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591.
Christopher Bone Suzana Dragićević Arthur Roberts 《Environmental Modeling and Assessment》2007,12(2):105-118
The objective of this study was to develop an integrated geographic information system (GIS) cellular automata (CA) model
for simulating insect-induced tree mortality patterns in order to evaluate the influence of different forest management activities
to control insect outbreaks. High-resolution multispectral images were used to determine susceptibility of trees to attack,
whereas the GIS-based CA model simulated the effectiveness of clear-cuts and thinning practices for reducing insect-induced
tree mortality. The results indicate that thinning susceptible forests should be more effective than clear-cutting for reducing
tree loss to insect outbreaks. This study demonstrates the benefits of an integrated approach for understanding and evaluating
forest management activities and expresses the need for spatial analysis and modeling for improving forest management practices. 相似文献
592.
Joanna Burger Keith Cooper Jorge Saliva D. Gochfeld D. Lipsky Michael Gochfeld 《Environmental monitoring and assessment》1992,22(3):181-197
We analyzed mercury levels in shrimp (Palaemonetes sp.), Blue Crabs (Callinectes sp.), fish (Tarpon Megalops atlantica and Tilapia Tilapia mossambica), lizards (Ameiva exsul), Cattle Egret (Bubulcus ibis) and Moorhen (Gallinula chloropus) in three estuaries in Puerto Rico in 1988. There were no quantifiable concentrations greater than the method detection limit of mercury in shrimp, crabs and lizards from any site. Mercury levels were also below detection limits in Tilapia, except for specimens collected at Frontera Creek, allegedly contaminated with mercury. However, mercury levels ranged from 92–238 g/kg (wet weight) in Tarpon, a predaceous fish that feeds on smaller fish. Few of the birds had detectable levels of mercury. Our results indicate relatively low concentrations of mercury in biota collected in all of the three estuaries at most trophic levels, although 10 of 12 Tarpon fillet samples from Frontera had detectable mercury compared to 3 of 12 fillet samples for the other two lagoons.This project was partially funded by an EPA consent decree (Dynamac, Inc.) and NIEHS grant (ESO 5022) to EOSHI. 相似文献
593.
Arthur Haas 《Die Naturwissenschaften》1937,25(45):733-734
594.
The Science of Nature - 相似文献
595.
Initial river rehabilitation efforts along the North Fork Gunnison River in Colorado focused on the use of in-stream structures and channel stabilization to create a single-thread channel with pools along a braided river. These efforts were based on the assumption that the river’s braided planform results primarily from land use during the past century. In order to establish a context for further rehabilitation, we evaluated the possibility that the river might be braided as a result of processes independent of land use. We estimated volume, grain-size distribution, and lithology of sediment sources along the river corridor and evaluated the planform stability of the river during the past century using historical sources, aerial photographs covering 1939–1997, and comparison of bankfull discharge and gradient in the study area to values published for braided and meandering rivers. Our results indicate that the North Fork Gunnison River has been primarily braided in its lower reaches during the past few hundred years, although the channel planform tends toward a single-thread channel during decades of lower precipitation and discharge. Although land use is not the primary cause of braiding along the North Fork Gunnison River, it has decreased channel stability, and rehabilitation efforts should be designed to reduce these effects. Our results illustrate the importance of planning river rehabilitation measures within a historical context that accounts for both catchment-scale and reach-scale controls on channel processes and planform. 相似文献
596.
597.
Jeff Cooper 《Local Environment》2013,18(3):325-330
598.
Amy M. Breman Jennifer C. Chow Lance U'Ren Elizabeth A. Normand Sadeem Qdaisat Li Zhao David M. Henke Rui Chen Chad A. Shaw Laird Jackson Yaping Yang Liesbeth Vossaert Rachel H. V. Needham Elizabeth J. Chang Daniel Campton Jeffrey L. Werbin Ron C. Seubert Ignatia B. Van den Veyver Jackie L. Stilwell Eric P. Kaldjian Arthur L. Beaudet 《黑龙江环境通报》2016,36(11):1009-1019
599.
D. Nacci L. Coiro D. Champlin S. Jayaraman R. McKinney T. R. Gleason W. R. Munns Jr. J. L. Specker K. R. Cooper 《Marine Biology》1999,134(1):9-17
Many aquatic species, including the estuarine fish Fundulus heteroclitus (mummichogs), adapt to local environmental conditions. We conducted studies to evaluate whether highly exposed populations
of mummichogs adapt to toxic environmental contaminants. These fish populations are indigenous to an urban estuary contaminated
with persistent and bioaccumulative contaminants (dioxin-like compounds, or DLCs) that are particularly toxic to the early
development of fish. We conducted laboratory challenge experiments to compare mummichog embryos and larvae from reference
sites and this highly contaminated site [New Bedford Harbor (NBH), Massachusetts, USA] for their sensitivity to DLCs. While
there was variation in DLC-responsiveness within each group, fish from NBH were profoundly less sensitive to DLCs than reference
fish. Specifically, concentrations of DLCs similar to those measured in NBH-collected mummichog eggs were lethal to reference
embryos. Further, DLC-responsiveness was inherited and independent of maternal contaminant contributions. These findings are
consistent with the conclusion that DLC contamination in NBH has contributed to the selection of fish that are resistant to
the short-term toxic effects of these environmental-contaminant exposures. This adaptation may be a critical mechanism by
which fish populations persist in this highly contaminated site. Further evaluation of this ecosystem may provide important
information concerning the direct and indirect consequences of this “unnatural” selection.
Received: 12 July 1998 / Accepted: 16 January 1999 相似文献
600.