全文获取类型
收费全文 | 16445篇 |
免费 | 174篇 |
国内免费 | 137篇 |
专业分类
安全科学 | 449篇 |
废物处理 | 627篇 |
环保管理 | 2287篇 |
综合类 | 2619篇 |
基础理论 | 4484篇 |
环境理论 | 5篇 |
污染及防治 | 4317篇 |
评价与监测 | 1009篇 |
社会与环境 | 856篇 |
灾害及防治 | 103篇 |
出版年
2022年 | 111篇 |
2021年 | 129篇 |
2020年 | 105篇 |
2019年 | 149篇 |
2018年 | 224篇 |
2017年 | 222篇 |
2016年 | 354篇 |
2015年 | 242篇 |
2014年 | 359篇 |
2013年 | 1266篇 |
2012年 | 445篇 |
2011年 | 635篇 |
2010年 | 539篇 |
2009年 | 523篇 |
2008年 | 701篇 |
2007年 | 696篇 |
2006年 | 659篇 |
2005年 | 508篇 |
2004年 | 588篇 |
2003年 | 522篇 |
2002年 | 485篇 |
2001年 | 706篇 |
2000年 | 471篇 |
1999年 | 287篇 |
1998年 | 241篇 |
1997年 | 217篇 |
1996年 | 229篇 |
1995年 | 249篇 |
1994年 | 271篇 |
1993年 | 221篇 |
1992年 | 248篇 |
1991年 | 222篇 |
1990年 | 255篇 |
1989年 | 238篇 |
1988年 | 193篇 |
1987年 | 173篇 |
1986年 | 158篇 |
1985年 | 168篇 |
1984年 | 193篇 |
1983年 | 180篇 |
1982年 | 186篇 |
1981年 | 180篇 |
1980年 | 138篇 |
1979年 | 153篇 |
1978年 | 131篇 |
1977年 | 118篇 |
1975年 | 118篇 |
1974年 | 115篇 |
1973年 | 110篇 |
1972年 | 133篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
995.
996.
997.
998.
999.
May TW Fairchild JF Petty JD Walther MJ Lucero J Delvaux M Manring J Armbruster M 《Environmental monitoring and assessment》2008,137(1-3):213-232
The Solomon River Basin is located in north-central Kansas in an area underlain by marine geologic shales. Selenium is an
indigenous constituent of these shales and is readily leached into the surrounding groundwater. Portions of the Basin are
irrigated primarily through the pumping of selenium-contaminated groundwater from wells onto fields in agricultural production.
Water, sediment, macroinvertebrates, and fish were collected from various sites in the Basin in 1998 and analyzed for selenium.
Selenium concentrations were analyzed spatially and temporally and compared to reported selenium toxic effect thresholds for
specific ecosystem components: water, sediments, food-chain organisms, and wholebody fish. A selenium aquatic hazard assessment
for the Basin was determined based on protocol established by Lemly. Throughout the Basin, water, macroinvertebrate, and whole
fish samples exceeded levels suspected of causing reproductive impairment in fish. Population structures of several fish species
implied that successful reproduction was occurring; however, the influence of immigration of fish from low-selenium habitats
could not be discounted. Site-specific fish reproduction studies are needed to determine the true impact of selenium on fishery
resources in the Basin.
The U.S. Government’s right to retain a non-exclusive, royalty free license in and to any copyright is acknowledged. 相似文献
1000.
V. A. Romanenkov J. U. Smith P. Smith O. D. Sirotenko D. I. Rukhovitch I. A. Romanenko 《Regional Environmental Change》2007,7(2):93-104
The Model of Humus Balance was used to estimate the influence of climate effects and changing agricultural practices on carbon
(C) levels in soddy–podzolic soils in the Russian Federation for the years 2000–2050. The model was linked with a spatial
database containing soil, climate and farming management layers for identification of spatial change of C sequestration potential.
Analysis of relationships between C, soil texture and climate indicated that compared with a business-as-usual scenario, adaptation
measures could increase the number of polygons storing soil organic carbon (SOC) by 2010–2020. The rate of possible C loss
is sensitive to the different climate scenarios, with a maximum potential for SOC accumulation expected in 2030–2040, thereafter
decreasing to 2050. The effect is most pronounced for the arid part of the study area under the emission scenario with the
highest rate of increase in atmospheric CO2 concentration, supporting findings from the dynamic SOC model, RothC. C sequestration during the study period was permanent
for clay and clay loam soils with a C content of more than 2%, suggesting that C sequestration should be focused on highly
fertile, fine-textured soils. We also show that spatial heterogeneity of soil texture can be a source of uncertainty for estimates
of SOC dynamics at the regional scale.
Figures in color are available at 相似文献