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121.
Kathryn E. Arnold Stephen D. Larcombe Lotta Ducaroir Lucille Alexander 《Behavioral ecology and sociobiology》2010,64(11):1857-1866
During mate choice, individuals are predicted to assess traits that honestly signal the quality of potential partners. Locomotor
capacity may be such a trait, potentially signalling condition and ability to resist oxidative damage. In this study, we experimentally
manipulated nutritional status: Male wild-type budgerigars, imported from Australia, were provided with either an enhanced
(EQ) or reduced quality (RQ) diet varying in vitamin (particularly retinol and α-tocopherol) and mineral levels. Then, we
assessed whether this influenced locomotor capacity, i.e. escape flight performance, and sexual attractiveness in male budgerigars
Melopsittacus undulatus. Males in the EQ group showed significantly greater total antioxidant capacity and higher blood plasma concentrations of the
dietary antioxidants retinol and α-tocopherol, but not carotenoids, than the RQ group. Over 8 weeks of flight training, males
on the EQ diet showed significantly greater improvement on the most strenuous flight test than RQ males. In mate choice trials,
females preferred EQ over RQ males. EQ males that were relatively fast in escape flight trials were more strongly preferred
in the mate preference arena than their RQ competitors. Interestingly, males with high plasma carotenoid levels flew slower
and were less attractive than males with low carotenoid levels. This might indicate that carotenoids are not effective antioxidants
in birds. Overall, our results show that dietary-derived antioxidants can influence sexual attractiveness and other fitness-related
traits through multiple pathways. Locomotor capacity appears to be an honest signal of male condition in birds. 相似文献
122.
Eichelter Johanna Wilhelm Harald Mautner Andreas Fahrngruber Barbara Schafler Erhard Eder Andreas Kozich Martin Bismarck Alexander 《Journal of Polymers and the Environment》2021,29(11):3509-3524
Journal of Polymers and the Environment - We evaluated the influence of blending various renewable polymer grades and amounts to allow for high stretchability during stretching at 800 mm/s... 相似文献
123.
Integrated Estimation of the Effect of Physical Factors on Human Functional State During Mental Work
German A. Suvorov Ralemma F. Afanasieva Nataliya S. Mikhailova Migran A. Babayan Alexander F. Bobrov 《International journal of occupational safety and ergonomics》2013,19(2):149-161
The purpose of this study was to develop a model for an integrated estimation of the functional state of the human organism (FSHO) and an integral estimation of physical factors (PF) for hygienic rating. Tests were performed twice with 3 men in 0.7-clo clothing during 4-hr mental work with 9 combinations of 4 PF: wideband noise (55–83 dB(A)), whole-body vibration (6 Hz, az = 0.2–1.8 ms?2), air temperature (18–30 °C), and illumination (1, 3, 5 lx). Thermoregulatory, cardiovascular, and psychophysiological reactions and temporary threshold of hearing (TTS2) shifts were studied. For the integral estimation of PF influence on FSHO the model F(y1, y2, ... ym) = f(x1, x2, ... xn) was used, relating both FSHO and PF sets. The most important physiological parameters in creating FSHO are defined and the contribution of individual parameters of FSHO and PF is found. 相似文献
124.
Christopher Brandl Alexander Mertens Christopher M. Schlick 《International journal of occupational safety and ergonomics》2013,19(1):110-117
In semi-trailer assembly, workers are exposed to several physical risk factors. Awkward working postures have not yet been investigated in semi-trailer assembly, although they are known to be a major risk factor for musculoskeletal disorders. We therefore conducted a comprehensive ergonomic analysis of working postures using the Ovako working posture analysing system (OWAS), with an individual sampling strategy. The postural load in semi-trailer assembly was assessed on the basis of 20,601 observations of 63 workers executing a representative set of nine work tasks. According to the OWAS, the postural load of various working postures and body part positions may have a harmful effect on the musculoskeletal system. We therefore give examples of corrective measures that could improve awkward working postures. Applying an individual sampling strategy was revealed to have advantages over a collective strategy, so this is recommended for future ergonomic analyses. 相似文献
125.
Assessing Sediment Yield for Selected Watersheds in the Laurentian Great Lakes Basin Under Future Agricultural Scenarios 总被引:1,自引:1,他引:0
Yang Shao Ross S. Lunetta Alexander J. Macpherson Junyan Luo Guo Chen 《Environmental management》2013,51(1):59-69
In the Laurentian Great Lakes Basin (GLB), corn acreage has been expanding since 2005 in response to high demand for corn as an ethanol feedstock. This study integrated remote sensing-derived products and the Soil and Water Assessment Tool (SWAT) within a geographic information system (GIS) modeling environment to assess the impacts of cropland change on sediment yield within four selected watersheds in the GLB. The SWAT models were calibrated during a 6 year period (2000–2005), and predicted stream flows were validated. The R 2 values were 0.76, 0.80, 0.72, and 0.81 for the St. Joseph River, the St. Mary River, the Peshtigo River, and the Cattaraugus Creek watersheds, respectively. The corresponding E (Nash and Sutcliffe model efficiency coefficient) values ranged from 0.24 to 0.79. The average annual sediment yields (tons/ha/year) ranged from 0.12 to 4.44 for the baseline (2000 to 2008) condition. Sediment yields were predicted to increase for possible future cropland change scenarios. The first scenario was to convert all “other” agricultural row crop types (i.e., sorghum) to corn fields and switch the current/baseline crop rotation into continuous corn. The average annual sediment yields increased 7–42 % for different watersheds. The second scenario was to further expand the corn planting to hay/pasture fields. The average annual sediment yields increased 33–127 % compared with baseline conditions. 相似文献
126.
Lerchl A 《Die Naturwissenschaften》2008,95(2):165-170
A previous study has shown a marked and continuing decline in weekend births in Germany between 1988 and 2003 (Lerchl, Naturwissenschaften 92:592-594, 2005). The present study was performed to investigate the possible influence of caesarean sections (CS) on weekend birth number and on the involvement of midwives in births for all 16 German states for the year 2003. In total, data from 706,721 births were sorted according to weekday of births and state, respectively, and the weekend births avoidance rates were calculated. Weekend births were consistently less frequent than births during the week, with an average of -15.3% for all states and due to fewer births on Saturdays (-13.6%) and Sundays (-16.7%). Between the states, weekend births avoidance rates ranged from -11.6% (Bremen) to -24.2% (Saarland). The proportion of CS was 25.5% for all states, ranging from 19.2% (Sachsen and Sachsen-Anhalt) to 30.5% (Saarland). CS and weekend births avoidance rates were significantly correlated, consistent with the hypothesis that primary (planned) CS are regularly scheduled on weekdays. The number of births per midwife (BPM) was calculated according to the number of active members in the states' professional midwives' organizations. The mean number of BPM was 59.5, ranging from 45.2 (Bremen) to 82.4 (Sachsen-Anhalt). CS and BPM were significantly correlated, consistent with the hypothesis that higher CS ratios are associated with lower midwife involvement in births. It is concluded that the decline in weekend births and lower involvement of midwives are caused, at least in part, by an increased number of caesarean sections. 相似文献
127.
Climate change and associated glacial recession create new stream habitat that leads to the assembly of new riverine communities through primary succession. However, there are still very few studies of the patterns and processes of community assembly during primary succession for stream ecosystems. We illustrate the rapidity with which biotic communities can colonize and establish in recently formed streams by examining Stonefly Creek in Glacier Bay, Alaska (USA), which began to emerge from a remnant glacial ice mass between 1976 and 1979. By 2002, 57 macroinvertebrate and 27 microcrustacea species had become established. Within 10 years of the stream's formation, pink salmon and Dolly Varden charr colonized, followed by other fish species, including juvenile red and silver salmon, Coast Range sculpin, and sticklebacks. Stable-isotope analyses indicate that marine-derived nitrogen from the decay of salmon carcasses was substantially assimilated within the aquatic food web by 2004. The findings from Stonefly Creek are compared with those from a long-term study of a similarly formed but older stream (12 km to the northeast) to examine possible similarities in macroinvertebrate community and biological trait composition between streams at similar stages of development. Macroinvertebrate community assembly appears to have been initially strongly deterministic owing to low water temperature associated with remnant ice masses. In contrast, microcrustacean community assembly appears to have been more stochastic. However, as stream age and water temperature increased, macroinvertebrate colonization was also more stochastic, and taxonomic similarity between Stonefly Creek and a stream at the same stage of development was <50%. However the most abundant taxa were similar, and functional diversity of the two communities was almost identical. Tolerance is suggested as the major mechanism of community assembly. The rapidity with which salmonids and invertebrate communities have become established across an entire watershed has implications for the conservation of biodiversity in freshwater habitats. 相似文献
128.
Stephen D. Preston Richard B. Alexander Gregory E. Schwarz Charles G. Crawford 《Journal of the American Water Resources Association》2011,47(5):891-915
Preston, Stephen D., Richard B. Alexander, Gregory E. Schwarz, and Charles G. Crawford, 2011. Factors Affecting Stream Nutrient Loads: A Synthesis of Regional SPARROW Model Results for the Continental United States. Journal of the American Water Resources Association (JAWRA) 47(5):891‐915. DOI: 10.1111/j.1752‐1688.2011.00577.x Abstract: We compared the results of 12 recently calibrated regional SPARROW (SPAtially Referenced Regressions On Watershed attributes) models covering most of the continental United States to evaluate the consistency and regional differences in factors affecting stream nutrient loads. The models – 6 for total nitrogen and 6 for total phosphorus – all provide similar levels of prediction accuracy, but those for major river basins in the eastern half of the country were somewhat more accurate. The models simulate long‐term mean annual stream nutrient loads as a function of a wide range of known sources and climatic (precipitation, temperature), landscape (e.g., soils, geology), and aquatic factors affecting nutrient fate and transport. The results confirm the dominant effects of urban and agricultural sources on stream nutrient loads nationally and regionally, but reveal considerable spatial variability in the specific types of sources that control water quality. These include regional differences in the relative importance of different types of urban (municipal and industrial point vs. diffuse urban runoff) and agriculture (crop cultivation vs. animal waste) sources, as well as the effects of atmospheric deposition, mining, and background (e.g., soil phosphorus) sources on stream nutrients. Overall, we found that the SPARROW model results provide a consistent set of information for identifying the major sources and environmental factors affecting nutrient fate and transport in United States watersheds at regional and subregional scales. 相似文献
129.
Valentin Becher Sonnik Clausen Alexander Fateev Hartmut Spliethoff 《International Journal of Greenhouse Gas Control》2011
Combustion of hydrocarbon fuels with pure oxygen results in a different flue gas composition as combustion with air. Standard CFD spectral gas radiation models for air combustion are out of their validity range. The series of three articles provides a common spectral basis for the validation of new developed models. In part A of the series gas cell transmissivity spectra in the spectral range of 2.4–5.4 μm of water vapor and carbon dioxide in the temperature range from 727 to 1500 ° C and at different concentrations were compared at a nominal resolution of 32 cm?1 to line-by-line models from different databases, two statistical-narrow-band models and the exponential wide band model. The two statistical-narrow-band models EM2C and RADCAL showed a good agreement with a maximal band transmissivity deviation of 3%. The exponential-wide-band model showed a deviation of 6%. The new line-by-line database HITEMP2010 had the lowest band transmissivity deviation of 2.2% and was recommended as a reference model for the validation of simplified CFD models. 相似文献
130.
Zhulidov AV Robarts RD Pavlov DF Kämäri J Gurtovaya TY Meriläinen JJ Pospelov IN 《Environmental monitoring and assessment》2011,181(1-4):539-553
The Norilsk industrial ore smelting complex (Taymyr Peninsula, Russian Federation) has significantly impacted many components of local terrestrial and aquatic environments. Whether it has had a major impact on the wider Russian Arctic remains controversial as studies are scarce. From 1986 to 2004, data on heavy metal (Cu, Ni, Zn, Hg, Cd and Hg) concentrations in fish (burbot), moss, lichens, periphyton, hydric soils and snow in and around Norilsk and the most northern parts of the Taymyr Peninsula were analysed. Very high concentrations of Cu (203 μg L?1 ± 51 μg L?1) and Ni (113 μg L?1 ± 15 μg L?1) were found in the water of the Schuchya River close to Norilsk. Heavy metal concentrations in burbot liver were highest in Lake Pyasino near Norilsk compared to other study regions that were >100 km distant. From 1989-1996, Cu (121 μg L?1 ± 39 μg L?1 SD), Zn (150 μg L?1) ± 70 μg L?1) and Ni (149 μg L?1 ± 72 μg L?1) snow concentrations were greatest in Norilsk, but were low elsewhere. By 2004, these concentrations had dropped significantly, especially for Cu-74 μg L?1 (±18.7 μg L?1 SD), Zn-81.7 μg L?1 (± 31.3 μg L?1 SD) and Ni-80 μg L?1(±18.0 μg L?1 SD). Norilsk and its surroundings are subject to heavy pollution from the Norilsk metallurgical industry but these are absent from the greater Arctic region due to the prevailing winds and the Byrranga Mountains. Pollution abatement measures have been made so further investigations are necessary in order to assess their efficiency. 相似文献