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161.
Cacops, one of the most distinctive Paleozoic amphibians, is part of a clade of dissorophoid temnospondyls that diversified in the
equatorial region of Pangea during the Late Carboniferous and Early Permian, persisting into the Late Permian in Central Russia
and China. Dissorophids were a successful group of fully terrestrial, often spectacularly armoured predators, the only amphibians
apparently able to coexist with amniotes when the latter started to dominate terrestrial ecosystems. In this paper, we describe
excellent new skulls from the Early Permian of Oklahoma attributed to Cacops, Cacops morrisi sp. nov. and provide for the first time detailed information about this iconic dissorophid. These specimens show anatomical
and ontogenetic features that will impact on future studies on the evolution of terrestriality in tetrapods. For example,
the large, posteriorly closed tympanic embayment has fine striations on an otherwise smooth surface, documenting the oldest
known clear evidence for the presence of a tympanic membrane in the fossil record, a structure that is used for hearing airborne
sound in extant tetrapods. The skull of C. morrisi also has several features associated with predatory behaviour, indicating that this dissorophid may have been one of the
top terrestrial predators of its time. 相似文献
162.
Ahmad B. Moradi Héctor M. Conesa Brett H. Robinson Eberhard Lehmann Anders Kaestner Rainer Schulin 《Environmental pollution (Barking, Essex : 1987)》2009,157(8-9):2189-2196
We compared root responses of the Ni-hyperaccumulator plant Berkheya coddii Rossler with the non-accumulator plant Cicer arietinum L. to Ni heterogeneity in soil. We grew plants in growth containers filled with control soil, homogeneously spiked, and heterogeneously spiked soil with Ni concentrations of 62 and 125 mg kg?1. Neutron radiography (NR) was used to observe the root distribution and the obtained images were analysed to reveal the root volumes in the spiked and unspiked segments of the growth container. There was no significant difference in root distribution pattern of B. coddii among different concentrations of Ni. Unlike B. coddii, the roots of C. arietinum initially grew into the spiked segments. However, the later developing roots did not penetrate the spiked segment suggesting an avoidance strategy. Our results indicate that, B. coddii does not forage towards the Ni-rich patches, although presence of Ni in soil changes its root morphology. 相似文献
163.
Stefan Siebert Friederike Anton-Erxleben Rainer Kiko Maike Kramer 《Marine Biology》2009,156(4):541-554
Various cnidarians have adapted their life style to interstitial habitats of marine sediments. Recently, for the first time
a hydroid was reported from the interstitial brine channel system of Arctic fast ice. Due to its derived features, the new
genus and species Sympagohydra tuuli was introduced. Here we describe findings of S. tuuli in sea ice at several sites within the central Arctic Ocean. In our view the results of this study do not allow assignment
of Sympagohydra to any known family and we, therefore, suggest the introduction of a new family Sympagohydridae which is placed within the
hydrozoan subclass Hydroidolina, order Anthomedusae, suborder Capitata. A first detailed histological analysis of S. tuuli is presented. In vivo analysis of locomotion and reproduction revealed a remarkable convergent evolution in S. tuuli and distant meiobenthic relatives. Shared traits are a flagellated epidermis enabling the animals to glide within small interstices
by means of flagellar beating as well as an internalised embryogenesis. In S. tuuli gametogenesis occurs in the absence of gonophores inbetween gastro- and epidermis clearly separated from the epidermis. Budding
was observed as the vegetative mode of reproduction. Documentation of feeding behaviour identified copepod nauplii and rotifers
as prey items and demonstrates a high trophical position of the hydroids within the sympagic food web. Occurrence of reproducing
individuals and pronounced tolerances towards changing temperatures and salinities indicate S.
tuuli as a truly sympagic species.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
164.
165.
What catch data can tell us about the status of global fisheries 总被引:1,自引:0,他引:1
The only available data set on the catches of global fisheries are the official landings reported annually by the Food and
Agriculture Organization of the United Nations (FAO). Attempts to detect and interpret trends in these data have been criticized
as being both technically and conceptually flawed. Here, we explore and refute these claims. We show explicitly that trends
in catch data are not an artifact of the applied method and are consistent with trends in biomass data of fully assessed stocks.
We also show that, while comprehensive stock assessments are the preferred method for evaluating single stocks, they are a
biased subsample of the stocks in a given area, strongly underestimating the percentage of collapsed stocks. We concur with
a recent assessment-based analysis by FAO that the increasing trends in the percentage of overexploited, depleted, and recovering
stocks and the decreasing trends in underexploited and moderately exploited stocks give cause for concern. We show that these
trends are much more pronounced if all available data are considered. 相似文献
166.
Nature for water: Ecosystem services and water management 总被引:2,自引:0,他引:2
167.
Rainer Haas 《Environmental Sciences Europe》1998,10(4):198-199
2-Chlorovinylarsine dichloride (Lewisite I) and 2,2′-dichlorodivinylarsine chloride (Lewisite II) react by room temperature rapidly and quantitatively with dithiols in a substitution reaction. The derivatives were identified with mass spectrometry. They can be detected with GC/ECD. This reactions can be used for the gas chromatographic detection of Lewisites in water and soil samples. 相似文献
168.
Rainer Haas Alfred Krippendorf 《Environmental science and pollution research international》1997,4(3):123-124
A gas Chromatographic method for the determination of phenylarsenic compounds (sternutators) and their metabolites in soil and material samples is described. The chemical warfare agents (CWA), but not their hydrolysis and oxidation products, can be detected with GC/ECD. After derivatization with thiols or dithiols, the sum of diphenylarsenic and phenylarsenic compounds can be determined with GC/ECD. The comparison of the analytical results with and without derivatization shows that the sternutators in the investigated samples are metabolized in part. 相似文献
169.
This study investigates the stabilization of As in the contaminated sludge after treatment with MnO(2) or Ca(OH)(2), and the influence of the stabilizing materials on the leachability of the co-existing elements Pb and Zn. By exploiting a continuous-flow assembly facilitating a modified Wenzel's sequential extraction scheme (designed for the fractionation of arsenic), it is possible to ascertain the leachability, mobility and fractional alteration of these elements under stimulated natural (flow-through) leaching conditions. The fractionation data show that more than 80% of As, Pb and Zn in the untreated sludge are bound in the amorphous Fe oxides fraction and residual fraction. The addition of MnO(2) has only an insignificant effect on As fractional transformation, while Ca(OH)(2) caused an increase in As mobility. For Pb, the decrease in leachability was clearly visible. The extractable Pb was reduced by 18% and 40% in stabilized MnO(2) and Ca(OH)(2) sludge samples, respectively. Unlike that of Pb, the mobility of Zn was not affected by the additives used. Their fractional distribution patterns before and after the stabilization process remained the same. The ability to produce detailed leaching profiles for As and other elements (Pb, Zn, Ca, Mn and Fe) meant that elemental associations in individual fractions could be examined. From the MnO(2)-treated sludge, the coincidence of the As, Pb, Zn, Fe, and Mn peaks seems to indicate a close association of these elements in the Fe-oxides-bound fraction. Furthermore, the leaching profiles may be used as evidence of a strong affinity between these elements and added MnO(2). 相似文献
170.
Birgit Reger Patrick Sheridan Dietmar Simmering Annette Otte Rainer Waldhardt 《Environmental management》2009,43(6):1026-1038
Farmland habitat diversity in marginal European landscapes changed significantly in the past decades. Further changes toward
homogenization are expected, particularly in the course of European agricultural policy. Based on three alternative transfer
payment schemes, we modeled spatially explicit potential effects on the farmland habitat diversity in a marginal European
landscape. We defined (1) a scenario with direct transfer payments coupled to production, (2) a scenario with direct transfer
payments decoupled from production, and (3) a scenario phasing out all direct transfer payments. We characterized habitat
diversity with three indices: habitat richness, evenness, and rarity. The habitat pattern in 1995 served as reference for
comparison. All scenarios predicted a general trend of homogenization of the farmland habitat pattern, yet to a differing
extent. Transfer payments coupled to production (Scenario 1) favored the abandonment of agricultural production, particularly
in low-productive areas and arable land use in more productive areas. Habitat richness and habitat evenness had intermediate
values in this scenario. Decoupling transfer payments from production (Scenario 2) supported grassland as most profitable
farming system. This led to a grassland-dominated landscape with low values of all habitat diversity indices. Phasing out
transfer payments (Scenario 3) resulted in complete abandonment or afforestation of agricultural land and extremely low values
in all habitat diversity indices. Scenario results indicate that transfer payments may prevent cessation of agricultural production,
but may not counteract homogenization in marginal landscapes. Conserving high farmland habitat diversity in such landscapes
may require support schemes, e.g., Pillar Two of EU Common Agricultural Policy. 相似文献