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281.
Thomas Hari Roland von Arx Hans Ulrich Ammon Georg Karlaganis 《Environmental science and pollution research international》1996,3(1):32-38
The primary aim of this study was to evaluate the “clearance concept” as a tool for describing the behavior of xenobiotic movement into and through soils. As an example, degradation of 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine) with the formation of metabolites 2-chloro-6-isopropylamino-s-triazine (desethylatrazine) and 2-chloro-4-ethylamino-s-triazine (desisopropylatrazine) was investigated. Atrazine was sprayed post-emergently in doses of 0.125 or 0.5 g active ingredient/m2 each on four test plots. Soil type was a sandy-loam, on which corn (Zea mays L.) was cultivated. Soil samples were taken as cores of 0.2 m depth 0, 1, 2, 4, 8, 12, 16 and 20 weeks after application of atrazine, and analyzed by HPLC. Soil concentrations of atrazine were highly correlated (r=0.993, p< 0.001) between the two applications of 0.125 g/m2 and 0.5 g/m2. Up to 50% of the atrazine was measured as metabolites during the whole vegetation period. Clearance of atrazine from soil was calculated as the total load of atrazine divided by the area under the soil atrazine concentration time curve. Soil atrazine clearance was calculated as 5.13 +/? SD 1.10 and 5.17 +/? SD 1.02 liter of soil per day for doses of 0.125 g/m2 and 0.5 g/m2, respectively (from a “soil unit” of 1 × 1 × 0.2 meter). The clearance concept might be a tool for risk assessment of xenobiotics. 相似文献
282.
Ulrich Schlottmann 《Umweltwissenschaften und Schadstoff-Forschung》1997,9(2):107-108
Ohne Zusammenfassung 相似文献
283.
Wolf von Tümpling Peter Zeilhofer Ulrich Ammer Jürgen Einax Rolf -D. Wilken 《Environmental science and pollution research international》1995,2(4):225-228
As in many other parts of the world, gold is produced in the surface mining region of Poconé, Mato Grosso, Brazil, using mercury.
The goal of this investigation was to estimate the amount of mercury in certain tailings and to determine the area of the
land that has been contaminated by the gold mining operations. Mercury concentrations from 2 to 495 ng/g (dw) were determined
in the tailing materials. It was observed that only isolated sites were acting as central points of contamination. Using digital
Landsat satellite data (The-matic Mapper) and aerial photos, the sites degraded by the mining were classified, and their total
area was estimated to be 12.3 km2 in the region of Poconé. It was estimated, that 4.9 km2 were occupied by the contaminated tailings. The mean height of the pile slags was determined to be 4.5 m. From the experimentally
calculated average density of the material in the tailings, 2.01 g/cm3, the total mercury content in the piles of tailings was estimated to be 1600 ± 350 kg. 相似文献
284.
Detlev Kayser Ulrich R. Boehringer Friedrich Schmidt-Bleek 《Environmental monitoring and assessment》1982,1(3):241-255
Thousands of chemicals are on the market, but only in a few exceptional cases is it known where these chemicals remain in the environment and what effects they are able toexert in correlation to their environmental concentration. In addition to monitoring the actual concentrations of chemicals in the environment, it is necessary to establish an environmental specimen banking program which will, in the future, make possible the retrospective monitoring of chemicals. The feasibility of such a program is being studied in a joint U.S.-German pilot project. The German project is described here, including its organizational structure, technical and scientific considerations, and methods of specimen selection. 相似文献
285.
286.
Pr?ambel
Ziel und Absicht Zur Entwicklung eines Bewusstseins für die Artenvielfalt in unserer Umwelt hat die Zeitschrift GEO 1999 den ‚Tag der Artenvielfalt’
ausgerufen. Seitdem finden jedes Jahr europaweit Feldforschungsaktionen statt. Für Bayer Industry Services ist die Artenbestimmung
auf der Sonderabfalldeponie in Bürrig eine Gelegenheit zu zeigen, dass sich Umweltschutz und fachgerechte Deponierung von
Sonderabf?llen nicht widersprechen.
Methoden Die Teilnehmer am ‚Tag der Artenvielfalt’ bestimmen selbst, welches Gel:ande sie untersuchen wollen. Innerhalb eines Tages
im Juli werden die dort vorkommenden Tier- und Pflanzenarten bestimmt und an GEO gemeldet.
Ergebnisse und Schlussfolgerungen Innerhalb eines Nachmittages wurden 47 Pflanzen-, 25 Vogel- und 7 weitere Tierarten bestimmt. Das Interesse der Teilnehmer
an der Naturbeobachtung wurde durch die Aktion gef?rdert. Weitere Termine zur Bestimmung der Artenvielfalt wurden vereinbart.
Empfehlung und Ausblick Zur genauen Beobachtung eines definierten Naturraumes ist die Begehung zu unterschiedlichen Jahreszeiten sinnvoll. Bei Schulklassen
müssen die Exkursionen mit dem Lehrplan abgestimmt werden. 相似文献
287.
Jose de Anda Harvey Shear Ulrich Maniak Pedro F. Zdrate‐del Valle 《Journal of the American Water Resources Association》2004,40(1):97-109
ABSTRACT: Lake Chapala is the largest natural water body in Mexico and also one of the most important shallow lakes in Latin America. For the past several years it has suffered various environmental problems such as the upstream overuse of water, contamination, and sedimentation. For the past 10 years the lake has had less than 50 percent of its historical water level over the past century. No criteria are reported in the literature that establish a water storage volume that will guarantee water quality conditions necessary for the survival of the lake. After determining the behavior of total solids concentrations in relation to the variations in the lake's depth, we proposed a minimum water column height of 5.0 m, representing a storage volume of about 5,000 Mm3. This volume would result in the recommended water quality standards for total dissolved solids. Calculated distribution maps show that the total solids concentration in the lake has increased since the end of the 1970s. The solids are primarily concentrated in the eastern part of the lake, as a consequence of the high solids discharged from the Lerma River, its main tributary. 相似文献
288.
289.
King brown snakes or mulga snakes (Pseudechis australis) are the largest and among the most dangerous and wide-ranging venomous snakes in Australia and New Guinea. They occur in diverse habitats, are important predators, and exhibit considerable morphological variation. We infer the relationships and historical biogeography of P. australis based on phylogenetic analysis of 1,249 base pairs from the mitochondrial cytochrome b, NADH dehydrogenase subunit 4 and three adjacent tRNA genes using Bayesian, maximum-likelihood, and maximum-parsimony methods. All methods reveal deep phylogenetic structure with four strongly supported clades comprising snakes from New Guinea (I), localities all over Australia (II), the Kimberleys of Western Australia (III), and north-central Australia (IV), suggesting a much more ancient radiation than previously believed. This conclusion is robust to different molecular clock estimations indicating divergence in Pliocene or Late Miocene, after landbridge dispersal to New Guinea had occurred. While members of clades I, III and IV are medium-sized, slender snakes, those of clade II attain large sizes and a robust build, rendering them top predators in their ecosystems. Genetic differentiation within clade II is low and haplotype distribution largely incongruent with geography or colour morphs, suggesting Pleistocene dispersal and recent ecomorph evolution. Significant haplotype diversity exists in clades III and IV, implying that clade IV comprises two species. Members of clade II are broadly sympatric with members of both northern Australian clades. Thus, our data support the recognition of at least five species from within P. australis (auct.) under various criteria. We discuss biogeographical, ecological and medical implications of our findings.Electronic Supplementary Material Supplementary material is available in the online version of this article at 相似文献
290.
Herbert Jäckle Ulrike Gaul Ulrich Nauber Nicole Gerwin Michael J. Pankratz Eveline Seifert Reinhard Schuh Detlef Weigel 《Die Naturwissenschaften》1989,76(11):512-517
Drosophila proved an excellent system to study molecular processes in establishing the body pattern of an embryo. Genes which are active during oogenesis provide localized cues which regulate a cascade of zygotic genes that determines the developmental fate of the blastoderm cells along the longitudinal axis of the embryo. 相似文献