全文获取类型
收费全文 | 978篇 |
免费 | 109篇 |
国内免费 | 191篇 |
专业分类
安全科学 | 200篇 |
废物处理 | 10篇 |
环保管理 | 122篇 |
综合类 | 541篇 |
基础理论 | 122篇 |
污染及防治 | 53篇 |
评价与监测 | 87篇 |
社会与环境 | 87篇 |
灾害及防治 | 56篇 |
出版年
2024年 | 2篇 |
2023年 | 12篇 |
2022年 | 34篇 |
2021年 | 51篇 |
2020年 | 48篇 |
2019年 | 56篇 |
2018年 | 38篇 |
2017年 | 57篇 |
2016年 | 69篇 |
2015年 | 51篇 |
2014年 | 65篇 |
2013年 | 71篇 |
2012年 | 87篇 |
2011年 | 66篇 |
2010年 | 51篇 |
2009年 | 49篇 |
2008年 | 38篇 |
2007年 | 69篇 |
2006年 | 60篇 |
2005年 | 43篇 |
2004年 | 33篇 |
2003年 | 29篇 |
2002年 | 20篇 |
2001年 | 20篇 |
2000年 | 14篇 |
1999年 | 24篇 |
1998年 | 21篇 |
1997年 | 11篇 |
1996年 | 9篇 |
1995年 | 15篇 |
1994年 | 14篇 |
1993年 | 13篇 |
1992年 | 11篇 |
1991年 | 13篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1980年 | 2篇 |
1977年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有1278条查询结果,搜索用时 703 毫秒
901.
Jongdeuk Ahn Jong-Gyu Kim In-Yong Seo Jae Hoon Roh Seung Heon Song Jeonghun Song 《International Journal of Green Energy》2017,14(11):961-969
An ideal off-grid island can become 100% energy-sufficient if one installs renewable energy systems such as solar photovoltaic (PV) and wind turbine (WT) systems. However, the intermittent and uncertain nature of the power supply from renewable energy systems hinders a 100% autonomy level (AL) without an infinite energy storage capacity. The thermoeconomic installation limit (TEIL) of a PV/WT hybrid energy system was studied using hourly weather data and the energy demand profile for off-grid islands. An appropriate battery size for the TEIL was also determined. Given the current installation cost of the hybrid energy system and the battery unit, the AL for a PV/WT hybrid energy system at the TEIL is calculated to be approximately 70%. Above the limit, the size of the energy storage unit and, correspondingly, the total annual cost of the PV/WT hybrid energy system increase sharply. 相似文献
902.
We spend a substantial part of our daily life waiting, and unfortunately, wait time can fuel aggressive tendencies. Our study examines the relationship between wait time, perceived wait time, and aggressive tendencies from a construal level perspective. In Study 1, we found that the higher the construal level, the stronger the relationship between actual and perceived wait time and the stronger relationship between perceived wait time and aggressive tendencies. In Study 2, we manipulated construal level and found that power explains the moderating impact of construal on the wait—aggressive tendencies relationships. Results demonstrate the role of construal in explaining both perceived wait time and aggressive responses to long wait times, suggesting that mental construal influences both the psychological experience of time and the subsequent reaction to that experience. Overall, these results contribute to research on subjective time perspective by enhancing the knowledge and understanding of the determinants and effects of perceived wait time. 相似文献
903.
Climate change incurs costs, but government adaptation budgets are limited. Beyond a certain point, individuals must bear
the costs or adapt to new circumstances, creating political-economic tipping points that we explore in three examples. First,
many Alaska Native villages are threatened by erosion, but relocation is expensive. To date, critically threatened villages
have not yet been relocated, suggesting that we may already have reached a political-economic tipping point. Second, forest
fires shape landscape and ecological characteristics in interior Alaska. Climate-driven changes in fire regime require increased
fire-fighting resources to maintain current patterns of vegetation and land use, but these resources appear to be less and
less available, indicating an approaching tipping point. Third, rapid sea level rise, for example from accelerated melting
of the Greenland ice sheet, will create a choice between protection and abandonment for coastal regions throughout the world,
a potential global tipping point comparable to those now faced by Arctic communities. The examples illustrate the basic idea
that if costs of response increase more quickly than available resources, then society has fewer and fewer options as time
passes. 相似文献
904.
针对2007年7月8日发生在苏皖淮河流域的暴雨,采用WRF中尺度数值模式模拟结果、FNL每日4次1°*1°再分析资料、6h地面实况观测降水资料和FY-2相当黑体亮温TBB资料对该次降水的发生、发展过程进行了分析研究。结果表明:(1)该次降水在有利的大气环流形势下,强降水发生在呈准东西向分布的梅雨锋上。位于蒙古国与我国华北—东北交界处上空的切断低压给淮河流域输入了冷空气。冷空气与西南低空急流带来的暖湿气流交汇,增强了大气斜压性;(2)正的非热成风涡度的发展促进了高层相对于低层的辐散减压,有利于垂直上升运动的发展;(3)低空强急流带所形成的动力、热力和水汽条件对暴雨落区位置产生了重要影响。 相似文献
905.
Yuzhou Luo 《Environmental pollution (Barking, Essex : 1987)》2010,158(5):1629-1637
Field runoff is an important transport mechanism by which pesticides move into the hydrologic environment of intensive agricultural regions such as California's Central Valley. This study presents a spatially explicit modeling approach to extend Pesticide Root Zone Model (PRZM), a field-scale pesticide transport model, into basin level. The approach was applied to simulate chlorpyrifos use in the Central Valley during 2003-2007. The average value of loading as percent of use (LAPU) is 0.031%. Results of this study provide strong evidence that surface runoff generation and pesticide application timing are the two influencing factors on the spatial and temporal variability of chlorpyrifos sources from agricultural fields. This is one of the first studies in coupling GIS and field-scale models and providing simulations for the dynamics of pesticides over an agriculturally dominated landscape. The demonstrated modeling approach may be useful for implementations of best management practice (BMP) and total maximum daily load (TMDL). 相似文献
906.
Correlation Between Economic Development Level and Landscape Pattern in Beijing Peri-urban Areas 总被引:1,自引:0,他引:1
With the rapid changes of demographic and socio-economic structure, various ecological and environmental problems have emerged in peri-urban areas. Studies on the correlation between socio-economic development and eco-environmental preservation are inadequate. This paper analyzes the landscape pattern of peri-urban areas to address this issue. First, it studies the differentiation of economic development levels in Beijing peri-urban areas. Then, it explores the correlation between economic development level... 相似文献
907.
To analyze China’s actual urbanization level, we iden- tified two statistical approaches: using the population living within the administrative boundaries (administrative-based method) and within the urbanized or built-up areas (infrastructure-based method) of cities and towns as urban population. To illustrate the two approaches and the associated problems, we used data for Tangshan City as a case study. The estimates on the administrative-based method were unreliable and the infrastructurebased method pro... 相似文献
908.
湘江流域生态补偿系数定量分析 总被引:1,自引:0,他引:1
充分考虑生态补偿主体的社会经济发展水平、支付能力、对环境污染的贡献率,科学、公平、合理制定生态补偿标准是推动生态补偿机制实施的关键点之一。本文应用主成分分析法对湘江流域内各市社会经济发展水平、支付能力、环境污染的贡献率进行界定与定量分析,在此基础上形成补偿系数,对统一的补偿标准进行修正,实现补偿标准的科学、客观、公平。 相似文献
909.
区域发展是城市化与工业化进程中需要解决的重大理论与实际问题,评估区域发展态势是进一步研究区域发展前景的基础。基于区域可持续发展理论,从区域发展水平与发展成本的辩证关系出发,以长江沿江产业带40个地级城市为基本评价单元,选取标识发展水平和发展成本最重要的指标,构建了基于“经济-社会-资源-环境”的复合指标体系。在综合评价长江沿江地区经济社会发展水平和资源环境发展成本的基础上,依据二维判别矩阵,将长江沿江地区划分为高发展高成本区、高发展低成本区、低发展高成本区和低发展低成本区等4种类型区,并针对不同类型区域,分别从产业发展、生态保护、区域协调等方面提出了相应的发展政策和措施,为长江沿江地区新一轮的区域发展提供依据 相似文献
910.
Analyzing trophic transfer of heavy metals for food webs in the newly-formed wetlands of the Yellow River Delta, China 总被引:3,自引:0,他引:3
Cui B Zhang Q Zhang K Liu X Zhang H 《Environmental pollution (Barking, Essex : 1987)》2011,159(5):1297-1306
Nine heavy metals sampled from water, sediments, and aquatic organisms in the newly-formed wetlands of the Yellow River Delta (YRD) of China were analyzed to evaluate their concentrations and trophic transfer in food webs. The stable carbon (δ13C) and nitrogen (δ15N) isotopes were used to investigate trophic interactions. Results show that most of heavy metals detected in water and sediments are lower than that in Yangtze River Delta and Pearl River Delta. The longest food web is approximately 4 with the highest trophic level of birds. The difference of heavy metal concentrations between endangered Saunders’s Gull and other three kinds of protected birds is not obvious. Cd, Zn, and Hg were identified to have an increase with the trophic level (TL), while As, Cr, Cu, Mn, Ni and Pb show an opposite trend, however, the biomagnification of the selected nine heavy metals in the food webs is not significant. 相似文献