全文获取类型
收费全文 | 1566篇 |
免费 | 8篇 |
专业分类
公路运输 | 663篇 |
综合类 | 57篇 |
水路运输 | 410篇 |
铁路运输 | 45篇 |
综合运输 | 399篇 |
出版年
2023年 | 12篇 |
2022年 | 21篇 |
2021年 | 8篇 |
2020年 | 8篇 |
2019年 | 7篇 |
2018年 | 68篇 |
2017年 | 70篇 |
2016年 | 156篇 |
2015年 | 12篇 |
2014年 | 33篇 |
2013年 | 139篇 |
2012年 | 77篇 |
2011年 | 172篇 |
2010年 | 151篇 |
2009年 | 67篇 |
2008年 | 120篇 |
2007年 | 53篇 |
2006年 | 10篇 |
2005年 | 21篇 |
2004年 | 29篇 |
2003年 | 11篇 |
2002年 | 18篇 |
2001年 | 8篇 |
2000年 | 16篇 |
1999年 | 15篇 |
1998年 | 25篇 |
1997年 | 14篇 |
1996年 | 19篇 |
1995年 | 16篇 |
1994年 | 6篇 |
1993年 | 7篇 |
1992年 | 12篇 |
1991年 | 8篇 |
1990年 | 11篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 9篇 |
1986年 | 8篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 12篇 |
1982年 | 7篇 |
1981年 | 12篇 |
1980年 | 8篇 |
1979年 | 15篇 |
1977年 | 15篇 |
1976年 | 11篇 |
1975年 | 10篇 |
1974年 | 8篇 |
1973年 | 6篇 |
排序方式: 共有1574条查询结果,搜索用时 281 毫秒
921.
B. -L. Choi D. -H. Choi J. Min K. Jeon J. Park S. Choi J. -M. Ko 《International Journal of Automotive Technology》2009,10(1):49-54
This research proposes an automatic torsion beam axle optimization process with a multidisciplinary approach and generates
the optimal torsion design parameters, such as thickness and shape. In order to construct an automatic analysis process, multidisciplinary
analysis models, such as modal analysis, roll mode dynamic analysis, and fatigue analysis, were applied in batch mode. To
understand the design space, a parametric study using the torsion beam thickness and shape was performed. Considering roll
durability and K&C characteristics, the torsion beam axle could be optimized. For the automated design process, a PIDO tool
called PIAnO was used. In conclusion, a reduction in the computer-aided simulation time was achieved, and the durability and
K&C characteristics of the torsion beam were enhanced by optimizing the thickness and shape. 相似文献
922.
Online license plate matching procedures using license-plate recognition machines and new weighted edit distance 总被引:1,自引:0,他引:1
Francisco Moraes Oliveira-NetoLee D. Han Myong K. Jeong 《Transportation Research Part C: Emerging Technologies》2012,21(1):306-320
License-plate recognition (LPR) technology has been widely applied in many different transportation applications such as enforcement, vehicle monitoring, and access control. Recently, there has been effort to exploit an LPR database for vehicle tracking using popular template matching procedures. Existing template matching procedures assume that the true reference string is always available. However, under a two-point LPR survey, a vehicle could have its plate misread at both locations generating a pair of misread strings (or templates) with no reference for matching. To compensate for LPR misreading problem, we propose a new weight function based on a probability model to match the observed outcomes of a dual LPR setup. Also, considering that reversal errors are never made in LPR machines, new editing constraints as a function of the string lengths are proposed to avoid compensation for reversal errors. These editing constraints are incorporated into the constraint edit distance formulation to improve the performance of the matching procedure. Finally, considering that previous template matching procedures do not take advantage of passage time information available in LPR databases, we present an online tracking procedure that considers the properties of probability distribution of vehicle journey times in order to increase the probability of correct matches. Experimental results show that our proposed procedure can improve the accuracy of LPR systems and achieve up to 97% of positive matches with no false matches. Further research is needed to extend the ideas proposed herein to plate-matching with multiple, i.e., more than two, LPR units. 相似文献
923.
Jing-Quan Li Somak D. GuptaLiping Zhang Kun ZhouWei-Bin Zhang 《Transportation Research Part D: Transport and Environment》2012,17(1):73-77
In this paper, we use second-by-second automatic vehicle location data to estimate bus emissions near far-side and near-side stops. We classify the bus running state near a stop into approach, dwell, and departure. A vehicle specific power approach is used to estimate bus emissions for each state. We show that bus emissions generated near stops can be significantly reduced by using certain intelligent transportation systems techniques. 相似文献
924.
With increasing gasoline prices, electric high‐speed rail (HSR) systems represent one means to mitigate overexposure to volatile prices. However, additional research is needed related to funding this infrastructure. In this paper, we develop a new integer optimization model to address this problem and use a hypothetical case study to demonstrate the approach. The objective of the approach is to minimize the time period in which the cost of HSR construction and operation can be recovered. This is an iterative process based on an integer optimization model, whose objective function is to determine the optimum recovery time (ORT), by setting the HSR ticket price and frequency. Embedded in the optimization model is a multinomial logit model for calculating the demand for HSR as a function of these decision variables, thus capturing the effects of level of service on market share. In particular, the optimization model accounts for the role of different types of subsidies toward HSR construction (one‐time subsidies at construction, annual subsidies, and subsidies depending on frequency). This method can also help determine whether an HSR system should be built or how much subsidy should be provided given a fixed expected cost recovery time. By integrating the logit model into the objective function evaluation, the effects of ticket price and service frequency on service demand can be directly captured. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
925.
Social inclusivity through public transportation: a strategic approach to improve quality of life in developing countries
下载免费PDF全文
![点击此处可从《先进运输杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Welfare services such as healthcare and education are commonly recognised as determinants of physical quality of life indices during the early phases of development in the third world. In order to benefit from these services, it is important that the general public have the mobility means to access welfare provision centres. However, very low vehicle ownership under the conditions of low per‐capita incomes and large shares of population living in deep rural areas prevent the masses from accessing such services, thereby retarding the process of social development, which is reflected in the very poor physical quality of life indices in low‐income countries. Public transportation could offer a viable and affordable solution to this apparent ambivalence. It could permit mobility for poor masses in spite of low per‐capita vehicle ownership enabled by the national income levels. The present research demonstrates this strategic niche through an econometric examination of the evolution of the physical quality of life indices such as maternal mortality, infant mortality and literacy as against the healthcare, education and affordable mobility proxies in post‐independent Sri Lanka. The country, which was then referred to as Ceylon, is often cited as a rare example of achieving social inclusion and reduced marginalisation and thereby a high social welfare standing, in spite of relatively poor per‐capita income levels. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
926.
绕Wigley船自由表面粘性流场计算 总被引:7,自引:1,他引:6
本文采用商用粘性流场求解软件COMET计算带自由液面绕Wigley船的粘性流动,网格数约为216000。计算中使用标准k-ε湍流模式和壁函数。用HRIC算法确定自由面。同时域步进法得到稳态解,计算的在傅氏数为0.30时的阻力结果与模型试验测量值吻合良好。预报的船体周围的波型及船体表面的波面形状也较合理。 相似文献
927.
The Bay of La Paz, a coastal and shallow basin of the Gulf of California (depth<420 m), exchanges mixed-layer waters with the Gulf of California predominantly through Boca Grande (Big Mouth), in the northeastern part of the bay. Equatorial Surface Water (ESW) flows from the gulf to the bay; once there, due to evaporation processes, this water increases its salinity above 35.00, therefore becoming Gulf of California Water (GCW) Mass. During June 1998, the baroclinic circulation in the bay was dominated by a cyclonic gyre. The hydrographic dome, related to this gyre, is depicted until approximately 150-m depth. However, the vertical mixing of water between the mixed-layer and the ones below practically does not occur because of the development of a sharp pycnocline. This fact and the isolation of the bottom of the bay by a bathymetric sill (approximately 250-m depth) at Boca Grande induce low oxygen content, particularly in the bottom-waters (O2<0.1 ml/l). Chlorophyll values are higher and with larger vertical fluctuations within the Bay of La Paz than outside. 相似文献
928.
Market segmentation studies in travel behavior research are ordinarily based on socioeconomic characteristics and personality
traits. This study explores the usefulness of a different approach, where the actual overall mobility levels across different
ground transportation modes, along with desired changes in the use of cars and transit, are used as clustering variables.
Using a given mode can in fact influence the personal representation of that mode, which in turn has been proven to be a key
element in transport behaviours. We form such multimodality-based clusters from two field studies, one involving employees
of the French transportation research institute INRETS and the other a representative sample of residents of the US San Francisco
Bay Area. We find that strong users of a given mode would like to bring more balance to their “modal consumptions” by decreasing
the use of this mode more than the average, and increasing the use of the alternative mode. However, concerning ground transport
travel budgets, the desire to travel more (or less) overall seems less strongly related to the composition of the modal balance. The US dataset shows also a greater latent demand for
travel than the French one. Socioeconomic characteristics of the clusters could not explain the patterns that were found,
confirming the importance of taking into account multimodality issues in travel behavior research. Some policy implications
from these findings are finally reported.
相似文献
Patricia L. MokhtarianEmail: |
929.
Studying travel-related individual assessments and desires by combining hierarchically structured ordinal variables 总被引:1,自引:1,他引:0
Ordinal measures are frequently encountered in travel behavior research. This paper presents a new method for combining them
when a hierarchical structure of the data can be presumed. This method is applied to study the subjective assessment of the
amount of travel by different transportation modes among a group of French clerical workers, along with the desire to increase
or decrease the use of such modes. Some advantages of this approach over traditional data reduction technique such as factor
analysis when applied to ordinal data are then illustrated. In this study, combining evidence from several variables sheds
light on the observed moderately negative relationship between the personal assessment of the amount of travel and the desire
to increase or decrease it, thus integrating previous partial (univariate) results. We find a latent demand for travel, thus
contributing to clarify the behavioral mechanisms behind the induced traffic phenomenon. Categorizing the above relationship
by transportation mode shows a desire for a less environmental-friendly mix of modes (i.e., a greater desire to use heavy
motorized modes and a lower desire to use two-wheeled modes), whenever the respondents do not feel to travel extensively.
This result, combined with previous theoretical investigations concerning the determinants of the desire to alter trips consumption
levels, shows the importance of making people aware of how much they travel.
Marco Diana is a permanent researcher working at the Department of Hydraulics, Transport and Civil Infrastructures of Politecnico di Torino, Italy. His research interests include the study of innovative forms of public transport services and the analysis of multimodality behaviors. Tingting Song is a Scientific Programmer at The Rockefeller University, Center for Clinical and Translational Science, Biostatistics, Epidemiology, and Research Design Core, New York, NY, USA. She works on algorithms for non-parametric methods and their applications in medical research. She maintains the muStat package on CRAN.r-project.org and the Web server on muStat.rockefeller.edu. Knut M. Wittkowski is a Senior Research Associate at The Rockefeller University and Head of Biostatistics, Epidemiology, and Research Design at its Center for Clinical and Translational Science, New York, NY, USA. His research focuses on methods, meta data, and user interfaces to integrate nonparametric statistics into research and decision support systems. 相似文献
Knut M. WittkowskiEmail: |
Marco Diana is a permanent researcher working at the Department of Hydraulics, Transport and Civil Infrastructures of Politecnico di Torino, Italy. His research interests include the study of innovative forms of public transport services and the analysis of multimodality behaviors. Tingting Song is a Scientific Programmer at The Rockefeller University, Center for Clinical and Translational Science, Biostatistics, Epidemiology, and Research Design Core, New York, NY, USA. She works on algorithms for non-parametric methods and their applications in medical research. She maintains the muStat package on CRAN.r-project.org and the Web server on muStat.rockefeller.edu. Knut M. Wittkowski is a Senior Research Associate at The Rockefeller University and Head of Biostatistics, Epidemiology, and Research Design at its Center for Clinical and Translational Science, New York, NY, USA. His research focuses on methods, meta data, and user interfaces to integrate nonparametric statistics into research and decision support systems. 相似文献
930.
平推式推板造波机是近岸及海洋工程波浪物理模型试验中非常重要的试验设备.文章通过垂向二维数学模型,利用线性造波理论来模拟造波板运动,分析了造波板前后水体动力过程,以及当造波板后不设消波设施时,造波板至后墙距离对水体动力过程的影响.该数学模型以包含水气二相流系统的Navier-Stokes方程为基本控制方程,应用粒子Lev... 相似文献