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871.
Rainer Haas Alfred Krippendorf und Klaus Steinbach 《Umweltwissenschaften und Schadstoff-Forschung》1997,9(5):243-244
Zusammenfassung Phenylarsindichlorid (PFIFFIKUS) reagiert bei Raumtemperatur in einer Gleichgewichtsreaktion schnell mit Alkoholen unter Bildung
von Phenylarsinbisether und Phenylarsinchloridether. Die Reaktionen verlaufen nicht quantitativ. Die Derivate wurden massenspektrometrisch
identifiziert.
相似文献
872.
Jochen Harnisch Reinhard Borchers Peter Fabian 《Environmental science and pollution research international》1995,2(4):229-232
Measurements of carbonyl sulfide (COS) and carbondisulfide (CS2) were carried out on samples drawn from a smoke stack of an aluminium smelter. Volume mixing ratios of 6 ppm COS and 0.1
ppm CS2 were measured for gases from the electrolysis unit that had previously passed an Al2O3 fluid bed reactor and electrostatic precipitators. Specific emissions of 1.6 kg COS and 0.03 kg CS2 per ton of primary aluminium were found. Extrapolating from this particular smelter’s conditions to a world mix specific
COS emissions of about 4 kg/t(Al) are calculated resulting in emissions of annually 0.08 Tg COS into the atmosphere due to
electrolytic aluminium production in 1995. Besides the photochemical conversion of anthropogenic CS2 aluminium production is established to be the second major industrial source of COS probably exceeding automotive tire wear’s
and coal combustion’s contributions. 相似文献
873.
874.
875.
Daniel R Engstrom Shawn P Schottler Peter R Leavitt Karl E Havens 《Ecological applications》2006,16(3):1194-1206
Lake Okeechobee, the hydrological lynchpin of the Everglades ecosystem, is the subject of an ambitious, multiagency restoration effort aimed at reducing phosphorus inputs and resulting algal blooms and impaired water clarity. This restoration is predicated on returning the lake to something closer to its predisturbance condition, but that goal has been challenged on the premise that the lake has always been eutrophic. The resolution of this debate and the appropriateness of the nutrient reduction goals thus depend on obtaining a reliable sediment record of past limnological conditions--the aim of this study. Because of the potential for severe sediment mixing from tropical storms, this investigation used multiple dating tools to examine the integrity of the sediment record and then analyzed proxies for nutrient enrichment, phytoplankton composition, and paleoproductivity. Sediment profiles for atmospheric pollutants, fertilizer contaminants, and radiocesium from three widely spaced cores showed good preservation of stratigraphic detail and coherence with the 210Pb chronologies. These results demonstrated that sediment stratigraphy is largely intact and retains a reliable record of limnological change. Geochemical proxies provide strong evidence of increased nutrient loading beginning ca. 1950. Concentrations of sediment P double, and N:P and C:N ratios drop, while those for N isotopes (delta15N) increase. At the same time, tracers of phosphate fertilizers (uranium, vanadium, and arsenic) rise. These changes are synchronous among cores and constitute a robust, internally consistent record of increasing water-column P. Biotic responses are manifested in higher concentrations and in changing composition of fossil algal pigments, including (1) large increases in the concentrations of chemically robust carotenoids, (2) corresponding decreases in the ratios of pigments from diatoms to chlorophyte and cyanobacterial algae, and (3) increases in UVR-photo-protective compounds indicating greater prevalence of surface algal blooms. This study provides strong evidence that Lake Okeechobee has experienced accelerated eutrophication linked with post-1950s land use changes in its watershed, a conclusion consistent with the nutrient reduction goals of the Lake Okeechobee Protection Program. The results contradict recent claims that the lake's trophic state has not changed over time, as well as the assertion that sediments of large shallow lakes cannot support a reliable chronology of past events. 相似文献
876.
877.
The purpose of this paper is to develop a set of associated statistical tests for spatial clustering. In particular, a set
of three associated tests will be developed; these will correspond to the three types of tests set out by Besag and Newell
(general tests, focused tests, and tests for the detection of clustering). The associated tests draw primarily, though not
exclusively, upon existing tests and results. The principal contributions are based upon the score statistic for focused tests,
which has been an important approach to testing for clustering around environmental hazards. The first contribution consists
of the formulation of a global statistic for general tests that corresponds to focused score statistics, along with an assessment
of the distribution of the statistic under the null hypothesis of no raised incidence. The local score statistics used for
focused tests will have the property of summing to the global statistic used for the corresponding general test. Attention
is also given to the maximum local score statistic for the “test for the detection of clustering”. The critical values of
this statistic which are required for testing the null hypothesis are described. Application of the methods is made to leukemia
data for central New York State. 相似文献
878.
879.
Vegetation Diversity after Logging in the Southern Appalachians 总被引:1,自引:0,他引:1
880.
After the discovery of high dioxin levels (>100 000 ng TE BGA/kg) in copper slag (Kieselrot) from a specific chlorinating roasting process performed in Marsberg, human milk samples from mothers living in Marsberg were analyzed for polychlorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF) and other pollutants. PCDD/F levels in all samples were comparable with levels in human milk samples from other locations in the Federal Republic of Germany. An increase in congeners, especially of those predominating in ?Kieselrot“, could not be measured. Although several thousand tons of dioxin contaminated copper slag still lie on the slagheap, a higher burden in human milk from Marsberg could not be observed. 相似文献