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71.
通过对大巴山区主要分布的早古生代地层中的碎屑岩,碳酸盐岩和石煤的原岩,风化岩,原生土壤的硒含量及其相关关系分析,及对南秦岭早古生代地层和石煤中硒的化学活动性进行了研究。结果表明:其岩石和石煤中的硒在地层环境下有较大的活动性,不同类型岩石中硒淋失率和硒的淋失量不同,富硒而淋失率低但淋失量高的下寒武统鲁家坪组和早志留世大贵坪组的炭质板岩和石煤的分布区土壤(主要为当地岩石的风化残积物)的含硒量可达10mg/kg,甚至更高,是大巴山的富硒带和硒中毒带,含硒低而且淋失率高的志留系砂岩和粉砂岩以及寒武系统砾屑灰岩分布区是大巴山区的低硒带。 相似文献
72.
涕灭威、呋喃丹和拉索三种农药在土壤中的淋溶结果表明,经过30cm土柱下渗到收集器中的涕灭威为88.0%,呋喃丹为69.1%,拉索为1.84%;农药在四种土壤中的淋溶速度,砂土>砂壤土>粘壤土>粘土;土壤性质对农药移动的影响比农药自身性质的影响要小。 相似文献
73.
This paper analyzes the investment/environment overlap using a two stage model of two jurisdictions. Capital exports are modeled as choice variables for capital owners who weigh income considerations against the effects of capital exports on the quality of their local environments and on environmental policy. This framework reveals that capital owners have an incentive to cross-haul polluting factors across jurisdictions when direct controls are used to regulate emissions and that this cross-hauling induces policymakers to ratchet up environmental policies in both locations. The importance of instrument type and commitment on environmental policy is also analyzed. 相似文献
74.
在室内模拟条件下,研究了4种农药在土壤薄板上的移动性能。结果表明,甲基异柳磷与嘧啶氧磷属不易迁移的Ⅱ级农药;克草胺属中等迁移性的Ⅲ级农药;单甲脒属可移动性农药。 相似文献
75.
Rishi Raj Khare 《Journal of environmental science and health. Part. B》2013,48(6):391-399
This study was conducted to evaluate cyhalofop‐p‐butyl mobility in a sandy loam soil and subsequent distribution of residues at various depths under field conditions. Soil samples were taken from 0 to 150 cm depths at 3–90 d after rains in lysemeter of 1 and 2 m depths. Cyhalofop‐p‐butyl application at two rates and subsequent precipitation had a significant impact on soil, physico‐chemical properties and herbicide mobility. Precipitation caused substantial mobility of cyhalofop‐p‐butyl in the soil and 1.1–7.6 μg L?1 of cyhalofop‐p‐butyl was found in leachates. Cyhalofop‐p‐butyl residues in the leachates were probably due to preferential flow through the soil. Cyhalofop‐p‐butyl residues were detected in significant amounts from the soil up to 10 d, later, residues were found below the detection limit but its three transformation products viz., cyhalofop acid, diacid, and phenol were detected. 相似文献
76.
Mobility and Methylation of Mercury in Forest Soils Development of an In-Situ Stable Isotope Tracer Technique and Initial Results 总被引:2,自引:0,他引:2
Munthe John Lyvén Benny Parkman Helena Lee Ying-Hua Iverfeldt Åke Haraldsson Conny Verta Matti Porvari Petri 《Water, Air, & Soil Pollution: Focus》2001,1(3-4):385-393
A method for investigating in-situmethylation and mobility of mercury has beendeveloped and applied to forest soil. The methodis based on additions of stable 199Hgisotopes to forest soil plots followed bysampling and analysis of isotope ratios of totalmercury and MeHg using ICP-MS. Initial resultsindicate that a fraction (30%) of the mercuryadded to the forest soils is immobilised over atime scale of 16 months. A small but significantfraction of the mercury is methylated during thesame time scale. Higher methylation rates werefound in wetland soil than in dry forest podzolsoil. 相似文献
77.
José Fenoll Isabel Garrido Pilar Hellín Pilar Flores Nuria Vela 《Journal of environmental science and health. Part. B》2013,48(8):601-608
In this study, we examined the effect of four different organic wastes (OW)—composted sheep manure (CSM), spent coffee grounds (SCG), composted pine bark (CPB) and coir (CR)—on the potential groundwater pollution of propanil and isoxaben (herbicides), cadusafos (insecticide) and pencycuron (fungicide) under laboratory conditions. For this purpose, leaching studies were conducted using disturbed soil columns filled with a clay loam soil (Hipercalcic calcisol). The addition of organic matter (OM) drastically reduced the movement of the studied pesticides. The results obtained point to the interest in the use of agro-industrial and composted OW in reducing the groundwater pollution by pesticide drainage. 相似文献
78.
Employees' beliefs about how promotions are awarded within their organizations can have important consequences. We conducted two studies that focus on perceptions of the criteria used to make promotion decisions. In Study 1, we identified two types of perceived promotion criteria, performance‐based and nonperformance‐based. Then we use justice and social exchange theories to develop a model linking employee perceptions of promotion criteria to performance via their relationships with promotional justice and organizational commitment. In a sample of 305 employee–supervisor pairs, we found that both promotional justice and organizational commitment mediated between perceptions of promotion criteria and supervisor rated in‐role and extra‐role performance, and that having received a promotion in the past predicted attributions that promotions were based relatively more on performance or nonperformance criteria. Study 2 further examined the role of promotions themselves in the formation of perceptions of promotion criteria. Drawing from image and attribution theories, we hypothesized that the relationship between having received a promotion or not and perceptions of promotion criteria depends on ego defensiveness. In a sample of 145 employees, we found that those who scored high on ego defensiveness and who had not been promoted were especially likely to attribute promotion decisions to nonperformance criteria. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
79.
Elizabeth Eastman Kelly A. Stevens Cesunica Ivey Haofei Yu 《Frontiers of Environmental Science & Engineering》2022,16(5):63
80.
The Gunnison River in the Black Canyon of the Gunnison National Park (BCNP) near Montrose, Colorado is a mixed gravel and
bedrock river with ephemeral side tributaries. Flow rates are controlled immediately upstream by a diversion tunnel and three
reservoirs. The management of the hydraulic control structures has decreased low-frequency, high-stage flows, which are the
dominant geomorphic force in bedrock channel systems. We developed a simple model to estimate the extent of sediment mobilization
at a given flow in the BCNP and to evaluate changes in the extent and frequency of sediment mobilization for flow regimes
before and after flow regulation in 1966. Our methodology provides a screening process for identifying and prioritizing areas
in terms of sediment mobility criteria when more precise systematic field data are unavailable. The model uses the ratio between
reach-averaged bed shear stress and critical shear stress to estimate when a particular grain size is mobilized for a given
reach. We used aerial photography from 1992, digital elevation models, and field surveys to identify individual reaches and
estimate reach-averaged hydraulic geometry. Pebble counts of talus and debris fan deposits were used to estimate regional
colluvial grain-size distributions. Our results show that the frequency of flows mobilizing river bank sediment along a majority
of the Gunnison River in the BCNP has significantly declined since 1966. The model results correspond well to those obtained
from more detailed, site-specific field studies carried out by other investigators. Decreases in the frequency of significant
sediment-mobilizing flows were more pronounced for regions within the BCNP where the channel gradient is lower. Implications
of these results for management include increased risk of encroachment of vegetation on the active channel and long-term channel
narrowing by colluvial deposits. It must be recognized that our methodology represents a screening of regional differences
in sediment mobility. More precise estimates of hydraulic and sediment parameters would likely be required for dictating quantitative
management objectives within the context of sediment mobility and sensitivity to changes in the flow regime. 相似文献