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131.
摘要:某微型轿车在开发初期,制动距离偏长,不满足技术标准要求。制动距离偏长的原因有很多,一般分析起来比较繁琐。通过运用理论分析和试验相结合的方法,较为容易的找到了问题的关键点,并提出了解决措施,最终使其制动性能达到既定目标。 相似文献
132.
以重庆机场路渝州隧道扩挖工程为研究对象,通过在隧道施工爆破过程中对邻近隧道、地表房屋等建筑物进行振动监测,应用萨道夫斯基经验公式对现场监测数据进行回归分析,确定爆破应力波在泥岩、砂岩中的传播衰减规律,进而控制不同目标、不同间距情况下每次最大起爆药量,以指导后续施工,保证邻近隧道、房屋等建筑物振动速度控制在安全范围内。 相似文献
133.
为了准确掌握气象因素对某新型炮兵雷达探测距离的影响规律,提高雷达的作战效能。分别建立了大气、雨、雾影响下雷达探测距离的修正模型,依据此模型设计了可视化界面平台,可以得到不同气象条件下的雷达波衰减系数和预测雷达的最大作用距离,为在不同气象环境中使用此雷达提供了基本数据依据。 相似文献
134.
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136.
本研究以有缺陷预埋的隧道曲面砌衬管片作为目标结构试件,以室内实验分析的方式,对隧道砌衬激振回波检测中的振激部位和测点距离,给激振回波信号带来的影响课题开展专题分析探究,以为同类激振回波检测法工程应用提供研究和技术参考,助力实现有效适用的隧道砌衬激振回波检测。 相似文献
137.
This paper studies link travel time estimation using entry/exit time stamps of trips on a steady-state transportation network. We propose two inference methods based on the likelihood principle, assuming each link associates with a random travel time. The first method considers independent and Gaussian distributed link travel times, using the additive property that trip time has a closed-form distribution as the summation of link travel times. We particularly analyze the mean estimates when the variances of trip time estimates are known with a high degree of precision and examine the uniqueness of solutions. Two cases are discussed in detail: one with known paths of all trips and the other with unknown paths of some trips. We apply the Gaussian mixture model and the Expectation–Maximization (EM) algorithm to deal with the latter. The second method splits trip time proportionally among links traversed to deal with more general link travel time distributions such as log-normal. This approach builds upon an expected log-likelihood function which naturally leads to an iterative procedure analogous to the EM algorithm for solutions. Simulation tests on a simple nine-link network and on the Sioux Falls network respectively indicate that the two methods both perform well. The second method (i.e., trip splitting approximation) generally runs faster but with larger errors of estimated standard deviations of link travel times. 相似文献
138.
The relationship between land use and the utility of automobile travel is examined by refining the utility concept, particularly by combining the microeconomic utility theory, which is concerned with the disutility of travel, and the perspective on the positive utility. A conceptual model is accordingly developed and then adjusted considering different purposes of travel. The purpose-specific models are tested through a Multiple Indicators Multiple Causes approach in Seoul, Korea, using datasets from a sample survey and geographic information systems. The major finding is that land use affects the utility mainly by changing synergy and affective utility rather than instrumental utility, which encompasses disutility variables. Among land use variables, the utility is found to be the most sensitive to the number of transit facilities for commuting and shopping travel and land use balance for leisure travel. 相似文献
139.
Transit market segmentation enables transit providers to comprehend the commonalities and heterogeneities among different groups of passengers, so that they can cater for individual transit riders’ mobility needs. The problem has recently been attracting a great interest with the proliferation of automated data collection systems such as Smart Card Automated Fare Collection (AFC), which allow researchers to observe individual travel behaviours over a long time period. However, there is a need for an integrated market segmentation method that incorporating both spatial and behavioural features of individual transit passengers. This algorithm also needs to be efficient for large-scale implementation. This paper proposes a new algorithm named Spatial Affinity Propagation (SAP) based on the classical Affinity Propagation algorithm (AP) to enable large-scale spatial transit market segmentation with spatial-behavioural features. SAP segments transit passengers using spatial geodetic coordinates, where passengers from the same segment are located within immediate walking distance; and using behavioural features mined from AFC data. The comparison with AP and popular algorithms in literature shows that SAP provides nearly as good clustering performance as AP while being 52% more efficient in computation time. This efficient framework would enable transit operators to leverage the availability of AFC data to understand the commonalities and heterogeneities among different groups of passengers. 相似文献
140.
Interests in studying of the built environment impacts on travel behavior have proliferated from North America to other parts of the world including China. Until very recently, there has been very little research into travel behavior in China. However, during the last decade, there has been a fast growing interest in studying the built environment and travel behavior in Chinese cities, perhaps motivated by China’s unprecedented urbanization and rapid urban transport development. Case studies from China provide new insights into the impacts of built environment on travel behavior that can help to enrich existing scholarship. However, currently there is a generally poor understanding of the role played by Chinese research and how it has enriched the international literature. This paper aims to fill this gap by reviewing studies in and outside China by both Chinese and non-Chinese scholars. The focus is on the contribution of these studies to the international literature. We identify four areas of contribution: how the built environment has been developed and its implications for travel behavior; the importance of housing sources in defining residential built environment and explaining travel behavior; the unique Danwei (or work unit) perspective on jobs-housing relationships and commuting behavior; and the importance of neighborhood types in explaining travel behavior in Chinese cities. The findings from this review should be relevant for researchers interested in developing future studies that will further advance geographic knowledge of the built environment and travel behavior, specifically in China and with broader global contexts. 相似文献