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81.
Richard O. Carey George Vellidis Richard Lowrance Catherine M. Pringle 《Journal of the American Water Resources Association》2007,43(5):1183-1193
Abstract: We examine the potential for nutrient limitation of algal periphyton biomass in blackwater streams draining the Georgia coastal plain. Previous studies have investigated nutrient limitation of planktonic algae in large blackwater rivers, but virtually no scientific information exists regarding how algal periphyton respond to nutrients under different light conditions in smaller, low‐flow streams. We used a modification of the Matlock periphytometer (nutrient‐diffusing substrata) to determine if algal growth was nutrient limited and/or light limited at nine sites spanning a range of human impacts from relatively undisturbed forested basins to highly disturbed agricultural sites. We employed four treatments in both shaded and sunny conditions at each site: (1) control, (2) N (NO3‐N), (3) P (PO4‐P), and (4) N + P (NO3‐N + PO4‐P). Chlorophyll a response was measured on 10 replicate substrates per treatment, after 15 days of in situ exposure. Chlorophyll a values did not approach what have been defined as nuisance levels (i.e., 100‐200 mg/m2), even in response to nutrient enrichment in sunny conditions. For Georgia coastal plain streams, algal periphyton growth appears to be primarily light limited and can be secondarily nutrient limited (most commonly by P or N + P combined) in light gaps and/or open areas receiving sunlight. 相似文献
82.
R. J. Brozka G. L. Rolfe L. E. Arnold 《Journal of the American Water Resources Association》1981,17(3):443-447
Two intermittent streams on oak-hickory watersheds in southern Illinois were gaged with a V-notched weir and sampled with an automatic water sampler. For three years data were collected on flow volume and water quality. Flow volumes show large variations between years and watersheds. Samples were analyzed for Na+, K+, Ca++, Mg++, P, and NO-3. Water quality was consistently high, although there were significant differences between watersheds. A baseline for water quality has been established for comparison after one of the watersheds is clearcut at a later date. 相似文献
83.
Michael N. Beaulac Kenneth H. Reckhow 《Journal of the American Water Resources Association》1982,18(6):1013-1024
ABSTRACT: Lake and watershed management strategies and recent environmental legislation dictate that nonpoht nutrient sources associated with storm water runoff must be assessed. Accordingly, a nutrient flu assessment for phosphorus and nitrogen is conducted through an extensive literature review of nutrient export studies. These studies are reevaluated. The nutrient export coefficients are screened according to sampling design criteria and compiled according to land use. The ecological mechanisms within each land use influencing the magnitude of nutrient flux are also discussed 相似文献
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This investigation conducted a full-scale survey the drinking water distribution system in Kaohsiung city, Taiwan. The aim
was to investigate whether the distribution system was capable of maintaining high water quality from the water treatment
facilities through to the end user. The results showed that the distribution system can maintain high water quality, except
for suitable chlorine residuals. The authors plotted chlorine residual contour maps to identify areas with low chlorine residuals,
helping them prioritize sections that must be flushed or renewal. The contour maps also provide sufficient and clear information
for locating booster chlorination stations. Contour maps enable water facilities to identify how water quality decays in the
distribution systems and the locations of such decay. Water quality decay can be caused by properties of pipeline materials,
hydraulic conditions, and/or biofilm thickness. However, understanding the exact reasons is unnecessary because the contour
maps provide sufficient information for trouble-shooting the distribution systems. 相似文献
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89.
河流型硅藻水华研究进展 总被引:7,自引:0,他引:7
通过对硅藻水华发生机制相关文献的研究分析,对硅藻水华发生机制做了一般性探讨,并重点关注了河流型水华的发生机制的独特点。河流水华种类主要为中心硅藻纲,静水生态系统水华种类除中心硅藻纲还包括部分羽纹硅藻纲种类。河流水华硅藻种类对营养盐浓度、温度和光照等环境因子具有一定的适应范围。与静水生态系统相比,河流硅藻水华受气象和水文等物理指标的影响更为明显。河流硅藻水华中常具有时滞现象,其中由气象和水文因素引起的时滞现象最为明显。目前河流硅藻水华的防治仍然以上游水库下泄稀释为主,但是这种方法会造成一定的水资源浪费。河流水华硅藻的生理属性、硅藻水华对生态系统的影响、节水与抑制水华的统筹以及其他控制水华的方法都是未来河流硅藻水华研究的重点。 相似文献
90.
Spatial distribution of nutrient and phytoplankton variables is often illustrated using categorical mapping for each variable.
However, the assessment of eutrophication cannot be derived from a single parameter since a synthesis of the environmental
variables related to eutrophication is required. These shortcomings are further complicated since it is difficult to discriminate
between distinct trophic states along natural environmental gradients. In the present work, a methodological procedure for
quantitative assessment of eutrophication at a spatial scale was examined in the Gulf of Saronicos, Greece, based on a thematic
map generated from the synthesis of four variables characterising eutrophication. The categorical map of each variable was
developed using the Kriging interpolation method and four trophic levels were indicated (eutrophic, upper-mesotrophic, lower-mesotrophic
and oligotrophic) based on nutrient and phytoplankton concentration scaling. Multi-criteria choice methods were applied to
generate a final categorical map showing the four trophic levels in the area. This synthesis of categorical maps for assessing
eutrophication at a spatial scale is proposed as a methodological procedure appropriate for coastal management studies. 相似文献