全文获取类型
收费全文 | 1153篇 |
免费 | 45篇 |
专业分类
公路运输 | 271篇 |
综合类 | 353篇 |
水路运输 | 287篇 |
铁路运输 | 228篇 |
综合运输 | 59篇 |
出版年
2024年 | 4篇 |
2023年 | 7篇 |
2022年 | 23篇 |
2021年 | 38篇 |
2020年 | 37篇 |
2019年 | 26篇 |
2018年 | 13篇 |
2017年 | 20篇 |
2016年 | 20篇 |
2015年 | 30篇 |
2014年 | 90篇 |
2013年 | 70篇 |
2012年 | 84篇 |
2011年 | 96篇 |
2010年 | 83篇 |
2009年 | 65篇 |
2008年 | 77篇 |
2007年 | 84篇 |
2006年 | 103篇 |
2005年 | 62篇 |
2004年 | 44篇 |
2003年 | 22篇 |
2002年 | 20篇 |
2001年 | 15篇 |
2000年 | 11篇 |
1999年 | 5篇 |
1998年 | 11篇 |
1997年 | 10篇 |
1996年 | 7篇 |
1995年 | 1篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 1篇 |
排序方式: 共有1198条查询结果,搜索用时 15 毫秒
971.
972.
以某新开发的变速器箱体为研究对象,利用HyperWorks软件建立该变速器箱体的有限元模型。对变速器箱体做自由模态分析和频率响应分析,得到其模态频率分布和相应振型,避开共振点,获得箱体表面振动的速度响应云图。最后对变速器箱体进行辐射噪声分析,提取箱体表面的噪声分布图以得到声辐射敏感区域,提出改进箱体结构的措施。该研究为变速器减震降噪提供重要参考。 相似文献
973.
The shape characterization and spatial distribution of aggregate,mastic and air void phases for asphalt mixture were analyzed.Three air void percentage asphalt mixtures,4%,7% and 8%,respectively,were cut into cross sections and polished.X-ray scanning microscope was used to capture aggregate,mastic,air void phase by the image.The average of polygon diameter was chosen as a threshold to determine which aggregates would be retained on a given sieve.The aggregate morphological image from scanned image was utilized by digital image processing method to calculate the gradation of aggregate and simulate the real gradation.Analysis result shows that the air void of asphalt mixture has influence on the correlation between calculation gradation and actual gradation.When comparing 4.75 mm sieve size of 4%,7% and 8% air void asphalt mixtures,7% air void asphalt mixture has 55% higher than actual size gradation,8% air void asphalt mixture has 8% higher than actual size gradation,and 4% air void asphalt mixture has 3.71% lower than actual size gradation.4% air void asphalt mixture has the best correlation between calculation gradation and actual gradation comparing to other specimens.The air void percentage of asphalt mixture has no obvious influence on the air void orientation,and three asphalt mixtures show the similar air orientation along the same direction. 相似文献
974.
975.
张冬瑜 《广东交通职业技术学院学报》2013,12(1):61-63
在职业学校会计教学中,案例分析教学法是具有较大启发与引导性和非常强的实践操作性的一种教学方法,对课堂教学与知识传授具有举一反三、融会贯通的教学效果。文中分析了案例分析教学法在职业学校会计教学中的重要性,并就如何有效进行案例分析教学法进行了介绍。 相似文献
976.
韩素文 《国防交通工程与技术》2013,(2):23-26
以隧道施工TBM为研究对象,设计了主轴承声发射检测试验,进行了声发射信号采集,并取得较理想的分析信号。根据信号的时域图像特征及相关技术人员的数据支持,初步对TBM主轴承的工作状态做了判断,并采用了时变峭度法对实测信号进行分析,获取了强背景噪声下明显的故障特征,达到了抑制噪声、突出特征成分的目的。试验分析结果证明了该方法用于声发射故障信号特征提取的有效性,同时对TBM的状态监测提供了新思路。 相似文献
977.
Abstract This paper attempts to propose a framework on driving cycle development based on a thorough review of 101 transient driving cycles. A comparison of the driving cycles highlighted that Asian driving is the slowest but most aggressive while European driving is the fastest and smoothest. Further review of the cycle development methodologies identified three major elements for developing a driving cycle; test route selection, data collection and cycle construction methods. A framework was eventually proposed based on these findings and recommendations from this review. First, traffic activity patterns and quantitative statistics should be considered in determining the test routes. Speed data can be collected by using chase car method, on‐board measurement techniques or their hybrid. As for the construction of driving cycle, the matching approach has been more commonly used. It is recommended that the tendency of zero change in acceleration, which has been commonly ignored in the literature, and the application of succession probability at second‐by‐second level should be further explored. A fifth mode, creeping, is also recommended for modal analysis for characterizing urban congested driving conditions. 相似文献
978.
Raj Bridgelall 《运输规划与技术》2013,36(8):711-737
Parking demand is a significant land-use problem in campus planning. The parking policies of universities and large corporations with facilities located in small urban areas shape the character of their campuses. These facilities will benefit from a simplified methodology to study the effects of parking availability on transportation mode mix and impacts on recruitment and staffing policies. This paper, based on a case study of North Dakota State University in the United States, introduces an analytical framework to provide planners with insights about how parking supply and demand affects campus transportation mode choice. The methodology relies only on aggregate mode choice data for the special generator zone and the average aggregate volume/capacity ratio projections for all external routes that access the zone. This reduced data requirement significantly lowers analysis cost and obviates the need for specialized modelling software and spatial network analysis tools. Results illustrate that the framework is effective for analysing mode choice changes under different scenarios of parking supply and population growth. 相似文献
979.
ABSTRACTThrough the comprehensive consideration of four subsystems – overall development level, infrastructure construction, public transportation service level and policy support – an index system of public transport priority performance evaluation is established. A performance evaluation of bus priority implementation in Wuhan City from 2007 to 2016 is carried out by applying the difference coefficient CRITIC-TOPSIS model. The obstacle factor model is also used to diagnose the factors affecting the priority performance of urban public transport. The research results show that, during this decade, the comprehensive performance of Wuhan City’s public transport priority developed from poor to medium, then to good and finally to excellent. The overall development level and infrastructure construction performance subsystems have the highest obstacle degree, followed by public transportation service levels and policy support performance subsystems. The research idea and method of this paper provide a realistic basis for promoting the priority performance of urban public transport. 相似文献
980.
Qisheng Pan 《运输规划与技术》2013,36(1):43-74
Abstract In comparison to personal travel, freight movements within large metropolitan areas are much less studied. Most conventional transportation models and planning analysis that disregarded freight flows have been criticized on the plausibility of their results and conclusions. To alleviate these problems, this study proposes a non-survey based approach to assemble and process freight data in a systematic way. A freight origin–destination (OD) matrix of freight flows can be developed using secondary data sources. The estimated freight flows can be loaded together with conventional passenger flows onto the regional highway network of a large metropolitan area. As a case study, this non-survey based approach was applied to build a freight OD and study the traffic flows in Los Angeles. It concluded that this approach can be used to analyze urban freight movement in a low-cost way in which planning agencies can overcome the common omission of freight flow information in their transportation plans. 相似文献