全文获取类型
收费全文 | 1945篇 |
免费 | 293篇 |
国内免费 | 1345篇 |
专业分类
安全科学 | 182篇 |
废物处理 | 57篇 |
环保管理 | 149篇 |
综合类 | 2169篇 |
基础理论 | 396篇 |
污染及防治 | 380篇 |
评价与监测 | 185篇 |
社会与环境 | 47篇 |
灾害及防治 | 18篇 |
出版年
2024年 | 9篇 |
2023年 | 63篇 |
2022年 | 147篇 |
2021年 | 164篇 |
2020年 | 162篇 |
2019年 | 163篇 |
2018年 | 142篇 |
2017年 | 157篇 |
2016年 | 192篇 |
2015年 | 201篇 |
2014年 | 174篇 |
2013年 | 218篇 |
2012年 | 213篇 |
2011年 | 195篇 |
2010年 | 174篇 |
2009年 | 154篇 |
2008年 | 154篇 |
2007年 | 162篇 |
2006年 | 150篇 |
2005年 | 81篇 |
2004年 | 82篇 |
2003年 | 82篇 |
2002年 | 60篇 |
2001年 | 47篇 |
2000年 | 42篇 |
1999年 | 32篇 |
1998年 | 38篇 |
1997年 | 24篇 |
1996年 | 27篇 |
1995年 | 21篇 |
1994年 | 11篇 |
1993年 | 10篇 |
1992年 | 4篇 |
1991年 | 11篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有3583条查询结果,搜索用时 15 毫秒
961.
Mark S. Wipfli John S. Richardson Robert J. Naiman 《Journal of the American Water Resources Association》2007,43(1):72-85
Abstract: Headwater streams make up a large proportion of the total length and watershed area of fluvial networks, and are partially characterized by the large volume of organic matter (large wood, detritus, and dissolved organic matter) and invertebrate inputs from the riparian forest, relative to stream size. Much of those inputs are exported to downstream reaches through time where they potentially subsidize river communities. The relative rates, timing, and conversion processes that carry inputs from small streams to downstream reaches are reasonably well quantified. For example, larger particles are converted to smaller particles, which are more easily exported. Also, dissolved organic matter and surface biofilms are converted to larger particles which can be more easily intercepted by consumers. However, the quality of these materials as it affects biological activity downstream is not well known, nor is the extent to which timing permits biological use of those particles. These ecological unknowns need to be resolved. Further, land uses may disrupt and diminish material transport to downstream reaches by removing sources (e.g., forest harvest), by affecting transport and decomposition processes (e.g., flow regulation, irrigation, changes in biotic communities), and by altering mechanisms of storage within headwaters (e.g., channelization). We present conceptual models of energy and nutrient fluxes that outline small stream processes and pathways important to downstream communities, and we identify informational gaps that, if filled, could significantly advance the understanding of linkages between headwater streams and larger rivers. The models, based on empirical evidence and best professional judgment, suggest that navigable waters are significantly influenced by headwater streams through hydrological and ecological connectivities, and land use can dramatically influence these natural connectivities, impacting downstream riverine ecosystems. 相似文献
962.
某金铜矿山含铜酸性废水处理研究 总被引:1,自引:0,他引:1
采用石灰调pH—铁屑置换—石灰沉淀处理工艺对废水进行试验,结果表明,采用该工艺处理含铜酸性矿山废水,不仅能使处理后的水满足排放标准,同时还能回收废水中的铜。 相似文献
963.
湖泊沉积物中硫的地球化学循环机制研究 总被引:2,自引:0,他引:2
湖泊沉积物中的硫是控制氧化还原体系的重要元素之一。湖泊硫酸盐还原作用主要发生在沉积物表层几厘米范围内,界面硫酸盐还原具有双重环境效应。硫酸盐还原主要形成黄铁矿和有机硫,黄铁矿的生成要受到沉积物中硫酸盐、有机质以及铁氧化物活性的控制。单硫化物不稳定,并且会影响沉积物中重金属的迁移。 相似文献
964.
965.
966.
967.
生活垃圾焚烧厂贮坑沥滤液的污染与可处理特性 总被引:12,自引:4,他引:8
通过对生活垃圾焚烧厂贮坑沥滤液历时6个月的常规污染物监测,分析了沥滤液中溶解性有机物(DOM)分子量分级和重金属在不同分子量DOM中的分布,以探讨沥滤液的污染与可处理特性结果表明:沥滤液有机污染程度高.沥滤液中有机物以非溶解性(约占有机物总量的23%)和分子量<4 ku的DOM(超过DOM总量的88%)为主,低碳有机酸和醇的总量占沥滤液中DOM(分子量<4 ku)的50%.沥滤液中重金属含量高,在DOM各分子量分级中,重金属主要与分子量<4 ku的DOM相关,尤其是Zn和Ni的分布占90%以上,并且重金属(除As和Hg外)的分布与有机物的分布呈显著的正相关性.根据沥滤液的性质,宜采用混凝或厌氧-好氧生物方法对其进行处理. 相似文献
968.
969.
三峡库区填埋场和焚烧厂渗滤液水质季节性差异 总被引:5,自引:3,他引:2
分析了重庆长生桥垃圾填埋场和同兴焚烧厂渗滤液在常规水质和溶解性有机质组成结构方面的季节性差异. 结果表明,填埋场渗滤液在夏季的ρ(CODCr), ρ(TOC), ρ(BOD5),ρ(BOD5)/ρ(CODCr)和ρ(VFA)均高于其他季节,相应指标在冬季最低,但ρ(NH3-N)和 pH的季节性差异不明显. 填埋场渗滤液中DOM组成结构的季节性差异较大,表现在冬季渗滤液中HA所占比例最高,为16.1%,而春、夏季分别为6.6%和8.1%;冬季渗滤液中HyI所占比例最低,为32.7%,其他季节为41.9%~43.5%;ρ(FA)的季节性差异相对较小. 填埋场中ρ(FA)/ρ(HA)的季节性差异较大,夏季较高,冬季较小. 焚烧厂渗滤液的常规水质,DOM的构成及ρ(FA)/ρ(HA)的季节性差异均很小. 相似文献
970.
Biochemical composition and early diagenesis of organic matter in coastal sediments of the NW Adriatic Sea influenced by riverine inputs 总被引:1,自引:0,他引:1
River inputs influence trophodynamic and biogeochemical processes of adjacent continental shelves. In order to provide new insights on the influence of continental inputs on the benthic trophic state and early diagenesis of sediment organic matter we collected surface sediments in the NW Adriatic Sea at three stations located at increasing distance from the Po River. Sediment samples were collected in four periods characterized by different river outflows and analysed for chloropigment content (chlorophyll-a and phaeopygments), protein, carbohydrate and lipid concentrations, prokaryote abundance and aminopeptidase activity. Sediments of the NW Adriatic Sea displayed high organic loads, tightly coupled with the outflow dynamics of the Po River. A major flooding event was responsible of an enhanced accumulation of organic material on the sea bottom. The resulting increased nutrient load in the sediment impaired organic matter degradation processes. The results of the present study suggest that the enhanced trophic state of marine coastal sediments subjected to riverine inputs are related not only to the increased nutrient inputs, but that they may be amplified by impaired degradation processes. 相似文献