全文获取类型
收费全文 | 830篇 |
免费 | 183篇 |
专业分类
安全科学 | 97篇 |
废物处理 | 73篇 |
环保管理 | 272篇 |
综合类 | 45篇 |
基础理论 | 365篇 |
污染及防治 | 87篇 |
评价与监测 | 12篇 |
社会与环境 | 7篇 |
灾害及防治 | 55篇 |
出版年
2022年 | 2篇 |
2021年 | 9篇 |
2020年 | 12篇 |
2019年 | 38篇 |
2018年 | 58篇 |
2017年 | 35篇 |
2016年 | 56篇 |
2015年 | 49篇 |
2014年 | 59篇 |
2013年 | 221篇 |
2012年 | 37篇 |
2011年 | 43篇 |
2010年 | 54篇 |
2009年 | 33篇 |
2008年 | 38篇 |
2007年 | 29篇 |
2006年 | 26篇 |
2005年 | 16篇 |
2004年 | 22篇 |
2003年 | 24篇 |
2002年 | 28篇 |
2001年 | 24篇 |
2000年 | 21篇 |
1999年 | 15篇 |
1998年 | 3篇 |
1997年 | 6篇 |
1994年 | 6篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1962年 | 2篇 |
1961年 | 1篇 |
1960年 | 1篇 |
1954年 | 1篇 |
1935年 | 1篇 |
1913年 | 1篇 |
排序方式: 共有1013条查询结果,搜索用时 31 毫秒
291.
Meeting lateness is pervasive and potentially highly consequential for individuals, groups, and organizations. In Study 1, we first examined base rates of lateness to meetings in an employee sample and found that meeting lateness is negatively related to both meeting satisfaction and effectiveness. We then conducted 2 lab studies to better understand the nature of this negative relationship between meeting lateness and meeting outcomes. In Study 2, we manipulated meeting lateness using a confederate and showed that participants' anticipated meeting satisfaction and effectiveness were significantly lower when meetings started late. In Study 3, participants holding actual group meetings were randomly and blindly assigned to either a 10 min late, 5 min late, or a control condition (n = 16 groups in each condition). We found significant differences concerning participants' perceived meeting satisfaction and meeting effectiveness, as well as objective group performance outcomes (number, quality, and feasibility of ideas produced in the meeting). We also identified differences in negative socioemotional group interaction behaviors depending on meeting lateness. In concert, our findings establish meeting lateness as an important organizational phenomenon and provide important conceptual and empirical implications for meeting research and practice. 相似文献
292.
Patterns of preference and practice: bridging actors in wildfire response networks in the American Northwest 下载免费PDF全文
A.J. Faas Anne‐Lise K. Velez Clare FitzGerald Branda L. Nowell Toddi A. Steelman 《Disasters》2017,41(3):527-548
The roles of bridging actors in emergency response networks can be important to disaster response outcomes. This paper is based on an evaluation of wildfire preparedness and response networks in 21 large‐scale wildfire events in the wildland—urban interface near national forests in the American Northwest. The study investigated how key individuals in responder networks anticipated seeking out specific people in perceived bridging roles prior to the occurrence of wildfires, and then captured who in fact assumed these roles during actual large‐scale events. It examines two plausible, but contradictory, bodies of theory—similarity and dissimilarity—that suggest who people might seek out as bridgers and who they would really go to during a disaster. Roughly one‐half of all pre‐fire nominations were consistent with similarity. Yet, while similarity is a reliable indicator of how people expect to organise, it does not hold up for how they organise during the real incident. 相似文献
293.
This paper analyses the relationship between nitrous oxide (N2O) emissions, economic growth, agricultural land used and exports in Germany. We use time‐series data between 1970 and 2012 and the Autoregressive Distributed Lag (ARDL) methodology to test for cointegration in the long run. Results show that there is a quadratic long run relationship between N2O emissions and economic growth, confirming the existence of an Environmental Kuznets Curve (EKC) for Germany. Agricultural land area affects N2O emissions positively, whereas exports affect emissions negatively. The turning point is $27,880, which is within the sample and implies that Germany is in the decreasing part of the curve of environmental degradation. The paper shows that, contrary to testing the EKC in less developed countries, mitigation of N2O emissions does not negatively affect growth in Germany. As such, it is feasible to undertake any conservative policy in order to reduce emissions without major consequences on economic sectors. 相似文献
294.
Revealing the Diversity of Natural Hydrologic Regimes in California with Relevance for Environmental Flows Applications 下载免费PDF全文
Belize A. Lane Helen E. Dahlke Gregory B. Pasternack Samuel Sandoval‐Solis 《Journal of the American Water Resources Association》2017,53(2):411-430
Alterations to flow regimes for water management objectives have degraded river ecosystems worldwide. These alterations are particularly profound in Mediterranean climate regions such as California with strong climatic variability and riverine species highly adapted to the resulting flooding and drought disturbances. However, defining environmental flow targets for Mediterranean rivers is complicated by extreme hydrologic variability and often intensive water management legacies. Improved understanding of the diversity of natural streamflow patterns and their spatial arrangement across Mediterranean regions is needed to support the future development of effective flow targets at appropriate scales for management applications with minimal resource and data requirements. Our study addresses this need through the development of a spatially explicit reach‐scale hydrologic classification for California. Dominant hydrologic regimes and their physio‐climatic controls are revealed, using available unimpaired and naturalized streamflow time‐series and generally publicly available geospatial datasets. This methodology identifies eight natural flow classes representing distinct flow sources, hydrologic characteristics, and catchment controls over rainfall‐runoff response. The study provides a broad‐scale hydrologic framework upon which flow‐ecology relationships could subsequently be established towards reach‐scale environmental flows applications in a complex, highly altered Mediterranean region. 相似文献
295.
Chemical oxidation using stabilized hydrogen peroxide in high temperature,saline groundwater impacted with hydrocarbons and MTBE 下载免费PDF全文
In situ chemical oxidation (ISCO) of petroleum hydrocarbons (PHCs) within groundwater is considered a proven approach to addressing PHC‐impacted groundwater in nonsaline environments. One of the most common oxidants used for oxidation of PHCs in groundwater is hydrogen peroxide (H2O2). Due to its highly reactive nature, H2O2 is often stabilized to aid in increasing its reactivity lifespan. Limited research and application of ISCO has been completed in warm, saline groundwater environments. Furthermore, even fewer studies have been completed in these environments for ISCO using stabilized H2O2. In this research, stabilized H2O2 was examined to determine its effectiveness in the treatment of PHCs and the additive methyl tert‐butyl ether (MTBE). Three stabilizers (citrate, phytate, silica [SiO2]) were tested to determine if the stabilizers could enhance and extend the treatment life of H2O2 within saline groundwater. To determine the effect of salinity on the three stabilizers, groundwater and aquifer samples were collected from two saline locations that had different salinity (total dissolved solids of about 7,000 mg/L and 18,000 mg/L). Specific target chemicals for treatment were water soluble, mobile components of gasoline including benzene, toluene, ethylbenzene, xylenes, (BTEX) and MTBE. Previous studies using unactivated persulfate indicated that the PHCs within the groundwater could be oxidized, however, only limited oxidation of the MTBE could be affected. The results of the laboratory tests indicated that greater than 95 percent of the target hydrocarbons were removed within 7 days of treatment. Microcosms with citrate‐stabilized H2O2 demonstrated a significantly faster and greater decline with most hydrocarbon concentrations reaching < 5 μg/L. The exceptions were ethylbenzene and m‐xylene, which were slightly decreased to about 30 and 20 μg/L, respectively. Initial mean concentrations of the BTEX compounds within the citrate‐stabilized microcosms were 10,554 μg/L, 9,318 μg/L, 6,859 μg/L, and 14,435 μg/L, respectively. The silicate‐stabilized H2O2 microcosms showed no significant benefit over the unstabilized control microcosms. The better performance of citrate‐stabilized microcosms was confirmed by increasing δ13C values of remaining hydrocarbons. MTBE declined from > 400 mg/L to < 100 mg/L in all microcosms, again with the best removal (> 90 percent) being measured in the citrate‐stabilized microcosms. Unfortunately, H2O2 oxidation in the microcosms also resulted in production of up to 40 mg/L TBA or approximately 10 percent of the MTBE oxidized. 相似文献
296.
Jae H. Ryu Richard N. Palmer Sangman Jeong Joo Heon Lee Young‐Oh Kim 《Journal of the American Water Resources Association》2009,45(2):485-499
Abstract: A decision support system for sustainable water resources management in a water conflict resolution framework is developed to identify and evaluate a range of acceptable alternatives for the Geum River Basin in Korea and to facilitate strategies that will result in sustainable water resource management. Working with stakeholders in a “shared vision modeling” framework, sustainable management strategies are created to illustrate system tradeoffs as well as long‐term system planning. A multi‐criterion decision‐making (MCDM) approach using subjective scales is utilized to evaluate the complex water resource allocation and management tradeoffs between stakeholders and system objectives. The procedures used in this study include the development of a “shared vision model,” a simulated decision‐making support system (as a tool for sustainable water management strategies associated with water conflicts, management options, and planning criteria), and the application of MCDM techniques for evaluating alternatives provided by the model. The research results demonstrate the utility of the sustainable water resource management model in aid of MCDM techniques in facilitating flexibility during initial stages of alternative identification and evaluation in a basin suffering from severe water conflicts. 相似文献
297.
Deepti Puri R. Karthikeyan M. Babbar‐Sebens 《Journal of the American Water Resources Association》2009,45(4):928-944
Abstract: The two main rivers of southeast Texas: Guadalupe and San Antonio have shown high temporal increase in bacteria concentration during the last decade. The SPAtially Referenced Regression On Watershed (SPARROW) attributes model, developed by the U.S. Geological Survey (USGS), has been applied to predict the fluxes and concentrations of contaminants in unmonitored streams and to identify the sources of these contaminants. This model identifies every reach as a basic network unit to distribute the sources, delivery, and attenuation factors. The model is data intensive and implements nonlinear regression to solve the parsimonious relations for describing various watershed processes. This study explored watershed and hydrological characteristics (land uses, precipitation, human and animal population, point sources, areal hydraulic load and drainage density, etc.) as the probable sources and delivery mechanisms of waterborne pathogens and their indicator (Escherichia coli [E. coli]) in the Guadalupe and San Antonio River basins. The effect of using various statistical indices for model selection on the final model’s ability to explain the various E. coli sources and transport processes was also analyzed. 相似文献
298.
Development of a SWAT Patch for Better Estimation of Sediment Yield in Steep Sloping Watersheds1 总被引:1,自引:0,他引:1
Jong‐Gun Kim Younshik Park Dongsun Yoo Nam‐Won Kim Bernard A. Engel Seong‐joon Kim Ki‐Sung Kim Kyoung Jae Lim 《Journal of the American Water Resources Association》2009,45(4):963-972
Abstract: The watershed scale Soil and Water Assessment Tool (SWAT) model divides watersheds into smaller subwatersheds for simulation of rainfall‐runoff and sediment loading at the field level and routing through stream networks. Typically, the SWAT model first needs to be calibrated and validated for accurate estimation through adjustment of sensitive input parameters (i.e., Curve Number values, USLE P, slope and slope‐length, and so on). However, in some instances, SWAT‐simulated results are greatly affected by the watershed delineation and Digital Elevation Models (DEM) cell size. In this study, the SWAT ArcView GIS Patch II was developed for steep sloping watersheds, and its performance was evaluated for various threshold values and DEM cell size scenarios when delineating subwatersheds using the SWAT model. The SWAT ArcView GIS Patch II was developed using the ArcView GIS Avenue program and Spatial Analyst libraries. The SWAT ArcView GIS Patch II improves upon the SWAT ArcView GIS Patch I because it reflects the topographic factor in calculating the field slope‐length of Hydrologic Response Units in the SWAT model. The simulated sediment value for 321 subwatersheds (watershed delineation threshold value of 25 ha) is greater than that for 43 subwatersheds (watershed delineation threshold value of 200 ha) by 201% without applying the SWAT ArcView GIS Patch II. However, when the SWAT ArcView GIS Patch II was applied, the difference in simulated sediment yield decreases for the same scenario (i.e., difference in simulated sediment with 321 subwatersheds and 43 subwatersheds) was 12%. The simulated sediment value for DEM cell size of 50 m is greater than that for DEM cell size of 10 m by 19.8% without the SWAT ArcView GIS Patch II. However, the difference becomes smaller (3.4% difference) between 50 and 10 m with the SWAT ArcView GIS Patch II for the DEM scenarios. As shown in this study, the SWAT ArcView GIS Patch II can reduce differences in simulated sediment values for various watershed delineation and DEM cell size scenarios. Without the SWAT ArcView GIS Patch II, variations in the SWAT‐simulated results using various watershed delineation and DEM cell size scenarios could be greater than those from input parameter calibration. Thus, the results obtained in this study show that the SWAT ArcView GIS Patch II should be used when simulating hydrology and sediment yield for steep sloping watersheds (especially if average slope of the subwatershed is >25%) for more accurate simulation of hydrology and sediment using the SWAT model. The SWAT ArcView GIS Patch II is available at http://www.EnvSys.co.kr/~swat for free download. 相似文献
299.
Evenset A Christensen GN Carroll J Zaborska A Berger U Herzke D Gregor D 《Environmental pollution (Barking, Essex : 1987)》2007,146(1):196-205
Ellasj?en receives contaminants from both atmospheric and biological transport (seabird guano). Historical trends of selected persistent organic pollutants and metals were determined by interpretation of down-core contaminant profiles in conjunction with sediment layer ages, determined by the (210)Pb method. Polychlorinated biphenyls (PCBs) and dichloro-diphenyl-trichloroethane and metabolites (DDTs) increased from about 1930 until 1970 (max. sum PCBs 71.8 ng/g dry weight (dw), max sum DDTs 4.0 ng/g dw), declining afterwards to 46.4 ng/g dw and 1.6 ng/g dw, respectively. Polybrominated diphenylethers (PBDEs) concentrations are increasing in Ellasj?en, reaching 0.73 ng/g dw in 2001. Hexabromocyclododekane (HBCD) was measured only in sediment from 1-2 cm depth (0.43 and 3.88 ng/g dw of alpha- and gamma-HBCD, respectively). Most metals (As, Cd, Co, Ni and Zn) showed a similar pattern as PCBs. No clear trends were observed for Cr, Pb or V. Mercury (Hg) has increased gradually since the beginning of the industrial era. 相似文献
300.
Plant species sorghum (Sorghum vulgar L.), clover (Trifolium pratense L.), panikum (Panicum antidotal), and canola (Brassica napus) were tested to determine their phytoremediation potential. After a period of about 90 days, plant samples (shoots and roots) and soil samples (before and after cultivation) were collected for zinc and cobalt analyses using atomic absorption spectrometry. The highest zinc uptake was observed in canola, while panikum grass showed a high zinc accumulation affinity compared to sorghum and clover. Calculation of the recovery percentage, based on the amount of zinc removed from the soil after cultivation, ranged between 12.8 and 36.3 percent of the total initial zinc. Canola shoots exhibited the highest cobalt uptake compared to the other plant species. Calculation of the recovery percentage based on cobalt removed from the soil after cultivation ranged between 10.1 and 40.7 percent of the total initial cobalt concentration. © 2007 Wiley Periodicals, Inc. * 1 This article is a U.S. Government work and, as such, is in the public domain of the United States of America. 相似文献