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181.
The National Phosphorus Project rainfall simulator was used to quantify overland flow and P transport from nine sites distributed throughout the watershed of a New York City Watershed Agriculture Program collaborating dairy farm. Observed concentrations of total dissolved phosphorus (TDP) were low (0.007-0.12 mg L(-1)) in flow from deciduous forest, extensively managed pasture, and hillside seeps; moderate (0.18-0.64 mg L(-1)) in flow from intensively managed pastures, a hayfield, and a cow path; and extremely high (11.6 mg L(-1)) in flow from a manured barnyard. Concentrations of TDP from sites without fresh manure were strongly correlated with soil test P (TDP [mg L(-1)] = 0.0056 + 0.0180 x Morgan's soil test phosphorus [STP, mg kg(-1)]; R2 = 84%). Observed concentrations of suspended solids were low (16-137 mg L(-1)) in flow from vegetated sites, but were higher (375-615 mg L(-1)) in flow from sites with little ground cover (barnyard, cow path, plowed field). Under dry summer conditions the time to observed overland flow was shorter (<18 min) for nonfield areas (seeps, barnyard, cow path) than for field and forest areas (27-93 min), indicating that hydrologically active nonfield areas of minor spatial extent but with high soil P (e.g., cow paths and barnyards) can play a significant role in summertime P loading. When soils started from field capacity (second-day) time to overland flow was uniformly less than 23 min, indicating that under wet watershed conditions low-P source areas can dilute overland flow from concentrated sources. 相似文献
182.
Survival of dippers Cinclus cinclus in the wild was studied in relation to their dominance. Dominance was assessed amongst groups of temporary captives in a
laboratory arena. Adults tended to be more dominant than juveniles, and within age classes males generally dominated females.
Dominant individuals also sang more. Logistic regression was used to examine survival in the wild in relation to dominance
and other factors. Annual survival of juvenile males was negatively related to dominance during the previous autumn. No significant
effects of dominance on winter or annual survival were found amongst females or adult males. Dominance effects on overwinter
survival approached significance for adult females, however, and were significant for both winter and annual survival when
the data from adult females and juvenile males were combined. None of the other factors considered, which included body size,
song frequency and year, had a significant effect on overwinter or annual survival. We concluded that dominance either had
no influence on survival, or had a negative effect particularly on dippers of intermediate status. We were unable to show
if dominance had a direct effect, however, or acted indirectly on survival via an unidentified factor we did not examine.
Received: 23 June 1994/Accepted after revision: 28 October 1995 相似文献
183.
G. Richard Dreese Harold L. Bryant 《Journal of the American Water Resources Association》1972,8(2):320-327
The purpose of the study was to use economic analysis in determining the ability of a small strip mining company to incure the financial burden of carrying out various alternative mine drainage abatement programs. The quantity and quality of water with which the company has to deal were determined and treatment and diversion programs were costed out. The company's market area and the market structure were analyzed. It was found that pricing policies were determined by a dominant firm, so the target company had no control over its price per ton of coal. The costs and revenue of the firm were analyzed for the period 1960-1970 and, even without a water quality program, losses were incurred in six out of eleven years. Analysis of the average cost curve indicates that the per unit cost could have been reduced by increasing output thereby increasing efficiency. The conclusions of the study were that the small company could not unilaterally implement mine drainage programs because the added costs would seriously worsen its already precarious financial position. Even uniformly enforced legislation might reduce the small firms competitive position because of economies of scale associated with the large treatment facilities used by big mining companies. 相似文献
184.
H. Jack Walker Hubert S. Feild William F. Giles Jeremy B. Bernerth L. Allison Jones‐Farmer 《组织行为杂志》2007,28(4):485-507
Our study investigated applicant characteristics in response to organizations incorporating an affirmative action policy (AAP) statement in recruitment material. Study participants (N = 217; White upper‐level management students) randomly received recruitment material containing one of three statements (e.g., affirmative action, equal employment opportunity (EEO), or no statement regarding affirmative action or EEO) and were asked to evaluate the attractiveness of the organization publicizing the designated policy. Results indicated that individuals responded negatively to AAPs in recruitment material because of prejudice attitudes, the perceived unfairness of such programs (which we relate to equity sensitivity), or in an attempt to protect their own self‐interest (which we relate to general self‐efficacy). Additionally, individuals' equity sensitivity and general self‐efficacy both moderated the relationship between racial prejudice and organizational attractiveness. Specifically, the negative relationships between participants' prejudice attitudes and the attractiveness of organizations publicizing an affirmative action policy were stronger for benevolents (persons tolerant of situations where they are under‐rewarded) and for persons low in self‐efficacy. Implications of our findings for organizational recruitment practices are discussed. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
185.
Bottom sediment and suspended sediment samples from Hamilton Harbour (western Lake Ontario) and from a major tributary were profiled using polycyclic aromatic hydrocarbons (PAH) and thia-arenes as source apportionment tracers. Ratios of selected PAH and ratios of monomethyl and dimethyl/ethyl dibenzothiophenes to the parent dibenzothiophenes were calculated. Thia-arene and PAH profiles of Standard Reference Material SRM 1649 (urban dust/organics), SRM 1650 (diesel), SRM 1597 (coal tar), Hamilton coal tar and a composite Hamilton air particulate sample provided source sample data. The gas chromatography-mass spectrometry (GC-MS) chromatograms of all sample extracts were dominated by homocyclic PAH but interpretation of PAH profiles with respect to source was difficult. In contrast, thia-arene analyses revealed more distinct differences in profiles of samples collected in different areas of the harbour, including the tributary. These results indicated that areas of coal tar-contaminated sediment are potential contributors to the overall contaminant burden of sediments and suspended sediments in Hamilton Harbour. These data also indicated that contaminants related to mobile combustion sources were entering the harbour via a major tributary. 相似文献
186.
Avian incubation dramatically reduces the abundance and diversity of microbial assemblages on eggshells, and this effect has
been hypothesized as an adaptive explanation for partial incubation, the bouts of incubation that some birds perform during
the egg-laying period. However, the mechanisms for these antimicrobial effects are largely unknown. In this study, we hypothesized
that microbial inhibition is partly achieved through removal of liquid water, which generally enhances microbial growth, from
eggshells, and experimentally tested this hypothesis in two ways. First, we placed the first- and second-laid eggs of tree
swallow (Tachycineta bicolor) clutches in unincubated holding nests with either ambient or increased water on eggshells. Second, we added water to eggshells
in naturally partially incubated nests. We compared microbial growth on shells during a 5-day experimental period and found
that, as predicted, both unincubated groups had higher microbial growth than naturally partially incubated controls, and that
only in the absence of incubation did wetted eggs have higher microbial growth than unwetted eggs. Thus, we have shown that
water increases microbial growth on eggshells and that incubation nullifies these effects, suggesting that removal of water
from egg surfaces is one proximate mechanism for the antimicrobial effects of incubation. 相似文献