全文获取类型
收费全文 | 256篇 |
免费 | 48篇 |
国内免费 | 7篇 |
专业分类
废物处理 | 6篇 |
环保管理 | 260篇 |
综合类 | 11篇 |
基础理论 | 8篇 |
污染及防治 | 5篇 |
评价与监测 | 16篇 |
社会与环境 | 5篇 |
出版年
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 3篇 |
2019年 | 8篇 |
2018年 | 11篇 |
2017年 | 11篇 |
2016年 | 15篇 |
2015年 | 16篇 |
2014年 | 20篇 |
2013年 | 16篇 |
2012年 | 16篇 |
2011年 | 16篇 |
2010年 | 9篇 |
2009年 | 20篇 |
2008年 | 17篇 |
2007年 | 24篇 |
2006年 | 19篇 |
2005年 | 22篇 |
2004年 | 6篇 |
2003年 | 4篇 |
2002年 | 9篇 |
2001年 | 6篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1974年 | 1篇 |
1972年 | 2篇 |
排序方式: 共有311条查询结果,搜索用时 15 毫秒
241.
Steven W. Effler Anthony R. Prestigiacomo David A. Matthews Feng Peng 《Journal of the American Water Resources Association》2012,48(2):321-335
Effler, Steven W., Anthony R. Prestigiacomo, David A. Matthews, and Feng Peng, 2012. Sources and Sinks of Phosphorus for a Perturbed Stream and the Effects of Mineral Deposits. Journal of the American Water Resources Association (JAWRA) 48(2): 321‐335. DOI: 10.1111/j.1752‐1688.2011.00617.x Abstract: Patterns of concentrations and loading rates of multiple forms of phosphorus (P) are resolved and analyzed along Ninemile Creek, New York, a stream perturbed by a domestic waste discharge and residual effects of a closed industry. This analysis is based on biweekly monitoring of total, dissolved, and soluble reactive P (SRP) for 19 months at four sites that bracket each of these effects, and 15 years of biweekly measurements at the two sites that bound industrial deposits. The minerogenic particle populations of the stream and the surficial sediments along the reach with extensive CaCO3 and clay mineral deposits are characterized with an individual particle analysis technique. Mass balance analyses depict: (1) increasing nonpoint inputs of particulate and dissolved organic P along the stream length; (2) input of P from a domestic waste facility, almost entirely in the form of SRP; and (3) a compensating downstream loss of SRP over the reach with the extensive industrial deposits of CaCO3. The downstream sink process for SRP is attributed to sorption processes with minerogenic deposits. The domestic waste‐based source and the compensating industrial waste‐based sink are noteworthy fluxes relative to other prevailing loads received by downstream Onondaga Lake, for which a major rehabilitation program targeting cultural eutrophication is underway. The P source/sink conditions of this stream are considered in the context of this rehabilitation program. 相似文献
242.
Kristin Bunte John P. Potyondy Kurt W. Swingle Steven R. Abt 《Journal of the American Water Resources Association》2012,48(3):530-545
Bunte, Kristin, John P. Potyondy, Kurt W. Swingle, and Steven R. Abt, 2012. Spatial Variability of Pool-Tail Fines in Mountain Gravel-Bed Stream Affects Grid-Count Results. Journal of the American Water Resources Association (JAWRA) 48(3): 530-545. DOI: 10.1111/j.1752-1688.2011.00629.x Abstract: Fine sediment (<2 and <6 mm) particles underlying a 49-intersection grid placed on a streambed at 25, 50, and 75% of the wetted pool-tail width are commonly counted to assess the status and trend of aquatic ecosystems or to monitor changes in the supply of fines in mountain gravel-bed streams. However, results vary even when crews perform nearly identical procedures. This study hypothesized that spatial variability of pool-tail fines affects grid-count results and that a sampling scheme can be optimized for precision and accuracy. Grid counts taken at seven evenly spaced locations across the wetted width of 10 pool tails in a pool-riffle study stream indicated a bankward fining trend with secondary peaks of fines within the stream center. Sampling locations close to the waterlines harbored more than twice as many fines as central locations. Most of the five grid-count schemes derived from the seven sampled locations produced significantly different results. Compared with sampling at all seven locations, schemes that focus near waterlines overpredicted fines, while those that focus on the center underpredicted them. Variability of fines among pool tails was the highest within a broad band along the waterlines; hence, focusing sampling there yielded the most variable results. The scheme sampling at 25, 50, and 75% of the wetted width had the lowest precision and moderate accuracy. Accuracy and precision of grid-count results can be greatly improved by sampling at seven even-spaced locations across the pool tail. 相似文献
243.
Kris W. Knight Richard C. Schultz Cathy M. Mabry Thomas M. Isenhart 《Journal of the American Water Resources Association》2010,46(2):311-322
Knight, Kris W., Richard C. Schultz, Cathy M. Mabry, and Thomas M. Isenhart, 2010. Ability of Remnant Riparian Forests, With and Without Grass Filters, to Buffer Concentrated Surface Runoff. Journal of the American Water Resources Association (JAWRA) 46(2):311-322. DOI: 10.1111/j.1752-1688.2010.00422.x Abstract: Riparian forest buffers established according to accepted conservation practice standards have been recommended as one of the most effective tools for mitigating nonpoint source pollution. The midwestern United States is characterized by many kilometers of narrow, naturally occurring forests along streams. However, little is known about the relative effectiveness of these remnant forests compared with these newly established buffers. This study compared the ability of naturally occurring remnant forests with and without adjacent planted grass filters to buffer concentrated flow paths (CFPs) originating in crop fields along first- and second-order streams in three northeast Missouri watersheds. Remnant forests breached by runoff through CFPs were narrower than those that dispersed 100% of the CFPs. Remnant forests with adjacent grass buffers were nearly twice the width as those without grass filters. We also found that CFPs, which developed within remnant forests and at the base of in-field grass waterways, were potential sources of sediments to streams. Methods to mitigate these CFPs warrant further investigation. Our study suggests that although these natural remnant forests provide substantial buffering capacity, both improved management and/or the addition of an adjacent grass filter would improve water quality by reducing sediment loss to streams. Inferences can be used to inform the design and management of similar conservation buffer systems within the region. 相似文献
244.
Kris Crockett Jonathan B. Martin Henri D. Grissino-Mayer Evan R. Larson Thomas Mirti 《Journal of the American Water Resources Association》2010,46(5):919-931
Crockett, Kris, Jonathan B. Martin, Henri D. Grissino-Mayer, Evan R. Larson, and Thomas Mirti, 2010. Assessment of Tree Rings as a Hydrologic Record in a Humid Subtropical Environment. Journal of the American Water Resources Association (JAWRA) 1-13. DOI: 10.1111/j.1752-1688.2010.00464.x Abstract: Information about long-term variability of streamflow is important to allocate water resources, but few historical records extend more than 75 years into the past, requiring proxy records to evaluate flow prior to that time. Flow proxies have been found in tree-ring widths in temperate regions, but have rarely been used in humid subtropical environments because the relationship between tree growth and climate was believed to be weakened by limited seasonality and stress on tree growth from drought conditions. Tree-ring residual chronologies from two forests sampled from northern Florida correlate well with historical annual discharge (r² values as high as 0.47) from 3 of 15 river-gauging stations that were used to compare with the tree-ring chronologies. The best correlations occur where streamflow has little contribution from spring discharge or continuous flow from lakes and wetlands. Streams lack correlations with the tree-ring residual chronologies (r² values as low as 0.0002) where springs and continuous discharge from lakes mute variations in their flow. Tree-ring chronologies appear to be useful for reconstruction of prehistorical variations of some streamflow in humid subtropical regions, but interpretations of the reconstructions must consider the local hydrologic conditions. 相似文献
245.
Megan MH Nash MS Neale AC Pitchford AM 《Environmental monitoring and assessment》2007,124(1-3):141-156
The objective of this study was to assess the applicability of using landscape variables in conjunction with water quality
and benthic data to efficiently estimate stream condition of select headwater streams in the Mid-Atlantic Coastal Plains.
Eighty-two streams with riffle sites were selected from eight-two independent watersheds across the region for sampling and
analyses. Clustering of the watersheds by landscape resulted in three distinct groups (forest, crop, and urban) which coincided
with watersheds dominant land cover or use. We used non-parametric analyses to test differences in benthos and water chemistry
between groups, and used regression analyses to evaluate responses of benthic communities to water chemistry within each of
the landscape groups. We found that typical water chemistry measures associated with urban runoff such as specific conductance
and dissolved chloride were significantly higher in the urban group. In the crop group, we found variables commonly associated
with farming such as nutrients and pesticides significantly greater than in the other two groups. Regression analyses demonstrated
that the numbers of tolerant and facultative macroinvertebrates increased significantly in forested watersheds with small
shifts in pollutants, while in human use dominated watersheds the intolerant macroinvertebrates were more sensitive to shifts
in chemicals present at lower concentrations. The results from this study suggest that landscape based clustering can be used
to link upstream landscape characteristics, water chemistry and biotic integrity in order to assess stream condition and likely
cause of degradation without the use of reference sites. Notice: Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency
policy. 相似文献
246.
Michael A. Collins 《Journal of the American Water Resources Association》1972,8(6):1253-1258
Steady state experimental studies with a viscous analog of the aquifer system in central Long Island, New York, have shown there to be significant interaction between surface accretion, stream base flow, well recharge, and the degree of salt water intrusion. Reductions in accretion are found to cause a proportionately larger decrease in stream base flow. The degree of intrusion is found to be related to the distribution of accretion and well recharge between stream base flow and submarine flow to the sea. This interaction poses a conflict between development of the groundwater resource and maintenance of the surface water resource. Well recharge apparently offers a potential solution to the conflict. 相似文献
247.
Governmental mandates and public awareness have forcedprogressively smaller and less sophisticated agencies andorganizations to initiate stream monitoring programs,particularly in urban and urbanizing areas. Yet many of thesemonitoring efforts lack either a coherent conceptual frameworkor appropriately chosen methods, and they rely on monitoringtechniques that are simply infeasible for these institutionalsettings. We propose a monitoring strategy, and specificexisting monitoring protocols, that will be useful for themanagement and rehabilitation of streams in urbanizing watersheds.A monitoring strategy must be developed by 1) identifying the management question(s) being addressed, 2) determining theinstitional level of effort required (and available) toeffectively make particular kinds of measurements, and 3) identifying what specific parameters should and can be measured.Only a limited set of parameters show much utility orfeasibility in addressing the most common management questionsbeing faced by municipalities in urbanizing, humid-area regionsof the United States. These include measures of riparian canopy,bank erosion and bank hardening, and in-stream large woodydebris. With some additional expertise useful data can also beincluded on channel gradient, substrate composition, and pools.Nearly all of the other myriad parameters that have beenmeasured historically on rivers and streams show little apparentvalue in these watershed and institutional settings. 相似文献
248.
Jimmy S. Millican Jeffrey A. Back Anne M.S. McFarland 《Journal of the American Water Resources Association》2008,44(5):1219-1230
Abstract: Nutrient dose‐response bioassays were conducted using water from three sites along the North Bosque River. These bioassays provided support data for refinement of the Soil and Water Assessment Tool (SWAT) model used in the development of two phosphorus TMDLs for the North Bosque River. Test organisms were native phytoplanktonic algae and stock cultured Pseudokirchneriella subcapitata (Korshikov) Hindak. Growth was measured daily by in vivo fluorescence. Algal growth parameters for maximum growth (μmax) and half‐saturation constants for nitrogen (KN) or phosphorus (KP) were determined by fitting maximum growth rates associated with each dose level to a Monod growth rate function. Growth parameters of native algae were compared between locations and to growth parameters of P. subcapitata and literature values. No significant differences in half‐saturation constants were indicated within nutrient treatment for site or algal type. Geometric mean KN was 32 μg/l and for KP 7 μg/l. A significant difference was detected in maximum growth rates between algae types but not between sites or nutrient treatments. Mean μmax was 1.5/day for native algae and 1.2/day for stock algae. These results indicate that watershed‐specific maximum growth rates may need to be considered when modeling algal growth dynamics with regard to nutrients. 相似文献
249.
Devendra Swaroop Bhargava 《The Environmentalist》2008,28(2):128-136
The classical Streeter–Phelps models for Dissolved oxygen (DO) sag do not account for a significantly settleable portion (about
10% in treated to about 60% in the untreated wastewater discharged) of the total biochemical oxygen demand (BOD) inputs into
rivers through wastewater outfalls, and therefore, they can not be used to predict the DO sag to any accuracy and rationality.
The author’s rationally composited model for an accurate prediction of stream BOD, accounting for near linear removal of settleable
BOD as well as simultaneous exponential decay of the non-settleable BOD, is used to predict the DO sag resulting from a multi-wastewater-outfall
system, wherein the settling fields of some of the outfalls interfere and overlap. An illustrative case example has been presented
to demonstrate use of the models evolved under varying locations of the multi-wastewater-outfalls. A universal and integrated
PC based computer program can also be evolved for the computation of the overall resultant DO sag to confirm the manually
computed DO sag. 相似文献
250.
Headwater Influences on Downstream Water Quality 总被引:2,自引:0,他引:2
We investigated the influence of riparian and whole watershed land use as a function of stream size on surface water chemistry
and assessed regional variation in these relationships. Sixty-eight watersheds in four level III U.S. EPA ecoregions in eastern
Kansas were selected as study sites. Riparian land cover and watershed land use were quantified for the entire watershed,
and by Strahler order. Multiple regression analyses using riparian land cover classifications as independent variables explained
among-site variation in water chemistry parameters, particularly total nitrogen (41%), nitrate (61%), and total phosphorus
(63%) concentrations. Whole watershed land use explained slightly less variance, but riparian and whole watershed land use
were so tightly correlated that it was difficult to separate their effects. Water chemistry parameters sampled in downstream
reaches were most closely correlated with riparian land cover adjacent to the smallest (first-order) streams of watersheds
or land use in the entire watershed, with riparian zones immediately upstream of sampling sites offering less explanatory
power as stream size increased. Interestingly, headwater effects were evident even at times when these small streams were
unlikely to be flowing. Relationships were similar among ecoregions, indicating that land use characteristics were most responsible
for water quality variation among watersheds. These findings suggest that nonpoint pollution control strategies should consider
the influence of small upland streams and protection of downstream riparian zones alone is not sufficient to protect water
quality. 相似文献