首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   78篇
  免费   2篇
公路运输   18篇
综合类   14篇
水路运输   11篇
铁路运输   15篇
综合运输   22篇
  2022年   1篇
  2021年   7篇
  2020年   4篇
  2019年   4篇
  2018年   6篇
  2017年   1篇
  2016年   5篇
  2015年   4篇
  2014年   4篇
  2013年   7篇
  2012年   2篇
  2011年   3篇
  2010年   5篇
  2009年   5篇
  2008年   6篇
  2007年   2篇
  2006年   7篇
  2005年   2篇
  2004年   1篇
  2003年   2篇
  2002年   1篇
  1997年   1篇
排序方式: 共有80条查询结果,搜索用时 15 毫秒
71.
This article presents the results of a scenario-based study carried out at the European Commission’s Joint Research Centre aimed at analyzing the future growth of aviation, the resulting fuel demand and the deployment of biofuels in the aviation sector in Europe. Three scenarios have been produced based on different input assumptions and leading to different underlying patterns of growth and resulting volumes of traffic. Data for aviation growth and hence fuel demand have been projected on a year by year basis up to 2030, using 2010 as the baseline. Data sources are Eurostat statistics and actual flight information from EUROCONTROL. Relevant variables such as the number of flights, the type of aircrafts, passengers or cargo tonnes and production indicators (RPKs) are used together with fuel consumption and CO2 emissions data. The target of the European Advanced Biofuels Flightpath to ensure the commercialization and consumption of 2 million tons of sustainably produced paraffinic biofuels in the aviation sector by 2020, has also been taken into account. Results regarding CO2 emission projections to 2030, reveal a steady annual increase in the order of 3%, 1% and 4% on average, for the three different scenarios, providing also a good correlation compared to the annual traffic growth rates that are indicated in the three corresponding scenarios. In absolute values, these ratios correspond to the central, the pessimistic and the optimistic scenarios respectively, corresponding to 360 million tonnes CO2 emissions in 2030, ranging from 271 to 401 million tonnes for the pessimistic and optimistic scenarios, respectively. This article also reports on the supply potential of aviation biofuels (clustered in HEFA/HVOs and biojet) based on the production capacity of facilities around the world and provides an insight on the current and future trends in aviation based on the European and national policies, innovations and state-of-the art technologies that will influence the future of sustainable fuels in aviation.  相似文献   
72.
The implementation of transport infrastructure plans often has significant impacts on landscapes, especially where new roads and railroads are built. Key decisions regarding the building of new transport infrastructures are often made on a strategic level, where the long-term development of a region is determined, and before the infrastructure project actually begins. In this paper we build on previous advances in Strategic Environmental Assessment theory by linking the process-related issues of the integration of these assessments in general to landscape issues in particular; we use a multiple case study of Swedish transport planning.Results of this study indicate that the particular planning processes we looked at failed to carry out strategic landscape assessments and integrate landscape assessments in the planning process. We conclude that this can be explained by the flawed procedure of assessing landscape, the unhelpful structuring of SEA reports and by process-related issues. The idea of applying a holistic understanding of landscape, in line with the ELC, was notably absent from the studied cases. The lack of consideration of landscape as a whole can be attributed to poor use of dissipated and fragmented knowledge about landscapes as well as weaknesses in the assessment procedure. Our results indicate that the traditions of EIA are still prevalent in the practice of SEA, despite the fact that SEA theory has moved away from EIA-based methodology to become a tool for integrating environmental concerns into decision-making and for paying close attention to strategic decision processes.  相似文献   
73.
This paper explores the relationships between the spatial patterns of the distribution of the young hakes of the year (YOY) and the oceanographical features in two areas of the Central Mediterranean (the Ligurian Sea and the Strait of Sicily), characterised by the occurrence of straits and channels. Comparative and correlative approaches were used to investigate coupling between biological and physical patterns. Density indices of the YOY were derived from annual trawl surveys from 1994 to 2004 in spring and autumn. Mean patterns of the YOY distributions were compared with the mesoscale oceanographical features reported in literature. No evident trends in recruitment strength were found in either areas. Inter-annual variability in YOY abundance in the Ligurian Sea was higher than in the Strait of Sicily. The location of nursery grounds in the study areas coincides with zones of relatively higher production, where upwelling and other enrichment processes regularly occur. The presence of predictable eddies and the frontal systems play a major role in the localization of nursery areas in the Strait of Sicily, maintaining their stable position throughout the years. The strongest transport of southern waters from the Tyrrhenian to the Ligurian Sea, due to the East Corsica Current, which is negatively correlated to winter North Atlantic Oscillation, is associated with the highest abundance of hake recruits in the nurseries of the Northern Ligurian Sea.  相似文献   
74.
结合国外项目经验,以较大的信息量,全面介绍欧美铁路通信标准体系,为国外项目团队提供较合理的建议,对国外项目投标有一定的帮助和指导意义.  相似文献   
75.
本文以2011年为例对欧洲男子篮球锦标赛的特点进行分析.2011年欧洲男篮锦标赛也是2012年伦敦奥运会欧洲区的预选赛,比赛中,多支球队实力接近,争夺激烈.与弱队相比,强队的主要优势表现为内线球员的身高占优、内线攻击的比重大且效率高、防守能力强.而在实力接近的强强对抗中,防守的破坏性加剧,此时,防守质量及外围远投成为决定胜负的关键.  相似文献   
76.
利用中国传统工艺改进生产欧标双块式轨枕的探讨   总被引:1,自引:1,他引:0  
介绍采用中国加工的生产设备,利用中国工艺生产欧标双块式轨枕,为今后其他承包商或项目生产类似的双块式轨枕提供经验借鉴。  相似文献   
77.
通过对欧洲列车时刻表等相关数据的统计和分析,总结欧洲主要类型高速列车基于路网节点系统的行车组织特点及规律,包括列车开行方案中的列车起迄点选择、停站方案设计、列车之间的接续和换乘、直达与中转换乘方案结合方式、时刻表结构和高速列车下线运行方式等,并结合我国实际路情提出建议方案,欧洲的一些先进的设计理念对我国未来快速客运网中高速列车的行车组织方案的研究具有借鉴意义.  相似文献   
78.
Vehicles are considered to be an important source of ammonia (NH3) and isocyanic acid (HNCO). HNCO and NH3 have been shown to be toxic compounds. Moreover, NH3 is also a precursor in the formation of atmospheric secondary aerosols. For that reason, real-time vehicular emissions from a series of Euro 5 and Euro 6 light-duty vehicles, including spark ignition (gasoline and flex-fuel), compression ignition (diesel) and a plug-in electric hybrid, were investigated at 23 and −7 °C over the new World harmonized Light-duty vehicle Test Cycle (WLTC) in the Vehicle Emission Laboratory at the European Commission Joint Research Centre Ispra, Italy. The median HNCO emissions obtained for the studied fleet over the WLTC were 1.4 mg km−1 at 23 °C and 6 mg km−1 at −7 °C. The fleet median NH3 emission factors were 10 mg km−1 and 21 mg km−1 at 23 and −7 °C, respectively. The obtained results show that even though three-way catalyst (TWC), selective catalytic reduction (SCR), and NOx storage catalyst (NSC) are effective systems to reduce NOx vehicular emissions, they also lead to considerable emissions of the byproducts NH3 and/or HNCO. It is also shown that diesel light-duty vehicles equipped with SCR can present NH3 emission factors as high as gasoline light-duty vehicles at both, 23 and −7 °C over the WLTC. Therefore, with the introduction in the market of this DeNOx technology, vehicular NH3 emissions will increase further.  相似文献   
79.
This paper deals with the need of introducing biofuels for the use of the civil aviation sector, and the different possibilities of application of incentive mechanisms if the existing market conditions do not allow their direct commercialisation. After an introduction on the main features of the civil aviation impact on climate change, a historical review of the European Union regulations to promote the energy extraction from biological resources is presented. The different incentive policies around the world are revised and compared and some indications are offered on the most recommendable procedures that might be carried out in the near future.  相似文献   
80.
从中欧不同的标准起源开始,对中欧铁路标准分别进行简要介绍,并分析中欧铁路标准差异.以铁路通信信号领域标准为主要关注点,分析中外铁路工程项目执行差异,将海外铁路工程项目划分为初步设计阶段、详细设计阶段、安装调试阶段、和测试验收阶段4个通用性阶段,描述了各阶段的主要任务.最后,基于工程项目实际,分析标准体系差异对海外项目实...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号