全文获取类型
收费全文 | 1743篇 |
免费 | 39篇 |
国内免费 | 112篇 |
专业分类
安全科学 | 54篇 |
废物处理 | 19篇 |
环保管理 | 263篇 |
综合类 | 483篇 |
基础理论 | 262篇 |
污染及防治 | 483篇 |
评价与监测 | 247篇 |
社会与环境 | 66篇 |
灾害及防治 | 17篇 |
出版年
2024年 | 3篇 |
2023年 | 13篇 |
2022年 | 18篇 |
2021年 | 28篇 |
2020年 | 54篇 |
2019年 | 23篇 |
2018年 | 43篇 |
2017年 | 34篇 |
2016年 | 45篇 |
2015年 | 55篇 |
2014年 | 52篇 |
2013年 | 113篇 |
2012年 | 90篇 |
2011年 | 186篇 |
2010年 | 112篇 |
2009年 | 188篇 |
2008年 | 167篇 |
2007年 | 139篇 |
2006年 | 83篇 |
2005年 | 55篇 |
2004年 | 40篇 |
2003年 | 55篇 |
2002年 | 38篇 |
2001年 | 26篇 |
2000年 | 40篇 |
1999年 | 24篇 |
1998年 | 19篇 |
1997年 | 17篇 |
1996年 | 20篇 |
1995年 | 12篇 |
1994年 | 15篇 |
1993年 | 28篇 |
1992年 | 20篇 |
1991年 | 3篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 6篇 |
1985年 | 2篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有1894条查询结果,搜索用时 140 毫秒
501.
全自动淋洗-智能蒸馏联合技术检测土壤中阳离子交换量 总被引:3,自引:0,他引:3
针对土壤中阳离子交换量检测国标方法的不足,介绍了一种全自动淋洗法结合自动智能一体化蒸馏的联合技术。通过对实际样品和6种土壤标样的比较实验,表明,淋洗时间设置为20 min、乙醇洗涤次数设置为4次、蒸馏液质量设置为130 g较佳,在该条件下,土壤标样及实际样品的相对标准偏差(0.87%~1.07%)远小于行业标准方法的标准偏差(3.87%~5.18%),方法准确度也均在保证值范围内。该方法自动化程度高、可操作性强且检测结果的准确度、精密度及重现性都符合标准规定,可满足大批量土壤样品分析要求。 相似文献
502.
Development and Testing of a Physically Based Model of Streambank Erosion for Coupling with a Basin‐Scale Hydrologic Model SWAT 下载免费PDF全文
B. Narasimhan P.M. Allen S.V. Coffman J.G. Arnold R. Srinivasan 《Journal of the American Water Resources Association》2017,53(2):344-364
A comprehensive streambank erosion model based on excess shear stress has been developed and incorporated in the hydrological model Soil and Water Assessment Tool (SWAT). It takes into account processes such as weathering, vegetative cover, and channel meanders to adjust critical and effective stresses while estimating bank erosion. The streambank erosion model was tested for performance in the Cedar Creek watershed in north‐central Texas where streambank erosion rates are high. A Rapid Geomorphic field assessment (RAP‐M) of the Cedar Creek watershed was done adopting techniques developed by the Natural Resources Conservation Service (NRCS), and the stream segments were categorized into various severity classes. Based on the RAP‐M field assessment, erosion pin sites were established at seven locations within the severely eroding streambanks of the watershed. A Monte Carlo simulation was carried out to assess the sensitivity of different parameters that control streambank erosion such as critical shear stress, erodibility, weathering depth, and weathering duration. The sensitive parameters were adjusted and the model was calibrated based on the bank erosion severity category identified by the RAP‐M field assessment. The average observed erosion rates were in the range 25‐367 mm year?1. The SWAT model was able to reasonably predict the bank erosion rates within the range of variability observed in the field (R2 = 0.90; E = 0.78). Editor's note : This paper is part of the featured series on SWAT Applications for Emerging Hydrologic and Water Quality Challenges. See the February 2017 issue for the introduction and background to the series. 相似文献
503.
An Open Source GIS‐Based Decision Support System for Watershed Evaluation of Best Management Practices 下载免费PDF全文
Hui Shao Wanhong Yang John Lindsay Yongbo Liu Zhiqiang Yu Anatoliy Oginskyy 《Journal of the American Water Resources Association》2017,53(3):521-531
Economic costs, water quantity/quality benefits, and cost effectiveness of agricultural best management practices (BMPs) at a watershed scale are increasingly examined using integrated economic‐hydrologic models. However, these models are typically complex and not user‐friendly for examining the effects of various BMP scenarios. In this study, an open source geographic information system (GIS)‐based decision support system (DSS), named the watershed evaluation of BMPs (WEBs), was developed for creating BMP scenarios and simulating economic costs and water quantity/quality benefits at farm field, subbasin, and watershed scales. This DSS or WEBs interface integrated a farm economic model, the Soil and Water Assessment Tool (SWAT), and an optimization model within Whitebox Geospatial Analysis Tools (GAT), an open source GIS software. The DSS was applied to the 14.3‐km2 Gully Creek watershed, a coastal watershed in southern Ontario, Canada that drains directly into Lake Huron. BMPs that were evaluated included conservation tillage, nutrient management, cover crop, and water and sediment control basins. In addition to assessing economic costs, water quantity/quality benefits, and cost effectiveness of BMPs, the DSS can be also used to examine prioritized BMP types/locations and corresponding economic and water quantity/quality tradeoffs in the study watershed based on environmental targets or budget constraints. Further developments of the DSS including interface transfer to other watersheds are also discussed. Editor's note : This paper is part of the featured series on SWAT Applications for Emerging Hydrologic and Water Quality Challenges. See the February 2017 issue for the introduction and background to the series. 相似文献
504.
通用土壤流失方程式是世界上应用最广泛的估测土壤侵蚀量的公式,在我国建设项目水土流失的环境影响评价中也有重要的应用价值。本文根据方程式各因子的物理意义和工程施工的特点,具体说明了各因子在环境评价中的取值方法及方程式的应用范围。 相似文献
505.
酸性红壤上添加石灰显著增加土壤对镉的吸附量并降低吸附态镉的解吸量。但石灰用量较低时,镉的解吸率反而比未施石灰时增加。盆栽试验亦表明,在石灰用量较低时,土壤pH虽有所升高,但小麦和黑麦草植株镉含量降低不明显甚至有所升高;只有较高的石灰用量使土壤pH得以明显升高,植株吸镉量才能明显降低。对这一现象的原因进行了讨论。 相似文献
506.
J. Bierkens G. Klein P. Corbisier R. Van Den Heuvel L. Verschaeve R. Weltens G. Schoeters 《Chemosphere》1998,37(14-15)
Increasing evidence suggests that the use of a single bioassay will never provide a full picture of the quality of the environment. Only a test battery, composed of bioassays of different animal and plant species from different trophic levels will reduce uncertainty, allowing an accurate assessment of the quality of the environment. In the present study, a test battery composed of 20 bioassays of varying biological endpoints has been compared Apart from lethality and reproductive failure in earthworms, springtails, nematoda, algae and vascular plants, these endpoints also included bioavailibility of metals (bacteria), heat-shock induction (nematodes, algae), DNA damage (bacteria, earthworm, vascular plants), β-galactosidase (Daphnia) and esterase activity (algae) and a range of immunological parameters (earthworm). Four chemicals (cadmium, phenol, pentachlorophenol and triflurahn) — each representing a different toxic mode of action — were applied in a dilution series (from 1 mg/kg up to 1000 mg/kg) onto OECD standard soil. The tests have been performed both on these artificially contaminated soil samples and on aqueous extracts subsequently obtained from these soils. The results show that the immunological parameters and the loss of weight in the earthworms were among the most sensitive solid phase assays. Esterase inhibition and heat-shock induction in algae were shown to be extremely sensitive when applied to soil extracts. As previously shown at the species level, no single biological endpoint was shown to be the most sensitive for all four modes of toxic action. 相似文献
507.
508.
509.
The thawing and subsequent decomposition of large stocks of soil organic carbon (SOC) currently stored in the northern circumpolar permafrost region are projected to result in a ‘positive’ feedback on global warming. The magnitude of this feedback can only be assessed with improved knowledge about the total size and geographic distribution of the permafrost SOC pool. This study investigates SOC storage in an under-sampled mountain permafrost area in the Russian High Altai. SOC stocks from 39 soil pits are upscaled using a GIS-based land cover classification. We found that the top 100 cm of soils in Aktru Valley and the adjacent Kuray Basin only holds on average 2.6 ± 0.6 kg C m−2 (95% confidence interval), of which only c. 1% is stored in permafrost. Global warming will result in an upward shift of alpine life zones, with new plant cover and soil development at higher elevations. As a result, this type of mountain permafrost area might act as a net C sink in the future, representing a ‘negative’ feedback on global warming.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01433-6) contains supplementary material, which is available to authorized users. 相似文献
510.
Moving Beyond Strawmen and Artificial Dichotomies: Adaptive Management When an Endangered Species Uses an Invasive One 总被引:1,自引:1,他引:0
Daniel Simberloff 《Journal of Agricultural and Environmental Ethics》2009,22(1):73-80
Evans et al. (Journal of Agricultural and Environmental Ethics, 2008) have attempted to enmesh me in their dispute with the Florida Bureau of Invasive Plant Management about a specific
system, Kings Bay/Crystal River. In so doing, they repeatedly mischaracterize my positions in order to depict, incorrectly,
invasion biology as monolithic and me as a representative of one extreme of a false dichotomy about management of introduced
species. In addition, they introduce an issue irrelevant in this case (extinctions) and cite incorrect data. Proposing to
manage people, manatees, introduced plants, and cyanobacteria in Kings Bay by participative adaptive management, they ignore
the fact that living organisms can both disperse autonomously and hitchhike. Finally, they present few details on any aspect
of their management proposal and do not address the myriad problems that have beset previous attempts at scientific adaptive
management, especially at large scales. Until such a management approach is fleshed out and implemented, it is impossible
to assess its validity for Kings Bay, and it is very premature to suggest it as a general model for dealing with invasive
species disputes. 相似文献