全文获取类型
收费全文 | 49篇 |
免费 | 13篇 |
国内免费 | 18篇 |
专业分类
安全科学 | 6篇 |
废物处理 | 2篇 |
环保管理 | 4篇 |
综合类 | 29篇 |
基础理论 | 12篇 |
污染及防治 | 13篇 |
评价与监测 | 3篇 |
社会与环境 | 3篇 |
灾害及防治 | 8篇 |
出版年
2023年 | 5篇 |
2022年 | 6篇 |
2021年 | 3篇 |
2020年 | 8篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 1篇 |
2014年 | 5篇 |
2013年 | 4篇 |
2012年 | 2篇 |
2011年 | 5篇 |
2010年 | 5篇 |
2009年 | 5篇 |
2008年 | 3篇 |
2007年 | 3篇 |
2006年 | 1篇 |
2005年 | 1篇 |
2003年 | 2篇 |
2001年 | 1篇 |
1998年 | 1篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 1篇 |
排序方式: 共有80条查询结果,搜索用时 31 毫秒
31.
32.
33.
强度折减法是边坡稳定性分析中广泛使用的数值计算方法,传统整体强度折减法对黏聚力和内摩擦角采用同一系数进行折减。由于两强度参数发挥作用先后以及衰减程度的不同,传统整体强度折减法不能真实的反映土体渐进破坏过程,一些学者提出运用双折减法来探究边坡的破坏问题。基于土体应变软化特性,通过土体的峰值与残余强度建立起黏聚力和内摩擦角之间的关系,将得到的强度参数关系式作为双参数折减组合的依据。该方法以破坏接近度作为判别土体是否破坏的标准,引入局部阶梯折减的思想,对局部破损区域(FAI>0.8)采用不同的折减组合,研究均质土坡的渐进破坏过程。计算结果表明,局部软化阶梯双折减法可以体现两强度参数发挥作用的先后顺序,整理出两参数间的关系式为一次函数,自变量对应的参数先发挥,因变量对应的参数后发挥;在算例中,黏聚力的折减系数大于内摩擦角的折减系数,黏聚力的强度储备比内摩擦角大,发挥得较为充分;模拟计算出的破损区面积以及边界处的塑性应变差值更加连续、平稳;阶梯双折减方法得到的综合安全系数小于整体折减法的安全系数,在工程应用上偏于安全,与其他学者得出的结论一致;受网格密度的影响,综合安全系数的范围为 1.207~1.229,该范围可为工程设计和施工提供参考。 相似文献
34.
35.
通过强度折减法获取边坡的潜在滑裂带是目前数值计算广泛使用的方法,研究边坡滑裂带形成的渐进过程及坡体内部土体的应力状态具有重要的理论意义和工程价值。基于边坡破坏的渐进性思想,针对均质边坡提出了一种局部强度阶梯折减的方法。该方法以屈服接近度(YAI)作为判别土体是否存在破损区的评价标准,将局部破损区按不同破损次序分配予不同的折减系数,利用通用软件ABAQUS对局部坡体进行强度折减计算,研究边坡渐进变形过程,直至边坡发生整体破坏。计算结果表明,坡体内部初始破损区参与了潜在滑裂面的形成过程,对边坡后期渐进变形具有贡献;有效解决了传统强度折减法潜在滑裂面上折减区和非折减区边界处的塑性应变值的跳跃性问题,合理地演化了边坡的渐进失稳进程。 相似文献
36.
37.
为研究人群中恐慌心理蔓延规律,基于传染病传播模型,构建NPCN(Normal-Panic-Cool-Normal)恐慌心理蔓延模型,通过加入干预因子得到优化模型,对NPCN模型及优化模型进行数值模拟,并对模拟结果进行对比分析。结果表明:恐慌人群比例随恐慌率α和冷静损失率γ增大而增大,随冷静率β增大而减小;在干预因子ω和ψ作用下,恐慌人群比例P明显下降,说明采取及时干预措施对恐慌心理蔓延抑制效果较好。 相似文献
38.
39.
Distribution and transportation of mercury from glacier to lake in the Qiangyong Glacier Basin, southern Tibetan Plateau, China 总被引:1,自引:0,他引:1
Shiwei Sun Shichang Kang Jie Huang Chengding Li Junming Guo Qianggong Zhang Xuejun Sun Lekhendra Tripathee 《环境科学学报(英文版)》2016,28(6):213-223
The Tibetan Plateau is home to the largest aggregate of glaciers outside the Polar Regions and is a source of fresh water to 1.4 billion people. Yet little is known about the transportation and cycling of Hg in high-elevation glacier basins on Tibetan Plateau. In this study, surface snow,glacier melting stream water and lake water samples were collected from the Qiangyong Glacier Basin. The spatiotemporal distribution and transportation of Hg from glacier to lake were investigated. Significant diurnal variations of dissolved Hg(DHg) concentrations were observed in the river water, with low concentrations in the morning(8:00 am–14:00 pm) and high concentrations in the afternoon(16:00 pm–20:00 pm). The DHg concentrations were exponentially correlated with runoff, which indicated that runoff was the dominant factor affecting DHg concentrations in the river water. Moreover, significant decreases of Hg were observed during transportation from glacier to lake. DHg adsorption onto particulates followed by the sedimentation of particulate-bound Hg(PHg) could be possible as an important Hg removal mechanism during the transportation process. Significant decreases in Hg concentrations were observed downstream of Xiao Qiangyong Lake, which indicated that the high-elevation lake system could significantly affect the distribution and transportation of Hg in the Qiangyong Glacier Basin. 相似文献
40.
The global urbanization process poses a serious challenge to achieving sustainable development. The significance of sustainable urbanization has been increasingly appreciated, yet, very little empirical evidence has been provided for this prospect. In this paper, we use the Human Development Index and the ecological footprint to measure the sustainability of the coastal Liaoning area. We then use the quadrant map approach to determine the relationship between sustainability and urbanization. The results show that the coastal area has made progress in sustainable urbanization in the social dimension. Improvement in the environmental dimension has been dynamic. Our results indicate that sustainable urbanization is a dynamic, multi-dimensional progress that requires regular monitoring and reevaluation. This paper also highlights the importance of choosing more complete indicators for measuring the sustainability of urbanization, as no single model or measurement is sufficient for quantifying the different dimensions of sustainability. 相似文献