全文获取类型
收费全文 | 4769篇 |
免费 | 112篇 |
专业分类
公路运输 | 1552篇 |
综合类 | 817篇 |
水路运输 | 1293篇 |
铁路运输 | 555篇 |
综合运输 | 664篇 |
出版年
2023年 | 26篇 |
2022年 | 134篇 |
2021年 | 122篇 |
2020年 | 78篇 |
2019年 | 53篇 |
2018年 | 97篇 |
2017年 | 88篇 |
2016年 | 131篇 |
2015年 | 95篇 |
2014年 | 205篇 |
2013年 | 444篇 |
2012年 | 297篇 |
2011年 | 318篇 |
2010年 | 303篇 |
2009年 | 325篇 |
2008年 | 289篇 |
2007年 | 334篇 |
2006年 | 285篇 |
2005年 | 218篇 |
2004年 | 81篇 |
2003年 | 94篇 |
2002年 | 90篇 |
2001年 | 83篇 |
2000年 | 59篇 |
1999年 | 54篇 |
1998年 | 55篇 |
1997年 | 43篇 |
1996年 | 56篇 |
1995年 | 46篇 |
1994年 | 23篇 |
1993年 | 30篇 |
1992年 | 27篇 |
1991年 | 21篇 |
1990年 | 15篇 |
1989年 | 18篇 |
1988年 | 9篇 |
1987年 | 11篇 |
1986年 | 13篇 |
1985年 | 16篇 |
1984年 | 18篇 |
1983年 | 14篇 |
1982年 | 11篇 |
1981年 | 20篇 |
1980年 | 19篇 |
1979年 | 16篇 |
1978年 | 11篇 |
1977年 | 16篇 |
1976年 | 17篇 |
1975年 | 24篇 |
1973年 | 8篇 |
排序方式: 共有4881条查询结果,搜索用时 15 毫秒
101.
在"互联网+"环境下,城市道路交通传统信号控制优化存在的技术瓶颈将得到有效突破。结合信号控制优化实际工作指出传统信号控制优化技术的瓶颈,分析"互联网+"技术辅助信号控制优化的解决思路及工作流程。重点探讨"互联网+"环境下的信号控制优化关键技术,例如主动发现问题、精准优化方案和客观量化评估优化效果等。其中针对方案优化还研究了利用"互联网+"数据校核交通模型以提高信号方案仿真精度。实践结果表明:利用"互联网+"技术可以有效辅助信号控制优化工作,提高信号控制方案与交通流的适配水平,有效缓解交通拥堵。 相似文献
102.
Julian Arellana María Saltarín Ana Margarita Larrañaga Vilma Alvarez César Augusto Henao 《运输评论》2020,40(2):183-203
ABSTRACTNumerous methodologies measuring walkability have been developed over the last years. This paper reviews the Walkability Index (WI) literature of the last decade (2009–2018) and highlights some limitations in the current approaches. Only a few studies have evaluated walkability in Latin America, mainly in big cities but not in medium and small-sized cities in the region, which present their own urbanisation dynamics, security issues, sidewalk invasion problems, and poor planning. Furthermore, most WIs in the literature use objective mesoscale variables to assess walkability in a given area. This paper contributes to filling these gaps by generating new evidence from a medium-sized city in Latin America to question if characteristics of the built environment encourage walking trips, as found in the literature, are transferable among regions. The study also proposes a novel index comprised of microscale and mesoscale built environment variables to assess walkability using virtual tools and considering users’ perceptions. The WI estimation relies on ranking probability models. The results of the case study suggest that subjective Security and Traffic Safety are the most crucial factors influencing walkability in these kind of cities, which is different from what is found in the literature from cities in developed countries where Sidewalk Condition and Attractiveness are the most important factors. Security appeared to be strongly associated with a subjective dimension, represented by the fear of crime or perceived risk for crime, instead of the actual occurrence of crimes. This result evidences the importance of the physical attributes of the real world and how they are captured, judged, and processed by pedestrians. Then, regional transferability of WIs needs to be done carefully. Finally, results in this paper highlight the importance of microscale built environment characteristics in the WI formulation in these cities. Results are in line with other research in some cities of the region, which found that microscale variables such as pavement quality and presence of obstacles on the sidewalks are relevant components to promote walkability. 相似文献
103.
J.A. Calvo C. Álvarez-Caldas J.L. San Román P. Cobo 《Transportation Research Part D: Transport and Environment》2012,17(7):509-513
In this work, a sample of vehicles has been instrumented to measure of variables that influence vehicle noise emissions in Madrid. A circuit reproducing a normal travel pattern in large city is traveled by a fleet of vehicle models representing the fleets of cars in a European city. A sample of drivers covers the test track under different traffic conditions. Driving parameters and noise emitted have been recorded in each test and average values have been extracted. These data have been analyzed to define the noise emissions produced by a vehicle in real driving conditions and to identify the noisiest driving behaviors. 相似文献
104.
Transportation - The associations between objective and subjective dimensions of the built environment and walking behaviour have been examined extensively in existing studies. However, the... 相似文献
105.
This study discusses the analysis of various modeling approaches and maintenance techniques applicable to the Liquefied Natural Gas (LNG) carrier operations in the maritime environment. Various novel modeling techniques are discussed; including genetic algorithms, fuzzy logic and evidential reasoning. We also identify the usefulness of these algorithms in the LNG carrier industry in the areas of risk assessment and maintenance modeling. 相似文献
106.
In this study, we optimize the loading and discharging operations of the Liquefied Natural Gas (LNG) carrier. First, we identify the required precautions for LNG carrier cargo operations. Next, we prioritize these precautions using the analytic hierarchy process (AHP) and experts’ judgments, in order to optimize the operational loading and discharging exercises of the LNG carrier, prevent system failure and human error, and reduce the risk of marine accidents. Thus, the objective of our study is to increase the level of safety during cargo operations. 相似文献
107.
交通运输是国民经济基础性行业,经济新常态下改革交通运输执法体制是贯彻中央全面深化改革、全面依法治国方针的内在要求,是消除执法体制机制弊端、根治执法乱象、破解交通运输发展瓶颈的有效途径,改革的主要内容和目的主要有整合职能、精简机构、核定编制、保障经费四个方面。改革中市辖区不设置执法机构,市管公路治超站移交县级管理,妥善进行富余人员转岗分流,要制定配套政策、采取措施保障改革顺利进行,处理好改革与稳定的关系,做到改革与治理两不误。 相似文献
108.
Transportation - Recent research has contrasted the travel patterns of young adults of Generation Y (or, synonymously, the Millennial Generation) with the travel patterns of earlier generations of... 相似文献
109.
110.
Cooper Crispin H. V. Harvey Ian Orford Scott Chiaradia Alain J. F. 《Transportation》2021,48(2):643-672
Transportation - Predicting how changes to the urban environment layout will affect the spatial distribution of pedestrian flows is important for environmental, social and economic sustainability.... 相似文献