全文获取类型
收费全文 | 9789篇 |
免费 | 0篇 |
国内免费 | 5篇 |
专业分类
安全科学 | 2篇 |
废物处理 | 795篇 |
环保管理 | 1216篇 |
综合类 | 959篇 |
基础理论 | 3123篇 |
污染及防治 | 1781篇 |
评价与监测 | 1011篇 |
社会与环境 | 907篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 1473篇 |
2017年 | 1373篇 |
2016年 | 1196篇 |
2015年 | 126篇 |
2014年 | 18篇 |
2013年 | 21篇 |
2012年 | 470篇 |
2011年 | 1347篇 |
2010年 | 692篇 |
2009年 | 607篇 |
2008年 | 884篇 |
2007年 | 1232篇 |
2006年 | 11篇 |
2005年 | 23篇 |
2004年 | 43篇 |
2003年 | 66篇 |
2002年 | 103篇 |
2001年 | 19篇 |
2000年 | 12篇 |
1999年 | 6篇 |
1998年 | 10篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 15篇 |
1983年 | 8篇 |
1982年 | 4篇 |
1980年 | 1篇 |
1976年 | 1篇 |
1972年 | 1篇 |
1954年 | 1篇 |
1935年 | 2篇 |
排序方式: 共有9794条查询结果,搜索用时 0 毫秒
181.
K. Abdel Tawab M. M. Magida Sayeda M. Ibrahim 《Journal of Polymers and the Environment》2011,19(2):440-446
Blends of water—soluble polymers based on Poly vinyl alcohol (PVA) and Polyethylene glycol (PEG) have been prepared by the
solution casting technique. The effect of various doses of γ-radiation on the structural properties of PVA/PEG polymer blends
with all its compositions has been investigated. From the visual observation of all the blend compositions, it was found that,
the best compatibility of the blend is up to 40% PVA/60%PEG. The structure–Property behavior of all the prepared blends before
and after γ-irradiation was investigated by IR Spectroscopy, thermogravimetric analysis (TGA), mechanical properties and Scanning
electron microscope (SEM). The gel content and the swelling behavior of the PVA/PEG blends were investigated. It was found
that the gel content increases with increasing irradiation dose and PVA concentration in the blend. Swelling percent increased
as the composition of PEG increased in the blend. The results obtained by FTIR analysis and SEM confirm the existence of possible
interaction between PVA and PEG homopolymers. TGA of PVA/PEG blend, before and after γ-irradiation, showed that the unirradiated
and irradiated PVA/PEG blends are more stable against thermal decomposition than pure PVA. Improvement in tensile mechanical
properties of PVA/PEG blends was occurred. 相似文献
182.
Poly-β-hydroxybuyrate (PHB) is a carbon—energy storage material which is accumulated as intracellular granule in variety of
microorganism under nutrient starved conditions. Solid PHB is a biodegradable thermoplastic polymer and is utilizable in various
ways similar to many conventional plastics. Ralstonia eutropha (Alcaligenes sp.), a gram negative bacteria accumulates PHB as insoluble granules inside the cells when nutrients other than carbon are
limited. In this report effort has been made to analyze PHB granule synthesis inside Alcaligenes sp. NCIM 5085 by transmission electron microscopy and qualitative estimation of PHB was carried out by fourier transform
infrared spectroscopy which provide better precision compared to other conventional techniques previously applied for PHB
determination. Maximum PHB concentration of 2.20 ± 0.40 g/L and cell biomass of 3.42 ± 0.20 g/L was obtained after 48.0 h
of fermentation. Leudking-Piret equation deduced mixed growth associated product formation which varies from earlier reports. 相似文献
183.
Process,Characterization and Biodegradability of Aliphatic Aromatic Polyester/Sisal Fiber Composites
Chin-San Wu 《Journal of Polymers and the Environment》2011,19(3):706-713
The biodegradability, morphology, and mechanical properties of composite materials made of Poly(butylene adipate-co-terephthalate) (PBAT) and sisal fiber (SF) were evaluated. Composites containing acrylic acid-grafted PBAT (PBAT-g-AA/SF)
exhibited noticeably superior mechanical properties due to greater compatibility between the two components. The dispersion
of SF in the PBAT-g-AA matrix was highly homogeneous as a result of ester formation between the carboxyl groups of PBAT-g-AA
and hydroxyl groups in SF and the consequent creation of branched and cross-linked macromolecules. Each composite was subjected
to biodegradation tests in Rhizopus oryzae compost. Morphological observations indicated severe disruption of film structure after 60 days of incubation, and both the
PBAT and the PBAT-g-AA/SF composite films were eventually completely degraded. Water resistance of PBAT-g-AA/SF was higher
than that of PBAT/SF, although weight loss of composites buried in Rhizopus oryzae compost indicated that both were biodegradable, even at high levels of SF substitution. The PBAT-g-AA/SF films were more
biodegradable than those made of PBAT, implying a strong connection between these characteristics and biodegradability. 相似文献
184.
Hisanori Watanabe Hidekichi Yoshino 《Journal of Material Cycles and Waste Management》2011,13(2):113-117
Since hydrogen is a renewable energy source, biohydrogen has been researched in recent years. However, data on hydrogen fermentation
by a leachate from a waste landfill as inoculum are scarce. We investigated hydrogen production using a leachate from an industrial
waste landfill in Kanagawa Prefecture. The results showed no methane gas production, and the leachate was a suitable inoculum
for hydrogen fermentation. The maximum H2 yield was 2.67 mol of H2 per mol of carbohydrate added, obtained at 30°C and an initial pH of 7. The acetate and butyrate production was significant
when the H2 yield was higher. Oxidation–reduction potential analysis of the culture suggested that hydrogen-producing bacteria in the
leachate were facultative anaerobic. Scanning electron microscope observations revealed that the hydrogen-producing bacteria
comprised bacilli about 2 μm in length. 相似文献
185.
186.
László Zsolt Garamszegi 《Behavioral ecology and sociobiology》2011,65(1):1-11
Scientific thinking may require the consideration of multiple hypotheses, which often call for complex statistical models at the level of data analysis. The aim of this introduction is to provide a brief overview on how competing hypotheses are evaluated statistically in behavioural ecological studies and to offer potentially fruitful avenues for future methodological developments. Complex models have traditionally been treated by model selection approaches using threshold-based removal of terms, i.e. stepwise selection. A recently introduced method for model selection applies an information-theoretic (IT) approach, which simultaneously evaluates hypotheses by balancing between model complexity and goodness of fit. The IT method has been increasingly propagated in the field of ecology, while a literature survey shows that its spread in behavioural ecology has been much slower, and model simplification using stepwise selection is still more widespread than IT-based model selection. Why has the use of IT methods in behavioural ecology lagged behind other disciplines? This special issue examines the suitability of the IT method for analysing data with multiple predictors, which researchers encounter in our field. The volume brings together different viewpoints to aid behavioural ecologists in understanding the method, with the hope of enhancing the statistical integration of our discipline. 相似文献
187.
To investigate the ability of elasmobranchs to distinguish between differing prey-type electric fields we examined the electroreceptive
foraging behaviour of a model species, Scyliorhinus canicula (small-spotted catshark). Catshark preferences were studied by behaviourally conditioning them to swim through narrow tunnels,
and on exit presenting them simultaneously with two different electric fields. Their subsequent choices of the following paired
options were recorded; (i) Two artificial electric fields (dipole electrodes) with different magnitude direct current (D.C.),
(ii) Two artificial electric fields, one D.C. and the other alternating current (A.C.), of the same magnitude, and (iii) similar
magnitude, natural and artificial D.C. electric fields associated with shore crabs and dipole electrodes respectively. We
found a highly significant preference for the stronger D.C. electric field and a less pronounced, but still significant, preference
for the A.C. electric field rather than the D.C. electric field. No preference was demonstrated between the artificial and
natural D.C. electric fields. The findings are discussed in relation to the animal’s diet and ecology and with regard to anthropogenic
sources of electric fields within their habitat. 相似文献
188.
Loss of zooxanthellae (dinoflagellate Symbiodinium) from corals will sometimes lead to mass mortality of corals. To detect and quantify Symbiodinium released from corals, we developed a zooxanthellae “trap” and a quantitative PCR (qPCR) system with Symbiodinium clades A–F-specific primer sets. The trap was attached to a branch or the surface of several wild stony corals, and the water samples within the traps, including released Symbiodinium, were subjected to qPCR. All tested corals released clade C Symbiodinium at estimates of ~5,900 cells h−1 cm−2 of coral surface. Although all tested Pocillopora eydouxi harboured both clades C and D, some of these colonies released only clade C or released a lesser amount of clade D than that in the tissues. Our Symbiodinium quantification system revealed that wild hermatypic corals constantly release Symbiodinium to the environment. Our result suggests that some corals may discharge certain clades of Symbiodinium alternatively. 相似文献
189.
Metal contamination of surface soils of industrial city Sialkot,Pakistan: a multivariate and GIS approach 总被引:3,自引:0,他引:3
Riffat Naseem Malik Waqar Azeem Jadoon Syed Zahoor Husain 《Environmental geochemistry and health》2010,32(3):179-191
In this study concentrations of selected metals viz., Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Na, Ni, Pb and Zn in surface soils of
Sialkot city known worldwide for tanneries and pharmaceutical industries were measured to assess the status of urban soil
pollution and to identify sources of contamination. Hierarchical cluster analysis (HACA) indicated concentrations of Mg and
Ca related to parent rock material, Cd, Co, and Pb with traffic related activities, Cr, Cu, Ni and Zn either associated with
automobiles activities or industrial pollution and Fe, K and Na related with anthropogenic activities or lithogenous materials.
Correlation analyses and principal component analysis based on factor analysis confirmed the results of HACA. Spatial distribution
maps exhibited relatively higher concentrations of Cd, Co, Cu, Ni, Pb, Cr and Zn along traffic routes in the city and streams.
The results highlighted concentration of Cd, Ni, Cr, Zn, and Pb measured in urban soil exceeded the permissible limit of surface
soils and advocated an imperative need for detailed baseline investigations of spatial distribution of heavy metals and other
contaminants for the formulation of geochemical database that should be made available to stakeholder involved in monitoring,
assessment and conservation of soil contamination for future planning and management of the Sialkot city. 相似文献
190.
Alecos Demetriades Xiangdong Li Michael H. Ramsey Iain Thornton 《Environmental geochemistry and health》2010,32(6):529-552
In the Lavrion urban area study, Hellas, a five-step sequential extraction method was applied on samples of ‘soil’ (n = 224), affected by long-term mining and metallurgical activities, and house dust (n = 127), for the purpose of studying the potential bioaccessibility of lead and other metals to humans. In this paper, the
Pb concentrations in soil and house dust samples are discussed, together with those in rocks and children’s blood. Lead is
mainly associated with the carbonate, Fe–Mn oxides and residual fractions in soil and house dust. Considering the very low
pH of gastric fluids (1–3), a high amount of metals, present in soil (810–152,000 mg/kg Pb) and house dust (418–18,600 mg/kg Pb),
could be potentially bioaccessible. Consequently, children in the neighbourhoods with a large amount of metallurgical processing
wastes have high blood-Pb concentrations (5.98–60.49 μg/100 ml; median 17.83 μg/100 ml; n = 235). It is concluded that the Lavrion urban and sub-urban environment is extremely hazardous to human health, and the
Hellenic State authorities should urgently tackle this health-related hazard in order to improve the living conditions of
local residents. 相似文献