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111.
112.
The equations of Parsons and Strickland (1963) have been applied to calculate the concentration of total carotenoids in Phaeodactylum tricornutum, and the same pigments have simultaneously been determined on the individual fractions after TLC (thinlayer chromatography) separation. Comparison of both sets of data shows that for diverse carotenoids: chlorophyll a ratios, the direct spectrophotometric values range from 80 to 130% of the chromatographic values; wide variations in the proportions of different carotenoids account for such difference. On the basis of correlations between the proportion of each carotenoid and the absorbance ratio 480:663 nm, an indirect method for the rapid estimation of individual carotenoids of P. tricornutum is proposed. Its eventual application to other Chrysophyta species and to sea water is discussed.Contribución del Instituto de Biología Marina No. 320. 相似文献
113.
Incorporating anthropogenic variables into a species distribution model to map gypsy moth risk 总被引:1,自引:0,他引:1
Christopher D. Lippitt John Rogan James Toledano Florencia Sangermano J. Ronald Eastman Victor Mastro Alan Sawyer 《Ecological modelling》2008
This paper presents a novel methodology for multi-scale and multi-type spatial data integration in support of insect pest risk/vulnerability assessment in the contiguous United States. Probability of gypsy moth (Lymantria dispar L.) establishment is used as a case study. A neural network facilitates the integration of variables representing dynamic anthropogenic interaction and ecological characteristics. Neural network model (back-propagation network [BPN]) results are compared to logistic regression and multi-criteria evaluation via weighted linear combination, using the receiver operating characteristic area under the curve (AUC) and a simple threshold assessment. The BPN provided the most accurate infestation-forecast predictions producing an AUC of 0.93, followed by multi-criteria evaluation (AUC = 0.92) and logistic regression (AUC = 0.86) when independently validating using post model infestation data. Results suggest that BPN can provide valuable insight into factors contributing to introduction for invasive species whose propagation and establishment requirements are not fully understood. The integration of anthropogenic and ecological variables allowed production of an accurate risk model and provided insight into the impact of human activities. 相似文献
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Restoring Forests and Associated Ecosystem Services on Appalachian Coal Surface Mines 总被引:1,自引:0,他引:1
Zipper CE Burger JA Skousen JG Angel PN Barton CD Davis V Franklin JA 《Environmental management》2011,47(5):751-765
Surface coal mining in Appalachia has caused extensive replacement of forest with non-forested land cover, much of which is
unmanaged and unproductive. Although forested ecosystems are valued by society for both marketable products and ecosystem
services, forests have not been restored on most Appalachian mined lands because traditional reclamation practices, encouraged
by regulatory policies, created conditions poorly suited for reforestation. Reclamation scientists have studied productive
forests growing on older mine sites, established forest vegetation experimentally on recent mines, and identified mine reclamation
practices that encourage forest vegetation re-establishment. Based on these findings, they developed a Forestry Reclamation
Approach (FRA) that can be employed by coal mining firms to restore forest vegetation. Scientists and mine regulators, working
collaboratively, have communicated the FRA to the coal industry and to regulatory enforcement personnel. Today, the FRA is
used routinely by many coal mining firms, and thousands of mined hectares have been reclaimed to restore productive mine soils
and planted with native forest trees. Reclamation of coal mines using the FRA is expected to restore these lands’ capabilities
to provide forest-based ecosystem services, such as wood production, atmospheric carbon sequestration, wildlife habitat, watershed
protection, and water quality protection to a greater extent than conventional reclamation practices. 相似文献
116.
Kim K Steuerwald AJ Parsons PJ Fujimoto VY Browne RW Bloom MS 《Journal of environmental monitoring : JEM》2011,13(9):2413-2419
Humans are exposed to concentrations of multiple trace elements through a variety of background sources; many are suspected reproductive toxicants. Prior to investigating associations between trace elements and human reproductive health, potential biomarkers of exposure should be characterized by sources of variability in the population at risk. Factors influencing elemental exposure should also be identified to ensure their consideration as potential confounding variables. The principal aim of this study is to characterize sources of variability for 19 trace elements measured in urine specimens collected from 55 women and 36 male partners completing a 1st cycle of in vitro fertilization (IVF). Urine specimens were analyzed using a biomonitoring method based on inductively coupled plasma-mass spectrometry (ICP-MS). Randomly selected urine specimens (~6%) were analyzed in duplicate, and these data were used to characterize sources of variability. Nine trace elements including As, Ba, Cd, Cs, Co, Cu, Mn, Mo, and Zn, were quantified in most specimens, indicating their utility in future epidemiologic studies of trace elements exposure and IVF outcomes. With few exceptions, normalizing urine using the traditional creatinine-correction procedure, or an alternative approach based on a linear regression model, increased residual variability only slightly. Sex and race appear to be important factors to consider in epidemiologic studies conducted in this population. Urine concentrations for most elements are similar to those reported in the 2005-2006 National Health and Nutrition Examination Survey (NHANES); however, differences in others may indicate regional trends or a unique exposure history for this infertile study population. 相似文献
117.
Peter Bröde Kalev Kuklane Victor Candas Emiel A. Den Hartog Barbara Griefahn Ingvar Holmér 《International journal of occupational safety and ergonomics》2013,19(2):231-244
The heat transferred through protective clothing under long wave radiation compared to a reference condition without radiant stress was determined in thermal manikin experiments. The influence of clothing insulation and reflectivity, and the interaction with wind and wet underclothing were considered. Garments with different outer materials and colours and additionally an aluminised reflective suit were combined with different number and types of dry and pre-wetted underwear layers. Under radiant stress, whole body heat loss decreased, i.e., heat gain occurred compared to the reference. This heat gain increased with radiation intensity, and decreased with air velocity and clothing insulation. Except for the reflective outer layer that showed only minimal heat gain over the whole range of radiation intensities, the influence of the outer garments’ material and colour was small with dry clothing. Wetting the underclothing for simulating sweat accumulation, however, caused differing effects with higher heat gain in less permeable garments. 相似文献
118.
处理社会生态系统的不确定性和复杂性,深深地有赖于自然资源用户从使人惊讶的生态事件和危机中学习并适应的能力.本文分析了为什幺学习过程受自然资源用户中间的战略行为的影响,怎样影响,并且社会冲突是怎样受到社会和生态不确定性影响的.本文的主张是自然资源用户中的社会冲突严重抑止了从社会生态系统中学习并适应的可能性.这是结合了政治学、实验经济学、社会心理学并研究了一个分析案例后得出的,该案例研究了瑞典水管理制度中复杂的社会冲突和制度变化.本文还探讨了在瑞典水管理制度中,制度背景在确定学习过程的结果中扮演的关键性角色,并因此突出了以前在社会生态系统中学习过程和制度变化的较不详尽的政治方面. 相似文献
119.
120.
Victor M. Ponce Donna S. Lindquist 《Journal of the American Water Resources Association》1990,26(2):259-268
ABSTRACT: Baseflow augmentation refers to the temporary storage of subsurface water in floodplains, streambanks, and/or stream bottoms during the wet season, either by natural or artificial means, for later release during the dry season to increase the magnitude and permanence of low flows. Management strategies for baseflow augmentation fall into the following categories: (1) range management, (2) upland vegetation management, (3) riparian vegetation management, (4) upland runoff detention and retention, and (5) the use of instream structures. The benefits of a management strategy focused on baseflow augmentation are many, including: (1) increased summer flows, (2) healthier riparian areas, (3) increased channel and bank stability, (4) decreased erosion and sediment transport, (5) improved water quality, (6) enhanced fish and wildlife habitat, (7) lower stream temperatures, and (8) improved stream aesthetics. This review has shown that baseflow augmentation has been successfully accomplished in a few documented cases. Given its clear impact on soil and water conservation, particularly in the semiarid western U.S., it appears that baseflow augmentation is a concept whose time has come. Research is needed on how to successfully integrate baseflow augmentation within comprehensive resource management strategies. 相似文献