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41.
Michael J. White Daniel E. Storm Philip Busteed Scott Stoodley Shannon J. Phillips 《Environmental management》2010,45(5):1164-1174
In the United States, many state and federally funded conservation programs are required to quantify the water quality benefits
resulting from their efforts. The objective of this research was to evaluate the impact of conservation practices subsidized
by the Oklahoma Conservation Commission on phosphorus and sediment loads to Lake Wister. Conservation practices designed to
increase vegetative cover in grazed pastures were evaluated using Landsat imagery and the Soil and Water Assessment Tool (SWAT).
Several vegetative indices were derived from Landsat imagery captured before and after the implementation of conservation
practices. Collectively, these indicators provided an estimate of the change in vegetative soil cover attributable to conservation
practices in treated fields. Field characteristics, management, and changes in vegetative cover were used in the SWAT model
to simulate sediment and phosphorus losses before and after practice implementation. Overall, these conservation practices
yielded a 1.9% improvement in vegetative cover and a predicted sediment load reduction of 3.5%. Changes in phosphorus load
ranged from a 1.0% improvement to a 3.5% increase, depending upon initial vegetative conditions. The use of fertilizers containing
phosphorus as a conservation practice in low-productivity pastures was predicted by SWAT to increase net phosphorus losses
despite any improvement in vegetative cover. This combination of vegetative cover analysis and hydrologic simulation was a
useful tool for evaluating the effects of conservation practices at the basin scale and may provide guidance for the selection
of conservation measures subsidized in future conservation programs. 相似文献
42.
The combined effects of urea application and simulated acid rain on soil acidification and microbial community structure 总被引:2,自引:0,他引:2
Xingmei Liu Jian Zhou Wanlu Li Jianming Xu Philip C. Brookes 《Environmental science and pollution research international》2014,21(10):6623-6631
Our aim was to test the effects of simulated acid rain (SAR) at different pHs, when applied to fertilized and unfertilized soils, on the leaching of soil cations (K, Ca, Mg, Na) and Al. Their effects on soil pH, exchangeable H+ and Al3+ and microbial community structure were also determined. A Paleudalfs soil was incubated for 30 days, with and without an initial application of urea (200 mg N kg?1soil) as nitrogen (N) fertilizer. The soil was held in columns and leached with SAR at three pH levels. Six treatments were tested: SAR of pH 2.5, 4.0 and 5.6 leaching on unfertilized soil (T1, T2 and T3), and on soils fertilized with urea (T4, T5 and T6). Increasing acid inputs proportionally increased cation leaching in both unfertilized and fertilized soils. Urea application increased the initial Ca and Mg leaching, but had no effect on the total concentrations of Ca, Mg and K leached. There was no significant difference for the amount of Na leached between the different treatments. The SAR pH and urea application had significant effects on soil pH, exchangeable H+ and Al3+. Urea application, SAR treated with various pH, and the interactions between them all had significant impacts on total phospholipid fatty acids (PLFAs). The highest concentration of total PLFAs occurred in fertilized soils with SAR pH5.6 and the lowest in soils leached with the lowest SAR pH. Soils pretreated with urea then leached with SARs of pH 4.0 and 5.6 had larger total PLFA concentrations than soil without urea. Bacterial, fungal, actinomycete, Gram-negative and Gram-positive bacterial PLFAs had generally similar trends to total PLFAs. 相似文献
43.
CHANGING RAINFALL-RUNOFF RELATIONSHIPS IN THE URBANIZING PEACHTREE CREEK WATERSHED,ATLANTA, GEORGIA1
Bruce K Ferguson Philip W. Suckling 《Journal of the American Water Resources Association》1990,26(2):313-322
ABSTRACT: Peachtree Creek is a gaged watershed that has experienced a substantial increase in urbanization. The relationships of runoff to rainfall were studied for total annual flows, low flows, and peak flows. For each type of flow the relationship in the later, more urbanized period was compared to that in the earlier, less urbanized period. An increase in total runoff in wet years was observed as urbanization increased, but a decrease occurred during dry years. For low flows a similar decrease of runoff in dry years was found. An increase in peak runoff was observed over most of the range of precipitation. Increasing peak flows and declining low flows can be adequately explained by urban hydrologic theoryshed. which focuses on the effects of urban impervious surfaces upon direct runoff and infiltration. However, a decline of total runoff in dry years can be explained only by taking into account evapotranspiration as well. The concept of advectively assisted urban evapotranspiration, previously discovered by climatologists, is needed to explain such a loss of total runoff. Urban hydrologic theory must take into account vegetation and evapotranspiration, as well as impervious surfaces and their direct runoff, to explain the magnitude of total annual flows and low flows. Urban stormwater management should address the restoration of low flows, as well as the control of floods. 相似文献
44.
Robert C. Borden Philip B. Bedient 《Journal of the American Water Resources Association》1987,23(4):629-636
ABSTRACT: A three well injection-production test was performed at the United Creosoting Company (UCC) site in Conroe, Texas, to estimate the effective in situ retardation factors for adsorption and to evaluate the significance of biotransformation in limiting the transport of polycydic aromatics present in the shallow aquifer. The field test was also used as a model to determine if this type of testing would be feasible at other hazardous waste sites. During the test, chloride, a non-reactive tracer and two organic compounds, naphthalene and paradichlorobenzene (pDCB), were injected into a center well for 24 hours followed by clean ground water for six days. Ground water was continuously produced from two adjoining wells and monitored to observe the breakthrough of these compounds. Data from the test were analyzed by comparing the statistical moments of the chloride and organics distributions. Retardation factors for naphthalene and pDCB were estimated to be 1.03 and 0.97 by comparison of the statistical moments. A significant loss of naphthalene and pDCB was also observed during the three well test, apparently due to biotransformation. These results suggest that biotransformation is the major process limiting the transport of naphthalene and similar compounds at the UCC site. 相似文献
45.
46.
Development of a bird integrity index: using bird assemblages as indicators of riparian condition 总被引:7,自引:0,他引:7
We describe the development of a bird integrity index (BII) that uses bird assemblage information to assess human impacts
on 13 stream reaches in the Willamette Valley, Oregon, USA. We used bird survey data to test 62 candidate metrics representing
aspects of bird taxonomic richness, tolerance or intolerance to human disturbance, dietary preferences, foraging techniques,
and nesting strategies that were affected positively or negatively by human activities. We evaluated the metric responsiveness
by plotting each one against a measure of site disturbance that included aspects of land use/land cover, road density, riparian
cover, and stream channel and substrate conditions. In addition, we eliminated imprecise and highly correlated (redundant)
metrics, leaving 13 metrics for the final index. Individual metric scores ranged continuously from 0 to 10, and index scores
were weighted to range from 0 to 100. Scores were calibrated using historical species information to set expectations for
the number of species expected under minimally disturbed conditions. Site scores varied from 82 for the least disturbed stream
reach to 8.5 for an urban site. We compared the bird integrity index site scores with the performance of other measures of
biotic response developed during this study: a fish index of biointegrity (IBI) and two benthic macroinvertebrate metrics.
The three assemblages agreed on the general level of disturbance; however, individual sites scored differently depending on
specific indicator response to in-stream or riparian conditions. The bird integrity index appears to be a useful management
and monitoring tool for assessing riparian integrity and communicating the results to the public. Used together with aquatic
indicator response and watershed data, bird assemblage information contributes to a more complete picture of stream condition. 相似文献
47.
Philip W. Gassman Edward Osei Ali Saleh Larry M. Hauck 《Journal of the American Water Resources Association》2002,38(2):423-438
ABSTRACT: A National Pilot Project (NPP) on Livestock and the Environment was initiated in 1992 to help provide solutions to environmental problems associated with livestock production. A major development of the NPP was the Comprehensive Economic and Environmental Optimization Tool‐Livestock and Poultry (CEEOT‐LP), an integrated modeling system designed to produce economic and environmental indicators for alternative policy scenarios applied to intensive livestock production watersheds. The system consists of a farm‐level economic model (FEM) and two environmental models: the field‐scale APEX model and the watershed‐level SWAT model. To date, CEEOT‐LP has been applied to two watersheds in Texas and one in Iowa. Predicted reductions in P losses for two P‐based manure application rate scenarios, relative to baseline conditions, ranged from ?4 to ?54 percent across the three watersheds; however, N loss impacts ranged from a decrease of 34 percent to an increase of 79 percent. For five other alternative scenarios that were simulated for only one watershed, N and P loss impacts ranged between a reduction of 78 percent to an increase of 20 percent. Aggregate watershed‐level economic impacts of the seven scenarios spanned a spectrum of a 27 percent decrease to a 25 percent increase in profit, relative to the baseline. 相似文献
48.
Recovery of temperate-stream fish communities from disturbance: A review of case studies and synthesis of theory 总被引:3,自引:0,他引:3
Naomi E. Detenbeck Philip W. DeVore Gerald J. Niemi Ann Lima 《Environmental management》1992,16(1):33-53
To evaluate the relative effect of autecologic factors, site-specific factors, disturbance characteristics, and community
structure on the recovery of temperate-stream fish communities, we reviewed case histories for 49 sites and recorded data
on 411 recovery end points. Most data were derived from studies of low-gradient third- or fourth-order temperate streams located
in forested or agricultural watersheds. Species composition, species richness, and total density all recovered within one
year for over 70% of systems studied. Lotic fish communities were not resilient to press disturbances (e.g., mining, logging,
channelization) in the absence of mitigation efforts (recovery time >5 to >52 yr) and in these cases recovery was limited
by habitat quality. Following pulse disturbances, autecological factors, site-specific factors, and disturbance-specific factors
all affected rates of recovery. Centrarchids and minnows were most resilient to disturbance, while salmonid populations were
least resilient of all families considered. Species within rock-substrate/nest-spawning guilds required significantly longer
time periods to either recolonize or reestablish predisturbance population densities than did species within other reproductive
guilds. Recovery was enhanced by the presence of refugia but was delayed by barriers to migration, especially when source
populations for recolonization were relatively distant. Median population recovery times for systems in which disturbances
occurred during or immediately prior to spawning were significantly less than median recovery times for systems in which disturbances
occurred immediately after spawning. There was little evidence for the influence of biotic interactions on recovery rates. 相似文献
49.
Patrick A. Mower J. Philip J. O'Kane Jerry D.F. Sherrif Tim Wyatt J. David Barrett 《Journal of the American Water Resources Association》1971,7(4):831-843
ABSTRACT .Operating rule procedures are developed for the optimal use of desalination in conjunction with surface water impoundments. Results obtained from the use of hill-climbing and dynamic programming methods are compared. Benefits to be obtained from the integrated use of desalination are demonstrated through a case study for the Barcelona area of Spain. 相似文献
50.
Sa V. Ho B. Mason Hughes Philip H. Brodsky John S. Merz Larry P. Egley 《补救:环境净化治理成本、技术与工艺杂志》1999,9(3):103-116
Originated from a recognized need for significantly more effective technologies for soil cleanup, the LasagnaTM project provides an interesting case study in which industry, government, and academia successfully collaborated to rapidly advance the technology from the laboratory to the field. Called LasagnaTM because of its layered configurations, the technology combines electrically induced contaminant transport in soils, treatment in place, and geotechnical methods to achieve completely in situ clean-up of contaminated soils. Experiences with respect to the partnership, the development of technology and its current commercialization status are described. 相似文献