全文获取类型
收费全文 | 8267篇 |
免费 | 673篇 |
国内免费 | 2926篇 |
专业分类
安全科学 | 514篇 |
废物处理 | 979篇 |
环保管理 | 910篇 |
综合类 | 6136篇 |
基础理论 | 1097篇 |
环境理论 | 1篇 |
污染及防治 | 1848篇 |
评价与监测 | 266篇 |
社会与环境 | 99篇 |
灾害及防治 | 16篇 |
出版年
2024年 | 5篇 |
2023年 | 45篇 |
2022年 | 112篇 |
2021年 | 139篇 |
2020年 | 179篇 |
2019年 | 173篇 |
2018年 | 185篇 |
2017年 | 223篇 |
2016年 | 284篇 |
2015年 | 375篇 |
2014年 | 559篇 |
2013年 | 613篇 |
2012年 | 777篇 |
2011年 | 775篇 |
2010年 | 648篇 |
2009年 | 629篇 |
2008年 | 479篇 |
2007年 | 799篇 |
2006年 | 871篇 |
2005年 | 638篇 |
2004年 | 503篇 |
2003年 | 528篇 |
2002年 | 461篇 |
2001年 | 368篇 |
2000年 | 305篇 |
1999年 | 266篇 |
1998年 | 197篇 |
1997年 | 153篇 |
1996年 | 133篇 |
1995年 | 122篇 |
1994年 | 80篇 |
1993年 | 81篇 |
1992年 | 48篇 |
1991年 | 26篇 |
1990年 | 32篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 2篇 |
1986年 | 6篇 |
1984年 | 5篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1971年 | 4篇 |
1970年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
991.
992.
993.
994.
995.
996.
研究了用Fenton试剂处理选矿废水中残余的黄药,分别考查了氧化时间、反应初始pH值、Fe2+浓度及H2O2用量对黄药降解效果的影响,用正交试验确定了4个因素的最好条件。结果表明:初始pH值和H2O2用量是影响去除效果的主要因素;氧化时间为60 m in,反应初始pH=4,[Fe2+]=20 mg/L,[H2O2]=20 mg/L,黄药的浓度为125 mg/L时,黄药的去除率达到99.5%;初步探讨了Fenton试剂净化废水中黄药的机理是.OH自由基先将黄药氧化为过氧化黄原酸盐,再将其氧化为CO2,黄药得到去除。 相似文献
997.
碳氮磷比例失调城市污水的同步脱氮除磷 总被引:1,自引:0,他引:1
为解决现行同步脱氮除磷工艺处理南方地区碳、氮、磷比例失调城市污水中,因C/N、C/P偏低,碳源不足而降低脱氮除磷效率的难题,试验以碳源偏低的广州市城市污水为研究对象,采用厌氧/好氧交替运行的SBR系统,通过对厌氧、好氧时段的合理调控,在无需额外添加碳源的条件下,有机物、氨氮、总氮和总磷的平均去除率分别可达90%、72%、41%和99%,不仅能使有机物和氮的出水指标达到国家排放标准,而且总磷出水浓度能达0.5 mg/L以下。通过进一步分析同步高效脱氮除磷的影响因素和控制条件,得出合理污泥龄的控制是实现同步脱氮除磷的关键,厌氧/好氧交替运行的方式不仅强化了磷的释放和吸收,而且降低了碳源偏低和硝酸盐对同步脱氮除磷影响的结论。 相似文献
998.
介绍了氧化铁黄生产中的废水治理情况,同时其产生的废渣可回收利用。经过治理产生的环境、经济和社会效益显著。 相似文献
999.
The Influence of Mycorrhiza on Uranium and Phosphorus Uptake by Barley Plants from a Field-contaminated Soil (7 pp) 总被引:3,自引:0,他引:3
Chen B Zhu YG Zhang X Jakobsen I 《Environmental science and pollution research international》2005,12(6):325-331
Background Recent studies indicated that arbuscular mycorrhizal fungi (AMF) play important roles in plant accumulation of uranium (U)
from contaminated environments, but the impacts of fertilization practices on functioning of the symbiotic associations, which
are crucial factors influencing plant nutrition and growth responses to mycorrhiza, have rarely been considered.
Materials and Methods In a greenhouse experiment, a bald root barley mutant (brb) together with the wild type (wt) were used to test the role of
root hairs and AMF in uranium (U) uptake by host plants from a U contaminated soil. Nil, 20 and 60 mg KH2PO4-P kg–1 soil were
included to investigate the influences of phosphorus (P) fertilization on plant growth and accumulation of U.
Results Dry matter yield of barley plants increased with increasing P additions and wt produced significantly higher dry weight than
brb. Mycorrhiza markedly improved dry matter yield of both genotypes grown at nil P, whereas only brb responded positively
to mycorrhiza at 20 mg P kg-1. At the highest P level, mycorrhiza resulted in growth depressions in both genotypes, except
for the roots of wt. In general, plant P concentrations increased markedly with increasing P additions and in response to
mycorrhiza.
Mycorrhiza and P additions had no significant effects on shoot U concentrations. However, root U concentrations in both genotypes
were significantly increased by mycorrhiza. On the other hand, shoot U contents increased with increasing P levels, while
20 mg P kg-1 stimulated, but 60 mg P kg-1 marginally affected the U accumulation in roots. Root length specific U uptake was
moderately enhanced both by root hairs and strongly enhanced by mycorrhiza. Moreover, non-inoculated plants generally had
higher shoot-root ratios of U content than the corresponding inoculated controls.
Conclusion Our study shows that AMF and root hairs improves not only P acquisition but also the root uptake of U, and mycorrhiza generally
decreases U translocation from plant root to shoot. Hence, mycorrhiza is of potential use in the phytostabilization of U contaminated
environments.
Perspectives The complex impacts of P on U accumulation by barley plants suggested that U behavior in mycorrhizosphere and translocation
along the soil-fungi-plant continuum as affected by fertilization practices deserve extensive studies for optimizing the function
of mycorrhizal associations for phytoremediation purposes. 相似文献
1000.
Background Worldwide, large amounts of sediments have to be dredged annually from waterways and harbours. These sediments are sometimes
polluted with a variety of toxic compounds. In some countries, including Belgium, the load with the biocide tributyltin (TBT)
from ship coatings prohibits the dumping of harbour sludge into the sea. Land-based dumping is a commonly used alternative.
Objective This research investigated the feasibility to use land-deposited harbour sludge for plant production. In a field trial, the
growth of 38 more or less salt-tolerant plant species on low and high TBT-contaminated sediments was studied. The elimination
of TBT from sludge with and without vegetation was compared. The uptake of TBT and its degradation products di- and monobutyltin
(DBT and MBT) into harvest products under field conditions was determined.
- Experimental Set-up. Sediments dredged in May 2003 from the brackish waters of the port of Antwerp were analysed in the laboratory
for soil texture, pH, electroconductivity, sodium, magnesium, potassium, calcium, ammonium, nitrate, total nitrogen, chloride,
sulphur and the organotins TBT, DBT and MBT. The sediments were lagooned for one year to dewater, desalinate and improve their
structure. Salt-tolerant domestic and wild plants were selected and sown in May 2004. In August 2004, plants were harvested
and the produced biomass was determined. Samples were taken from vegetated and non-vegetated top and bottom sediments and
from plants growing above soil and analysed for TBT, DBT and MBT.
Results The fresh sediments showed a good supply with nutrients and a neutral pH, but were rather saline (EC 14 mS cm-1 of the saturated
paste extract). The salinity decreased to 3.7 mS cm-1 during lagoonation. The high and the low contaminated sediment had initially
43 and 1.6 mg TBT kg-1 dry weight, respectively. Besides TBT, several other contaminants were present in the sediments at
critical levels. The biomass production of the plant species from the field trial ranged from 0.2 to 13 tons dry mass per
hectare. Plants performing excellently were barley, sorghum, rape seed, a clover/grass mix and reed. If at all, a positive
influence of TBT on plant growth was seen. TBT was degraded significantly faster (>40%) below barley. The uptake of TBT, DBT
and MBT into stem and leaves of reed, grass and clover was very low, but measurable and not related to concentrations in soil.
No uptake of TBT or its metabolites into corn of barley was found.
Discussion This study confirmed former results: the toxicity of TBT to higher plants is low, and even high levels in soils would not
be a hindrance for crop production. The removal of TBT seemed to be increased by both lagooning and plant growth, although
the target values for sea dumping in use in certain European countries were not reached. A plausible explanation for the faster
degradation of TBT under vegetation is that oxygen is a limiting factor, and plants dewater the soil, thus aerating it. The
uptake of the organotins TBT, DBT and MBT into harvest products is probably due to attached soil particles.
Conclusions To summarize, barley was the optimal species: it grew very well despite the salinity of the dredged sediments, it had a significantly
positive effect on TBT removal; it showed no measurable uptake of TBT or the other butyltins into the harvested product; and
it is a cash crop well established in European agriculture.
Outlook The amounts of dredged sediments are high, and good soils are becoming increasingly rare. The feasibility of using dredged
sediments for non-food production, such as energy crops, should be investigated by a critical risk assessment. 相似文献