全文获取类型
收费全文 | 956篇 |
免费 | 5篇 |
专业分类
公路运输 | 260篇 |
综合类 | 61篇 |
水路运输 | 305篇 |
铁路运输 | 29篇 |
综合运输 | 306篇 |
出版年
2022年 | 19篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 10篇 |
2018年 | 30篇 |
2017年 | 32篇 |
2016年 | 38篇 |
2015年 | 15篇 |
2014年 | 35篇 |
2013年 | 121篇 |
2012年 | 37篇 |
2011年 | 40篇 |
2010年 | 48篇 |
2009年 | 41篇 |
2008年 | 44篇 |
2007年 | 18篇 |
2006年 | 30篇 |
2005年 | 32篇 |
2004年 | 14篇 |
2003年 | 24篇 |
2002年 | 19篇 |
2001年 | 16篇 |
2000年 | 15篇 |
1999年 | 18篇 |
1998年 | 28篇 |
1997年 | 20篇 |
1996年 | 16篇 |
1995年 | 8篇 |
1994年 | 4篇 |
1993年 | 13篇 |
1992年 | 13篇 |
1991年 | 12篇 |
1990年 | 7篇 |
1989年 | 12篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 12篇 |
1984年 | 8篇 |
1983年 | 7篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1975年 | 6篇 |
1974年 | 10篇 |
1972年 | 5篇 |
排序方式: 共有961条查询结果,搜索用时 15 毫秒
671.
Ronny Püschel Christos Evangelinos 《Transportation Research Part D: Transport and Environment》2012,17(8):598-604
This study estimates airport noise annoyance cost around Düsseldorf, Germany by examining rental apartment market data. Using data on regional apartment offers we estimate rent discounts of 1.04% per additional decibel of airport noise. Other sources of traffic noise induce significantly lower price effects. As a result, airport noise annoyance costs amount to about €7.5 million a year. While the noise protection fund recovers annoyance costs, the charging regime of the airport fails to fully internalize them. 相似文献
672.
M. Isinibilir L. Svetlichny E. Hubareva I.N. Yilmaz F. Ustun G. Belmonte B. Toklu-Alicli 《Journal of Marine Systems》2011,84(1-2):18-27
During 2005–2008 species composition, abundance patterns, natural mortality rates and salinity effects on zooplankton were studied in the Bosphorus regions of the Black and Marmara Seas. The tendencies to diminish for abundance and biomass of the Black Sea originated zooplankton species and to increase for the proportion of their carcasses in the direction from the Black Sea toward the Marmara Sea were found. The mortality in the Black Sea species increased with depth in the Marmara Sea. The contribution of organic matter of carcasses of the Black Sea originated organisms to bacterial processes in the deep strata of the Marmara Sea was estimated. Different salinity and temperature regimes restrict mutual penetration of the species in these seas. 相似文献
673.
674.
The selection and evaluation of road schemes through the Leitch framework is based on a combination of cost-benefit analysis and environmental impact assessment. Both techniques involve the definition and valuation of a number of costs and benefits. These costs and benefits are defined and valued in isolation to each other so that we know virtually nothing about the relative valuation that people assign to different types of costs and benefits which might affect them directly or indirectly. This paper outlines the development of a method which allows people to conceptualise the costs and benefits of a road scheme in their own terms and then to rank schemes in relation to those costs and benefits. This method is based upon an interview process involving the use of repertory grid technique. The information from the repertory grid technique is used as a sound basis for determining trade-offs between attributes and for attempting to obtain monetary valuations of different project attributes. A number of exploratory interviews are reported which outline some of the difficulties with a number of the survey features including the choice of case-study, interviewer and information biases and sample and non-response biases. Various ways of dealing with these difficulties are discussed. 相似文献
675.
676.
Dimitrios V. Lyridis Nikolaos P. Ventikos Panayotis G. Zacharioudakis Konstantinos Dilzas Harilaos N. Psaraftis 《WMU Journal of Maritime Affairs》2005,4(1):33-55
This paper proposes a tool to estimate crew composition based on safety/operational and financial requirements. As there is
a tendency of ship owners to implement improved technologies on board their vessels, there is no systematic way to predict
their potential effect on crew size and composition (typically determined by flag state authorities on a case-to-case basis)
nor on the type and complexity of on board duties new technologies might dictate. The main aim of this paper is to develop
a tool to assist in determining crew composition, by taking into account both administration’s and the ship owner’s point
of view. Based on data collected from ship owners, a data mining technique is implemented in order to form a generalized framework
that estimates crew composition as a function of ship type, size, and degree of automation. The agreement of model predictions
with records from specific (vessel) cases is very good in terms of safety (for operations such as watchkeeping, mooring/unmooring,
loading/unloading). The specific intended use of this tool is to help a ship owner decide whether it is cost-beneficial to
retrofit a conventional vessel with advanced technologies that would potentially entail a reduced crew (probably dealing with
different and more complex on board duties). Its main benefits are that it can be used to estimate crew composition before
any vessel construction or upgrade has actually taken place and that it allows crew composition to be easily adapted to the
technological evolution of ship systems even at their current rapid pace. 相似文献
677.
Two hydrobiological transects across the East Greenland Shelf and the open waters of Fram Strait in summer were chosen to illustrate the distribution and production of phyto- and zooplankton in relation to water masses and ice cover. The parameters used were temperature and salinity, inorganic nutrients, chlorophyll a, primary production, phytoplankton species composition, abundance of the dominant herbivorous copepods Calanus finmarchicus, C. glacialis, C. hyperboreus, Metridia longa and egg production of C. finmarchicus and C. glacialis. Grazing impact of copepodites and adults of these four species was modelled for each station by using egg production rates as an index of growth. Seasonal development of plankton communities was closely associated with the extent of the ice cover, hydrographic conditions and the water masses typical of the different hydrographic domains. Four regions were identified from their biological activities and physical environment: The Northeast Water polynya on the East Greenland Shelf, with a springbloom of diatoms and active reproduction of herbivorous copepods. The pack ice region, dominated by small flagellates and negligible grazing activities. The marginal ice zone, with high variability and strong gradients of autotroph production related to eddies and ice tongues, an active microbial loop and low egg production. The open water, with high station-to-station variability of most of the parameters, probably related to hydrographic mesoscale activities. Here, Phaeocystis pouchetii was a prominent species in the phytoplankton communities. Its presence may at least partly be responsible for the generally low egg production in the open waters. Grazing impact on primary production was always small, due to low zooplankton biomass in the polynya and due to low ingestion in the remaining regions. 相似文献
678.
R. G. Rice 《先进运输杂志》1988,21(3):239-253
Expo 86, the World Exposition held last year in Vancouver, Canada, was the largest, special-category world's fair ever staged, with 54 international participants. Given the designated theme of transportation and communications, it is interesting to interpret the statements made by the participants in regard to particular sub-theme areas such as urban transit. This paper reviews the presentations (exhibits, demonstrations, conferences, and seminars) developed by all participants in Expo 86 in regard to urban transit technology, and assesses the significance and direction of technological developments in the areas of vehicle and terminal design, network and system operation and control, and planning and management systems. 相似文献
679.
Preview Estimation and Control for (Semi-) Active Suspensions 总被引:3,自引:0,他引:3
R.G.M. Huisman F.E. Veldpaus J.G.A.M. Van Heck J.J. Kok 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1993,22(5):335-346
An active suspension with preview is tested for rounded pulses and a stochastic road surface, and is compared to a passive suspension. The spectacular performance improvement obtained for a step function as road surface is not achieved but the improvement is still significant. The frequency response of the active suspension is determined for comparison with some suspension systems found in literature
An observer to reconstruct the preview information is presented. No model of the road surface is needed. From simulations, it appears that the observer reconstructs both deterministic and stochastic road surfaces satisfactory. However, the influence of measurement noise is not reduced sufficiently. 相似文献
An observer to reconstruct the preview information is presented. No model of the road surface is needed. From simulations, it appears that the observer reconstructs both deterministic and stochastic road surfaces satisfactory. However, the influence of measurement noise is not reduced sufficiently. 相似文献
680.