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161.
162.
An Overview of Contaminant-Related Issues Identified by Monitoring in San Francisco Bay 总被引:1,自引:0,他引:1
Bruce Thompson Rainer Hoenicke Jay A. Davis Andrew Gunther 《Environmental monitoring and assessment》2000,64(1):409-419
The San Francisco Estuary Regional Monitoring Program for Trace Substances (RMP) began in 1993 and is sponsored by 74 local, state, and federal agencies and companies through their discharge or Bay use permits. The RMP monitors water, sediment, toxicity, and bivalve bioaccumulation at 25 sites in the Bay that are considered to represent "background" conditions. Several major environmental issues have been identified by the RMP. Polychlorinated biphenyls and mercury were often above water quality guidelines, and often occurred in fish tissues above U.S. Environmental Protection Agency (U.S. EPA) screening values. Concentrations do not appear to be decreasing, suggesting continuing inputs. Episodes of aquatic toxicity often occurred following runoff events that transport contaminants into the Bay from urbanized and agricultural portions of the watershed. Sediment toxicity occurred throughout the Bay, and has been correlated with concentrations of specific contaminants (chlordanes, polynuclear aromatic hydrocarbons) at some locations; mixtures of contaminants were probably also important. Since the RMP does not monitor all ecosystem components, assessments of the overall condition of the Bay cannot be made. However, in terms of contamination, the RMP samples suggest that the South Bay, and North Bay sites are moderately contaminated. 相似文献
163.
164.
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
165.
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
166.
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
167.
168.
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
169.
Nature for water: Ecosystem services and water management 总被引:2,自引:0,他引:2
170.
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