全文获取类型
收费全文 | 3081篇 |
免费 | 86篇 |
国内免费 | 185篇 |
专业分类
安全科学 | 142篇 |
废物处理 | 15篇 |
环保管理 | 747篇 |
综合类 | 1254篇 |
基础理论 | 201篇 |
污染及防治 | 269篇 |
评价与监测 | 582篇 |
社会与环境 | 107篇 |
灾害及防治 | 35篇 |
出版年
2024年 | 4篇 |
2023年 | 42篇 |
2022年 | 45篇 |
2021年 | 69篇 |
2020年 | 93篇 |
2019年 | 49篇 |
2018年 | 48篇 |
2017年 | 84篇 |
2016年 | 106篇 |
2015年 | 119篇 |
2014年 | 137篇 |
2013年 | 150篇 |
2012年 | 126篇 |
2011年 | 235篇 |
2010年 | 85篇 |
2009年 | 229篇 |
2008年 | 196篇 |
2007年 | 196篇 |
2006年 | 149篇 |
2005年 | 124篇 |
2004年 | 115篇 |
2003年 | 115篇 |
2002年 | 100篇 |
2001年 | 85篇 |
2000年 | 83篇 |
1999年 | 79篇 |
1998年 | 78篇 |
1997年 | 59篇 |
1996年 | 42篇 |
1995年 | 52篇 |
1994年 | 64篇 |
1993年 | 38篇 |
1992年 | 24篇 |
1991年 | 18篇 |
1990年 | 11篇 |
1989年 | 7篇 |
1988年 | 11篇 |
1987年 | 7篇 |
1986年 | 12篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 9篇 |
1978年 | 6篇 |
1974年 | 2篇 |
1973年 | 5篇 |
1969年 | 2篇 |
1968年 | 2篇 |
排序方式: 共有3352条查询结果,搜索用时 15 毫秒
971.
Groundwater overdraft is a resource management issue that poses a threat for the security of communities. Impacts of groundwater overdraft are influenced by the biophysical and social contexts of water management. This paper presents a method for assessing vulnerability to water scarcity in spatial terms using biophysical and social indicators. A geographic information system was used to establish areas of vulnerability based upon hydrologic variability in water resource availability within a groundwater basin, three types of water management systems, and 10 sociodemographic characteristics. Our study area is in the rapidly urbanizing Arizona Central Highlands, located 150 km north of the Phoenix metropolitan region, USA. Results indicate that the most biophysically vulnerable places do not necessarily intersect with the most vulnerable populations and that local differences in vulnerability are interrelated, rather than independent, outcomes in a process of socioenvironmental transformation. Vulnerability is influenced by laws that deny access to local surface waters and lead to dependence on fossil groundwater, and by economic reliance on urbanization. Localities attempt to reduce vulnerability through the development of community water systems and the expansion of water frontiers. While such strategies may reduce local vulnerability, they are not sustainable solutions because they transfer risks to other places, and thus contribute to vulnerability elsewhere. 相似文献
972.
Angeler DG Sánchez-Carrillo S Rodrigo MA Alvarez-Cobelas M Rojo C 《Environmental monitoring and assessment》2007,125(1-3):9-17
This study evaluates whether the size structure of seston (the sum of living and nonliving particles in the water column)
reflects the effects of fish on wetland water quality. Using enclosures, we measured water quality and zooplankton community
structure in the presence and absence of two fish species with distinct foraging strategies [benthivorous carp (Cyprinus
carpio) and planktivorous mosquitofish (Gambusia
holbrooki)]. Seston collected from the enclosures was counted and sized automatically with a Coulter counter, and the size structure
in the range of 1–60 μm was modelled using the underlying Pareto distribution of particles. Only Cyprinus contributed to a loss of water quality (increased nutrient levels, algal and non-algal turbidity, hypoxia), while both fish
species changed zooplankton community composition compared to fishless controls. However, these changes were not reflected
in parameters [goodness of fit (r
2) and parameter c (slopes)] of Pareto models. Multivariate statistics suggest that seston size structure responded more to environmental gradients
related to water depth but the relationships were also weak. Our overall result contrasts with the regulation of size spectra
constructed from living organisms. Although seston integrates many structural and functional features of the water column,
the lack of strong relationships between Pareto model parameters and water quality suggests that a size-based approach to
characterise seston structure has a limited potential for assessing biota-mediated effects in wetlands in a straightforward
manner. 相似文献
973.
974.
介绍高纯铜锌合金滤材的特性和先进性,以及讨论了去除水中铅、砷、汞的机理,可应用的范围,应用现状及前景。介绍高纯铜锌合金滤材的特性和先进性,以及讨论了去除水中铅、砷、汞的机理,可应用的范围,应用现状及前景。 相似文献
975.
固相微萃取-气相色谱法测定水中痕量有机氯农药 总被引:4,自引:0,他引:4
建立了固相微萃取-气相色谱联用快速测定水中14种痕量有机氯农药的方法,对比研究了浸入式直接固相微萃取与顶空固相微萃取两种方式对不同有机氯农药的富集效率,优化了试验条件.方法线性关系良好,检出限为0.1 ng/L~10 ng/L,定量下限为0.2 ng/L~40 ng/L,RSD<8%,实际水样的加标回收率为67.0%~133%. 相似文献
976.
乙酰丙酮分光光度法测定水中甲醛时影响空白值的因素 总被引:2,自引:0,他引:2
针对水质中甲醛测定时试剂水、pH值、乙酰丙酮试剂、加热温度和显色时间等影响因素进行了讨论,并提出了减小空白值的对策. 相似文献
977.
选择出11项评价因子,采用单项分指数法和平均分指数法,在涨潮、落潮、涨落潮时分别对伶仃洋东部海域水质进行监测,并与历史资料进行对比,对评价因子超标进行评价和原因分析,提出了补救与预防措施. 相似文献
978.
979.
吹扫捕集-GC-MS测定废水中的硝基氯苯 总被引:1,自引:0,他引:1
建立了吹扫捕集-GC-MS测定水样中硝基氯苯类化合物的方法.考察了吹扫温度、吹扫时间等对吹扫捕集效率和方法检出限的影响.在室温下,当吹扫时间为30 min时,该方法的最低检出限可达0.002 mg/L,工作曲线的线性范围为2×10 -3 ~2 mg/L,相对标准偏差在2%~6%,加标回收率在97.0%~110.0%.与国家标准方法相比,该法具有操作简便、灵敏度高、线性范围宽且无须使用有毒有机溶剂等优点,可满足工业废水和地表水中硝基氯苯的测定要求. 相似文献
980.
Healthy watersheds provide valuable services to society, including the supply and purification of fresh water. Because these natural ecosystem services lie outside the traditional domain of commercial markets, they are undervalued and underprotected. With population and development pressures leading to the rapid modification of watershed lands, valuable hydrological services are being lost, which poses risks to the quality and cost of drinking water and the reliability of water supplies. Increasing the scale and scope of programmes to protect hydrological services requires policies that harmonize land uses in watersheds with the provision of these important natural services. This article summarizes key attributes of hydrological services and their economic benefits; presents a spectrum of institutional mechanisms for safeguarding those services; discusses programmes in Quito (Ecuador), Costa Rica and New York City; and offers some lessons learned and recommendations for achieving higher levels of watershed protection. 相似文献