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31.
Monitoring of iodinated X-ray contrast media in surface water 总被引:1,自引:0,他引:1
A monitoring programme was carried out in order to determine iodinated X-ray contrast media (ICM) in the River Danube and to investigate the raw water quality for drinking water production at Langenau waterworks. The study revealed that the maximum concentrations of ICM (over 500 ng l(-1) for diatrizoic acid and iopamidol) were found in 2h-composite samples taken from the downstream of the Ulm/Neu-Ulm metropolitan area. By means of a concentration profile over one month the highest ICM concentrations were observed on weekdays. The extended data evaluation with principal component analysis shows that the upstream and downstream samples had different pattern of variations in ICM concentration and also demonstrates a clear change in ICM composition by the discharge of municipal wastewater. In addition to load profiles of ICM, time-dependent plots of principal component 1 exhibited peaks, indicating a short-term discharge of ICM between the two sampling sites. In conclusion, a point source for ICM contamination between the sampling sites in Ulm upstream and Leipheim downstream seems to be the reasonable explanation for peak ICM concentrations. Due to the observed high variations of ICM concentrations in river, the evaluation of natural waters by means of a single analysis is not representative. 相似文献
32.
Bode M Haas M Faymonville T Thiede B Schuphan I Schmidt B 《Journal of environmental science and health. Part. B》2006,41(3):201-222
In the present investigation, the oxidative metabolism of 14C-labeled metamitron was examined in plant cell cultures of tobacco overexpressing human P450 enzymes CYP1A1 or CYP1A2; special interest was in the aromatic hydroxylation of the herbicide. The oxidative metabolites deaminometamitron (DAM) and 4-hydroxydeaminometamitron (4-HDAM) were found in the untransformed control culture as well as in the transgenic culture. The transgenic cultures, however, exhibited higher turnover rates after 48 h of incubation with 20 microg 14C-metamitron per assay (untransformed: 40%, CYP1A1: 80%, CYP1A2: 100%). Primary metabolite 4-HDAM was partially found in glucosylated form in the transgenic cultures. As minor oxidative metabolites, 6-hydroxyphenyl-3-methoxymethyl-1,2,4-triazine-5(4H)-one and 3-hydroxymethyl-6-phenyl-1,2,4-triazine-5(4H)-one were identified in the transgenic cultures by GC-MS, LC-MS. Additionally, it could be demonstrated that both foreign enzymes (CYP1A1, CYP1A2) also catalyzed the deamination of metamitron. In a large-scale study (up to 400 microg per assay) with the transgenic culture expressing CYP1A2, the high efficiency of this P450 system toward metamitron was demonstrated: turnover of the xenobiotic was almost complete with 400 microg. Since large portions of unglucosylated 4-H-DAM were found, the activity of foreign CYP1A2 apparently exceeded that of endogenous O-glucosyltransferases of the tobacco cell culture. We concluded that in comparison to the nontransformed cell culture, the extent of metabolism was considerably higher in the transgenic cultures. The transgenic cell cultures expressing human CYP1A1 or CYP1A2 are thus suitable tools for the production of large quantities of primary oxidized metabolites of metamitron. 相似文献
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Summary In four fruit-eating bats sniff-rate analysis revealed the threshold value for natural banana odour to be 1 × 10–4 vol% of head-space while the threshold values for its major components were found to be 3–6 orders of magnitude higher; even the total of molecules present at the threshold dilution of banana odour was 2 orders of magnitude below the lowest threshold values obtained for single components. Thus, the responsiveness of the bats to threshold concentration of natural banana odour is discussed as an example of synergism of stimuli. 相似文献
36.
Pelagic snake pipefish, Entelurus aequoreus (Linnaeus, 1758), occurred regularly in plankton catches that were conducted in areas off the shelf during the German 2004
mackerel and horse mackerel egg survey. Out of a total of 196 plankton hauls 57 tows yielded 112 specimens of adult snake
pipefish with a total length between 15.0 and 35.2 cm. A proportion of 56.3% were egg-carrying males. Also seven recently
released juveniles were caught indicating that off shore reproduction in this species starts much earlier than in the inshore
habitat. 相似文献
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Newly mated queens of monogynous (single queen) ants usually found their colonies independently, without the assistance of workers. In polygynous (multiple queen) species queens are often adopted back into their natal nest and new colonies are established by budding. We report that the Australian 'living-fossil' ant, Nothomyrmecia macrops, is exceptional in that its single queen can be replaced by one of the colony's daughters. This type of colony founding is an interesting alternative reproductive strategy in monogynous ants, which maximizes fitness under kin selection. Successive queen replacement results in a series of reproductives over time (serial polygyny), making these colonies potentially immortal. Workers raise nieces and nephews (relatedness h 0.375) the year after queen replacement. Although N. macrops is 'primitive' in many other respects, colony inheritance is likely to be a derived specialization resulting from ecological constraints on solitary founding. 相似文献
39.
Assessing the microbial activity of soil samples,its nutrient limitation and toxic effects of contaminants using a simple respiration test 总被引:4,自引:0,他引:4
Eight soil samples from five wells of a former gas plant site differing in the contamination with BTEX and PAHs as well as the nutrient content were investigated by soil respiration measurements. The basal, glucose as well as NH4+ and PO4(3-) induced cumulative oxygen consumption and carbon dioxide production in 72 and 120 h were determined and additionally the maximal turnover rates and the limitation quotients were calculated. Without additional carbon source only one of five investigated samples was clearly nutrient limited. After glucose supplementation four of seven investigated samples showed nutrient limitation that was in accordance with the available ammonium and phosphorous content. BTEX and PAHs did not exhibit an inhibiting effect on the respiration rate. In contrast, BTEX containing samples exhibited the highest oxygen consumption indicating biodegradation of the contaminants. The results show that oxygen consumption and carbon dioxide production as well as the kinetic of these processes are all informative parameters characterizing the whole microbial respiration potential and their nutrient limitation in soil samples. Therefore this fast respirometric method can be used for the decision if further detailed studies of the bioremediation are useful and if nutrient supplementation is recommended to enhance natural attenuation. 相似文献
40.
Skotnica J Gilbert M Weingart I Wilhelm C 《Environmental pollution (Barking, Essex : 1987)》2003,123(1):15-20
The effect of ozone (6 h, various concentrations from 0 to 350 ppb) on barley (Hordeum vulgare L., cv. Bomi) and tomato (Lycopersicon esculentum L., cv. Yellow Cherry) leaves was investigated in parallel by thermoluminescence (TL) and fluorescence (FL) methods. Several significant changes were found in TL glow curves measured after excitation by one single turnover flash at +2 degree C in the temperature range from 2 to 170 degree C immediately after ozone exposure. Contrary to TL, ozone induced only negligible changes in FL parameters F0, FM and Fv/FM. Measurements done 24 h after ozone exposure showed partial recovery of ozone-induced changes. The extent of recovery was not the same in different parts of TL curves. Fluorescence parameters were not significantly changed. The results demonstrate that TL parameters are more sensitive to ozone than conventially used FL parameters F0, FM and Fv/FM. Moreover, TL measurements seem to give information not only about the PSII electron transport, but also about the extent of oxidative damage and membrane lipid peroxidation. It is concluded, that TL can be a highly informative tool for monitoring the impact of ozone on plants. 相似文献