全文获取类型
收费全文 | 895篇 |
免费 | 56篇 |
国内免费 | 201篇 |
专业分类
安全科学 | 12篇 |
废物处理 | 21篇 |
环保管理 | 110篇 |
综合类 | 675篇 |
基础理论 | 113篇 |
污染及防治 | 63篇 |
评价与监测 | 70篇 |
社会与环境 | 71篇 |
灾害及防治 | 17篇 |
出版年
2024年 | 2篇 |
2023年 | 14篇 |
2022年 | 33篇 |
2021年 | 31篇 |
2020年 | 35篇 |
2019年 | 28篇 |
2018年 | 12篇 |
2017年 | 23篇 |
2016年 | 27篇 |
2015年 | 38篇 |
2014年 | 35篇 |
2013年 | 46篇 |
2012年 | 65篇 |
2011年 | 79篇 |
2010年 | 60篇 |
2009年 | 43篇 |
2008年 | 36篇 |
2007年 | 70篇 |
2006年 | 64篇 |
2005年 | 65篇 |
2004年 | 59篇 |
2003年 | 59篇 |
2002年 | 39篇 |
2001年 | 21篇 |
2000年 | 22篇 |
1999年 | 21篇 |
1998年 | 16篇 |
1997年 | 9篇 |
1996年 | 11篇 |
1995年 | 11篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 8篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有1152条查询结果,搜索用时 15 毫秒
981.
《地表水环境质量标准》是水环境管理的尺度,在推动我国水污染防治、公众健康与水生态安全保障等方面发挥着十分重要的作用.随着我国进入生态文明建设新阶段,水环境保护和社会经济发展形势发生深刻变化,如何与时俱进,及时修订丰富现行标准成为迫在眉睫的问题.全面剖析了我国现行GB 3838—2002《地表水环境质量标准》修订历程、修订依据、重要贡献、存在问题及国家需求,结合国际标准发展趋势和我国社会发展阶段,提出未来将《地表水环境质量标准》由单项标准向系列标准转变的修订思路框架.初步阐述了由系列标准构成的“1+N”的标准体系框架,其中,“1”是地表水环境质量基本项目标准,用于判断地表水环境质量的优劣程度,反映水环境功能的基本水质要求;“N”是不同的特定保护项目标准,包括保护水生生物的有毒有害污染物项目水质标准、地表饮用水源地水质标准、湖泊营养物状态评价标准以及地表水水生物状况评价标准,并提出了各分标准的相关制修订方案. 相似文献
982.
湖泊是陆地水圈的重要组成部分,不仅参与自然界水循环,而且具有提供水源、调节洪水、维持生态环境健康等功能,研究湖泊面积的动态变化特征,探讨湖泊面积动态对气候变化的响应对水资源的合理利用及生态环境保护具有重要的现实意义。以胶东半岛为研究区,基于1985—2017年的Landsat遥感影像数据为数据源,提取了胶东半岛近33年的湖泊面积和数量信息,揭示了胶东半岛湖泊水体面积变化特征及其对气候变化的响应关系。结果显示:1985—2017年,胶东半岛湖泊面积和湖泊数量均呈波动减少趋势,分别减少100.02 km2和79个。[0.01, 0.1) km2等级的湖泊面积表现为波动增加趋势,其他等级的湖泊面积均表现为波动减少趋势,≥10 km2等级的湖泊面积下降最明显。胶东半岛湖泊面积与降水呈正相关,显著水平均在0.05以上;湖泊面积与气温呈负相关,未达显著水平。胶东半岛影响湖泊面积突变的降水量阈值为626.9 mm左右。低于626.9 mm,湖泊面积随降水量减少而急剧下降;高于626.9 mm,湖泊面积随降水量增加而稳定增长。“引黄济青”工程对大型湖泊面积变化具有重要影响,且极大地缓解了烟威地区的旱情,对胶东半岛自然生态环境和社会经济的可持续发展发挥了重要作用。 相似文献
983.
程海湖流域生态环境现状及保护 总被引:1,自引:0,他引:1
由于自然原因和人为影响,程海湖周围生态系统严重退化,湖泊水质污染加重,已进入营养向富营养化趋进的过程。必须从宏观调控、入湖污染物总量控制、水资源管理、水污染控制和陆地生态建设等方面采取相应对策,以控制恶化,改善生态环境。 相似文献
984.
Between 1986 and 2001, thirty-nine lakes in southwestern New Brunswick in Atlantic Canada were surveyed for acid precipitation-related water quality changes. Most of the study lakes are located on granite bedrock and represent the most acid sensitive lakes in the province. Between 1987 and 1992, hydrogen ion deposition to the lake study area averaged 452 eq ha–1 yr–1, compared to 338 eq ha–1 yr–1 between 1993 and 2000, a 25% reduction. The lake chemistry data were evaluated by dividing the lakes into four clusters for each survey year based on their acid neutralizing capacity. Twenty percent of the lakes (cluster IV) had an average ANC of 40 eq L–1or greater and maintained an average pH of greater than 6 over the duration of the study period. A pH of 6 or greater is considered a healthy benchmark for maintaining biodiversity. The remaining 31 lakes (clusters I to III) had an average ANC of less than 40 eq L–1and maintained an average pH of less than 6. Other lake chemistry changes included a general decline in lake sulphate and colour over the duration of the survey period, followed by more recent improvements in calcium ion, pH and ANC, and notably higher but declining aluminum levels in lower ANC and pH lakes. Nitrate accounted for 37% of the acid deposition to the study area, however it was not detectable in the lakes. Although acid deposition has declined and these lakes are beginning to show signs of acid recovery, 80% of the study lakes remain acid sensitive having little buffering capacity with low calcium, pH and ANC. 相似文献
985.
Lars Håkanson 《Environmental Modeling and Assessment》2003,8(4):275-283
This work exemplifies how a given lake (Lake Huljesjön, Sweden) would likely respond to changes in pH-values and to liming (a standard measure against anthropogenic acidification). The basic questions are: How would a liming influence pH? How long would the changes last? How would the changes influence the structure and function of lake ecosystems? The work uses a comprehensive lake ecosystem model, LakeWeb, which accounts for production, biomasses, predation, abiotic/biotic interactions of nine key functional groups of organisms, phytoplankton, bacterioplankton, two types of zooplankton (herbivorous and predatory), two types of fish (prey and predatory), zoobenthos, macrophytes and benthic algae. LakeWeb is a dynamic model and gives weekly variations. It has been critically tested using empirical data and regressions from many lakes. Those tests are not presented here but have shown that the model can capture typical functional and structural patterns in lakes very well. This gives credibility to the results presented in this work, which would be very costly to obtain in the traditional manner by extensive field studies in one or a few lakes. This work presents for the first time predictions at the ecosystem level of how functional groups of organisms (and not individual species) are likely to respond to acidification and liming. Two existing dynamic models, one for liming, the other for Hg-concentrations in fish, have been added to the LakeWeb-model. These two models have previously been tested and proven to yield good predictions. The results presented here indicate that there are several probable changes in the structure and function of the lake foodweb related to acidification and liming. The predicted changes in macrophyte cover will influence the predation pressure on fish, and thereby the fish biomass. Reductions in primary production at low pH-values will cause reductions in fish biomass. There are several interesting compensatory effects between factors that increase fish biomass and factors that tend to decrease the biomass. Such matters can be handled quantitatively by the LakeWeb-model. 相似文献
986.
通过对哈素海1989年度丰、平水期7个样点底栖动物的采集调查,共鉴定出底栖动物34种(属),初步摸清了哈素海丰、平水期不同样点底栖动物群落结构特点及其数量变动情况,并根据调查所获得的生态学资料,分别应用Beck生物指数、Goodnight生物指数、Glcason生物指数及Shannon多样性指数对哈素海水质进行了生物学评价。 相似文献
987.
988.
湖泊底泥环保疏浚是消除内源性污染最快捷、最有效的方法,并为生态恢复创造条件,而环保绞刀是湖泊底泥环保疏浚的必要条件。阐述了环保疏浚的技术要求,设计了绞吸式挖泥船用环保绞刀,满足了湖泊底泥环保疏浚的需要。 相似文献
989.
针对艾比湖所处的特殊地理位置及周边环境状况,对艾比湖流域生态退化问题提出了分区治理措施。将流域分成4大区8个小区,根据不同区域在艾比湖生态链中的作用和各区域的特点,提出相应的禁牧、砾石覆盖、防风林等保护和治理措施。可为艾比湖生态环境恢复提供参考。 相似文献
990.
A major focus of palynological research has been to assess the various pathways by which pollen is delivered to sedimentary
archives. In open lake systems, the contribution of streamborne pollen to lake sediments is thought to be highly significant.
Despite this, little research has attempted to identify changes in the pollen record that might be attributed to changing
sediment pathways rather than to changes in vegetation. This research aims to partially redress this gap by examining a dated
pollen sequence from Kyre Pool, Worcestershire, England. The results presented in this paper suggest that some changes in
sediment source, as determined by a fingerprinting approach, can influence the pollen record reconstructed from a lake sediment
profile. 相似文献