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951.
Richard A. Holland 《Behavioral ecology and sociobiology》2007,61(5):653-660
Bats have been extensively studied with regard to their ability to orient, navigate and hunt prey by means of echolocation,
but almost nothing is known about how they orient and navigate in situations such as migration and homing outside the range
of their echolocation system. As volant animals, bats face many of the same problems and challenges as birds. Migrating bats
must relocate summer and winter home ranges over distances as far as 2,000 km. Foraging bats must be able to relocate their
home roost if they range beyond a familiar area, and indeed circumstantial evidence suggests that these animals can home from
more than 600 km. However, an extensive research program on homing and navigation in bats halted in the early 1970s. The field
of bird navigation has advanced greatly since that time and many of the mechanisms that birds are known to use for navigation
were not known or widely accepted at this time. In this paper I discuss what is known about orientation and navigation in
bats and use bird navigation as a model for future research in bat navigation. Technology is advancing such that previous
difficulties in studying orientation in bats in the field can be overcome and so that the mechanisms of navigation in this
highly mobile animal can finally be elucidated. 相似文献
952.
Konstantinos Ganias 《Marine Biology》2008,155(3):293-301
Using previously published histological data on multiple, monthly samples of Sardina pilchardus collected in the central Aegean and Ionian Seas (September 1999–August 2000, and November 2000–February 2001), the Mediterranean
sardine was treated as a case study to investigate the biological characteristics of ephemeral spawning aggregations in multiple-spawning
clupeoids. Actively spawning (Day0) females in the Mediterranean sardine, i.e., the daily class of spawners caught a few hours prior, during, or after the spawning
act, were shown to separate spatially from late (Day1+) spawners and non-spawning females, taking with them a large proportion of conspecific males which were also in advanced
spawning condition and in better somatic condition compared to the remaining population. In addition, information from 28
stocks of multiple-spawning clupeoids from a wide range of geographic locations, belonging to 14 species and 2 families (Engraulidae
and Clupeidae), was reviewed and analyzed pertinent to the formation of ephemeral spawning aggregations. Results from the
latter analysis indicated similar patterns of spatial segregation of Day0 spawners in the reviewed clupeoid stocks as in the Mediterranean Sardine, which strongly suggested that the formation of
ephemeral spawning aggregations is a common behavioral trait among multiple-spawning clupeoids.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
953.
Direct solid sampling Zeeman atomic absorption spectrometric methods were developed and successfully applied to the determination of mercury, cadmium, lead and manganese in aquatic plants. Mercury was determined using a specially designed furnace. The other elements were determined by a third generation spectrometer. In 3-field- and dynamic mode the working range was substantially extended and high amounts of analyte were detectable without laborious dilution of solid samples. The measurements were based on calibrations using certified reference materials of organic origin. No matrix effects were observed under the optimised conditions. Results obtained were in good agreement with the certified values. 相似文献
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957.
Gail Krantzberg 《The Environmentalist》2008,28(3):301-305
Some argue that a collective vision for the future of the Laurentian Great Lakes is embodied in the␣Great Lakes Water Quality
Agreement (GLWQA). The GLWQA is a binational agreement, first signed in 1972 by Prime Minister Pierre Trudeau and President
Richard Nixon, wherein the two countries (the Parties) commit to “restore and maintain the chemical, physical and biological
integrity of the waters of the Great Lakes Basin Ecosystem.” Article X of the Agreement states that the Parties shall conduct
a comprehensive review of the operation and effectiveness of this Agreement following every third biennial report of the [International
Joint] Commission (IJC). The IJC’s 12th Biennial Report, released in 2004, triggered this important science, program, and
policy review which commenced May 2006. This essay makes the case for a rigorous review, that explores deliberately the future
scope of the Agreement to protect the world’s largest surface freshwater resource, and calls for innovation in the governance
regime of this binational ecosystem. 相似文献
958.
Maintenance of Forest Biodiversity in a Post-Soviet Governance Model: Perceptions by Local Actors in Lithuania 总被引:1,自引:1,他引:0
Successful biodiversity conservation does not depend on ecologic knowledge alone. Good conservation policies and policy implementation
tools are equally important. Moreover, the knowledge, skills, and attitudes of local actors, directly in charge of operations
in the field, are a key to successful policy implementation. The connections between policy objectives and their implementation
as well as the involvement of local actors’ efforts in implementing policy objectives largely depend on the governance model
in use. This article assesses the knowledge of local actors in relation to the biodiversity conservation objectives and tools
in Lithuanian forest management. As a main framework for this study, the needs assessment approach was applied. The study
used both in-depth open-ended interviews and follow-up telephone interviews. Two state forest enterprises in Lithuania were
selected as the study sites. The findings indicate that policy objectives in the field of forest biodiversity conservation
and the related tools are well known but not well understood by those in charge of forest biodiversity policy implementation.
To improve the situation, a transition toward adaptive learning and participatory governance as a means of facilitating conservation
efforts is proposed. 相似文献
959.
Reed MG 《Environmental management》2007,39(1):30-49
Advocates of community-based approaches to environmental management argue that by respecting local circumstances, skills,
and concerns we may improve the prospects of achieving environmental sustainability; yet, within nation states such as Canada,
environmental conditions, management and enforcement costs and capabilities, and power differentials within and among civic
and public sectors may result in a highly differentiated capacity for environmental management across different localities
and regions. This article draws on insights of political ecology to 1) create a conceptual framework that identifies key elements
shaping regional environmental management regimes and to 2) undertake a comparative analysis to assess how elements interact
to generate uneven management outcomes. I compare experiences of two Canadian biosphere reserves designated in 2000: Clayoquot
Sound, BC; and Redberry Lake, SK. Analysis reveals that differences in governance and institutional capacities in the biosphere
reserves are key to explaining uneven local outcomes. Where the public and civic sectors are strong, a robust and publicly
vetted form of management will emerge. Where these sectors are weak and land is held as private property, environmental nongovernmental
organizations can set the type and level of management, to the exclusion of effective civic and state involvement. This result
may improve environmental sustainability but hinder social sustainability of a management regime and raises questions about
the efficacy of community-based management. 相似文献
960.
Cost-efficient sample designs for collection of ground data and accurate mapping of variables are required to monitor natural
resources and environmental and ecological systems. In this study, a sample design and mapping method was developed by integrating
stratification, model updating, and cokriging with Landsat Thematic Mapper (TM) imagery. This method is based on the spatial
autocorrelation of variables and the spatial cross-correlation among them. It can lead to sample designs with variable grid
spacing, where sampling distances between plots vary depending on spatial variability of the variables from location to location.
This has potential cost-efficiencies in terms of sample design and mapping. This method is also applicable for mapping in
the case in which no ground data can be collected in some parts of a study area because of the high cost. The method was validated
in a case study in which a ground and vegetation cover factor was sampled and mapped for monitoring soil erosion. The results
showed that when the sample obtained with three strata using the developed method was used for sampling and mapping the cover
factor, the sampling cost was greatly decreased, although the error of the map was slightly increased compared to that without
stratification; that is, the sample cost-efficiency quantified by the product of cost and error was greatly increased. The
increase of cost-efficiency was more obvious when the cover factor values of the plots within the no-significant-change stratum
were updated by a model developed using the previous observations instead of remeasuring them in the field. 相似文献