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301.
302.
Helmut W. Fischer Susanne Ulbrich Daniela Pittauerov Bernd Hettwig 《Journal of environmental radioactivity》2009,100(12):1079-1085
Motivated by the detection of 131I in river sediment in routine long-term surveillance samples, a systematic short-term study of the wastewater treatment chain was planned and conducted. Inflow, effluent and primary sludge were collected on a daily basis during two weeks at a regional wastewater treatment plant. Samples were investigated by gamma spectroscopy. Four medically used isotopes could be identified (131I and 99mTc regularly, 153Sm and 123I sporadically). The concentration levels coincide well with literature data for 131I, and with our own long-term data for 131I and 99mTc for the same plant. Cosmogenic 7Be activity in primary sludge correlated well with rainfall intensity. Surface sediment was sampled at low tide at both shores of the river, up- and downstream of the plant. 131I was identified in all samples, with a sharp maximum (about 100 Bq kg−1 d.m.) at the discharge point of the plant and lower levels elsewhere, decreasing monotonically in downstream direction. 7Be and 137Cs showed the same behaviour, but no peak at the discharge point. Predictions from simple equilibrium models for the transport and sedimentation of 131I show good agreement with the experimental data and suggest that the wastewater treatment plant is the main source for this isotope. 相似文献
303.
Bidar G Pruvot C Garçon G Verdin A Shirali P Douay F 《Environmental science and pollution research international》2009,16(1):42-53
Background, aim, and scope The reclamation of nonferrous metal-polluted soil by phytoremediation requires an overall and permanent plant cover. To select
the most suitable plant species, it is necessary to study metal effects on plants over the time, thereby checking that metals
remain stored in root systems and not transferred to aerial parts. In this purpose, the seasonal and annual variations of
metal bioaccumulation, transfer, and phytotoxicity in Trifolium repens and Lolium perenne grown in a Cd-, Pb-, and Zn-contaminated soil were also studied.
Materials and methods The experimental site was located near a closed smelter. In spring 2004, two areas were sown with T. repens and L. perenne, respectively. Thereafter, the samplings of plant roots and shoots and surrounding soils were realized in autumn 2004 and
spring and autumn 2005. The soil agronomic characteristics, the Cd, Pb, and Zn concentrations in the surrounded soils and
plant organs, as well as the oxidative alterations (superoxide dismutase [SOD], malondialdehyde [MDA], and 8-hydroxy-2′-deoxyguanosine
[8-OHdG]) in plant organs were carried out.
Results Whatever the sampling period, metal concentrations in soils and plants were higher than background values. Contrary to the
soils, the fluctuations of metal concentrations were observed in plant organs over the time. Bioaccumulation and transfer
factors confirmed that metals were preferentially accumulated in the roots as follows: Cd>Zn>Pb, and their transfer to shoots
was limited. Foliar metal deposition was also observed. The results showed that there were seasonal and annual variations
of metal accumulation in the two studied plant species. These variations differed according to the organs and followed nearly
the same pattern for the two species. Oxidative alterations were observed in plant organs with regard to SOD antioxidant activities,
MDA, and 8-OHdG concentrations. These alterations vary according to the temporal variations of metal concentrations.
Discussion Metal concentrations in surrounded soils and plant organs showed the effective contamination by industrial dust emissions.
Metals absorbed by plants were mainly stored in the roots. With regard to this storage, the plants seemed to limit the metal
transfer to their aerial parts over the time, thereby indicating their availability for metal phytostabilization. Aerial deposition
was another source of plant exposure to nonferrous metals. Despite the occurrence of metal-induced oxidative alterations in
plant organs, both plant species seemed to tolerate a high metal concentration in soils.
Conclusions Taken together, these results indicated that T. repens and L. perenne were able to form a plant cover on highly Cd-, Pb-, and Zn-polluted soils, to limit the metal transfer to their aerial parts
and were relatively metal-tolerant. All these characteristics made them suitable for phytostabilization on metal-contaminated
soils. These findings also highlighted the necessity to take into account seasonal and annual variations for a future phytomanagement.
Recommendations and perspectives In this work, the behavior of plant species grown in metal-polluted soil has been studied during 2 years. Obviously, this
time is too short to ensure that metals remain accumulated in the root system and few are transferred in aerial parts over
the time. It is why regular monitoring should be achieved during more than a decade after the settlement of the plant cover.
This work will be completed by the study of the T. repens and L. perenne effects on mobility of metals in order to evaluate the quantities of pollutants which could be absorbed by the biota and
transferred to groundwater. Bioaccessibility tests could be also realized on polluted soils in order to evaluate the phytostabilization
impacts on the exposition risks for humans. 相似文献
304.
Sylwia Wojas Sonia Plaza Oskar Siemianowski Anna Ruszczyńska Danuta M. Antosiewicz 《Environmental pollution (Barking, Essex : 1987)》2009,157(10):2781-2789
Arabidopsis MRPs/ABCCs have been shown to remove various organic and inorganic substrates from the cytosol to other subcellular compartments. Here we first demonstrate that heterologous expression of AtMRP7 in tobacco (Nicotiana tabacum var. Xanthi) modifies cadmium accumulation, distribution and tolerance. Arabidopsis MRP7 was localized both in the tonoplast and in the plasma membrane when expressed in tobacco. Its overexpression increased tobacco Cd-tolerance and resulted in enhanced cadmium concentration in leaf vacuoles, indicating more efficient detoxification by means of vacuolar storage. Heterologous AtMRP7 expression also led to more efficient retention of Cd in roots, suggesting a contribution to the control of cadmium root-to-shoot translocation. The results underscore the use of AtMRP7 in plant genetic engineering to modify the heavy-metal accumulation pattern for a broad range of applications. 相似文献
305.
Seong Gu Hwang Fumio Matsumura Hiromi Sasagawa 《Journal of environmental science and health. Part. B》2013,48(1):115-123
Abstract Most modern pesticides are expensive. Application of excessive dosage rates is likely to cause undesirable biological side‐effects and is economically wasteful. Non‐uniform distribution of the spray cloud, or application at the wrong time, may result in failure to control the pest. It is the responsibility of the field operator to acquire sufficient knowledge and skill to ensure proper use of the control agents, to increase efficiency of their usage and to reduce unwanted side‐effects. To achieve this goal, he must take into consideration the various physical factors that govern field performance of pesticides. A simple relationship exists between the spray volume and emission rate used, and droplet size produced. The use of extremely low spray volumes (i.e., those less than 2.0 litre per ha) for forest insect control in Canada, as opposed to higher volumes used in agriculture, necessitates the release of fine droplets (ranging from 20 to 70 μm in diameter) to obtain adequate coverage of the target area. These droplets take a long time to sediment downwards, evaporate in‐flight, become smaller in size and/or form powdery residues, thus contributing to off‐target drift and impaired droplet adhesion to target surfaces. Physical factors such as rain washing, degradation by sunlight and erosion by wind also influence the longevity of pesticide deposits on foliage which is crucial during the critical period of pest control. Factors affecting the mode of entry into insects are related to the type of ingredients used in formulation. If a pesticide acts via crawling contact, formulations which would provide surface deposits would be more beneficial than emulsions or oil‐based mixes which tend to undergo penetration into foliar cuticle. Physical factors that affect field performance of a pesticide tank mix are related to phase separation and ‘breakdown of emulsions’ in the application equipment; ‘agglomeration and caking’ of wettable powder dispersions at the bottom of the tank; impaired flow behaviour of highly viscous formulations; and coarse atomization of high‐viscosity tank mixes leading to poor target cover. 相似文献
306.
307.
采用生物淋滤法处理电子垃圾焚烧迹地重金属严重污染的土壤。所用氧化亚铁硫杆菌是从矿坑废水中通过一系列培养、分离和纯化得到。实验结果表明,生物淋滤法可以有效地去除土壤中重金属Cu、Ph和Zn,去除率的大小顺序为Zn〉Cu〉Pb;采用五步连续提取法分析处理前后土壤中重金属的存在形态,结果表明,通过氧化亚铁硫杆菌处理受重金属污染的土壤,可以促使易移动的重金属结合态的溶解(可交换态、碳酸盐结合态和Fe—Mn氧化物结合态),并使难移动的重金属结合态向易移动的重金属结合态转变。 相似文献
308.
Hanzel J Thullner M Harms H Wick LY 《Environmental pollution (Barking, Essex : 1987)》2011,159(4):858-864
Limited information exists on influences of the diffusive transport of volatile organic contaminants (VOC) on bacterial activity in the unsaturated zone of the terrestrial subsurface. Diffusion of VOC in the vapor-phase is much more efficient than in water and results in effective VOC transport and high bioavailability despite restricted mobility of bacteria in the vadose zone. Since many bacteria tend to accumulate at solid-water, solid-air and air-water interfaces, such phase boundaries are of a special interest for VOC-biodegradation. In an attempt to evaluate microbial activity toward air-borne substrates, this study investigated the spatio-temporal interplay between growth of Pseudomonas putida (NAH7) on vapor-phase naphthalene (NAPH) and its repercussion on vapor-phase NAPH concentrations. Our data demonstrate that growth rates of strain PpG7 were inversely correlated to the distance from the source of vapor-phase NAPH. Despite the high gas phase diffusivity of NAPH, microbial growth was absent at distances above 5 cm from the source when sufficient biomass was located in between. This indicates a high efficiency of suspended bacteria to acquire vapor-phase compounds and influence headspace concentration gradients at the centimeter-scale. It further suggests a crucial role of microorganisms as biofilters for gas-phase VOC emanating from contaminated groundwater or soil. 相似文献
309.
采用对苯二甲酸(terephthalic acid,TA)作为羟基自由基(hydroxyl radical,·OH)捕捉剂,利用荧光分光光度法测定了二氧化氯(CIO2)接触后颤蚓体内-OH浓度变化,结合颤蚓灭活率、过氧化氢酶(catalase,CAT)和丙二醛(malondi.alderhyde,MDA)等指标的测试结果,研究了CIO2对颤蚓成虫的灭活效果及灭活机理。结果表明,ClO2对颤蚓成虫灭活效果显著。当C1O2投加浓度超过0.4mg/L,可对颤蚓体内·OH产生明显的诱导效应,并且·OH诱导效应与颤蚓灭活率直接相关。接触条件下CAT变化情况表明,颤蚓受到了明显的氧化胁迫,且对颤蚓体内抗氧化系统有破坏作用,MAD变化结果则表明ClO2对颤蚓的脂质过氧化作用不明显,可以对颤蚓表皮层有效渗透。上述结果证实了CIO2对颤蚓成虫的灭活作用机制之一是诱导其体内生成·OH,产生氧化胁迫,而CIO2对颤蚓抗氧化系统的破坏作用和对颤蚓表皮层的有效渗透进一步增强灭活效果。 相似文献
310.
Choi JW Lee W Lee DB Park CH Kim JS Jang YH Kim Y 《Environmental monitoring and assessment》2007,129(1-3):37-42
The immobilized cell using self-assembled synthetic oligopeptide was applied to the electrochemical detection of pathogen
infection. Thin films based on cysteine-terminated synthetic oligopeptides were fabricated for the immobilization of HeLa
cell on gold (Au) substrate. Layer formation and immobilization of the cell were investigated with surface plasmon resonance
(SPR) and electrochemical impedance spectroscopy (EIS). Experimental results showed that the thin film of cysteine-terminated
synthetic oligopeptide was successfully fabricated and it could be applied for the immobilization of HeLa cells. The adhered
living cell was exposed to E. coli O157:H7, which induced the change of SPR angle and electrochemical impedance signal. The proposed cell immobilization method
using self-assembly technique can be applied to construct the cell microarray for on-site pathogen monitoring. 相似文献