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681.
This paper describes the results of a survey of the North Sea and north Atlantic waters adjacent to the Orkney and Shetland Islands, from 23 May to 9 June, 1973, using simultaneous tows of the prototype Undulating Oceanographic Recorder (UOR) and the Continuous Plankton Recorder (CPR). The UOR sampled plankton and measured salinity and temperature over its undulation profile from 5 to 65 m in depth. The CPR sampled plankton at a fixed depth of 10 m. Three principal water masses were identified, each with a characteristic plankton community. 相似文献
682.
Lawrence D. Platt M.D. Greggory R. Devore Janet Horenstein Zdena Pavlova Bruce Kovacs Rena Ellen Falk 《黑龙江环境通报》1987,7(6):407-411
Fetal echocardiography was used to identify a cardiac rhabdomyoma in the second trimester. The combination of this finding with a maternal history of Tuberous Sclerosis allowed the patient and her family to make a more educated decision regarding termination of the pregnancy. Post mortem examination of the fetus confirmed the prenatal findings. This case report demonstrates the importance of ultrasound evaluation of the fetus at risk of recurrence of a genetic syndrome in which one or more anatomical defects might be seen. 相似文献
683.
Bruce H. Pugesek 《Behavioral ecology and sociobiology》1990,27(3):211-215
Summary Parental effort was studied among knownaged California gulls (Larus californicus) with a brood size of two. Results supported three of Triver's predictions from parent-offspring conflict theory. First, the amount of time parents withheld food from offspring increased with increasing offspring age. Second, older parents were less likely than younger parents to withhold food from offspring throughout the period of parental care. Third, older parents had a longer period of parental care compared to younger parents. Adult survival to future breeding seasons was inversely related to duration of parental care. Older parents, in association with their greater levels of parental effort, had a lower survival rate compared to that of younger parents. 相似文献
684.
In their analyses of the impact of pollution taxation on the location of polluting decisions, U. K. Mathur (J. Environ. Econom. Management 3, 16–28 (1976)) and S. S. Gokturk (J. Reg. Sci. 19, 461–467 (1979)) obtained the result that a tax increase on urban pollution concentration may not succeed in pushing the polluting firm away from the urban center. In this paper is shown that the sufficient condition for success in this case depends upon the specification of the production and pollution emissions technology and may be the opposite to the one posited by Mathur and has more intuitive appeal. 相似文献
685.
The effect of cadmium on antioxidant responses and the susceptibility to oxidative stress in the hydrothermal vent mussel Bathymodiolus azoricus 总被引:1,自引:0,他引:1
Rui Company Angela Serafim Richard Cosson Lionel Camus Bruce Shillito Aline Fiala-Médioni Maria João Bebianno 《Marine Biology》2006,148(4):817-825
Hydrothermal vents are a unique environment of extreme physical–chemical characteristics and biological species composition.
Cd is a toxic non-essential metal present in high concentrations in the hydrothermal vent environment, contrary to those found
in marine coastal areas. Cd toxicity has been related, among other things, with reactive oxygen species production, even though
this is a non-redox metal. Bathymodiolus azoricus is a deep-sea Mytilid bivalve very common in the Mid Atlantic Ridge (MAR) hydrothermal vent fields and very little is known
about the antioxidant defence system in this specie. Because lethal Cd concentration in B. azoricus is unknown, the aim of this study was to assess the effects of a Cd concentration higher than that found in the hydrothermal
vents on oxidative stress biomarkers, such as antioxidant enzymes. Mussels were exposed to 100 μg l−1 Cd during 24, 48 and 144 h, respectively, in a pressurized aquarium (IPOCAMP). Superoxide dismutase (SOD), catalase (CAT),
glutathione peroxidases (GPx), total oxyradical scavenging capacity (TOSC), metallothionein (MT) and lipid peroxidation (LPO)
were measured in the gills and mantle of B. azoricus. The results indicate that gills are first affected by Cd toxicity. This may be due to different physiological functions
of the tissues and by the presence of thio and methanotrophic symbiotic bacteria in the gills. The SOD and CAT are inhibited
during the first day of exposure in the gills, although TOSC and MT concentrations were the same in control and exposed mussels.
In the mantle, enzymatic activation only occurred after 6 days, and no significant differences in MT concentrations were found
in the control and exposed mussels during the first day, as observed in the gills. 相似文献
686.
Bruce E. Lyon 《Behavioral ecology and sociobiology》1993,33(2):87-100
Summary I examined the tactics adopted by a conspecific brood parasite, the American coot (Fulica americana), and the degree to which these tactics reflect sources of mortality for parasitic eggs. Only 8% of parasitic eggs produced independent offspring, compared to a 35% success rate for non-parasitic eggs, and most mortality was due to egg-rejection by hosts or the consequences of laying eggs too late in the host's nesting cycle. Parasites usually laid parasitically before initiating their own nests and usually parasitized immediate neighbours. Parasites did not remove host eggs before laying their own egg, and egg disappearance in general was not more common at parasitized nests. I found no evidence for non-random host choice, either on the basis of stage of the host's nesting cycle or the host's brood size. The absence of adaptive host choice is likely a consequence of the fact that, due to host limitation, only a small proportion of parasites had meaningful variation among potential hosts to choose from. The pattern of egg dispersion among host nests by individual parasites appears to be a compromise between constraints imposed by host limitation and the increased success obtained from spreading eggs among nests. Most females laying fewer than five parasitic eggs laid them in a single host nest while females laying five or more eggs normally parasitized two or more hosts. An examination of egg rejection and survival rates showed that parasites would maximize success by laying a single egg per host nest, and the pattern of laying several eggs per host nest is likely a consequence of host limitation. However, no egg that was the fifth laid, or later, parasitic egg in a host nest was ever successful and this probably explains why most females laying five or more eggs parasitized more than one host. 相似文献
687.
688.
Larry Larsen Terri Morrell David Wood Meghan Gallione Bruce Guerard Judith Karinen Kip Petersen Frederick Steiner 《Environmental management》1991,15(4):531-548
This is the second of three articles prepared to explain the Teller County growth management process. As part of an ongoing
growth management process in Teller County, Colorado, opportunities and constraints for development and conservation were
identified. The scenic mountain county faces a number of issues because of growth. The recognition of those issues has resulted
in the goal to direct future growth to the most appropriate and cost-effective places. To determine those places that are
best for new development, thorough ecological inventories were conducted for the entire county as well as for the City of
Woodland Park area. From these inventories, environmentally sensitive areas were identified. The environmentally sensitive
areas were considered constraints in conducting suitability analyses for a variety of potential land uses. The suitability
analyses resulted in the identification of opportunities for future growth in Teller County generally as well as the more
specific Woodland Park planning area. This article, like the other two, is part of a reflective analysis by the planners who
were involved.
Paper 2 in a series 3. 相似文献
689.
Marybeth Buechner Christine Schonewald-Cox Raymond Sauvajot Bruce A. Wilcox 《Environmental management》1992,16(6):799-809
In recent years, cross-boundary management has become an essential part of park management. In this article we compare the
perspectives of managers of several US national parks to the advice on this issue presented in the published literature. Data
were obtained from interviews of the superintendents, assistant superintendents and resources managers of five major western
national parks and from a survey of participants in a NPS workshop attended by park superintendents, scientists, and resource
managers; law enforcement personnel; and interpreters. Three themes related to boundary management were consistently stressed
by park managers: (10 a lack of sufficient funds and personnel within the parks; (2) the need for reliable information on
both political and natural processes; and, (3) the importance of personal interactions between park staff and individuals
from the surrounding area. Basic data collection, the documentation of trends, cooperative groups and personal contacts, educational
programs, and land acquisition were the most useful strategies. A lack of funds and information, ineffective communication,
enforcement problems, and a lack of motivation for parties to reach a negotiated agreement were the most serious obstacles.
A wide range of valuable institutional knowledge concerning boundary management exists within the National Park Service; however,
there appears to be a gap between published strategies and the approaches that work “on the ground”. 相似文献
690.
Bruce Hicks Robert McMillen Robert S. Turner George R. Holdren Jr Timothy C. Strickland 《Environmental management》1993,17(3):343-353
Methods are discussed for describing patterns of current wet and dry deposition under various scenarios. It is proposed that
total deposition data across an area of interest are the most relevant in the context of critical loads of acidic deposition,
and that the total (i.e., wet plus dry) deposition will vary greatly with the location, the season, and the characteristics
of individual subregions. Wet and dry deposition are proposed to differ in such fundamental ways that they must be considered
separately. Both wet and dry deposition rates are controlled by the presence of the chemical species in question in the air
(at altitudes of typically several kilometers in the case of wet deposition, and in air near the surface for dry). The great
differences in the processes involved lead to the conclusion that it is better to measure wet and dry deposition separately
and combine these quantifications to produce “total deposition” estimates than to attempt to derive total deposition directly.
A number of options for making estimates of total deposition to be used in critical loads assessment scenarios are discussed
for wet deposition (buckets and source receptor models) and for dry deposition (throughfall, micrometeorology, surrogate surfaces
and collection vessels, inference from concentrations, dry-wet ratios, and source-receptor models).
The research described in this article has been funded by the US Environmental Protection Agency. This document has been prepared
at the EPA Environmental Research Laboratory in Corvallis, Oregon, through contract #68-C8-0006 with ManTech Environmental
Technology, Inc., and Interagency Agreement #1824-B014-A7 with the U.S. Department of Energy and at Oak Ridge National Laboratory
managed by Martin Marietta Energy Systems, Inc., under Contract DE-AC05-84OR21400 with the US Department of Energy. Environmental
Sciences Division Publication No. 3905. It has been subjected to the Agency’s peer and administrative review and approved
for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. 相似文献