全文获取类型
收费全文 | 6356篇 |
免费 | 416篇 |
国内免费 | 1175篇 |
专业分类
安全科学 | 412篇 |
废物处理 | 341篇 |
环保管理 | 572篇 |
综合类 | 2585篇 |
基础理论 | 1230篇 |
环境理论 | 3篇 |
污染及防治 | 1724篇 |
评价与监测 | 492篇 |
社会与环境 | 413篇 |
灾害及防治 | 175篇 |
出版年
2024年 | 11篇 |
2023年 | 92篇 |
2022年 | 260篇 |
2021年 | 242篇 |
2020年 | 232篇 |
2019年 | 168篇 |
2018年 | 275篇 |
2017年 | 224篇 |
2016年 | 221篇 |
2015年 | 261篇 |
2014年 | 351篇 |
2013年 | 560篇 |
2012年 | 342篇 |
2011年 | 397篇 |
2010年 | 353篇 |
2009年 | 355篇 |
2008年 | 384篇 |
2007年 | 382篇 |
2006年 | 297篇 |
2005年 | 246篇 |
2004年 | 263篇 |
2003年 | 263篇 |
2002年 | 223篇 |
2001年 | 310篇 |
2000年 | 243篇 |
1999年 | 131篇 |
1998年 | 78篇 |
1997年 | 85篇 |
1996年 | 61篇 |
1995年 | 67篇 |
1994年 | 56篇 |
1993年 | 56篇 |
1992年 | 54篇 |
1991年 | 40篇 |
1990年 | 36篇 |
1989年 | 34篇 |
1988年 | 22篇 |
1987年 | 18篇 |
1986年 | 18篇 |
1985年 | 15篇 |
1984年 | 19篇 |
1983年 | 23篇 |
1982年 | 24篇 |
1981年 | 16篇 |
1980年 | 11篇 |
1979年 | 14篇 |
1978年 | 12篇 |
1975年 | 12篇 |
1973年 | 9篇 |
1972年 | 10篇 |
排序方式: 共有7947条查询结果,搜索用时 78 毫秒
41.
42.
43.
自然资源资产评估技术是开展自然资源资产负债表实践和实行环境责任离任审计的重要技术支撑。水资源作为一项重要自然资源,如何有效评估水资源资产是不可回避的问题。论文以深圳市为研究区域,一是采用综合污染指数法和主成分分析法,以总氮、氨氮、总磷、化学需氧量、生化需氧量、固体悬浮物为指标参数构建了深圳市综合水质指数以评价水资源综合水质。二是以该综合水质评估模型为基础,通过采用治污成本法分析综合水质与治污成本间的关系,从而构建深圳市景观水和饮用水资源的价值量评估模型。论文还以深圳市大鹏新区为试点开展了水资源价值量评估,评估结果显示,2015年大鹏新区景观水和饮用水资源的价值量分别为3.60亿、0.35亿元。 相似文献
45.
Qingru Wu Shuxiao Wang Mei Yang Haitao Su Guoliang Li Yi Tang Jiming Hao 《环境科学学报(英文版)》2018,30(6):91-99
Large-scale gold production(LSGP) is one of the five convention-related atmospheric mercury(Hg) emission sources in the Minamata Convention on Mercury. However, field experiments on Hg flows of the whole process of LSGP are limited. To identify the atmospheric Hg emission points and understand Hg emission characteristics of LSGP, Hg flows in two gold smelters were studied. Overall atmospheric Hg emissions accounted for 10%–17% of total Hg outputs and the Hg emission factors for all processes were 7.6–9.6 kg/ton. There were three dominant atmospheric Hg emission points in the studied gold smelters, including the exhaust gas of the roasting process, exhaust gas from the environmental fog collection stack and exhaust gas from the converter of the refining process. Atmospheric Hg emissions from the roasting process only accounted for 16%–29% of total emissions and the rest were emitted from the refining process. The overall Hg speciation profile(gaseous elemental Hg/gaseous oxidized Hg/particulate-bound Hg) for LSGP was 34.1/57.1/8.8. The dominant Hg output byproducts included waste acid, sulfuric acid and cyanide leaching residue. Total Hg outputs from these three byproducts were 80% in smelter A and 84% in smelter B. Our study indicated that previous atmospheric Hg emissions from large-scale gold production might have been overestimated.Hg emission control in LSGP is not especially urgent in China compared to other significant emission sources(e.g., cement plants). Instead, LSGP is a potential Hg release source due to the high Hg output proportions to acid and sludge. 相似文献
46.
针对油气田集输管道的内腐蚀问题,分别介绍了耐蚀材料、衬里技术、涂镀层技术与药剂防腐技术等管道内防腐技术及其现场应用效果,指出了耐蚀金属材料防腐效果显著,但存在经济效益差的缺点。为降低成本,选用双金属复合管替代耐蚀金属材料,但其焊缝位置腐蚀失效频发,成为制约其应用的薄弱环节。耐蚀非金属材料防腐效果显著,但耐高温性能与力学性能较差,受温度、压力与CO_2、H_2S、固体颗粒等介质成分的影响,衬里技术与涂镀层技术的应用范围受到限制。药剂防腐技术的防护效果与药剂类型、加药工艺密切相关,需要根据腐蚀工况监测结果进行实时调整。针对上述内防腐技术存在的问题,提出了未来内防腐技术的发展方向为改进现有内防腐技术存在的不足,提升其防护效果。同时,应开发防腐效果显著、经济成本低、施工简便、易于推广应用的防腐材料与防腐工艺技术。 相似文献
47.
48.
Hiraoka Y 《Environmental pollution (Barking, Essex : 1987)》1991,70(3):209-217
Cultured oysters from Hiroshima Bay were analysed to determine the content of nine trace elements, cadmium (Cd), lead (Pb), chromium (Cr), arsenic (As), manganese (Mn), nickel (Ni), copper (Cu), zinc (Zn), and iron (Fe) and compared with oysters treated for 48 h in both artificial sea water and a solution of 0.5% ethylenediaminetetraacetic acid (EDTA) in artificial sea water. It was found that the values of As and Fe in both groups of treated oysters were significantly lower than in the untreated oysters and that the Pb and Mn levels tended to be lower. It was also found that oysters treated in 0.5% EDTA solution in artificial sea water had lower levels of Cd and Cu than the oysters treated only in artificial sea water. 相似文献
49.
Particulate matter suspended in the air has adverse effects onhuman health. Its level of concentration is an important parameter in evaluating the degree of hazard it poses to the atmosphere. Conventional methods used in measuring particulatematter are often filter-based, which indicates some disadvantagesbecause such a base requires labor and time. In this study, to achieve real-time measurements, a new electrical method was developed for measuring PM10 and PM2.5 concentrations. The basicprinciple is to electrically charge particles passing through thePM inlet using a corona charger and measure the currents createdby charged particles to obtain the number concentration of particulate matter. A new type inlet based on the particle cupimpactor configuration was designed and its performance was evaluated. A unipolar diffusion charger was developed and thecharger's efficiency was determined experimentally in terms ofPn, which represents the penetration through the charger,P, times the average charge number acquired by a particle,n, for different particle sizes. The correlation was constructed between the PM10 (or the PM2.5) mass concentrationsand the electrical currents due to particles, which were chargedby the diffusion charger. 相似文献
50.
Analysis of pollutant levels in central Hong Kong applying neural network method with particle swarm optimization 总被引:6,自引:0,他引:6
Air pollution has emerged as an imminent issue in modernsociety. Prediction of pollutant levels is an importantresearch topic in atmospheric environment today. For fulfillingsuch prediction, the use of neural network (NN), and inparticular the multi-layer perceptrons, has presented to be acost-effective technique superior to traditional statisticalmethods. But their training, usually with back-propagation (BP)algorithm or other gradient algorithms, is often with certaindrawbacks, such as: 1) very slow convergence, and 2) easilygetting stuck in a local minimum. In this paper, a newlydeveloped method, particle swarm optimization (PSO) model, isadopted to train perceptrons, to predict pollutant levels, andas a result, a PSO-based neural network approach is presented. The approach is demonstrated to be feasible and effective bypredicting some real air-quality problems. 相似文献