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41.
Parasite transmission in complex communities: predators and alternative hosts alter pathogenic infections in amphibians 总被引:1,自引:0,他引:1
While often studied in isolation, host-parasite interactions are typically embedded within complex communities. Other community members, including predators and alternative hosts, can therefore alter parasite transmission (e.g., the dilution effect), yet few studies have experimentally evaluated more than one such mechanism. Here, we used data from natural wetlands to design experiments investigating how alternative hosts and predators of parasites mediate trematode (Ribeiroia ondatrae) infection in a focal amphibian host (Pseudacris regilla). In short-term predation bioassays involving mollusks, zooplankton, fish, larval insects, or newts, four of seven tested species removed 62-93% of infectious stages. In transmission experiments, damselfly nymphs (predators) and newt larvae (alternative hosts) reduced infection in P. regilla tadpoles by -50%, whereas mosquitofish (potential predators and alternative hosts) did not significantly influence transmission. Additional bioassays indicated that predators consumed parasites even in the presence of alternative prey. In natural wetlands, newts had similar infection intensities as P. regilla, suggesting that they commonly function as alternative hosts despite their unpalatability to downstream hosts, whereas mosquitofish had substantially lower infection intensities and are unlikely to function as hosts. These results underscore the importance of studying host-parasite interactions in complex communities and of broadly linking research on predation, biodiversity loss, and infectious diseases. 相似文献
42.
An Seongnam Kang Peter K. Stuyfzand Pieter J. Lee Woonghee Park Saerom Yun Seong-Taek Lee Seunghak 《Environmental geochemistry and health》2021,43(9):3583-3596
Environmental Geochemistry and Health - Various hydrogeochemical processes can modify the quality of river water during riverbank filtration (RBF). Identifying the subsurface processes responsible... 相似文献
43.
Ab Grootjans Rohani Shahrudin Annelies van de Craats Annemieke Kooijman Gerard Oostermeijer Jörg Petersen Donovan Amatirsat Chantal Bland Pieter Stuyfzand 《Journal of Coastal Conservation》2017,21(5):631-641
The present study aims at assessing the life span of populations of the orchid L. loeselii during successional in dune slacks on the Wadden Sea islands. An inventory of Liparis loeselii populations was carried out on 6 islands, while the population structure was assessed in more detail on the island of Texel. The occurrence of the orchid was related to soil factors and hydrological conditions. Groundwater levels were measured in a dune area with natural dune slack formation. The groundwater composition was analyses and the freshwater lenses were modelled. Various scenarios were investigated, including sea level rise and sand nourishment. The window of opportunity for L. loeselii to colonize a new slack is relatively narrow. Under favorable management, the population can survive c. 20 years. Soil pH was positively correlated with the occurrence of L. loeselii populations, while a high organic matter content was negatively correlated. Sites with large populations of L. loeselii, were situated in young dune slacks, that functioned as flow-through lakes and has top soilsinfluenced by anoxic calcareous groundwater. Modelling showed that the freshwater lens would decrease due to sea level rise, while artificial sand nourishment could counteract this effect. The populations of the Hors area on Texel, the Netherlands, can survive for several decades due to continuous formation of new slacks. Discharge of calcareous groundwater is essential to keep the pH on a high level. The hydrological systems that supply dune slack with groundwater are relatively small and are vulnerable for changes in sea level rise. 相似文献
44.
Christopher W. Woodall Jacques Rondeux Pieter J. Verkerk Göran Ståhl 《Environmental management》2009,44(4):624-631
Efforts to assess forest ecosystem carbon stocks, biodiversity, and fire hazards have spurred the need for comprehensive assessments
of forest ecosystem dead wood (DW) components around the world. Currently, information regarding the prevalence, status, and
methods of DW inventories occurring in the world’s forested landscapes is scattered. The goal of this study is to describe
the status, DW components measured, sample methods employed, and DW component thresholds used by national forest inventories
that currently inventory DW around the world. Study results indicate that most countries do not inventory forest DW. Globally,
we estimate that about 13% of countries inventory DW using a diversity of sample methods and DW component definitions. A common
feature among DW inventories was that most countries had only just begun DW inventories and employ very low sample intensities.
There are major hurdles to harmonizing national forest inventories of DW: differences in population definitions, lack of clarity
on sample protocols/estimation procedures, and sparse availability of inventory data/reports. Increasing database/estimation
flexibility, developing common dimensional thresholds of DW components, publishing inventory procedures/protocols, releasing
inventory data/reports to international peer review, and increasing communication (e.g., workshops) among countries inventorying
DW are suggestions forwarded by this study to increase DW inventory harmonization. 相似文献
45.
By means of questionnaires, 100 women were asked for their experiences concerning prenatal diagnosis. At four standardized stages of the pregnancy a questionnaire was filled in asking for: expectation, knowledge, attitude towards termination of the pregnancy in case of abnormal findings, reactions to the counselling and the obstetric treatment, interpretation of own risk, experiences since the normal test results were known and ideas to improve the treatment. With regard to the effect of pre-amniocentesis counselling it is concluded that the counselling had little impact on decision making; the counselling caused an increase of factual knowledge: somewhat more than half of the women who did not give a correct answer before counselling, indicated the right answer some time afterwards. Presumed differences in reaction patterns for a number of characteristics were not affirmed by the study; the reactions during the procedure of prenatal diagnosis seem to be highly individual and difficult to predict. In addition to the reactions of the 100 women described in this study, the responses to the first questionnaire of another 16 patients, declining amniocentesis after counselling, are presented. 相似文献
46.
This paper describes the modeling of the hydrogeochemical effects of deep well recharge of oxic water into an anoxic pyrite-bearing aquifer. Kinetic expressions have been used for mineral dissolution-precipitation rates and organic matter oxidation. Hydrological and chemical parameters of the model were calibrated to field measurements. The results showed that oxidation of pyrite (FeS(2)) and, to a lesser extent, organic matter dominate the changes in quality of the recharged water during its passage through the aquifer. The recharge leads to the consumption of oxygen and nitrate and the formation of sulfate and ferrihydrite. Complexation reactions, cation exchange and precipitation and dissolution of calcite, siderite and rhodochrosite were also identified through the modeling. Despite problems of non-uniqueness of the calibrated parameters, the model was used successfully to depict the geochemical processes occurring in the aquifer. Non-uniqueness can be avoided by constraining the model as much as possible to measurements and/or data from literature, although they cannot be considered always as fixed values and should be considered as stochastic variables instead. 相似文献
47.
Tina Heger Anna T. Pahl Zoltan Botta-Dukát Francesca Gherardi Christina Hoppe Ivan Hoste Kurt Jax Leena Lindström Pieter Boets Sylvia Haider Johannes Kollmann Meike J. Wittmann Jonathan M. Jeschke 《Ambio》2013,42(5):527-540
Invasion ecology has much advanced since its early beginnings. Nevertheless, explanation, prediction, and management of biological invasions remain difficult. We argue that progress in invasion research can be accelerated by, first, pointing out difficulties this field is currently facing and, second, looking for measures to overcome them. We see basic and applied research in invasion ecology confronted with difficulties arising from (A) societal issues, e.g., disparate perceptions of invasive species; (B) the peculiarity of the invasion process, e.g., its complexity and context dependency; and (C) the scientific methodology, e.g., imprecise hypotheses. To overcome these difficulties, we propose three key measures: (1) a checklist for definitions to encourage explicit definitions; (2) implementation of a hierarchy of hypotheses (HoH), where general hypotheses branch into specific and precisely testable hypotheses; and (3) platforms for improved communication. These measures may significantly increase conceptual clarity and enhance communication, thus advancing invasion ecology. 相似文献
48.
Arctostylopids are common in Late Palaeocene and Early Eocene mammal faunas of Asia, but they are rare in North America. From the time of their first discovery, arctostylopids were grouped with the strictly endemic South American Notoungulata based on their strikingly similar dental morphology. This relationship was challenged based on dental morphology of more recently discovered arctostylopids and on supposed tarsal morphology (based on unassociated material) of the Asian arctostylopid Palaeostylops. Therefore, Arctostylopidae were placed in a separate order, Arctostylopida, of enigmatic affinities. Many authors, however, continue to unite Arctostylopidae and Notoungulata based on dental similarities. In the Late Palaeocene Subeng site in Inner Mongolia, we identified the Palaeostylops tarsals based on their size and abundance. This identification is supported by comparison to unpublished Arctostylops tarsals from the North American Clarkforkian, derived from a semi-articulated skeleton also including dental material. Tarsal morphology shows moderate similarity to the gliriform Pseudictops, and strong resemblance to the tarsally conservative gliroid Rhombomylus. Hence, Arctostylopidae may best be grouped with Asian non-gliroid Gliriformes, which we interpret as having dispersed into North America in the Late Palaeocene.Pieter Missiaen is an aspirant of the Research Foundation-Flanders (RF-Flanders) 相似文献
49.
Despite the widespread introduction of nonnative species and the heterogeneity of ecosystems in their sensitivity to ecological impacts, few studies have assessed ecosystem vulnerability to the entire invasion process, from arrival to establishment and impacts. Our study addresses this challenge by presenting a probabilistic, spatially explicit approach to predicting ecosystem vulnerability to species invasions. Using the freshwater-rich landscapes of Wisconsin, USA, we model invasive rusty crayfish (Orconectes rusticus) as a function of exposure risk (i.e., likelihood of introduction and establishment of O. rusticus based on a species distribution model) and the sensitivity of the recipient community (i.e., likelihood of impacts on native O. virilis and O. propinquus based on a retrospective analysis of population changes). Artificial neural networks predicted that approximately 10% of 4200 surveyed lakes (n = 388) and approximately 25% of mapped streams (23 523 km total length) are suitable for O. rusticus introduction and establishment. A comparison of repeated surveys before vs. post-1985 revealed that O. virilis was six times as likely and O. propinquus was twice as likely to be extirpated in streams invaded by O. rusticus, compared to streams that were not invaded. Similarly, O. virilis was extirpated in over three-quarters of lakes invaded by O. rusticus compared to half of the uninvaded lakes, whereas no difference was observed for O. propinquus. We identified 115 lakes (approximately 3% of lakes) and approximately 5000 km of streams (approximately 6% of streams) with a 25% chance of introduction, establishment, and extirpation by O. rusticus of either native congener. By identifying highly vulnerable ecosystems, our study offers an effective strategy for prioritizing on-the-ground management action and informing decisions about the most efficient allocation of resources. Moreover, our results provide the flexibility for stakeholders to identify priority sites for prevention efforts given a maximum level of acceptable risk or based on budgetary or time restrictions. To this end, we incorporate the model predictions into a new online mapping tool with the intention of closing the communication gap between academic research and stakeholders that requires information on the prospects of future invasions. 相似文献
50.
Erik Meers Pieter Vervaeke Filip M.G. Tack Noel Lust Marc Verloo Els Lesage 《补救:环境净化治理成本、技术与工艺杂志》2003,13(3):87-97
Remediation of heavy metal contamination in soil is a widespread environmental issue. Conventional remediation techniques are invasive and often too expensive, particularly if large areas of soil are contaminated. Phytoremediation is the use of plants to remediate soil and groundwater. Phytoremediation of inorganic comtaminants such as metals can be further catagorized into phytostabilization and phytoextraction. These techniques have gained an increasing amount of attention and research over the last ten years. Phytoextraction of heavy metals and periodical removal of harvestable plant parts results in a gradual decrease of pollutant levels in the top soil. Woody species such as Salix sp. (willow) do not represent the fastest phytoextraction procedure compared to uptake by herbaceous species; however, they offer the added advantage of possible reuse of the produced biomass (wood) for the production of renewable energy. Here we present the results of a field experiment conducted to evaluate the use of Salix to remediate soil contaminated with cadmium and zinc at a dredged sediment disposal site in Flanders, Belgium. © 2003 Wiley Periodicals, Inc. 相似文献