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41.
The effects of livestock grazing on selected riparian and stream attributes, water chemistry, and algal biomass were investigated
over a two-year period using livestock enclosures and by completing stream surveys in the Cypress Hills grassland plateau,
Alberta, Canada. Livestock enclosure experiments, partially replicated in three streams, comprised four treatments: (1) early
season livestock grazing (June–August), (2) late season livestock grazing (August–September), (3) all season grazing (June–September),
and (4) livestock absent controls. Livestock grazing significantly decreased streambank stability, biomass of riparian vegetation,
and the extent to which aquatic vegetation covered the stream channels compared with livestock-absent controls. Water quality
comparisons indicated significant differences among the four livestock grazing treatments in Battle and Graburn creeks but
not in Nine Mile Creek. In Graburn Creek, the concentration of total phosphorus in the all-season livestock grazing treatment
was significantly higher than that in the livestock-absent control, and the early season and late season grazing treatments.
Concentrations of soluble reactive phosphorus in the all-season livestock grazing treatment also exceeded that in livestock-absent
control. In contrast, differences in water quality variables in the remaining 22 comparisons (i.e., 22 of the total 24 comparisons)
were minor even when differences were statistically significant. Effects of livestock grazing on algal biomass were variable,
and there was no consistent pattern among creeks. At the watershed scale, spatial variation in algal biomass was related (P < 0.05) with concentrations of NO2
− + NO3
− and soluble reactive phosphorus in two of the four study creeks. Nutrient diffusing substrata experiments showed that algal
communities were either nitrogen-limited or not limited by nutrients, depending on stream and season. 相似文献
42.
《环境科学学报(英文版)》2023,35(3):362-375
Frequent occurrence of harmful algal blooms has already threatened aquatic life and human health. In the present study, floating BiOCl0.6I0.4/ZnO photocatalyst was synthesized in situ by water bath method, and and applied in inactivation of Microcystis aeruginosa under visible light. The composition, morphology, chemical states, optical properties of the photocatalyst were also characterized. The results showed that BiOCl0.6I0.4 exhibited laminated nanosheet structure with regular shape, and the light response range of the composite BZ/EP-3 (BiOCl0.6I0.4/ZnO/EP-3) was tuned from 582 to 638 nm. The results of photocatalytic experiments indicated that BZ/EP-3 composite had stronger photocatalytic activity than a single BiOCl0.6I0.4 and ZnO, and the removal rate of chlorophyll a was 89.28% after 6 hr of photocatalytic reaction. The photosynthetic system was destroyed and cell membrane of algae ruptured under photocatalysis, resulting in the decrease of phycobiliprotein components and the release of a large number of ions (K+, Ca2+ and Mg2+). Furthermore, active species trapping experiment determined that holes (h+) and superoxide radicals (·O2−) were the main active substance for the inactivation of algae, and the p-n mechanism of photocatalyst was proposed. Overall, BZ/EP-3 showed excellent algal removal ability under visible light, providing fundamental theories for practical algae pollution control. 相似文献
43.
湖泊和水库中藻类去除方法的研究进展 总被引:6,自引:0,他引:6
由于富营养化的影响,在我省少部分湖泊和水库中多次发生因藻类的强烈光合作用而产生的高pH值污染和藻类毒素对饮用水的污染等现象。该文综合了除藻的各种方式以及对环境的污染和对人体健康的影响等多种因素,认为以生物除藻和物理除藻两种方法比较适合我省的实际情况。 相似文献
44.
利用藻类去除与回收工业废水中的金属 总被引:33,自引:0,他引:33
藻类对金属离子具有较强的富集能力,可作为生物吸附应用于工业污水中有毒、放射性金属的去除及稀有,贵重金属的回收,高效,经济、简便、选择性好,尤其适用于低浓度及一般方法不易去除的金属,是一种极有应用价值的传统方法的替代或辅助手段,藻类主要是通过生物吸附的途径去除及回收金属,多采用知细胞与固定化细胞两种富集体系。目前人类环境中金属污染仍相当严重,利用藻类富集这一生物工程技术处理含金属的工业污水,无论对于 相似文献
45.
46.
西昌邛海水质现状调查分析 总被引:3,自引:0,他引:3
四川西昌的邛海水体中浮游植物群体组成以硅藻、绿藻及鼓藻为主,据1986~1991年连续监测结果表明,邛海水质总体处于贫营养状况,仅局部有富营养性藻类出现。 相似文献
47.
Vera?I.?SlaveykovaEmail author Kevin?J.?Wilkinson 《Environmental Chemistry Letters》2003,1(3):185-189
The effect of pH on Pb bioaccumulation by Chlorella kesslerii was studied. Both Pb uptake fluxes and Pb bound to membrane transport sites increased with an increase in pH from 4.0–5.0, were relatively stable in the pH interval 5.0–6.5, and increased again at pH 7.0 and 8.0. Protons affected Pb adsorption to the algal surface by competing directly for surface sites, by modifying the overall algal surface charge and by modifying the chemical speciation of Pb in solution. These results indicate a failure of the free-ion activity or biotic ligand models above pH 6.5, possibly due to the bioaccumulation of hydroxo or carbonato Pb complexes. 相似文献
48.
49.
Burger J Gochfeld M Jeitner C Gray M Shukla T Shukla S Burke S 《Environmental monitoring and assessment》2007,128(1-3):311-321
Kelp may be useful as a bioindicator because they are primary producers that are eaten by higher trophic level organisms,
including people and livestock. Often when kelp or other algae species are used as bioindicators, the whole organism is homogenized.
However, some kelp can be over 25 m long from their holdfast to the tip of the blade, making it important to understand how
contaminant levels vary throughout the plant. We compared the levels of arsenic, cadmium, chromium, lead, manganese, mercury
and selenium in five different parts of the kelp Alaria nana to examine the variability of metal distribution. To be useful as a bioindicator, it is critical to know whether levels are
constant throughout the kelp, or which part is the highest accumulator. Kelp were collected on Adak Island in the Aleutian
Chain of Alaska from the Adak Harbor and Clam Cove, which opens onto the Bering Sea. In addition to determining if the levels
differ in different parts of the kelp, we wanted to determine whether there were locational or size-related differences. Regression
models indicated that between 14% and 43% of the variation in the levels of arsenic, cadmium, chromium, manganese, mercury,
and selenium was explained by total length, part of the plant, and location (but not for lead). The main contributors to variability
were length (for arsenic and selenium), location (mercury), and part of the plant (for arsenic, cadmium, chromium and manganese).
The higher levels of selenium occurred at Clam Cove, while mercury was higher at the harbor. Where there was a significant
difference among parts, the holdfast had the highest levels, although the differences were not great. These data indicate
that consistency should be applied in selecting the part of kelp (and the length) to be used as a bioindicator. While any
part of Alaria could be collected for some metals, for arsenic, cadmium, chromium, and manganese a conversion should be made among parts.
In the Aleutians the holdfast can be perennial while the blade, whipped to pieces by winter wave action, is regrown each year.
Thus the holdfast may be used for longer-term exposure for arsenic, cadmium, chromium and manganese, while the blade can be
used for short-term exposure for all metals. Cadmium, lead and selenium were at levels that suggest that predators, including
people, may be at risk from consuming Alaria. More attention should be devoted to heavy metal levels in kelp and other algae from Adak, particularly where they may play
a role in a subsistence diets. 相似文献
50.
Effects of pyridaphenthion on growth of five freshwater species of phytoplankton. A laboratory study
The acute toxicity of the insecticide and acaricide pyridaphenthion to five species of freshwater phytoplankton, Scenedesmus acutus, Scenedesmus subspicatus, Chlorella vulgaris, Chlorella saccharophila and Pseudanabaena galeata was determined. Insecticide concentrations eliciting a 50% growth reduction over 96 h (EC50) ranged from 2.2 to 30.9 mg/l. The two species of Chlorella and the cyanobacteria P. galeata were more tolerant than the two species of Scenedesmus. Concentrations of pyridaphenthion detected in some natural waters were less than the toxic threshold for these species. 相似文献