全文获取类型
收费全文 | 307篇 |
免费 | 5篇 |
专业分类
公路运输 | 69篇 |
综合类 | 26篇 |
水路运输 | 57篇 |
铁路运输 | 153篇 |
综合运输 | 7篇 |
出版年
2022年 | 6篇 |
2021年 | 6篇 |
2020年 | 17篇 |
2019年 | 10篇 |
2018年 | 6篇 |
2017年 | 7篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 31篇 |
2013年 | 9篇 |
2012年 | 27篇 |
2011年 | 32篇 |
2010年 | 26篇 |
2009年 | 20篇 |
2008年 | 15篇 |
2007年 | 31篇 |
2006年 | 19篇 |
2005年 | 10篇 |
2004年 | 12篇 |
2003年 | 5篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
排序方式: 共有312条查询结果,搜索用时 31 毫秒
201.
从ISO/TS 22163:2017《铁路应用质量管理体系铁路组织业务管理体系要求:ISO 9001:2015在铁路领域应用的特殊要求》对变更管理的要求出发,介绍变更管理的定义、分类、原则、控制要求等内容.分析典型变更管理流程,为铁路行业相关企业提供借鉴和参考. 相似文献
202.
The transition to low-carbon transportation fuels plays a key role in ongoing efforts to combat climate change. This analysis seeks to optimize potential alternative fuel portfolios that would lead to a 10% reduction in fuel carbon intensity by 2020 as required under California’s Low Carbon Fuel Standard (LCFS).We present a novel, probabilistic modeling approach for evaluating alternative fuel portfolios based on their marginal greenhouse gas (GHG) abatement costs. Applied to a case study region in Northwest California, our model enables us to quantify the financial cost of GHG reduction via each fuel pathway, as well as for a portfolio deployed to meet the LCFS target. It also enables us to explore the sensitivity of the alternative fuel portfolio, evaluating the impact of fluctuating prices, fuel carbon intensities, and technology penetrations on the makeup of the portfolio and on the average cost of GHG abatement.We find that battery electric vehicles play a critical role, as they offer the lowest-financial-cost significant abatement in almost all plausible scenarios. However, electric vehicles alone will not be sufficient to reach the target; low-carbon biofuels can be expected to play a role in the achievement of 2020 Low Carbon Fuel Standard targets. 相似文献
203.
In this study, we develop a Passenger Car Emission Unit (PCEU) framework for estimating traffic emissions. The idea is analogous to the use of Passenger Car Unit (PCU) for modeling the congestion effect of different vehicle types. In this approach, we integrate emission modeling and cost evaluation. Different emissions, typically speed-dependent, are integrated as an overall cost via their corresponding external costs. We then develop a normalization procedure to obtain a general trend that is applicable for all vehicle types, which is used to derive a standard cost curve. Different vehicle types with different emission standards are then mapped to this standard cost curve through their corresponding PCEUs that are to be calibrated. Once the standard cost curve and PCEUs have been calibrated, to estimate the overall cost of emission for a particular vehicle, we only need to multiply the corresponding PCEU of that vehicle type to the standard cost curve. We apply this PCEU approach to Hong Kong and obtain promising results. Compared with the results obtained by the full-blown emission model COPERT, the approach achieves high accuracy but obviates tedious inputs typically required for emission estimation. 相似文献
204.
The constant increase in air traffic demand increases a probability of the separation minima infringements in certain areas as a consequence of increased traffic density. The Annual Safety Report 2016 reports that in recent years the number of infringements, measured per million flight hours, had been increased at a lower rate (Eurocontrol, 2018). However, this level of infringements still generates a continuous pressure on the air traffic control (ATC) system and seeks for more control resources ready to tactically solve potential conflicts, while increasing at the same time the operational costs. Considering present air traffic management (ATM) trade-off criteria: increased airspace capacity and traffic efficiency but reducing the cost while preserving safety, new services must be designed to distribute the separation management ATC task loads among other actors. Based on the Single European Sky Air Traffic Management Research and Next Generation Air Transportation System initiatives, this paper proposes an innovative separation management service to shift the completely centralized tactical ATC interventions to more efficient decentralized tactical operations relying on an advanced surrounding traffic analysis tool, to preserve the safety indicators while considering the operational efficiency. A developed methodology for the proposed service is an application-oriented, trying to respond to characteristics and requirements of the current operational environment. The paper further analysis the traffic complexity taking into consideration the so-called domino effect, i.e. a number of the surrounding aircraft causally involved in the separation management service by the means of identification of the spatiotemporal interdependencies between them and the conflicting aircraft. This complexity is driven by the interdependencies structure and expressed as a time-criticality in quantifying the total number of the system solutions, that varies over time as the aircraft are approaching to each other. The results from two randomly selected ecosystem scenarios, extracted from a simulated traffic, illustrate different avoidance capacities for a given look-ahead time and the system solutions counts, that in discrete moments reach zero value. 相似文献
205.
对欧洲标准油压减振器测试规定的理解 总被引:2,自引:1,他引:1
根据对欧洲标准对测试机车车辆油压减振器的规定的理解,调查我国现有的减振器测试现状与检测各种试验台正弦激振精度后,找出差距,提出减振器测试中需试验台具备自测驱动精度、多点测试的发展目标。 相似文献
206.
石先明 《铁路通信信号工程技术》2004,(1):7-10
对铁道部新颁布的《机车信号信息定义及分配》标准进行了探讨,指出了存在的问题,提出了改进方法或思路。 相似文献
207.
本文阐述了川江及三峡库区运输船舶标准船型主尺度系列制定的原则和方法,分别对川江及三峡库区干散货船、化学品船、油船、驳船(队)、集装箱船、汽车滚装船和客船的主尺度系列作了说明。 相似文献
209.
210.
铁路系统推行职业安全卫生管理标准体系的思考 总被引:1,自引:0,他引:1
论述了铁路系统推行职业安全卫生管理标准体系(OHSMS)的必要性,详细介绍了OHSMS的发展、原则、内容以及实施方法,并对铁路系统实施OHSMS提出了设想和具体措施,以供各单位和各级领导参考。 相似文献