全文获取类型
收费全文 | 38篇 |
免费 | 2篇 |
专业分类
安全科学 | 6篇 |
环保管理 | 8篇 |
综合类 | 12篇 |
基础理论 | 5篇 |
污染及防治 | 3篇 |
评价与监测 | 3篇 |
社会与环境 | 3篇 |
出版年
2022年 | 1篇 |
2021年 | 4篇 |
2019年 | 1篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 1篇 |
2012年 | 2篇 |
2011年 | 1篇 |
2010年 | 2篇 |
2009年 | 1篇 |
2008年 | 1篇 |
2007年 | 1篇 |
2006年 | 3篇 |
2005年 | 3篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2001年 | 2篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1986年 | 2篇 |
1981年 | 1篇 |
排序方式: 共有40条查询结果,搜索用时 936 毫秒
31.
为探究心智技能对飞行员安全绩效的影响规律,提高飞行员的安全绩效,采用结构方程模型(SEM)建立了心智技能与飞行员安全绩效之间的假设关系模型.首先选取210名飞行员发放调查问卷,收集飞行员的观察力、记忆力、思维力和想象力相关数据;然后采用SPSS 21.0软件对调查问卷数据进行信效度分析和影响因子分析;最后从QAR(快速... 相似文献
32.
IntroductionThis study investigated the effects of pavement surface condition and other control factors on casualty crashes at signalized intersections. It involved conducting a before and after study for road surface condition and situational factors. It also included assessing the effects of geometric characteristics on safety performance of signalized intersections post resurfacing to control for the effect of pavement surface condition. Pavement surface condition included roughness, rutting, and skid resistance. The control factors included traffic volume, light and surface moisture condition, and speed limit. The geometric characteristics included approach width, number of lanes, intersection depth, presence of median, presence of shared lane, and presence of bus stop.MethodTo account for the repeated observations of the effect of light and surface moisture conditions in four occasions (day-dry, day-wet, night-dry and night-wet) Generalized Estimating Equation (GEE) with Negative Binomial (NB) and log link function was applied. For each signalized intersection in the sample, condition data are collected for the year before and after the year of surface treatment. Crash data, however, are collected for a minimum of three and maximum of five years before and after treatment years.ResultsThe results show that before treatment, light condition, road surface moisture condition, and skid resistance interaction with traffic volume are the significant contributors to crash occurrence. For after treatment; light condition, road surface moisture condition, their interaction product, and roughness interaction with light condition, surface moisture condition, and traffic volume are the significant contributors. The geometric variables that were found to have significant effects on crash frequency post resurfacing were approach width interactions with presence of shared lane, bus stop, or median.ConclusionsThe findings confirm that resurfacing is significant in reducing crash frequency and severity levels.Practical Applications: The study findings would help for better understanding of how geometric characteristics can be improved to reduce crash occurrence. 相似文献
33.
34.
Soil erosion is a severe problem for many developing regions that lack adequate infrastructure to combat the problem. The
authors established a first-order method for prioritizing areas to be examined and remediated using preexisting data and expert
knowledge where data are lacking. The Universal Soil Loss Equation was applied to the Rio Lempa Basin in Central America using
geographic information systems and remote sensing technologies, and the estimated erosion rates were compared with sediment
delivery ratios. Spatial analysis indicates that agriculture on very steep slopes contributes only a small fraction to the
total estimated soil erosion, whereas agriculture on gentle and moderately steep slopes contributes a large fraction of the
erosion. Although much of the basin is in El Salvador, the greatest estimated amount of erosion is from Honduras. Data quality
and availability were impaired by a lack of coordination among agencies and across countries. Several avenues for improving
the authors’ methods are described. 相似文献
35.
This article describes three applications of the Universal Soil Loss Equation for further defining differences between natural environments in terms of their suitabilities for recreation use. Physical capacity limits based upon vulnerability to erosion and loss of soil productivity are discussed. Examples include: (a) applications to site planning and comparison of existing campsites; (b) use of the methodology for setting limits of acceptable change; and (c) characterization of third-order or larger watersheds that compare ecological land type interpretations with those based upon application of the equation. 相似文献
36.
37.
社会信任、合作能力与农户参与小农水供给行为——基于黄河灌区五省数据的验证 总被引:2,自引:0,他引:2
在政府主管的小农水供给模式无法完全满足农业分户经营的需要的现实背景下,农户参与供给是实现小农水供需平衡的有效方式。本文利用黄河灌区宁夏、内蒙古、陕西、河南和山东五个省份1558户微观农户数据,引入农户社会信任和合作能力因子,考虑农户农业收入水平和所处省份差异,采用多群组结构方程模型,探究农户参与小农水供给的行为。首先,运用信度和效度检验对农户参与小农水供给行为量表进行了分析。在此基础上,运用多群组结构方程模型,以农户农业收入水平和所处省份为调节变量,分析农户社会信任和合作能力对其参与小农水供给行为的影响。研究结果表明:农户的社会信任和合作能力显著正向影响农户参与小农水供给的意愿,其中农户的合作能力影响程度较大,农户的社会信任影响程度次之;农户的社会信任、合作能力和参与供给意愿对其参与小农水供给行为有显著正向影响,且影响程度最大的是农户的参与供给意愿,其次是农户的合作能力,最后为农户的社会信任;农户的社会信任对其合作能力有显著正向影响。多群组分析表明,农户的农业收入水平及其所处省份显著调节农户参与小农水的供给行为。其中,农业收入作为调节变量结果显示,农业收入高的农户参与小农水供给的意愿更强烈,参与供给行为水平更高;产生参与供给意愿后,农业收入中等偏上和中等偏下的农户更容易将意愿转化为行为。省份作为调节变量的结果显示,陕西、河南和山东农户的社会信任和合作能力对其参与小农水供给意愿的影响较大,河南和山东农户更容易将参与供给意愿转化为行为;宁夏和内蒙古农户的合作能力对其参与供给行为影响程度较大。根据以上结果,政府应根据不同地区农户的收入水平、社会信任和合作能力等实际情况,充分调动本地的社会资源,引导农户认识到参与小农水供给的重要性和迫切性,提高农户参与小农水供给的意愿和行为水平,促进小农水供需平衡的实现。 相似文献
38.
John R. Henry 《Journal of the American Water Resources Association》1981,17(3):438-442
The Agricultural Conservation Program (ACP), is undergoing a new, rigorous evaluation to determine its effectiveness in conserving the Nation's agricultural soils and waters. ACP deals with many types of conservation practices, but the focus here is on the evaluation of soil and water related practices. ACP has depended heavily on the State and private forestry services, Soil Conservation Service, and the Cooperative Extension Services, for technical expertise. Thus, the process is an evaluation of the effectiveness of a “team of agencies,” as well as of the program itself. Results of the evaluation have helped to develop new thrusts which have moved ACP further into the position of treating the total conservation problem. Phase I has its limitations. It did not address the impact of wind erosion, water quality, change in productive capacity, soil quality, wildlife habitat, off site and farm income impacts. It does show that ACP has and is doing a very good job in meeting its stated purposes. It is clear that ACP's effectiveness can be improved with more and better advanced planning and more intensive use of soil maps, the USLE, and other scientific tools. ACP is headed in this direction. 相似文献
39.
An evaluation of grid size uncertainty in empirical soil loss modeling with digital elevation models 总被引:3,自引:0,他引:3
Simon?WuEmail author Jonathan?Li Gordon?Huang 《Environmental Modeling and Assessment》2005,10(1):33-42
This paper presents a study on the effect of topographic variability on grid-based empirical estimation of soil erosion and sediment transport with raster geographic information systems (GIS). An original digital elevation model (DEM) of 10 m resolution for a case watershed is resampled to six realizations of greater grid sizes for a comparative examination. The Universal Soil Loss Equation (USLE) and a distance-based sediment delivery equation are applied to the watershed to calculate soil loss from each cell and total sediment transport to streams, respectively. The results suggest that the selection of the DEM gird size has considerable influence on the soil loss estimation with the empirical models. The estimate of total soil loss from the watershed decreases significantly with the increasing DEM cell size as the spatial variability is reduced by the cell aggregation. The empirical modeling approach is a useful tool for qualitative assessment of soil erosion, provided that spatial variability can be adequately represented by applied DEMs. However, discretion is suggested for its applications to quantitative estimation of soil loss concerning the sensitivity to the grid size selection. 相似文献
40.
An experimental setup which is capable of simulation as well as monitoring contaminant transport through soil mass has been
developed. Efficiency of the experimental setup has been demonstrated by comparing the results obtained from the argentometric
method. Reynolds number (Re) and the Peclet number (Pe) have been found to be less than unity. This indicates that flow of the solute through soil mass is laminar and the dominant
contaminant transport mechanism is diffusion. 相似文献