全文获取类型
收费全文 | 1178篇 |
免费 | 47篇 |
国内免费 | 12篇 |
专业分类
安全科学 | 44篇 |
废物处理 | 49篇 |
环保管理 | 319篇 |
综合类 | 93篇 |
基础理论 | 294篇 |
环境理论 | 1篇 |
污染及防治 | 325篇 |
评价与监测 | 68篇 |
社会与环境 | 33篇 |
灾害及防治 | 11篇 |
出版年
2023年 | 11篇 |
2022年 | 9篇 |
2021年 | 11篇 |
2020年 | 17篇 |
2019年 | 8篇 |
2018年 | 25篇 |
2017年 | 33篇 |
2016年 | 30篇 |
2015年 | 30篇 |
2014年 | 33篇 |
2013年 | 113篇 |
2012年 | 52篇 |
2011年 | 58篇 |
2010年 | 49篇 |
2009年 | 53篇 |
2008年 | 62篇 |
2007年 | 66篇 |
2006年 | 65篇 |
2005年 | 38篇 |
2004年 | 36篇 |
2003年 | 43篇 |
2002年 | 42篇 |
2001年 | 25篇 |
2000年 | 35篇 |
1999年 | 20篇 |
1998年 | 19篇 |
1997年 | 17篇 |
1996年 | 27篇 |
1995年 | 22篇 |
1994年 | 16篇 |
1993年 | 13篇 |
1992年 | 15篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1989年 | 15篇 |
1988年 | 10篇 |
1987年 | 21篇 |
1986年 | 8篇 |
1985年 | 6篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 13篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 9篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1972年 | 3篇 |
排序方式: 共有1237条查询结果,搜索用时 15 毫秒
351.
Caroline S. Nash Gordon E. Grant John S. Selker Steven M. Wondzell 《Journal of the American Water Resources Association》2020,56(1):182-185
We discuss a recent paper which evaluated the hydrologic changes resulting from a pond‐and‐plug meadow restoration project in the Sierra Nevada Mountains of California. In the study, measurements of streamflow into and out of the meadow suggested late‐summer baseflow increased as much as five‐fold when compared with prerestoration conditions. However, the volume of streamflow attributed to the restored meadow (49,000–96,000 m3 over four months) would require that 2.5–4.8 m of saturated meadow soils drain during summer months. The groundwater data from this meadow record only 0.45 m of change over this timeframe, which is less than might be expected from plant use alone (0.75 m), suggesting this restored meadow may be acting as a water sink throughout summer rather than a source. 相似文献
352.
353.
We seek to develop a better understanding of interpersonal trust by bridging the gap between two heretofore distinct paradigms of trust. One paradigm views trust in terms of two dimensions: cognition- and affect-based. The other paradigm views trust as being distinct from trustworthiness, which has four dimensions: ability, behavioral integrity, benevolence, and values congruence. Currently, theoretical consensus is lacking about the antecedents of cognition- and affect-based trust in the first paradigm that incorporates insights from research on trustworthiness in the second paradigm. We show that this lack of consensus is problematic for internal knowledge development and external knowledge expansion. Thus, we join both paradigms by theorizing that ability and behavioral integrity are the most important predictors of cognition-based trust, whereas benevolence and values congruence are the most important predictors of affect-based trust. Across two samples, we found that our predictions were largely supported. Based on relative weights analysis, ability and behavioral integrity were more important than values congruence in predicting cognition-based trust, and benevolence was more important than ability in predicting affect-based trust. Furthermore, we found evidence that these relationships were largely robust to changes in the referent of analysis. 相似文献
354.
Spatial and temporal drivers of zoonotic pathogen contamination of an agricultural watershed 总被引:1,自引:0,他引:1
Jokinen CC Edge TA Koning W Laing CR Lapen DR Miller J Mutschall S Scott A Taboada EN Thomas JE Topp E Wilkes G Gannon VP 《Journal of environmental quality》2012,41(1):242-252
In regions where animal agriculture is prominent, such as southern Alberta, higher rates of gastrointestinal illness have been reported when compared with nonagricultural regions. This difference in the rate of illness is thought to be a result of increased zoonotic pathogen exposure through environmental sources such as water. In this study, temporal and spatial factors associated with bacterial pathogen contamination of the Oldman River, which transverses this region, were analyzed using classification and regression tree analysis. Significantly higher levels of fecal indicators; more frequent isolations of Campylobacter spp., Escherichia coli O157:H7, and Salmonella enterica spp.; and higher rates of detection of pig-specific Bacteroides markers occurred at downstream sites than at upstream sites, suggesting additive stream inputs. Fecal indicator densities were also significantly higher when any one of these three bacterial pathogens was present and where there were higher total animal manure units; however, occasionally pathogens were present when fecal indicator levels were low or undetectable. Overall, Salmonella spp., Campylobacter spp., and E. coli O157:H7 presence was associated with season, animal manure units, and total rainfall on the day of sampling and 3 d in advance of sampling. Several of the environmental variables analyzed in this study appear to influence pathogen prevalence and therefore may be useful in predicting water quality and safety and in the improvement of watershed management practices in this and other agricultural regions. 相似文献
355.
Bycatch of turtles in passive inland fyke net fisheries has been poorly studied, yet bycatch is an important conservation issue given the decline in many freshwater turtle populations. Delayed maturity and low natural adult mortality make turtles particularly susceptible to population declines when faced with additional anthropogenic adult mortality such as bycatch. When turtles are captured in fyke nets, the prolonged submergence can lead to stress and subsequent drowning. Fish die within infrequently checked passive fishing nets and dead fish are a potential food source for many freshwater turtles. Dead fish could thus act as attractants and increase turtle captures in fishing nets. We investigated the attraction of turtles to decomposing fish within fyke nets in eastern Ontario. We set fyke nets with either 1 kg of one-day or five-day decomposed fish, or no decomposed fish in the cod-end of the net. Decomposing fish did not alter the capture rate of turtles or fish, nor did it alter the species composition of the catch. Thus, reducing fish mortality in nets using shorter soak times is unlikely to alter turtle bycatch rates since turtles were not attracted by the dead fish. Interestingly, turtle bycatch rates increased as water temperatures did. Water temperature also influences turtle mortality by affecting the duration turtles can remain submerged. We thus suggest that submerged nets to either not be set or have reduced soak times in warm water conditions (e.g., >20 °C) as turtles tend to be captured more frequently and cannot withstand prolonged submergence. 相似文献
356.
Establishing the relationship between level of safety climate and safety performance is a current challenge. This work examines the relationship between level of safety climate and orientation toward safety in the decision making process and choice. Alternatively, this work seeks to answer the question of whether level of safety climate can predict safety-oriented decision making. A generalized safety climate questionnaire and a decision making simulation are utilized to examine this relationship. The results indicate that level of safety climate is not a significant predictor of the decision process; however, it was found to be a significant predictor of the selection of safer choices. 相似文献
357.
Daniel Dancer Craig Baker-Austin James A. Lowther Rachel E. Hartnell David N. Lees L. O. Roberts 《Environmental Forensics》2014,15(3):256-264
A novel microbial source tracking (MST) method based on the detection of human and non-human markers was developed and applied to track the origin of fecal pollution in water systems. Mitochondrial DNA sequences were used to develop new quantitative real-time polymerase chain reaction (qPCR) assays for dog, poultry, and gull. The targets were included as part of a toolbox including human, cow, pig, and sheep assays. A primer and probe set for the detection of the human-specific nifH gene of Methanobrevibacter smithii was also designed as an indicator of human fecal contamination. The assays were tested for specificity and applied to fecal-spiked surface waters and environmental samples collected from two river catchments impacted by sources of human and non-human fecal contamination. The MST methods described were applicable to both spiked waters and environmental samples, and using the two approaches the origin of fecal pollution could be successfully determined in mixed source fecally polluted waters. 相似文献
358.
Alexander M. R. Bakker Janette J. E. Bessembinder Allard J. W. de Wit Bart J. J. M. van den Hurk Steven B. Hoek 《Regional Environmental Change》2014,14(3):865-877
Excessive summer drying and reduced growing season length are expected to reduce European crop yields in future. This may be partly compensated by adapted crop management, increased CO2 concentration and technological development. For food security, changes in regional to continental crop yield variability may be more important than changes in mean yields. The assessment of changes in regional and larger scale crop variability requires high resolution and spatially consistent future weather, matching a specific climate scenario. Such data could be derived from regional climate models (RCMs), which provide changes in weather patterns. In general, RCM output is heavily biased with respect to observations. Due to the strong nonlinear relation between meteorological input and crop yields, the application of this biased output may result in large biases in the simulated crop yield changes. The use of RCM output only makes sense after sufficient bias correction. This study explores how RCM output can be bias corrected for the assessment of changes in European and subregional scale crop yield variability due to climate change. For this, output of the RCM RACMO of the Royal Netherlands Meteorological Institute was bias corrected and applied within the crop simulation model WOrld FOod STudies to simulate potential and water limited yields of three divergent crops: winter wheat, maize and sugar beets. The bias correction appeared necessary to successfully reproduce the mean yields as simulated with observational data. It also substantially improved the year-to-year variability of seasonal precipitation and radiation within RACMO, but some bias in the interannual variability remained. This is caused by the fact that the applied correction focuses on mean and daily variability. The interannual variability of growing season length, and as a consequence the potential yields too, appeared even deteriorated. Projected decrease in mean crop yields is well in line with earlier studies. No significant change in crop yield variability was found. Yet, only one RCM is analysed in this study, and it is recommended to extend this study with more climate models and a slightly adjusted bias correction taking into account the variability of larger time scales as well. 相似文献
359.
360.
Many metropolitan transit authorities are considering upgrading transit bus fleets to decrease ambient criteria pollutant
levels. Advancements in engine and fuel technology have lead to a generation of lower-emission buses in a variety of fuel
types. Dynamometer tests show substantial reductions in particulate mass emissions for younger buses (<10 years) over older
models, but particle number reduction has not been verified in the research. Recent studies suggest that particle number is
a more important factor than particle mass in determining health effects. In-vehicle particle number concentration measurements
on conventional diesel, oxidation-catalyst diesel and compressed natural gas transit buses are compared to estimate relative
in-vehicle particulate exposures. Two primary consistencies are observed from the data: the CNG buses have average particle
count concentrations near the average concentrations for the oxidation-catalyst diesel buses, and the conventional diesel
buses have average particle count concentrations approximately three to four times greater than the CNG buses. Particle number
concentrations are also noticeably affected by bus idling behavior and ventilation options, such as, window position and air
conditioning. 相似文献