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71.
Suhaila Salleh Yen Shan See N. A. Serri Sufia Hena H. A. Tajarudin 《Environmental Chemistry Letters》2016,14(2):189-194
There is a high demand for immobilized enzymes in the industry because it is a green technology, it improves the efficiency of the crude enzyme and it minimizes the step of product recovery. Selection of a suitable carrier for enzyme immobilization is crucial. Eggshells are abundantly available as an organic waste. Here, lipase from Thermomyces lanuginosus was immobilized on eggshell to produce butyl butyrate. We evaluated the effect of lipase loading, from 0.5 to 3.0 %, size of eggshells, lower than 1, 1–2 and 2–4 mm, and temperature, from 30 to 50 °C. Results show that the optimum conditions calculated by response surface methodology analysis for butyl butyrate synthesis were 40 % w/v of immobilized lipase loading and 0.2 M of substrate concentration at 38 °C during 24 h. The predicted yield was 92.78 %, and the yield obtained during synthesis was 93.48 %. 相似文献
72.
Micellar-enhanced ultrafiltration (MEUF) with mixed surfactants for removing Cu(II) ions 总被引:1,自引:0,他引:1
A nonionic surfactant, polyoxyethylene Octyl phenyl ether (Triton-X), is added to a micellar-enhanced ultrafiltration process to lower the critical micellar concentration (CMC) of an anionic surfactant, sodium dodecyl sulfate (SDS). The effects of adding Triton-X on the copper removal efficiency, the permeate SDS concentration, the copper binding capacity of SDS micelles, and membrane fouling are investigated. Our results show that the addition of Triton-X at concentrations greater than its CMC can reduce the SDS dosage required for effective Cu removal, and at the same time, minimize the permeate SDS concentration. Although, no adverse effect on the copper binding capacity of SDS micelle is observed by the addition of Triton-X, the membrane fouling is worsen. Cleaning the membrane with DI water allowed restoring the membrane flux, indicating that the fouling caused by Triton-X was reversible. 相似文献
73.
Although the cytotoxic effects of mercuric chloride (HgCl2) and methylmercury chloride (MeHg) have been extensively studied, the insoluble mercuric sulfide (HgS) has been the subject of fewer studies. Since the traditional Chinese mineral drug, cinnabar (containing >95% HgS) continues to be used as an ingredient for infant sedation, the pharmacological and toxicological effects of HgS need to be clarified. In previous experiments, HgS and cinnabar were shown to be absorbed from the gastrointestinal tract (GIT) and distributed in various tissues including the lungs. Thus, a preliminarily examination of whether HgS might exert any oxidative stress on a mouse lung was undertaken. HgS reduced GSH content and increased lipid peroxidation in the lung. Further studies on the cytotoxic effects and the possible mechanisms of action of HgS were compared with HgCl2 and MeHg in cultured lung fibroblast V79 cells. The results showed that HgS produced cytotoxicity at a concentration (400–1200 µM)in a dependent manner with IC50 of 795.6 µM, as compared to HgCl2 and MeHg, 8.1 µM and 5.9 µM, respectively. In addition, the HgS induced the phenomena of DNA fragmentation, increasing reactive oxygen species (ROS) and decreasing mitochondrial membrane potential, accompanied by decreased levels of intracellular ATP and GSH and higher lipid peroxidation levels, similar to HgCl2 and MeHg, but with different toxicokinetic properties. These findings provide evidence for understanding the mechanisms underlying the toxic effects of HgS. 相似文献
74.
Butyltin compounds (BTs) and organochlorine residues (OCs) were determined in green mussel (Perna viridis L.) collected along the coastal waters of India in 1994 and 1995 to elucidate their contamination levels and distribution. BTs were detected in all of the mussel samples, ranging from 2 to 378 ng/g wet wt, which indicated that BTs are widely distributed, with elevated concentrations in intense boating areas. BTs concentrations in green mussels were lower than those reported for developed nations as well as developing countries such as Thailand. Concentrations of OCs were much lower than those of BTs. Among OCs examined, DDTs were found to be greatest, followed by HCHs, PCBs, CHLs and HCB. Considering the fact that the usage of tributyltin (TBT), DDTs and HCHs are not controlled in India, their contamination in the aquatic environment may increase unless regulatory measures are imposed. To our knowledge, this is a first report on the detection of BTs in Indian mussels. 相似文献
75.
76.
Michael White Marilyn Gambone Haw Yen Prasad Daggupati Katrin Bieger Debjani Deb Jeff Arnold 《Journal of the American Water Resources Association》2016,52(1):269-274
The Soil and Water Assessment Tool (SWAT) is widely used in the United States (U.S.) to simulate hydrology and water quality simulation. Process‐based models like SWAT require a great deal of data to accurately represent the natural world, including topography, land use, soils, weather, and management. With the exception of management, all these data are available nationally from multiple sources. To date, credible SWAT studies in the U.S. have assembled suitable management data (operation scheduling, fertilization application rates, and plant growth parameterization). In this research, we develop a national management database for SWAT using existing U.S. Department of Agriculture data sources. These data are compatible with existing SWAT interfaces and are relatively easy to use. Although management data from local sources is preferred, these data are not always available. This work is intended to fill this void with more reasonable management data than the existing defaults. This national database covers all major cultivated crops and should facilitate improved SWAT applications in the U.S. These data were tested in two case studies and found to produce satisfactory SWAT predictions. The database developed in this research is freely available on the web. 相似文献
77.
Distribution of Selected Soil and Water Conservation Practices in the U.S. as Identified with Google Earth 下载免费PDF全文
Michael White Leighton Haglund Marcus Gloe Katrin Bieger Brandon Namphong Marilyn Gambone Eric Hardy Jungang Gao Haw Yen Jeff Arnold 《Journal of the American Water Resources Association》2017,53(5):1229-1240
The proper representation of conservation practices on agricultural lands is an important factor in large‐scale assessments of water quality in the United States. Unfortunately, there are few publicly available data sources at the local level and even fewer at the national scale. In this research, randomly selected points within agricultural lands were examined for selected conservation practices using Google Earth aerial imagery by a team of interpreters. In total, 13,530 points had field boundaries digitized, and were subsequently examined and classified. The presence of terraces, grassed waterways, contour farming, center pivot irrigation, strip cropping, ponds, riparian vegetation, filter strips, and land cover were noted. Subjectivity among interpreters was evaluated using duplicate samples and was found to be similar to image misclassification rates in other research. Conservation practice adoption rates for selected major river basins compared favorably with data collected by the Conservation Effects Assessment Project. The frequency of occurrence of each conservation practice was summarized and presented by ecoregion. To facilitate future research, point level data and software source code developed in this research are available via the web at http://nlet.brc.tamus.edu/Conservation . Aerial imagery was found to be a powerful, inexpensive, and easily accessible tool to assess large‐scale conservation practice implementation for certain conservation practices. 相似文献
78.
79.
A pathway of dieldrin transformation to aldrin by epoxide reduction was found in this study. Investigation of dieldrin degradation under anaerobic conditions was performed with a mixed culture containing indigenous microorganisms obtained from sediment of the Er-Jen River in Taiwan. During the incubation, the transformation of dieldrin to aldrin was analyzed by GC-ECD and GC-MS. Effects of incubation factors including dieldrin concentrations, incubation temperatures and kinds of carbon sources on the degradation of dieldrin were also studied. Original concentrations (from 0.5 to 10 microg ml(-1)) of dieldrin affect the transformation rate of dieldrin, and lower concentrations indicated the higher degradation rates. But once the concentration higher than 100 microg ml(-1), almost no degradation occurred. The optimal temperature for degradation in mixed culture was found at 40 degrees C in this study. Dieldrin transformation rates varied with the type of major carbon sources in the mixed culture and were in order of yeast extract > sodium acetate > glucose. In addition, the denaturing gradient gel electrophoresis (DGGE) fingerprint revealed that four microbials evolved in dieldrin-amended cultures, but not in the dieldrin-free cultures. Partial sequence of 16S rDNA for these four organisms exhibited 94-99% similarity to those of genera Clostridium, Acidaminobacter and an uncultured bacterial group. These results suggest that the four microbials might promote the dieldrin transformation. 相似文献
80.
Soil particle-size composition and coastal erosion and accretion study in Soc Trang mangrove forests
Coastal erosion results in loss of land, which impacts the economy, coastal residents and settlement plans, especially in the context of rising sea levels caused by climate change. Studying soil particle-size fractions in mangrove forests will help provide a better understanding of the relationship between soil proportions and coastal processes as well as the role of mangrove forests to support coastal planning and management. Soil samples were collected at 26 sampling plots at depths of 10 cm and 40 cm in the Cu Lao Dung (CLD), Long Phu (LP) and Vinh Chau (VC) mangrove forests in Viet Nam’s Soc Trang Province. The soil proportions based on six different particle-sizes (<0.074 mm, 0.074–0.1 mm, 0.1–0.25 mm, 0.25–0.5 mm, 0.5–1.0 mm, and >1.0 mm) were measured using a dry sieving method. Analysis showed that soil particle-sizes ranging between 0.074 and 0.5 mm made up 75–95 % of the soil sample weight at both depths. The high standard deviation values of soil proportions of each given particle-size among sampling plots indicated the soil proportions by particle-size varied widely across the sampling plots. Cluster analysis found similar pattern of soil particle-size proportions for samples collected in CLD and VC, and different pattern of soil particle-size proportions in samples collected at LP, which is more impacted by the Mekong River flow and has a thin mangrove forest belt.?Non-metric dimension scaling (NMDS) analysis showed that sampling plots across the landward sites of the three mangrove forest areas were distributed in the nearby locations (Stress?=?0.11). This indicated that soil proportions of particle-sizes of samples collected from areas of the natural forest composed of different species were more similar. Such similarities were not found, however, in samples collected from middle and seaward plots dominated by single-species plantations. 相似文献