全文获取类型
收费全文 | 5391篇 |
免费 | 397篇 |
国内免费 | 1986篇 |
专业分类
安全科学 | 117篇 |
废物处理 | 204篇 |
环保管理 | 765篇 |
综合类 | 3632篇 |
基础理论 | 2074篇 |
环境理论 | 3篇 |
污染及防治 | 412篇 |
评价与监测 | 282篇 |
社会与环境 | 175篇 |
灾害及防治 | 110篇 |
出版年
2024年 | 5篇 |
2023年 | 27篇 |
2022年 | 74篇 |
2021年 | 53篇 |
2020年 | 40篇 |
2019年 | 45篇 |
2018年 | 48篇 |
2017年 | 56篇 |
2016年 | 43篇 |
2015年 | 63篇 |
2014年 | 111篇 |
2013年 | 304篇 |
2012年 | 254篇 |
2011年 | 136篇 |
2010年 | 131篇 |
2009年 | 144篇 |
2008年 | 118篇 |
2007年 | 285篇 |
2006年 | 298篇 |
2005年 | 240篇 |
2004年 | 186篇 |
2003年 | 220篇 |
2002年 | 281篇 |
2001年 | 296篇 |
2000年 | 443篇 |
1999年 | 512篇 |
1998年 | 397篇 |
1997年 | 398篇 |
1996年 | 489篇 |
1995年 | 400篇 |
1994年 | 357篇 |
1993年 | 251篇 |
1992年 | 173篇 |
1991年 | 210篇 |
1990年 | 133篇 |
1989年 | 95篇 |
1988年 | 64篇 |
1987年 | 65篇 |
1986年 | 33篇 |
1985年 | 33篇 |
1984年 | 73篇 |
1983年 | 53篇 |
1982年 | 26篇 |
1981年 | 5篇 |
1980年 | 9篇 |
1979年 | 5篇 |
1977年 | 7篇 |
1976年 | 27篇 |
1975年 | 33篇 |
1974年 | 11篇 |
排序方式: 共有7774条查询结果,搜索用时 234 毫秒
501.
In the new European Pesticide Regulation (EC) No. 1107/2009, the harmonisation of approaches for estimation of the environmental exposure of pesticides is considered a major goal. Several member states currently require their own models for the calculation of predicted environmental concentrations (PEC) in surface water. The variety of methods makes risk evaluations rather time-consuming for both notifiers and evaluating authorities. In the present study we compare surface water concentrations of 19 compounds using EU and country-specific models and risk assessment approaches to evaluate to which extent the resulting estimated exposure concentrations differ. Our results show that EU and country specific approaches and the resulting surface water concentrations differ considerably regarding basic model assumptions and assessment methods. The results indicate that the aimed harmonisation of risk assessment approaches within the EU will be difficult based on current models. New scenarios may help to achieve a harmonisation taking country-specific features into account. 相似文献
502.
Reduction of viable airborne Staphylococcus epidermidis and Aspergillus niger spore concentrations using two types of photocatalytic fluorescent lamps under controlled environmental conditions (25 vs. 35 °C and 55 vs. 75% relative humidity) were investigated. Visible white-light and UVA black light were in-house spray-coated with TiO2 and then compared with a commercially coated visible white-light for microbial concentration reduction. The white-light photocatalytic lamps reduced the concentration of culturable S. epidermidis up to 92% independent of temperature or humidity change, while the black light photocatalytic lamps completely inactivated the culturable bacteria at 25 °C, 55% relative humidity. Humidity seemed to alleviate UVA damage since better bacteria survival was found. For A. niger spores, rising humidity or temperature could lower their concentration or drop their culturabilities so that a difference between the natural decay and photocatalytic disinfection could not be distinguished. Reductions of total bacteria and total fungi concentrations using these lamps were also examined under uncontrolled environmental conditions in an office and a waste-storage room. It was found that photocatalytic lamps could reduce total culturable bacteria concentration from 9 to 97% and total culturable fungi concentration from 3 to 95% within irradiation time of 30-480 min, respectively. Insignificant difference in concentration reduction among these photocatalytic lamps was pronounced. 相似文献
503.
The protective effect of hydroxytyrosol (HT), a strong antioxidant compound from extra virgin olive oil, against TCDD induced toxicity was investigated in human peripheral blood mononuclear cells (PBMC). PBMC (1 × 106 cells mL−1) were divided into four groups and were incubated in a CO2 incubator (5% CO2) for 12 h with vehicle, TCDD (10 nM), TCDD + HT (10 nM + 100 μM) and HT alone (100 μM) respectively. To clarify the role of HT against TCDD induced cytotoxicity, oxidative stress and the levels of antioxidant enzymes were assessed. Incubation of PBMC with TCDD significantly decreased cell viability, catalase (CAT) and glutathione peroxidase (GPx) and increased the levels of superoxide dismutase (SOD), glutathione reductase (GR) and oxidative stress markers such as lipid peroxidation products (LPO), protein carbonyl content (PCC) and reactive oxygen species (ROS). Whereas, HT had an effective antioxidant property as observed by the increased cell viability, normalization of antioxidant enzymes and decreased levels of LPO, PCC and ROS in PBMC co-treated with HT and TCDD. Apoptosis detection and comet assay results shows that HT, by acting as an antioxidant, prevents the damage to DNA induced by TCDD. In addition light microscopic and histopathological observations revealed that the cells are apoptotic and degenerated during TCDD treatment, whereas cells showed intact morphology during co-treatment with HT. On the whole, the results reveal that HT exerts a promising antioxidant potential in protecting the PBMC against TCDD induced oxidative stress, which might be due to the presence of catechol moiety in its structure. 相似文献
504.
骆永明 《环境监测管理与技术》2011,23(3):1-6
随着城市化和产业转移进程的加快,我国城镇工业企业搬迁或遗留的污染场地数量与日俱增,亟须开展污染场地治理与修复工作,以保障人居环境安全、国民健康和社会稳定.综述了我国污染场地及其产生、状态和风险,污染场地管理、修复技术及工程实践进展,污染场地管理和修复的主要问题,场地污染防治与修复政策、技术和融资机制需求,旨在推进污染场... 相似文献
505.
浸提分离法提取皂素清洁工艺研究 总被引:2,自引:0,他引:2
提出一种通过溶剂提取将游离皂苷与淀粉、纤维等成分分离,从源头上减少用水量、耗酸量和污染物排放量的皂素清洁生产工艺。首先对溶剂提取条件进行优化,得出最佳工艺条件为:90%(体积比)乙醇溶液,料液比1∶7,沸腾回流提取3 h,重复提取3次。然后通过气质联用(GC/MS)分析了皂素废水的有机物组成。研究结果表明,清洁工艺皂素产率为1.51%(降低3.82%),用酸量比传统工艺减少了71%,头道液COD浓度降低了46%,每100 g原料排放的COD总量下降了84%;皂素废水的有机物污染物主要为糠醛及其衍生物,清洁工艺废水的有机物含量更低,更易降解。 相似文献
506.
花叶芦竹水平潜流人工湿地脱氮性能研究 总被引:2,自引:1,他引:1
采用花叶芦竹水平潜流人工湿地处理生活污水,对其脱氮性能进行研究。结果表明:在HRT=5 d,对TOC,NH+4-N,NO-2-N,NO-3-N和TN的去除效果分别达到92%、93%、84%、51%和88%,相应空白湿地的去除率分别为91%、85%、-232%、-203%和66%。大部分TOC在湿地的前端被去除。花叶芦竹可以直接吸收氮素,向湿地输送氧气,通过根系分泌物提供碳源。因此,花叶芦竹人工湿地具有很好的硝化反硝化能力,实现了良好的脱氮性能。 相似文献
507.
Mosaddeghi MR Mahboubi AA Zandsalimi S Unc A 《Journal of environmental management》2009,90(2):730-739
Organic wastes are considered to be a source for the potentially pathogenic microorganisms found in surface and sub-surface water resources. Following their release from the organic waste matrix, bacteria often infiltrate into soil and may be transported to significant depths contaminating aquifers. We investigated the influence of soil texture and structure and most importantly the organic waste properties on the transport and filtration coefficients of Escherichia coli and total bacteria in undisturbed soil columns. Intact soil columns (diameter 16 cm and height 25 cm) were collected from two soils: sandy clay loam (SCL) and loamy sand (LS) in Hamadan, western Iran. The cores were amended with cow manure, poultry manure and sewage sludge at a rate of 10 Mg ha(-1) (dry basis). The amended soil cores were leached at a steady-state flux of 4.8 cm h(-1) (i.e. 0.12 of saturated hydraulic conductivity of the SCL) to a total volume of up to 4 times the pore volume of the columns. The influent (C(0)) and effluent (C) were sampled at similar time intervals during the experiments and bacterial concentrations were measured by the plate count method. Cumulative numbers of the leached bacteria, filtration coefficient (lambda(f)), and relative adsorption index (S(R)) were calculated. The preferential pathways and stable structure of the SCL facilitated the rapid transport and early appearance of the bacteria in the effluent. The LS filtered more bacteria when compared with the SCL. The effluent contamination of poultry manure-treated columns was greater than the cow manure- and sewage sludge-treated ones. The difference between cow manure and sewage sludge was negligible. The lambda(f) and S(R) values for E. coli and total bacteria were greater in the LS than in the SCL. This indicates a predominant role for the physical pore-obstruction filtration mechanisms as present in the poorly structured LS vs. the retention at adsorptive sites (chemical filtration) more likely in the better structured SCL. While the results confirmed the significant role of soil structure and preferential (macroporous) pathways, manure type was proven to have a major role in determining the maximum penetration risk of bacteria by governing filtration of bacteria. Thus while the numbers of bacteria in waste may be of significance for shallow aquifers, the type of waste may determine the risk for microbial contamination of deep aquifers. 相似文献
508.
六自由度气锤振动与电磁斜面振动是两种模拟产品三轴振动的振动技术。由于两种振动技术的机理不同,其对样品的振动影响也会有区别。本文研究讨论两种不同振动技术的不同特点,以及对不同产品的振动效果别,我们可以根据样品特点和测试需求,选择更合适的震动技术。 相似文献
509.
510.
Biosorption of nickel(II) from aqueous solution by Aspergillus niger: Response surface methodology and isotherm study 总被引:1,自引:0,他引:1
In the present study, the effects of biosorbent Aspergillus niger dosage, initial solution pH and initial Ni(II) concentration on the uptake of Ni(II) by NaOH pretreated biomass of A. niger from aqueous solution were investigated. Batch experiments were carried out in order to model and optimize the biosorption process. The influence of three parameters on the uptake of Ni(II) was described using a response surface methodology (RSM) as well as Langmuir and Freundlich isotherm models. Optimum Ni(II) uptake of 4.82 mg Ni(II) g−1 biomass (70.30%) was achieved at pH 6.25, biomass dosage of 2.98 g L−1 and initial Ni(II) concentration of 30.00 mg L−1 Ni(II). Langmuir and Freundlich were able to describe the biosorption isotherm fairly well. However, prediction of Ni(II) biosorption using Langmuir and Freundlich isotherms was relatively poor in comparison with RSM approaches. The biosorption mechanism was also investigated by using Fourier transfer infrared (FT-IR) analysis of untreated, NaOH pretreated, and Ni(II) loaded A. niger biomass. 相似文献