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   99篇
  免费   1篇
公路运输   30篇
综合类   28篇
水路运输   14篇
铁路运输   13篇
综合运输   15篇
  2022年   3篇
  2021年   2篇
  2020年   4篇
  2018年   2篇
  2017年   1篇
  2015年   3篇
  2014年   12篇
  2013年   14篇
  2012年   10篇
  2011年   9篇
  2010年   6篇
  2009年   10篇
  2008年   5篇
  2007年   8篇
  2006年   5篇
  2005年   2篇
  2004年   1篇
  2002年   1篇
  1997年   1篇
  1995年   1篇
排序方式: 共有100条查询结果,搜索用时 15 毫秒
41.
曹妃甸港作为毗邻京津冀城市群的北方大港,是响应国家“公转铁”的重要支点。在阐述曹妃甸港集疏运系统布局及集疏运方式的基础上,针对曹妃甸港集疏运存在的问题,从大力发展集装箱运输、推动物流信息平台建设、提升作业效率及能力、打造曹妃甸疏港矿粉“公转铁”等方面,提出曹妃甸港“公转铁”发展策略,促进曹妃甸港铁路发挥全要素生产力,合理配置运输资源,加快推进曹妃甸港“公转铁”物流体系建设,提高铁路货运服务能力和供给质量。  相似文献   
42.
Wilderness traditionally has been a terrestrial resource designation. This study examined user perceptions related to the existence of wilderness in the Great Barrier Reef Marine Park (GBRMP), and raises questions about the efficacy of the GIS based Australian National Wilderness Inventory (ANWI) as a method of inventorying and analyzing wilderness settings in the absence of such perceptions. Three hundred eighty‐three users of the GBRMP were surveyed. Results indicated that over 80% of the respondents believed that wilderness existed in the park, and that it existed both above and below the surface of the water. Characteristics of wilderness related to human presence, natural features, and remoteness were found to be important to marine wilderness. Responses revealed that remoteness (physical distance) from human development may warrant less weight in the designation of marine wilderness than implied as necessary by the ANWI. We discuss implications for selecting areas as wilderness and using the wilderness designation in marine settings.  相似文献   
43.
英国职业教育的启示与借鉴   总被引:1,自引:0,他引:1  
英国职业教育是世界职业教育模式的成功范例之一。本文介绍了英国职业教育的特色及其成功的经验,并结合我国实际,从法律保障、管理体制、资源整合、办学形式、资格体系、服务平台等方面,提出促进我国职业教育改革的一些建议。  相似文献   
44.
刘国栋 《北方交通》2006,(11):87-89
阐述了为适应国有公路建设公司法人治理结构的要求,在财务管理方面应采用的理财模式。  相似文献   
45.
郑建恩 《中国水运》2007,5(8):180-181
税务部门传统的考核方法无法有效调动税务人员工作积极性,存在诸多弊端,枣庄市X区国税局以量化积分制考核破解考核难题,提高了工作绩效,更新了管理理念。  相似文献   
46.
章针对现在出版的沈从传记中有关他在西南联大任教时间及聘任职务上的混乱情况。通过西南联大原始件的记录。并结合提议聘请沈从到联大任教的当事人朱自清的日记等相关献资料.对沈从进入西南联大任教的时间、聘任的职务以及改聘为教授的时间作了详细的考证。同时对沈从在联大任教期间遇到的压力作了简单的分析。章为人们了解沈从抗战时期的思想和学创作的变化提供了一个参考。  相似文献   
47.
GB/T 11032—2020《交流无间隙金属氧化物避雷器》已于2021年7月1日开始实施.介绍GB/T 11032—2020中有关避雷器类型、型式试验、抽样试验等内容的变化情况,结合电气化铁道用避雷器的检验检测工作,重点分析适用于电气化铁道用避雷器的条款、技术参数及试验方法,包括重复转移电荷试验、内部部件绝缘耐受试验...  相似文献   
48.
In 1992, scientists at National Estuarine Research Reserve (NERR) sites proposed establishing a national coordinated monitoring program that would attempt to identify and track short-term variability and long-term changes in representative estuarine ecosystems and coastal watersheds. Known as the NERR System-Wide Monitoring Program (SWMP), it currently consists of monitoring water quality and atmospheric variables over a range of spatial and temporal scales. Additional monitoring of ecological resources and land-water use will follow in subsequent components of the program. Water quality monitoring at NERR sites includes measurements of pH, conductivity, temperature, dissolved oxygen, turbidity, and water level. The NERR sites use data loggers that record at 30-minute intervals and relay measurements to internal memory. Standardized protocols assure that sampling, processing, and data management techniques are comparable among sites. Statistical techniques are being used to identify periodicity in water quality variables. Periodic regression analysis indicated that diel periodicity in dissolved oxygen is a larger source of variation than tidal periodicity at sites with less tidal amplitude. Tidal periodicity, however, is more important at sites with a tidal amplitude greater than 1 m. This finding suggests that natural processes controlling dissolved oxygen levels differ among sites depending upon tidal amplitude. Water quality data from the NERR SWMP have also been used to investigate occurrence of hypoxia. Results from analysis of water quality at several reserves indicate that hypoxia occurs but that the percentage of time that dissolved oxygen was less than 28% saturation varied substantially among sites and between years. Most of the hypoxic events occurred in summer but were also observed in winter and fall when low dissolved oxygen is usually not considered a problem. Without continuous monitoring by the NERR SWMP, many low dissolved oxygen events would have been missed, thus underestimating the duration and potential impact of this type of water quality variability. The NERR SWMP provides a unique opportunity to increase our understanding of how various environmental factors influence estuarine processes. Only by understanding how estuaries function and change naturally over time will we be able to predict how these systems respond to changes in climate and human-induced perturbations.  相似文献   
49.
为降低柴油机的排放污染,使柴油机达到国IV以上排放要求,参考国际柴油机的排放技术,目前,主要有2条技术路线可供选择,即SCR技术路线和EGR技术路线。文章对这2种技术路线从结构特点、工作原理、优缺点进行比较分析,结果表明,柴油机在我国近期和远期,不同的车型应采取不同的技术方案,为我国柴油机达到国IV以上排放标准提供了参考。  相似文献   
50.
由于地形地貌的原因,城市地面道路断面通常情况下均为常规设计。但在局部复杂地形、地质条件下,也会碰到一些常规断面设计方法无法实施的困难,在昆明320国道(眠山-车家壁)段改扩建工程中,电厂大沟鱼塘段断面设计时就碰到了该问题。该文对工程建设中碰到的问题,以及采取的方法进行了总结,以供借鉴。  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