梁桥的适用性及经济性进行比较,详细介绍了德国有代表性的3座钢-混结合梁桥.  相似文献   
76.
如何节油是人与汽车科学结合中出现的课题。为了减小这种矛盾关系,介绍了车辆参数变化后多耗油的过程,以及驾驶员容易忽视的驾驶细节对油耗的影响。分析了驾驶中正确运用高档低速,经济车速,滑行行驶等节油方法和原理。注意这些细节,运用这些技巧,并成为习惯,会比普通车手平均省油8~10%。  相似文献   
77.
步履式顶推跨铁路钢箱梁施工技术   总被引:1,自引:0,他引:1  
结合沈阳绕城高速公路后丁香大桥钢箱梁的施工,对步履式顶推法施工中的钢箱梁拼装平台的搭设、钢箱梁的拼装、临时墩设置、导梁拼装、顶推设备布设、顶推步骤及落梁作了简单叙述,并对顶推施工中的注意事项、控制措施、控制的重难点等进行了详细介绍,可为今后同类型桥梁的施工提供参考。  相似文献   
78.
随着社会经济的发展,机动车保有量急剧增长,城市化过程中交通拥堵问题日趋严重,交通能源消耗加剧。为了降低由此带来的损失,需要及时探明路网中交通效率低、能耗高的区域,并采取有效的交通管理措施。通过研究交通状态与能耗的关系,进行相应的交通参数分析,建立能耗区识别及等级划分模型,计算得到3个等级能耗区的界定阈值分别为0.411和0.678。  相似文献   
79.
The classical theory of transport equilibrium is based on the Wardrop’s first principle that describes a Nash User Equilibrium (UE), where in no driver can unilaterally change routes to improve his/her travel times. A growing number of economic laboratory experiments aiming at testing Nash-Wardrop equilibrium have shown that the Pure Strategy Nash Equilibrium (PSNE) is not able to explain the observed strategic choices well. In addition even though Mixed Strategy Nash Equilibrium (MSNE) has been found to fit better the observed aggregate choices, it does not explain the variance in choices well. This study analyses choices made by users in three different experiments involving strategic interactions in endogenous congestion to evaluate equilibrium prediction. We compare the predictions of the PSNE, MSNE and Stochastic User Equilibrium (SUE). In SUE, the observed variations in choices are assumed to be due to perception errors. The study proposes a method to iteratively estimate SUE models on choice data with strategic interactions. Among the three sets of experimental data the SUE approach was found to accurately predict the average choices, as well as the variances in choices. The fact that the SUE model was found to accurately predict variances in choices, suggests its applicability for transport equilibrium models that attempt to evaluate reliability in transportation systems. This finding is fundamental in the effort to determining a behaviourally consistent paradigm to model equilibrium in transport networks. The study also finds that Fechner error which is the inverse of the scale parameter in the SUE model is affected by the group sizes and the complexity of the cost function. In fact, the larger group sizes and complexity of cost functions increased the variability in choices. Finally, from an experimental design standpoint we show that it is not possible to estimate a noise parameter associate to Fechner error in the case when the choices are equally probable.  相似文献   
80.
Although several cities in India are developing the metro system, there are lacunas associated with transfer facilities in and around metro stations. The present work aims to investigate the perception of commuters of Kolkata city, India in terms of their willingness-to-pay (WTP) for improvement of transfer facilities. A stated preference survey instrument was designed to collect choice responses from metro commuters and the database was analysed by developing random parameter logit (RPL) models. The decomposition effects of various socioeconomic and trip characteristics on mean estimates were also investigated in random parameter logit models with heterogeneity. The work indicates significantly high WTP of metro commuters as compared to the average metro fare for improvement of various qualitative attributes of transfer facility such as ‘facility for level change’, ‘visual communication’, ‘pedestrian crossing’, and ‘pedestrian environment’. The WTP values are also found to vary across different groups of commuter formed on the basis of ‘trip purpose’, ‘monthly household income’, ‘station type’ and ‘metro fare’. ‘Work trip’ commuters are found to have higher WTP for improvement of access time, pedestrian environment and use of an escalator over the elevator. On the other hand, ‘high-income group’ commuters have shown higher WTP for improvement of access time, pedestrian crossing, and pedestrian environment. While ‘high fare group’ commuters have higher WTP for access time and pedestrian environment, heterogeneity is also observed in WTP for facility for level change, pedestrian crossing, and pedestrian environment across commuters using different ‘station type’ (underground, at-grade, and elevated). The findings from the study provide a basis for formulating policies for the improvement of transfer facilities in and around metro stations giving due attention to the preference of commuters having different socioeconomic and trip characteristics.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号