全文获取类型
收费全文 | 177篇 |
免费 | 0篇 |
国内免费 | 3篇 |
专业分类
安全科学 | 2篇 |
废物处理 | 13篇 |
环保管理 | 17篇 |
综合类 | 35篇 |
基础理论 | 39篇 |
环境理论 | 1篇 |
污染及防治 | 48篇 |
评价与监测 | 16篇 |
社会与环境 | 9篇 |
出版年
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 5篇 |
2014年 | 9篇 |
2013年 | 15篇 |
2012年 | 12篇 |
2011年 | 10篇 |
2010年 | 7篇 |
2009年 | 6篇 |
2008年 | 16篇 |
2007年 | 9篇 |
2006年 | 10篇 |
2005年 | 8篇 |
2004年 | 6篇 |
2003年 | 10篇 |
2002年 | 11篇 |
2001年 | 1篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有180条查询结果,搜索用时 15 毫秒
131.
Evaluation of the Biodegradation of Starch and Cellulose Under Controlled Composting Conditions 总被引:1,自引:1,他引:0
Francesco Degli-Innocenti Maurizio Tosin Catia Bastioli 《Journal of Polymers and the Environment》1998,6(4):197-202
In order to verify the response of the controlled composting test method (i.e., the ISO/DIS 14855:1997, the ASTM D 5338-92, or the CEN counterpart) to starch at different concentrations, the maximum amount prescribed by the test method (100 g) and lower amounts (60 and 30 g), as if starch were a coingredient in a blend, were tested. After 44 days of incubation (at a constant temperature of 58°C) the biodegradation curves were in a plateau phase, displaying the following final values (referred to a nominal starch initial amount of 100 g): starch 100 g, 97.5%; starch 60 g, 63.7%; and starch 30 g, 32.5%. The data show a CO2 evolution roughly equal, in each case, to the theoretical maximum, indicating a complete starch mineralization. We cannot discern whether the deviations found at lower concentrations are caused by a priming effect. In any case, the extent of the deviations is not high and is acceptable in biodegradation studies. The average biodegradation of cellulose, obtained gathering four independent experiments with 11 biodegradation curves, turned out to be 96.8 ± 6.7% (SD) after 47 ± 1 days. The data indicate that the controlled composting is a reliable test method also for starch and cellulose and, consequently, for starch-based and cellulose-based materials. 相似文献
132.
In 57 patients, following prenatal diagnosis of a fetus affected by β-thalassaemia major, we terminated the pregnancy by dilatation and evacuation. In 19, we have already performed DNA analysis to evaluate the feasibility of prenatal diagnosis in a subsequent pregnancy. 相似文献
133.
A routine study of the fetal karyotype was performed on samples obtained at 64 fetoscopic procedures. In 13 cases only pure amniotic fluid was available for the cultures, while in the remaining 51 cases the chromosome analysis was carried out on PHA-stimulated lymphocyte microcultures set up with any excess fetal blood above the requirements for globin-chain synthesis. Karyotype could be determined on fetal lymphocytes in 44 cases (86 per cent). All the fetuses were chromosomally normal. This experience shows that cytogenetic analysis using microaliquots of fetal blood is a relatively simple technique which should be introduced into routine prenatal diagnosis by fetoscopy. 相似文献
134.
135.
Soil erosion induced by land use changes as determined by plough marks and field evidence in the Aksum area (Ethiopia) 总被引:1,自引:0,他引:1
Rossano Ciampalini Paolo BilliGiovanni Ferrari Lorenzo BorselliStéphane Follain 《Agriculture, ecosystems & environment》2012,146(1):197-208
The aim of the research presented here was to analyse soil erosion in response to changes in agricultural and soil conservation practices throughout history. The Aksum area (Tigray, northern Ethiopia) presents favourable conditions for the development of a long-term approach for assessing soil conservation techniques that have been applied for centuries (i.e., since the Aksumite kingdom, 400 BC to 800 AD). These techniques have been maintained until the present day, and parts of the terraced systems of the area are still in use. During the 1970s, social and political events led to a remarkable change in land use patterns, and large arable areas were converted into grazing land, resulting in a significant increase in soil loss. The rates of soil erosion were evaluated based on analyses of the deep scratches (plough marks) left on stones in the soil by the maresha, the ard plough pulled by oxen used in agricultural practices of the area, and the patinas, varnishes and weathering rinds exposed by soil loss after the abandonment of the fields. The study results show average rates of soil erosion of 2.8 t ha−1 y−1 and 65.8 t ha−1 y−1 for the soil conservation conditions under traditional agriculture (long-term observations) and accelerated erosion after abandonment (short-term observations), respectively. A comparison using recently calibrated erosion evaluation techniques conducted to support the field measurements revealed a close correlation between the calculated and recorded data. 相似文献
136.
Flathead grey mullets Mugil cephalus are commonly found in Mediterranean lagoons, which are regularly subject to high environmental variations. Oxygen is one
of the factors that shows extremely high variation. The objective of this study was to test the effects of acute hypoxia exposure
at two experimental temperatures (i.e. 20 and 30°C) on the stamina (time to fatigue) in M. cephalus swimming at the minimal cost of transport (i.e. optimal swimming speed; U
opt). At each temperature, a relationship was established between swimming speed and oxygen consumption (MO2). This allowed estimation of U
opt at 45 cm s−1 (~1.12 Body Length s−1). Independent of temperature, stamina at U
opt was significantly reduced in severe hypoxia, i.e. at 15% of air saturation (AS). In these conditions, oxygen supply appears
therefore to be insufficient to maintain swimming, even at the low speed tested here. After the stamina test, MO2 measured in fish tested at 15% AS was significantly higher than that measured after the test in normoxia. Therefore, we suggest
that in hypoxia, fish used anaerobic metabolism to supplement swimming at U
opt, leading to an oxygen debt. Since flathead grey mullet is a hypoxia-tolerant species, it is possible that hypoxic conditions
less severe than those tested here may reduce stamina at low speed in less tolerant species. In addition, we suggest that
testing stamina at these speeds may be relevant in order to understand the effect of hypoxia on behavioural activities carried
out at low speed, such as food searching. 相似文献
137.
Daniela Cianelli Luciana Sabia Maurizio Ribera dAlcal Enrico Zambianchi 《Ecological modelling》2009,220(19):2380-2392
In marine ecosystems ecological and environmental conditions continuously change, possibly supporting the wide range of phytoplankton species coexisting in aquatic environments. Phytoplankton communities are not homogeneously distributed in the water column due to the spatial and temporal variability of turbulent mixing and the concurrent biological response. In this paper an individual-based model (Lagrangian method) simulating the basic physiology of two coexisting phytoplankton species has been developed. The species, sharing the same availability of light and nutrient resource, are characterized by different photo-physiological parameters. The spatial and temporal evolution of turbulent mixing is simulated introducing vertical profiles of measured eddy diffusivity. Three case studies have been examined to analyze the role of environment–individual interactions in determining bloom conditions for both the selected species. The organisms experience recurrent fluctuations of light, temperature, and nutrient concentration gradients, due to the turbulent mixing in the water column, which have significant effects on the growth of the phytoplankton species. In all the numerical experiments, the temporal and spatial variability of different forcings do not support the prevalence of one species over the other over the time scale typical of a phytoplankton bloom.A well mixed water column favours the growth of both the populations while a variable mixing regime limits their growth reducing the photophysiological differences between the species. 相似文献
138.
G. E. Brown M. C. O. Ferrari P. H. Malka L. Fregeau L. Kayello D. P. Chivers 《Behavioral ecology and sociobiology》2013,67(1):43-51
The ability to acquire information about predators allows prey to better balance threat-sensitive tradeoffs by responding only to ecologically relevant predation threats. However, predation risk is highly variable through time and responding to predators that no longer represent a threat would likely prove costly to prey. While a wealth of studies have examined the way in which prey learn, little attention has been paid to retention of acquired information. Recent studies suggest that retention is indeed plastic and shaped by a suite of intrinsic factors such as strength of initial conditioning and individual growth rate. Here, we investigated if the duration of retention of acquired information is influenced by individual behavioral tactics (i.e., ‘personality’). We recorded latency to escape an opaque acclimation chamber of juvenile rainbow trout (Oncorhynchus mykiss) as a measure of behavioral tactic. We then immediately conditioned individual trout to recognize pumpkinseed (Lepomis gibbosus) and tested for recognition 24 h or 8 days postconditioning. Our results demonstrate that while shy versus bold trout exhibited no difference in the strength of conditioned response to pumpkinseed odor during conditioning trials or when tested for recognition 24 h postconditioning, there was a significant effect of individual behavioral tactic on the retention of learned predator recognition. While shy trout continued to exhibit a learned response to pumpkinseed odor when tested 8 days postconditioning, bold trout were not different from our pseudoconditioned controls. These data suggest that the behavioral tactic employed at the time of conditioning influences the ‘memory window’ of acquired information. 相似文献
139.
Rafael S. Araújo Leonardo C. Ferreira Claudinei C. Rezende Maria F. V. Marques Maria Emanuela Errico Roberto Avolio Maurizio Avella Gennaro Gentile Pietro Russo 《Journal of Polymers and the Environment》2018,26(8):3149-3158
This work is focused on the hydrolysis of cotton fibers from waste textiles to obtain micro and nanofibers to be used as reinforcements in polymer composites. To promote their compatibility with polymeric matrix, hydrolyzed cotton fibers were surface modified with various silane compounds. Thus, these fibers were mixed with commercial poly(lactic acid) (PLA) at 5% w/w loading by melt compounding. Acid treatments caused a decrease of the crystallinity index whereas the thermal stability was significantly improved, especially for cellulose fibers hydrolyzed in two steps. Morphological analysis revealed a reduction of the fibers diameter and a decrease of their length as a consequence of the hydrolysis. NMR analysis confirmed the silanization of the fibers by reaction with the silane agent. Tensile tests revealed that silanization treatments were able to increase the composite Young’s modulus and the stress at break with respect to the neat matrix, indicating that silanization improved the polymer/fiber compatibility interfacial adhesion. The overall results demonstrated that applying suitable surface modification strategies, waste cotton textiles can be effectively recycled as fillers in polymer based composites. 相似文献
140.
Carlotta Ferrara Maurizio Marchi Margherita Carlucci Anastasios Mavrakis Piermaria Corona Luca Salvati 《Environmental monitoring and assessment》2018,190(12):714
Shifts in government priorities in response to the 2007 global recession have affected wildfire management and natural disaster funding arrangements, leading to a reduced effectiveness of fire suppression actions and increasing fire vulnerability. Our study investigates the role of local socioeconomic contexts on fire suppression effectiveness under economic expansion and recession in a Mediterranean region (Attica, Greece) strongly affected by 2007 crisis and displaying a persistently high density of peri-urban wildfires. Basic characteristics of wildfires (spatial distribution, intensity, and land use preferences) were investigated in the study area over two consecutive 8-year time intervals characterized by economic expansion (2000–2007) and recession (2008–2015). An integrated approach based on multivariate statistics and artificial neural networks was implemented to evaluate latent relationships between fire suppression time, wildfire characteristics, and socioeconomic dynamics. Controlling for wildfires’ characteristics over the two time intervals, fire time length increased under crisis—mainly for small and medium-sized fires—possibly as an indirect response to reduced effectiveness of forest land management. Local contexts and political decisions influenced by economic downturns are relevant factors shaping wildfires’ severity in the Mediterranean region. With recession, local contexts vulnerable to wildfires require more effective fire prevention measures, sustainable forest management, and regional planning. 相似文献