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   162篇
  免费   0篇
公路运输   18篇
综合类   8篇
水路运输   76篇
铁路运输   4篇
综合运输   56篇
  2021年   2篇
  2020年   2篇
  2019年   1篇
  2018年   7篇
  2017年   3篇
  2016年   3篇
  2015年   1篇
  2014年   3篇
  2013年   35篇
  2012年   5篇
  2011年   9篇
  2010年   4篇
  2009年   6篇
  2008年   7篇
  2007年   3篇
  2006年   3篇
  2005年   6篇
  2004年   4篇
  2003年   3篇
  2002年   4篇
  2001年   5篇
  2000年   2篇
  1999年   2篇
  1998年   4篇
  1997年   2篇
  1996年   1篇
  1995年   2篇
  1994年   2篇
  1993年   2篇
  1992年   1篇
  1990年   2篇
  1989年   3篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1985年   1篇
  1984年   2篇
  1983年   1篇
  1981年   5篇
  1980年   1篇
  1979年   1篇
  1978年   1篇
  1977年   4篇
  1976年   2篇
  1975年   1篇
  1974年   1篇
排序方式: 共有162条查询结果,搜索用时 343 毫秒
101.
Special attention has been paid to sustainable macroalgae cultivation in Europe. The question on where suitable cultivation areas lie, without conflicting with current marine socio-economic activities and respecting the environment, remains a great challenge. Considering 13 criteria critical to seaweed farming such as depth, shipping traffic, and distance to ports, this paper aimed to identify suitable and sustainable offshore areas on the West Coast of Sweden for the cultivation of the Sugar Kelp, Saccharina latissima. An integrated approach with the tools geographic information systems (GIS) and multi-criteria analysis (MCA) was used to aggregate the criteria by means of Boolean and weighted linear combination (WLC) techniques. The Boolean method singled out 544?km2 as suitable, whereas the WLC method indicated 475?km2 as highly suitable. Both techniques complement each other in finding optimal sites. Furthermore, the integrated models excelled in providing an overview for effective spatial decision-making that fosters sustainable development of macroalgae cultivations within marine and coastal systems.
  • Highlights
  • To the authors’ knowledge no study on seaweed aquaculture site selection has been conducted using such a range of criteria with the purpose of including sustainability aspects within a comparative GIS-MCDA.

  • The large areas identified on the West Coast of Sweden as suitable highlight the potential of this new industry and the complexity of associated marine spatial planning.

  • Boolean and weighted linear combination methods were applied and compared, providing valuable insights in the selection of methods for spatial decision-making support. These insights should support a more sustainable development of macroalgae cultivation in the region, as well as a more resilient marine spatial planning process for blue growth strategies.

  相似文献   
102.
This paper stresses the lack of attention paid to the geographical definitions of cities in LUTI models as one key detrimental aspect to transferring and generalising LUTI results. First, the argumentation develops from a meta-analysis of peer-reviewed publications about LUTI applications in European cities. We show that most authors do not assess findings against potential geographical biases. Second, theoretical simulations are conducted with UrbanSim applied to a synthetic urban area. By varying the geographical limits of the system and population endowments, our simulations confirm that the absence of control on city delineation weakens the results. Finally, the paper suggests methodological guidelines to improve the comparability of LUTI applications and push forward their theoretical agenda.  相似文献   
103.
Shipping traffic poses a worldwide threat to many large whale species. Spatially explicit risk assessments are increasingly being used as a tool to minimize ship-strike risk. These assessments often use static representations of shipping patterns. We used Automatic Identification System data to quantify variability in cargo shipping traffic entering and exiting San Francisco Bay, which contains some of the busiest ports in the United States, at three temporal resolutions: (1) before and after implementation of the California Air Resources Board's Ocean-Going Vessels Fuel Rule, (2) among seasons, and (3) day versus night. We used the nonparametric Mood's Median test to compare median daily distance traveled because the data were not normally distributed and the variance was not homogeneous. Our analyses show that shipping traffic off San Francisco is dynamic at both interannual and daily temporal resolutions, but that traffic was fairly consistent among the seasons considered. Our analyses emphasize the importance of economic and regulatory drivers on interannual shipping traffic patterns. Shipping traffic is expected to continue to change off the U.S. West Coast and to increase globally. These changes in shipping traffic could have implications for the risk of ships striking whales and should be included in risk assessments.  相似文献   
104.
The Gulf of California hosts astounding biodiversity that supports numerous economic activities in the region. These activities, and emerging threats, are placing pressure on the region's ecosystems. Government and civil society are working to address threats through several conservation and management mechanisms. Nevertheless, the use and incorporation of scientific information—a key component for creating effective and durable management—is still deficient. This article presents the concept of science integration and discusses the findings of a study that assesses the regional landscape, existing institutional arrangements, and capacity for using science to inform policy and management decisions. It also explores the current use of science within fisheries policy and management and the capacity of the National Network of Information and Research of Fisheries and Aquaculture (RENIIPA) and the State Fisheries and Aquaculture Councils, two mechanisms in the region. Finally, it shares lessons learned and offers recommendations on how the region can strengthen science-based decision-making. Results indicate that while there are some actors in the Gulf of California producing relevant science, there is varying capacity of intermediary groups connecting producers with users of science, or mechanisms in place to ensure that science is being utilized in decision-making processes. Moreover, despite having a well-developed landscape of producers and intermediaries and mechanisms in place for fisheries management in the region, effective science integration is not occurring.  相似文献   
105.
Liability is an important incentive‐based instrument for preventing oil spills and provides a sustainable approach for restoring coastal resources injured by spills. However, the use of liability for environmental damages raises many challenges, including quantification of money measures of damages. In this article, case studies are used to illustrate the issues, methods, and challenges associated with assessing a range of damages, from those that can be measured relatively easily using market information to more “esoteric,”; and much more difficult, cases involving non‐market‐valued losses. Also discussed are issues raised by the new national and international regulatory focus on restoration and by the simplified, compensatory formula used by some states.  相似文献   
106.
The paper examines the implementation of extended gate operations at the Los Angeles/Long Beach ports. The programme, known as PierPASS, assesses a Traffic Mitigation Fee (TMF) on eligible containers moved into and out of the ports during peak hours. The fees are intended to defray the costs of extended operations at the ports.

In this paper we focus on the implementation of the programme and its outcomes over a year of operation. We discuss the motivations and actions of key stakeholders and place our examination in the institutional framework of the goods movement supply chain. Our results are based primarily on a series of extended interviews with stakeholders, together with data provided by PierPASS and by three drayage trucker surveys. We find that the PierPASS programme was a response by terminal operators and steamship companies to growing political pressure. Given their market power within the supply chain, they were able to create a programme that protected their interests yet responded to political imperative. The PierPASS programme has been a success: the peak fee has shifted a significant share of cargo to evenings and weekends, as intended. Winners and losers of PierPASS reflect the larger structure of the international supply chain.  相似文献   
107.
The International Tribunal for the Law of the Sea (ITLOS) was established by the 1982 United Nations Convention on the Law of the Sea as a body to settle disputes between States Parties to the Convention regarding the interpretation or application of the Convention s provisions, including provisions concerning the exercise of the powers of States over shipping and the discharge by states of their responsibilities and obligations in relation to ships.ITLOS is competent to deal with disputes in which a State is alleged to have wrongly interfered with or otherwise restrained the operation of a vessel when it is in a port of the State or within the territorial sea or exclusive economic zone of the State.In its previous judgments, ITLOS has provided clarifications of some important areas of the law of the sea concerning the operation and regulation of shipping by flag States and other states.ITLOS plays a key role in the regime of the Law of the Sea Convention relating to the prompt release of ships and their crews that are arrested or detained in a foreign port.ITLOS also has the possibility to serve as ajudicial organ for the settlement of disputes under other maritime agreements and contracts, if the parties to the agreements or contracts agree to confer jurisdiction on it.There are many advantages to be gained by States and shipping operators from using ITLOS as the body for the settlement of disputes under agreements. These advantages include savings in time and expenses.  相似文献   
108.
有近40年隧道施工经验,曾在伦敦地铁的维多利亚(Victoria)线、伦敦主环线(London Ring Main)、英吉利海峡隧道以及朱比利(Jubilee)线经历过各种复杂工程地质状况的英国Amec公司隧道施工合同主管Peter South工程师认为:他目前从事的这个项目是他所遇到过的最艰难的项目,"真是出乎意料之外的困难."  相似文献   
109.
上海地铁的车辆   总被引:1,自引:0,他引:1  
由Adtranz管理的德沪地铁集团(GSMG,主要由Adtranz和Siemens两家公司组成),为上海地铁1号线提供了一些主要设备,并成功投入营运。自1996年以来,上海地铁2号线建设已在紧张进行,而主要机电设备仍由GSMG提供。1997年广州地铁1号线开始试运行。它也是由Adtranz起重要作用的一个德国集团提供主要设备。本文对这些工程项目的车辆作一个比较介绍。  相似文献   
110.
The evolution of dissolved organic matter (DOM) in a non-axenic batch culture of the marine diatom Thalassiosira tumida was studied by hydrophobic fractionation during a three month experiment. DOM was fractionated with XAD-2 resin into hydrophobic (acid and neutral, “humic”) and hydrophilic fractions. The combined amino acid contents of unfractionated filtered seawater, XAD-fractions and particulate material were determined during the growth, stationary and degradation phases of the culture, and variations related to changes in dissolved organic nitrogen (DON) in XAD-fractions, dissolved inorganic nitrogen, algal and bacterial biomass. XAD-fractionation enabled the discrimination of simultaneously ocurring release and uptake of organic nitrogenous compounds: During the diatom growth there was a net increase of tolal DON concentrations, which was mostly accounted for by the hydrophilic fraction. A concurrent heterotrophic uptake of combined amino acids and other non-amino acid organic nitrogen was discernible by the decrease of their concentrations in the hydrophobic fractions. In the stationary phase, during the prevailing net consumption of total DON, the production of algal exudates could be detected in the hydrophobic fractions, while uptake mainly involved non-amino acid organic nitrogen from the hydrophilic fraction. During the degradation phase, after two months part of the particulate amino acid pool was transformed into hydrophilic DON, which in contrast to the stationary phase, was not adequate for supporting sustained bacterial growth. This suggests that the generation of recalcitrant substances may begin in the hydrophilic fraction of DOM. A slight increase of the hydrophobic acid fraction was indicative of the incipient formation of humic substances. XAD-2 was able to adsorb substances from fast changing DOM pools and thus should be a useful tool in studies concerned with phytoplankton and bacterial dynamics.  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