全文获取类型
收费全文 | 141篇 |
免费 | 3篇 |
专业分类
公路运输 | 27篇 |
综合类 | 40篇 |
水路运输 | 26篇 |
铁路运输 | 37篇 |
综合运输 | 14篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 7篇 |
2017年 | 4篇 |
2016年 | 6篇 |
2015年 | 5篇 |
2014年 | 16篇 |
2013年 | 11篇 |
2012年 | 9篇 |
2011年 | 5篇 |
2010年 | 9篇 |
2009年 | 6篇 |
2008年 | 7篇 |
2007年 | 17篇 |
2006年 | 7篇 |
2005年 | 5篇 |
2004年 | 2篇 |
2003年 | 1篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1996年 | 2篇 |
1991年 | 1篇 |
1987年 | 1篇 |
排序方式: 共有144条查询结果,搜索用时 15 毫秒
1.
关于TJWX-2006型信号微机监测系统报警参数设置的探讨 总被引:1,自引:0,他引:1
为运用好微机监测设备,在分析了近一年的监测数据基础上,提出了监测项目报警参数的设置原则,并以实例,具体说明了监测项目报警参数的设置标准。 相似文献
2.
针对职业卫生噪声个体监测过程中异常导致的数据无法使用的问题,本文以某大型装置巡检工个体噪声监测中出现的异常情况为例,探讨数据调整方法。研究发现删除异常值或使用平均值替代两种方法,数据调整后与实际情况吻合度较好,两种方法均能满足个体声级计监测实践要求。 相似文献
3.
In this paper, the procedure for flaw acceptability assessment is examined through a case study of a semi-elliptical surface crack in an offshore monopile as it grows till it forms a through thickness crack. Using the procedure prescribed in an industrial standard (BS 7910), the fracture ratio, Kr is shown to increase monotonically with increasing crack depth. The load ratio, Lr, is initially insensitive to the crack depth. However, there is a rapid increase in Lr when the crack depth to thickness ratio exceeds 80%. Lr values obtained from detailed 3D FE limit analysis using elastic-perfectly-plastic material behaviour do not exhibit the asymptotic behaviour predicted by BS 7910 as the flaw transitions from deep crack to through-thickness crack. Furthermore, Kr predicted by BS 7910 is shown to be an over-estimation for the typical dimensions of offshore monopiles. The findings suggest that a structure with a deep flaw may be identified as unacceptable based on BS 7910 when it may still possess a non-trivial amount of structural residual life. This is a concern for monopiles where crack growth as a large flaw forms a significant part of the total life. 相似文献
4.
5.
6.
Kekuewa Kikiloi 'Aulani Wilhelm Nai'a Lewis Kalani Quiocho William 'Āila Jr. 《Coastal management》2017,45(6):436-451
Papahānaumokuākea Marine National Monument is one of the world's largest marine protected areas and was designated the first mixed conservation site in the United States due to its natural and cultural importance. It is also the world's first cultural seascape, being recognized for its continuing connections to indigenous people. As the westernmost place in the Hawaiian universe, many believe these islands and seas are the pathway that Native Hawaiians travel after death, returning to pō (night; realm of the gods). This intimate kinship has profound implications for contemporary management. Current management emphasizes integration of science, policy, cultural knowledge, traditions, and practices to create successful management strategies appropriate for both natural and cultural resources. This management is based on Native Hawaiian values and practices that incorporate observation and understanding of the natural world, indigenous principles and philosophies, cultural norms, community relationships, and unique epistemologies deeply imbedded in and formed by relationships of people with place. A cornerstone of this effort has been the direct involvement of cultural practitioners in policy, management, education, and research. This biocultural approach has led to more effective management of the monument and serves as a model for conservation around the world. 相似文献
7.
Nadine A. Marshall Matthew I. Curnock Jeremy Goldberg Margaret Gooch Paul A. Marshall Petina L. Pert 《Coastal management》2017,45(6):505-518
Understanding how people are dependent on Large Scale Marine Protected Areas (LSMPAs) is important for understanding how people might be sensitive to changes that affect these seascapes. We review how resource dependency is conceptualized and propose that it be broadened to include cultural values such as pride in resource status, scientific heritage, appreciation of aesthetics, biodiversity, and lifestyle opportunities. We provide an overview of how local residents (n = 3,181 face-to-face surveys), commercial fishers (n = 210, telephone surveys), and tourism operators (n = 119 telephone surveys) are potentially dependent on the Great Barrier Reef (GBR), a region currently experiencing significant environmental, social, and economic change. We found that commercial fishers and tourism operators were dependent not only financially on the GBR, but also because of their age, years in the industry and region, lack of education, and the number of dependents. These stakeholders lacked flexibility to secure alternative employment. All stakeholder groups, regardless of economic imperatives, were dependent on the GBR because of their cultural connections. We propose that resource dependency also provides an umbrella concept to describe the cultural services provided by an ecosystem, which can be described through place-based dependence and place-identity. 相似文献
8.
文章利用SLOPE/W模块,基于确定值方法和可靠度理论的极限平衡法.对隆林新洲养护站边坡在不采取支挡措施和采用锚索抗滑桩支挡措施情况下,如何保持边坡稳定性进行了对比分析。 相似文献
9.
各种钻探方法对粉细砂层原始状态的影响不一,获得的标贯N值有一定差异。冲击钻对粉细砂层原始状态的影响较大,获得的标贯N值与实际相差较大,而回转钻对粉细砂层原始状态的影响较小,获得的标贯N值与实际比较接近。 相似文献
10.
Giselle P. B. Samonte-Tan Alan T. White Mary Ann Tercero John Diviva Esperanza Tabara Ciemon Caballes 《Coastal management》2013,41(2-3):319-338
This article provides results on the net benefits generated from the natural resources in the Bohol Marine Triangle (BMT) in the Philippines. The BMT spans over 112,000 ha and its coastal ecosystems are rich in biodiversity and provide economic opportunities to the coastal communities. With a 10% discount rate, the accumulated total net benefits for the BMT resources over a 10-year period is US$11.54 million. Tourism and the municipal fisheries are the most important direct use values of the coastal and marine resources of the BMT accounting for 44% and 39% of the total net benefits. Annual revenues attributed to ecosystems were as follows: coral reefs, US$1.26 million; beach/intertidal area, US$1.12 million; marine waters, US$646,501; mangrove, US$239,561; and seagrass, US$105,990. The large market values indicate the dependence of the local community on the BMT coastal and marine resources. In the same way, non-market values show the important life-support functions of coastal and marine ecosystems. The net benefits reflect the magnitude of potential losses due to improper management of coastal and marine resources in the BMT. This valuation highlights the importance of the coastal services to the BMT economy and draws attention to the benefits the local stakeholders derive from BMT coastal resources. Policy measures can now take into account these values to justify a sufficient investment in coastal management efforts to sustain the flow of coastal services in the interest of current and future generations. 相似文献