全文获取类型
收费全文 | 1317篇 |
免费 | 4篇 |
专业分类
公路运输 | 346篇 |
综合类 | 36篇 |
水路运输 | 452篇 |
铁路运输 | 39篇 |
综合运输 | 448篇 |
出版年
2022年 | 5篇 |
2021年 | 10篇 |
2020年 | 12篇 |
2019年 | 8篇 |
2018年 | 27篇 |
2017年 | 26篇 |
2016年 | 43篇 |
2015年 | 16篇 |
2014年 | 26篇 |
2013年 | 215篇 |
2012年 | 63篇 |
2011年 | 66篇 |
2010年 | 54篇 |
2009年 | 55篇 |
2008年 | 63篇 |
2007年 | 47篇 |
2006年 | 27篇 |
2005年 | 29篇 |
2004年 | 24篇 |
2003年 | 26篇 |
2002年 | 20篇 |
2001年 | 28篇 |
2000年 | 18篇 |
1999年 | 22篇 |
1998年 | 41篇 |
1997年 | 18篇 |
1996年 | 22篇 |
1995年 | 22篇 |
1994年 | 16篇 |
1993年 | 18篇 |
1992年 | 16篇 |
1991年 | 13篇 |
1990年 | 8篇 |
1989年 | 14篇 |
1988年 | 16篇 |
1987年 | 15篇 |
1986年 | 16篇 |
1985年 | 11篇 |
1984年 | 12篇 |
1983年 | 8篇 |
1982年 | 13篇 |
1981年 | 12篇 |
1980年 | 15篇 |
1979年 | 16篇 |
1978年 | 8篇 |
1977年 | 12篇 |
1976年 | 9篇 |
1975年 | 17篇 |
1974年 | 10篇 |
1973年 | 9篇 |
排序方式: 共有1321条查询结果,搜索用时 15 毫秒
581.
Zheng Li John M. Rose David A. Hensher 《Transportation Research Part A: Policy and Practice》2010,44(1):16-38
Transport fuel consumption and its determinants have received a great deal of attention since the early 1970s. In the literature, different types of modelling methods have been used to estimate petrol demand, each having methodological strengths and weaknesses. This paper is motivated by an ongoing need to review the effectiveness of empirical fuel demand forecasting models, with a focus on theoretical as well as practical considerations in the model-building processes of different model forms. We consider a linear trend model, a quadratic trend model, an exponential trend model, a single exponential smoothing model, Holt’s linear model, Holt–Winters’ model, a partial adjustment model (PAM), and an autoregressive integrated moving average (ARIMA) model. More importantly, the study identifies the difference between forecasts and actual observations of petrol demand in order to identify forecasting accuracy. Given the identified best-forecasting model, Australia’s automobile petrol demand from 2007 through to 2020 is presented under the “business-as-usual” scenario. 相似文献
582.
583.
584.
585.
分析了俄罗斯18-100型三大件货车转向架摩擦楔块结构的特点,指出改变摩擦楔块形状可以改进转向架的性能. 相似文献
586.
This article examines the acceptance of aquaculture development by residents and visitors of two islands, Cephallonia and Ithaki, in the Ionian Sea, in western Greece. Aquaculture farms have been established recently in both islands, and processing and packaging units in Cephallonia, generating jobs for the local communities and land rents for the villages in the coastal areas near the fish cages. However, the farms and processing and packaging units entail certain negative impacts on the environment. This study reveals that aquaculture farms have found better acceptance in Ithaki, where aqua culture is a form of development suited to this remote, small, predominantly rural island. The degree of acceptability is higher for locals than for tourists, but also for islanders who do not live in the areas where the processing units are situated. Respondents who consider the pollution of the marine environment by the farms to be high, mostly locals and residents of the villages in the vicinity of the aquaculture infrastructure or the main cities in the islands, are more likely to express a negative attitude toward aquaculture and its further development. 相似文献
587.
Richard A. Walker 《Coastal management》2013,41(2):227-233
Note This article is a short response to a critique by William Odum and Stephen Skjei of an earlier article by this author in this Journal entitled “Wetlands Preservation and Management on Chesapeake Bay: The Role of Science in Natural Resource Policy.”; It is a continuation of themes begun in that paper. It focuses on the question of determining the social value of wetlands preservation and the contradictory positions which ecologists fall into when discussing the value of wetlands. 相似文献
588.
Elizabeth A. Wilman 《Coastal management》2013,41(3):211-230
As the controversy over Outer Continental Shelf (OCS) oil and gas leasing continues, with environmentalists and fishermen seeking to block or delay leasing decisions that they think will adversely affect their interests, the need for better estimates of the environmental costs associated with OCS development becomes increasingly apparent. Although high degrees of precision in such estimates may never be economic, let alone feasible, better knowledge would reduce the uncertainty surrounding the magnitude of such costs, and would make it easier to come to grips with the problem and reduce, if not resolve, the controversy. 相似文献
589.
Probabilistic modelling of the ultimate strength of ship plates with non-uniform corrosion 总被引:1,自引:0,他引:1
A. P. Teixeira C. Guedes Soares G. Wang 《Journal of Marine Science and Technology》2013,18(1):115-132
This paper presents the results of a parametric study of probabilistic modelling of the ultimate strength of ship plates with non-uniform corrosion represented by random fields. The load-shortening behaviour of the plates with non-uniform reduction of thickness due to corrosion under longitudinal compression is obtained using a general-purpose nonlinear finite element analysis program. A nonlinear time-dependent corrosion model is used to define the probabilistic characteristics of the random fields based on corrosion data measured in plate elements at different locations of bulk carriers. Based on the probabilistic models derived by Monte Carlo simulation, equations to predict the mean and the 5 % characteristic value of the ultimate strength of plates with non-uniform corrosion are developed. Finally a regression equation is proposed to take into account the effect of non-uniform corrosion patterns in the predictions of the ultimate strength of plates with uniform corrosion. 相似文献
590.
How Are Our MPAs Doing? Challenges in Assessing Global Patterns in Marine Protected Area Performance
Helen E. Fox Jed L. Holtzman Kelly M. Haisfield Catherine G. McNally Gonzalo A. Cid Michael B. Mascia 《Coastal management》2013,41(3):207-226
Without effective management, protected areas are unlikely to achieve the high expectations the conservation and development sectors have for them: conserving biodiversity and alleviating poverty. Numerous marine protected area (MPA) assessment initiatives have been developed at various spatial and temporal scales, including the guidebook How is your MPA doing? These management assessments have been useful to sites to clarify and evaluate their objectives, yet efforts to examine broader regional or global patterns in MPA performance are only beginning. The authors conducted exploratory trend analyses on How is your MPA doing? indicator data collected by 24 MPAs worldwide to identify challenges and areas for future work. Wide variability across sites with regard to the indicators examined and the constructs used to measure them prevented a true meta-analysis. Managers assessed biophysical indicators more often than socioeconomic and governance constructs. Investment by the conservation community to support collecting and reporting high-quality data at the site level would enable a better understanding of the variation in MPA performance, clarify the contribution of MPAs to both biodiversity conservation and poverty alleviation, and help drive better MPA performance. The absence of rigorous and consistent monitoring protocols and instruments and a platform to turn raw MPA monitoring data into actionable information is a critical but under-recognized obstacle to cross-project learning, comparative analyses, and adaptive resource management. 相似文献