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901.
902.
磁种-磁滤技术处理污染河水的试验研究 总被引:1,自引:0,他引:1
采用磁种-磁滤技术处理广州市两条河涌的污染水,考察了磁种投加量、混凝剂用量、磁场强度和磁滤速度对出水浊度的影响,并确定了最佳试验条件。结果表明,该工艺对TP、SS和浊度的去除效果较好,去除率分别为96.2%、92.4%和93.9%,对CODCr有一定的去除效果,去除率为68.2%,但对NH4^ -N的去除效果较差,去除率仅为25%。 相似文献
903.
Sulfikar Hanafi Michael R. Grace Barry T. Hart 《Water, Air, & Soil Pollution: Focus》2006,6(5-6):403-411
Nutrient spiralling measurements were conducted in Lyrebird Creek, a forested stream in the Dandenong Ranges, Victoria, Australia.
Spiralling indices from several nutrient (, ) enrichment experiments were correlated with seasonal variation in factors thought to control nutrient uptake, i.e., temperature,
light and algal biomass. It was hypothesized that nutrient uptake would be higher in summer as increased temperatures would
promote both biotic and abiotic processes and higher light levels in summer would stimulate photosynthesis. However, results
did not support this hypothesis. Uptake length for and and uptake velocity were not correlated with chlorophyll-a, light or temperature (r
2 < 0.30, P > 0.1) despite the seasonality of these biophysical factors (r
2 > 0.42, P < 0.02). Lyrebird Creek might had no seasonal trend in nutrient uptake and/or nutrient spiraling measurements only appears
suitable for contrasting streams with large differences in biophysical factors that supports biotic and abiotic nutrient processing.
In addition, small errors in measuring a nutrient concentration can result in a large range in the estimated S
w and increased difficulty in determining significant differences in nutrient spiralling indices. 相似文献
904.
Linking linear programming and spatial simulation models to predict landscape effects of forest management alternatives 总被引:1,自引:0,他引:1
Forest management planners require analytical tools to assess the effects of alternative strategies on the sometimes disparate benefits from forests such as timber production and wildlife habitat. We assessed the spatial patterns of alternative management strategies by linking two models that were developed for different purposes. We used a linear programming model (Spectrum) to optimize timber harvest schedules, then a simulation model (HARVEST) to project those schedules in a spatially explicit way and produce maps from which the spatial pattern of habitat could be calculated. We demonstrated the power of this approach by evaluating alternative plans developed for a national forest plan revision in Wisconsin, USA. The amount of forest interior habitat was inversely related to the amount of timber cut, and increased under the alternatives compared to the current plan. The amount of edge habitat was positively related to the amount of timber cut, and increased under all alternatives. The amount of mature northern hardwood interior and edge habitat increased for all alternatives, but mature pine habitat area varied. Mature age classes of all forest types increased, and young classes decreased under all alternatives. The average size of patches (defined by age class) generally decreased. These results are consistent with the design goals of each of the alternatives, but reveal that the spatial differences among the alternatives are modest. These complementary models are valuable for quantifying and comparing the spatial effects of alternative management strategies. 相似文献
905.
The general perceptions of prescribed burning were elicited from forest users for an area that has been subject to this form
of land management for at least 20 years. The largest group consisted of local residents living in and around the Wombat State
Forest with two smaller groups of students from a nearby university campus and local professional land managers. A questionnaire
was given to each participant in order to explore how the forest was used, to determine the level of knowledge of burning
in the targeted forest and Victoria and the perception of the appearance, effectiveness of protection, and accessibility to
the forest after prescribed burning. Generally all groups had similar responses with community members having stronger views
on the effectiveness and practicalities of prescribed burning, whereas students were more neutral in their opinions. All participants
claimed knowledge of prescribed burning activities within Victoria, but fewer had experience of planned fires in the Wombat
State Forest. All groups agreed that areas that had not been recently burned had a better appearance than those that had,
but this result may have included a range of value judgments. Land managers had a greater understanding of the ecological
importance of season and timing of burning; however, some students and community members were equally knowledgeable. Prescribed
burning did not impede access to the forest, nor did smoke from prescribed burns pose any great problem. The majority of the
participants felt that the amount of prescribed burning done in the forest was adequate for engendering a feeling of protection
to life and property, yet many were still suspicious of this management practice. These initial findings indicate several
areas in which further research would be useful including the efficacy of education programs for community members and improved
communication of burn plans by land managers. 相似文献
906.
管流电氧化杀藻及其影响要素 总被引:4,自引:0,他引:4
对藻种类、电流密度、电极材料、细胞密度和流量对电化学氧化杀藻的影响进行了研究.实验结果显示,铜绿微囊藻比水华鱼腥藻对电化学氧化更为敏感,藻的种类和形状对杀藻效果存在影响.使用普通镀锌水管、铜水管和钛管作为阴极进行实验,发现阴极材料对结果影响不大,而阳极对杀藻效果影响较大,钌钛电极效果明显好于钛电极.电流密度对杀藻效果影响很大,电流密度为1mA.cm-2时,杀藻效果不明显,当电流密度大于2.5mA.cm-2时,杀藻效果开始非常显著.细胞密度是影响杀藻效果的重要因素,在5mA.cm-2下,低密度(6×108个/L)水样的光密度值下降明显比高密度(6×109个/L)水样快.水样在反应器中的流量对结果影响不大. 相似文献
907.
908.
Removal of a type of endocrine disruptors-di-n-butyl phthalate from water by ozonation 总被引:1,自引:0,他引:1
Ozonation of synthetic water containing a type of endocrine disruptor-di-n-butyl phthalate (DBP) was examined. Key impact factors such as pH, temperature, ionic strength, ozone dosage and initial DBP concentration were investigated. In addition, the activities of radicals on uncatalysed and catalysed ozonation were studied. The degradation intermediate products were followed and the kinetic of the ozonation were assessed as well. Results revealed that ozonation of DBP followed two mechanisms. Firstly, the reaction rate of direct ozonation was slower at lower pH, temperature, and ionic strength. Secondly, when these factors were increased for indirect radical reaction, higher percentage of DBP was removed with the increase of the initial ozone dosage and the decrease of the initial DBP concentration. In addition, tea-butanol, humic substances and Fe(Ⅱ) affected DBP ozonation through the radical pathway. It was determined that ozonation was restrained by adding tea-butanol for its radical inhibition effect. Furthermore, humic substances enhanced the reaction to some extent, but a slight negative effect would be encountered if the optimum dosage was exceeded. As a matter of fact, Mn(Ⅱ) affected the ozonation by "active sites" mechanism. In the experiment, three different kinds of intermediate products were produced during ozonation, but the amount of products for each one of them decreased as pH, temperature, ionic strength and initial ozone dosage increased. A kinetic equation of the reaction between ozone and DBP was obtained. 相似文献
909.
McCarthy K 《Environmental monitoring and assessment》2006,118(1-3):293-318
Semipermeable membrane devices (SPMDs) were deployed at eight sites within the Buffalo Slough, near Portland, Oregon, to (1)
measure the spatial and seasonal distribution of dissolved polycyclic aromatic hydrocarbon (PAH) and organochlorine (OC) compounds
in the slough, (2) assess the usefulness of SPMDs as a tool for investigating and monitoring hydrophobic compounds throughout
the Columbia Slough system, and (3) evaluate the utility of SPMDs as a tool for measuring the long-term effects of watershed
improvement activities. Data from the SPMDs revealed clear spatial and seasonal differences in water quality within the slough
and indicate that for hydrophobic compounds, this time-integrated passive-sampling technique is a useful tool for long-term
watershed monitoring. In addition, the data suggest that a spiking rate of 2–5 μg/SPMD of permeability/performance reference compounds, including at least one compound that is not susceptible to photodegradation,
may be optimum for the conditions encountered here. 相似文献
910.
An assessment of tree health and trace element accumulation near a coal-fired generating station, Manitoba, Canada 总被引:2,自引:0,他引:2
A forest health assessment was performed in stands dominated by bur oak and trembling aspen to study the potential effects of airborne emissions from a 132 MW coal-fired station. Forty-two stands were sampled within a 16-km radius of the station for both foliar stress symptoms and trace element toxicology. The concentrations of tracer elements (As, Ba, Sr, and V) in the leaf litter were not spatially congruent with airborne emission deposition models (except Ba, which showed elevated levels immediately SE of the station), nor were they at phytotoxic levels. Elemental concentrations were significantly related to soil parameters including organic matter and texture. No patterns were found in forest health along directional or distance gradients from the generating station. Trembling aspen stands demonstrated little decline in general, but three of the 19 bur oak plots, all located on thin sandy soils developed on calcareous till, demonstrated branch dieback. In addition to poor soil conditions, two of these sites also had high water tables, and exhibited tree mortality. The bur oak decline did not appear to be related to emissions from the station, but is suspected to be a result of poor site quality, with urban development as a confounding factor. 相似文献