全文获取类型
收费全文 | 998篇 |
免费 | 89篇 |
国内免费 | 94篇 |
专业分类
安全科学 | 92篇 |
废物处理 | 17篇 |
环保管理 | 267篇 |
综合类 | 421篇 |
基础理论 | 156篇 |
环境理论 | 1篇 |
污染及防治 | 46篇 |
评价与监测 | 91篇 |
社会与环境 | 70篇 |
灾害及防治 | 20篇 |
出版年
2024年 | 4篇 |
2023年 | 17篇 |
2022年 | 20篇 |
2021年 | 31篇 |
2020年 | 39篇 |
2019年 | 35篇 |
2018年 | 33篇 |
2017年 | 40篇 |
2016年 | 53篇 |
2015年 | 35篇 |
2014年 | 57篇 |
2013年 | 70篇 |
2012年 | 74篇 |
2011年 | 84篇 |
2010年 | 47篇 |
2009年 | 43篇 |
2008年 | 46篇 |
2007年 | 68篇 |
2006年 | 71篇 |
2005年 | 44篇 |
2004年 | 32篇 |
2003年 | 34篇 |
2002年 | 30篇 |
2001年 | 24篇 |
2000年 | 27篇 |
1999年 | 14篇 |
1998年 | 16篇 |
1997年 | 17篇 |
1996年 | 14篇 |
1995年 | 12篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 7篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有1181条查询结果,搜索用时 171 毫秒
131.
在明析盈余管理概念的基础上,分析了盈余管理产生的内在基础及存在的外部条件.指出应正视盈余管理的客观存在及可能的危害,最后通过对盈余管理的规范化,探讨了其相应的措施与对策. 相似文献
132.
Elasmobranch stock assessment studies are usually made through fisheries surveys data. However, in large marine protected
areas (MPAs) the use of destructive techniques must be dismissed in order to avoid population impacts. In 2005, while conducting
a marine habitat survey in two marine Special Areas of Conservation (Sebadales de Playa de Inglés and Franja Marina de Mogán)
in south Gran Canary Island (Canary Islands, Spain) with underwater towed video (UTV) and underwater visual census (UVC) transects,
we recognized the opportunity rose to assess elasmobranch populations through UTV. Number of observed species and specimens,
overall field work effort and total surveyed area were determined and compared between methods. Mean observations per day
per unit of time (MOPUT) and mean observations per day per unit of surveyed area (MOPUA) were also compared through Mann–Whitney
rank sum statistical test (α = 0.05). Data analysis demonstrated that UTV is a very useful tool to rapidly assess elasmobranch
populations in large MPAs in good visibility underwater environments. It can assess larger areas than UVC with the same effort
(statistically significant difference found for the MOPUT; p =< 0.001), leading to more observed species (5 vs 2) and specimens (46 vs 3) per day of work, with no loss in resolution power (MOPUA values were not significantly different between UTV and UVC;
p = 0.104). 相似文献
133.
本文提出了两个治理印染废水的综合物化流程:(1)SE—J型絮凝剂絮凝→气浮→次氯酸钙氧化→炉渣吸附;(2)SE—型絮凝剂絮凝→气浮→活性炭吸附,并对每个处理过程进行了条件实验。实验结果表明:废水经流程(1)处理后,COD去除率达82—87%,色度去除率达88—92%,废水经流程(2)处理后,COD去除率达89—92%,色度去除率达97—98%。经两个流程处理后的出水水质分别接近或达到国家排放标准。 相似文献
134.
Will Simplified Modalities and Procedures Make More Small-Scale Forestry Projects Viable Under the Clean Development Mechanism? 总被引:2,自引:0,他引:2
Bruno Locatelli Lucio Pedroni 《Mitigation and Adaptation Strategies for Global Change》2006,11(3):621-643
Simplified modalities and procedures (M&P) are expected to increase the viability of small-scale project activities under
the Clean Development Mechanism (CDM). A small-scale afforestation or reforestation (AR) project is defined as a project removing
less than 8 kilotons of carbon dioxide equivalent (CO2e) per year. Depending on the project type and the method for measuring scale, 8 kilotons of CO2e per year correspond to highly diverse areas, possibly ranging from 200 to 6000 ha. Using a model to calculate the minimum
project scale above which the CDM is a positive financial incentive for eligible AR project activities, the paper analyzes
whether a reduction of transaction costs under simplified M&P will be a sufficient incentive to motivate small-scale participation
in the CDM. Model results show that, even under optimistic assumptions on carbon market conditions and transaction costs,
small-scale project activities will not benefit from simplified M&P. Results also show that project activities removing more
than 8 kilotons of CO2e per year and registered as small-scale would be the ones that could benefit the most from simplified M&P. It is concluded
that the participation of small-scale project activities to the CDM requires more than simplified M&P, the price of expiring
Certified Emission Reductions being one of the most critical parameters. 相似文献
135.
136.
引入稀释因素后的废水处理效果估算方法讨论 总被引:1,自引:0,他引:1
讨论了经稀释后废水处理时几种常州的污染物去除率及削减量的估算方法,通过实例分析了各估算方法的区别与联系,并提出了在选用估算方法时的注意事项。 相似文献
137.
Testing biodegradability with standardized methods 总被引:11,自引:0,他引:11
Udo Pagga 《Chemosphere》1997,35(12):2953-2972
Laboratory test methods are used by industry laboratories to determine biodegradability, an important parameter for the evaluation of the ecological behaviour of substances. Biodegradability has a key role due to the simple fact that a degradable substance will cause no long term risk in the environment. The great variety of biodegradation processes in the natural environment and in technical plants for treating waste water and solid wastes gave rise to a rather large number of test methods based on different test principles. To guarantee the acceptance of the test results by authorities and customers internationally standardized methods (ISO, OECD) and established quality criteria (GLP, EN 45000, ISO 9000) are used. 相似文献
138.
排污申报登记工作具有数据量大、逻辑性强、专业要求高的特点,环保部门必须力求通过强化数据的审核来获得完整、准确的排污申报数据。 相似文献
139.
土壤环境质量预警体系构建与应用 总被引:3,自引:2,他引:1
土壤环境质量预警是实施土壤污染风险分类分级管控措施的重要依据.为快速了解区域土壤环境质量水平,在土壤环境质量恶化前及时采取有效措施遏制土壤污染持续加重的态势,基于环境容量和污染物输入-输出通量理论分别构建了简易、有效和可量化的农用地和建设用地土壤环境质量预警体系,进一步结合土壤环境质量标准、食品安全标准和致癌风险系数提出相应的预警方法和预警机制,并以攸县农用地和北京市五环内建设用地为研究区域,评价土壤环境质量现状,预测不同情景下的土壤环境质量超标风险.结果表明,攸县网岭和桃水镇两地农用地土壤环境质量均隶属五级预警水平,相对其他修复措施,污染秸秆不还田可在较短时间内将土壤中镉含量降低至风险筛选值水平以下.北京市五环内建成区土壤质量状况良好,较长时间内不存在健康风险隐患,无突变情景和乐观情景下Cd、Cu、Pb和Zn的风险超标年限均远高于50 a,隶属一级预警水平. 相似文献
140.