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621.
In Ireland, mussels on exposed rocky shores constitute an interbreeding mixture of two forms of mussels, the blue mussel,
Mytilus edulis, and the Mediterranean mussel, M. galloprovincialis. Results from an Irish study in the 1980s, using partially diagnostic allozyme markers, indicated that mussels higher up
the shore were more galloprovincialis-like than those lower down. In this study we set out to test two hypotheses: (a) recruits arriving on the shore are composed
of genetically distinct cohorts that settle preferentially at different levels on the shore, and maintain genetic distinctiveness
into adulthood; (b) recruits are genetically homogeneous, but once settled they diverge genetically over time, due to within-habitat
site specific-selection. The diagnostic Me 15/16 DNA marker was used to analyse the genetic composition of newly-settled spat recruiting to artificial substrates, which were
placed at two-week intervals from May–October 2002, on the mid- and low shore areas of two exposed sites in Galway Bay. Adult
mussels were also collected on each sampling date. Results did not support the preferential settlement hypothesis, i.e., the
genetic composition of primary settlers (≤ 500 μm) was similar between tidal heights and shores. Neither was there evidence
of post settlement selective mortality, as adults were genetically similar to settling spat. In spat and adults the frequency
of the M. galloprovincialis allele was high (0.56–0.80), due to high frequencies of M. galloprovincialis (> 37%) and hybrid (> 33%) genotypes, and correspondingly low frequencies of the M. edulis genotype (< 11%). Adult mussels from a nearby sheltered estuarine site, while significantly different to exposed shore mussels,
still had low frequencies of the M. edulis genotype (< 17%), indicating no apparent advantage for the genotype in this environment. There are indications that the genetic
composition of mussels may be changing on the Atlantic coasts of Ireland. 相似文献
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623.
Unplanned natural and anthropogenic disasters provide unique opportunities for investigating the influence of perturbations on population vital rates and species recovery times. We investigated the potential effects of a major pesticide spill by comparing annual survival rates using mark-recapture techniques on a riparian bat species, Yuma Myotis (Myotis yumanensis). Demography and population dynamics for most bat species remain poorly understood despite advances in mark-recapture estimation and modeling techniques. We compared survival and population growth rates of two roost populations exposed to a large chemical (metam sodium) spill in the upper Sacramento River in Northern California with two roost populations outside the contaminated area from 1992 to 1996. Hypotheses about long-term effects of the spill on female juvenile and adult survival were tested using an information-theoretic approach (AIC). Working hypotheses included effects of age, chemical spill, and time trend on survival. Female adult survival was higher than female juvenile survival across all sites, suggesting stage-specific mortality risks. Model-averaged estimates of female juvenile survival in the contaminated area (0.50-0.74) were lower than in control roosts (0.60-0.78) for each year in the study, suggesting that the spill may have reduced juvenile survival for several years. Female adult survival (0.73-0.89) did not appear to be strongly affected by the spill during the years of the study. There was an increase in survival for both stage-classes across all populations during the study period, which may have been caused by the end of an extended drought in California in the winter of 1993. The spill-affected population was in decline for the first year of the study as indicated by an estimated growth rate (lambda) < 1, but population growth rates increased during the four-year period. 相似文献
624.
Perez-Perez E Rodríguez-Malaver AJ 《Journal of environmental biology / Academy of Environmental Biology, India》2005,26(3):603-608
The effect of Kraft black liquor on the lipid peroxidation of rat homogenates was examined. The lipid peroxidation of homogenates from different organs (kidney, brain, lung, and liver) was induced by Fenton's reagent. The products of lipid peroxidation, lipid hydroperoxides and TBARS were measured by FOX method and TBA assay, respectively. It was found that black liquor significantly reduced the concentration of TBARS, but not the concentration of lipid hydroperoxides. This inhibition was directly proportional to the concentration of Kraft black liquor and the incubation temperature. Conclusively, the black liquor from pulp and paper industry exhibited an antioxidant activity. 相似文献
625.
Is There a Link between Wild Meat and Food Security? 总被引:2,自引:0,他引:2
Elizabeth L. Bennett 《Conservation biology》2002,16(3):590-592
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Summary
Cnemidophorous uniparens, an all-female, parthenogenetic species of whiptail lizard (Teiidae), were housed in the laboratory under seminatural conditions in groups of four, in pairs, or as isolates. Group structure and an animal's position in the dominance hierarchy affect reproductive effort. Housed in pairs, the dominant animals exhibit a higher rate of reproduction, as measured by number of clutches and length of clutch cycle, than do their subordinate cagemates. Females housed with dihydrotestosterone-treated ovariectomized females lay more clutches than females housed with ovariectomized hormone-untreated females, those housed with intact females, or housed alone. 相似文献
628.
Elizabeth Kline 《Local Environment》2000,5(3):343-350
Eco-cities strive to become more liveable, enjoyable, and healthy. Indicators can be an effective mechanism for understanding people's values, needs, concerns, and expectations; guiding development decisions; evaluating progress and making revisions; and gaining support for desired actions. This Viewpoint describes how sustainability indicators can be developed to measure a community's environment, economy, quality of life, and governance. Five helpful hints are offered to guide this process. 相似文献
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