全文获取类型
收费全文 | 3848篇 |
免费 | 12篇 |
国内免费 | 68篇 |
专业分类
安全科学 | 106篇 |
废物处理 | 223篇 |
环保管理 | 386篇 |
综合类 | 474篇 |
基础理论 | 1240篇 |
环境理论 | 1篇 |
污染及防治 | 940篇 |
评价与监测 | 327篇 |
社会与环境 | 221篇 |
灾害及防治 | 10篇 |
出版年
2023年 | 27篇 |
2022年 | 133篇 |
2021年 | 108篇 |
2020年 | 42篇 |
2019年 | 46篇 |
2018年 | 169篇 |
2017年 | 180篇 |
2016年 | 239篇 |
2015年 | 77篇 |
2014年 | 54篇 |
2013年 | 144篇 |
2012年 | 465篇 |
2011年 | 261篇 |
2010年 | 65篇 |
2009年 | 57篇 |
2008年 | 71篇 |
2007年 | 90篇 |
2006年 | 86篇 |
2005年 | 403篇 |
2004年 | 543篇 |
2003年 | 412篇 |
2002年 | 50篇 |
2001年 | 46篇 |
2000年 | 26篇 |
1999年 | 35篇 |
1998年 | 5篇 |
1997年 | 11篇 |
1996年 | 4篇 |
1995年 | 15篇 |
1994年 | 9篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1991年 | 8篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1985年 | 3篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1964年 | 1篇 |
1961年 | 1篇 |
1959年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有3928条查询结果,搜索用时 31 毫秒
141.
Ali Naderi Beni Michael Kühn Robert Meyer Christoph Clauser 《Environmental Modeling and Assessment》2012,17(4):337-351
We study opportunities for CO2 sequestration in geological formations of the state North Rhine Westphalia in Germany. Simulations are performed for evaluating a potential site within the Bunter sandstone formation near the town of Minden in a depth?of around 3,000 m using the numerical simulator TOUGHREACT. Our focus is on three CO2 storage mechanisms: (1) hydrodynamic trapping, (2) dissolution trapping, and (3) mineral trapping. The results show that due to buoyancy the injected CO2 phase initially migrates towards the top of the reservoir and is hydrodynamically trapped beneath the confining layer of the cap rock. Then, the CO2 spreads laterally and dissolves partially in the formation water. The dissolution of CO2 results in an increase of the density of the brine causing a downward migration until it settles after 10,000 years at the bottom of the reservoir. The simulations indicate that after 10,000 years, 15% (17 Mt) from a total of 114 Mt injected CO2 are trapped hydrodynamically, 20% (23 Mt) are trapped by dissolution, and 65% (74 Mt) are fixed in newly formed carbonates such as dawsonite, ankerite, and siderite. Within our study pressure increases near the injection well by a factor of 1.1 which is lower than the upper limit usually accepted in gas storage operations. The mineral reactions cause a net decrease of porosity and in turn a decrease of permeability down to 9% of the initial value in parts of the reservoir. 相似文献
142.
A framework for dissolved oxygen (DO) modeling of the Ravi River has been developed based on a combination of laboratory measurements
and field and monitoring data. Both the classical Streeter-Phelps (CSP) and the modified Streeter-Phelps (MSP) models are
used for DO simulations. The MSP model considers the carbonaceous biochemical oxygen demand (CBOD) and nitrogenous biochemical
oxygen demand (NBOD) separately, whereas the CSP model is evaluated considering only the CBOD and NBOD is incorporated in
the overall BOD utilization rate. CBOD, NBOD and BOD rates have been determined through long-term BOD analysis of five main
wastewater outfalls and two surface drains discharging into the Ravi River over a 98 km stretch. Analysis by Thomas Method
manifests strong coefficient of determination “R2” between 0.72 and 0.98 for all the three types of BOD rates. Sensitivity analyses have also been carried out to find out
a suitable reaeration rate formula for highly variable flows in the Ravi River. The CSP model results based on classical approach
of considering only CBOD show significant difference between the model predictions and field measurements suggesting that
NBOD needs to be incorporated for the model development. The dissolved oxygen values calculated using the MSP model and the
CSP model based on overall BOD rate are in close agreement with field measurements and are thus suitable to model DO levels
in the Ravi River. 相似文献
143.
The technique of diffusion gradient in thin films (DGT) for assessing bioavailable metals has not been tested under field
conditions. We assessed the relationships of DGT- and cation exchange resin-membrane-measured concentrations of Cd, Cu, Pb,
and Zn with plant uptake of the metals under greenhouse and field conditions. In the greenhouse, the effective concentrations
of Cu, Pb, and Zn by DGT correlated significantly with uptake by sorghum (Sorghum bicolor), but cation exchange resin-membrane-measured concentrations of Cd, Pb, and Zn did not correlate with sorghum uptake. In
the field, the DGT-measured concentrations of Cd, Pb, and Zn were not linearly related to uptake Cd, Pb, and Zn by lettuce
(Lactuca sativa) except for Cu uptake (r = 0.87, p < 0.05). Similarly, it was only the resin-membrane-extractable Pb that correlated with Pb uptake by lettuce (r = 0.77; p < 0.05). However, fitting non-linear regression models improved the plant metal uptake predictions by DGT-measured bioavailable
Cd, Cu, Pb, and Zn under field conditions. In conclusion, the DGT technique was fairly predictive of bioavailability in the
greenhouse, but not in the field. 相似文献
144.
When agricultural lands are no longer used for agriculture and allowed to recover its natural vegetation, soil organic carbon
can accumulate in the soil. Measurements of soil organic carbon and aggregate stability changes under various forms of land
use are needed for the development of sustainable systems. Therefore, comparison of soil samples taken from both agricultural
and nearby area close to land-mined fields where no agricultural practices have been done since 1956 can be a good approach
to evaluate the effects of tillage and agriculture on soil quality. The objective of this study was to compare tillage, cropping
and no tillage effects on some soil-quality parameters. Four different locations along the Turkey–Syria border were selected
to determine effects of tillage and cropping on soil quality. Each location was evaluated separately because of different
soil type and treatments. Comparisons were made between non-tilled and non-cropped fallow since 1956 and adjacent restricted
lands that were tilled about every 2 years but not planted (T) or adjacent lands tilled and planted with wheat and lentil
(P). Three samples were taken from the depths of 0–20 and 20–40 cm each site. Soil organic carbon (SOC), pH ,electrical conductivity,
water soluble Ca++, Mg++, CO3-2{\rm CO}_{3}^{-2} and HCO3-{\rm HCO}_{3}^{-}, extractable potassium (K+) and sodium (Na+), soil texture, ammonium (NH4+{\rm NH}_{4}^{+}–N) and nitrate (NO3–N), extractable phosphorous and soil aggregate stability were determined. While the SOC contents of continuous tillage without
cropping and continuous tillage and cropping were 2.2 and 11.6 g kg−1, respectively, it was 30 g kg−1 in non-tilled and non-planted site. Tillage of soil without the input of any plant material resulted in loss of carbon from
the soil in all sites. Soil extractable NO3−N contents of non-tilled and non-cropped sites were greatest among all treatments. Agricultural practices increased phosphorus
and potassium contents in the soil profile. P2O5 contents of planted soils were approximately 20 to 39 times greater than those of non-tilled and non-cropped soils at different
sites. FTIR spectra showed that never tilled sites had greater phenol, carboxylic acid, amide, aromatic compounds, polysaccharide
and carbohydrates than other treatments. 相似文献
145.
Singh HP Sharma VP Batish DR Kohli RK 《Environmental monitoring and assessment》2012,184(4):1813-1821
Indiscriminate adoption and use of cell phone technology has tremendously increased the levels of electromagnetic field radiations
(EMFr) in the natural environment. It has raised the concerns among the scientists regarding the possible risks of EMFr to
living organisms. However, not much has been done to assess the damage caused to plants that are continuously exposed to EMFr
present in the environment. The present study investigated the biochemical mechanism of interference of 900 MHz cell phone
EMFr with root formation in mung bean (Vigna radiata syn. Phaseolus aureus) hypocotyls, a model system to study rhizogenesis in plants. Cell phone EMFr enhanced the activities of proteases (by 1.52
to 2.33 times), polyphenol oxidases (by 1.5 to 4.3 times), and peroxidases (by 1.5 to 2.0 times) in mung bean hypocotyls over
control. Further, EMFr enhanced malondialdehyde (an indicator of lipid peroxidation), hydrogen peroxide, and proline content,
indicating a reactive oxygen species-mediated oxidative damage in hypocotyls. It was confirmed by the upregulation in the
activities of antioxidant enzymes (superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase, catalase, and glutathione
reductase) suggesting their possible role in providing protection against EMFr-induced oxidative damage. The study concluded
that cell phone radiations affect the process of rhizogenesis through biochemical alterations that manifest as oxidative damage
resulting in root impairment. 相似文献
146.
Monavari SM Omrani GA Karbassi A Raof FF 《Environmental monitoring and assessment》2012,184(4):1841-1846
Environment problems associated with the generation of waste are part of societal changes where households play an important
role. These societal changes influence the size, structure and characteristic of given households. For the effective planning
of solid-waste handling infrastructure, it is essential to know the quantity of waste generation and its composition. This
paper presents the findings of a study carried out in an urban municipal area in Iran to determine the household solid-waste
generation rate and waste composition based on field surveys and to determine the related socioeconomic parameters. The dependent
variables were waste generation and composition, and independent variables were family size, family employment, age, number
of room and education. Over 400 sample households were selected for the study using a stratified random sampling methodology
and from five different socioeconomic groups. Waste collected from all groups of households were segregated and weighted.
Waste generation rate was 5.4 kg/household/day. Household solid waste comprised of ten categories of wastes and with the largest
component (76.9%). The generation and composition of household solid waste were correlated with family size, education level
and households income. This paper adequately suggests new insights concerning the role of socioeconomic parameters in affecting
the generation of household waste. 相似文献
147.
Chaudhary P Singh SB Chaudhry S Nain L 《Environmental monitoring and assessment》2012,184(2):1145-1156
The present study is aimed at analysing and comparing different soil enzymes in soil samples of native contaminated sites
of a Mathura refinery and adjoining agricultural land. Enzyme activities are considered as indicators of soil quality and
changes in biogeochemical function due to management or perturbations. Soil samples were collected from the premises and nearby
area of Mathura refinery, India. Biological health parameters (dehydrogenase, aryl esterase, aryl sulphatase,
\upbeta \upbeta -glucosidase, alkaline phosphatase, acid phosphatase, lipase, laccase and catalase activity) were estimated in the soil samples.
Among all the samples, sewage sludge soil showed maximum activity of enzymes, microbial biomass carbon and most probable number
of polycyclic aromatic hydrocarbon (PAH) degraders in soils spiked with three- to four-ring PAHs at 50 ppm. Available phosphorus,
potassium and nitrogen was also exceptionally high in this sample, indicating maximum microbial bioconversion due to presence
of nutrients stimulating potent PAH-degrading microorganisms. 相似文献
148.
Sediment quality guidelines (SQGs) can be derived using different approaches and are commonly used in environmental management,
reclamation, and risk assessment. The screening-level concentration (SLC) approach has been used in Ontario, Canada, to derive
lowest effect levels (LELs) and severe effect levels for use as SQGs. This approach was adopted by the Canadian Nuclear Safety
Commission (CNSC) to set guidelines for metals (As, Cr, Cu, Pb, Mo, Ni, Se, U, and V) and radionuclides (Ra-226, Pb-210, and
Po-210) in sediment at northern Saskatchewan uranium mining and milling operations. The SLC approach is based on total metal
and radionuclide concentrations in sediment, and corresponding benthic community composition data for a specific sampling
site. In this study, sediment chemistry (total metals and radionuclides) and benthic community data from northern Saskatchewan
uranium operations were compiled and examined. Results indicate that the CNSC-derived SQGs had limited relationships to observed
effects, or lack thereof, on benthic invertebrate communities near uranium operations in Saskatchewan. The LELs were found
to correctly align with effects at 95% of the sites that had effects, on a general basis, but on an element-specific basis
many of the elements had concentrations at effect sites below their LELs. Furthermore, concentrations of the evaluated elements
exceeded at least one LEL at 60% of the no-effect sites. The high number of exceedences of LELs at reference and no-effect
sites (false-positives) calls to question the appropriateness of the CNSC-derived SQGs. It is suggested that alternatives
to the SLC approach be explored. 相似文献
149.
Yassine Charabi Ali Al-Bulooshi Sultan Al-Yahyai 《Environmental monitoring and assessment》2013,185(3):2329-2342
In this paper, COSMO numerical weather prediction model is used to simulate land-sea breeze circulation in the north coast of Oman and to analyze the variability of the PBL depth. Typical summer day 1st August 2009 and winter day 1st January 2009 were simulated and verified by surface observations. The COSMO model was initialized using the German global model which runs as 40 km resolution and 40 vertical layers. The simulations show differences in the onset, strength, and inland penetration of the sea breeze. The high sea-land thermal contrast in the summer season induces earlier onset and progression of the sea breeze with larger horizontal and vertical extents. The summer and winter inland penetration is simulated around 150 and 65 km, respectively. The PBL depth was defined from the verticals profiles of the turbulence kinetic energy (TKE). The simulated PBL height varied at 1,600 m in summer and 700 m in the winter case. These results are in general in good agreement with the simulations of the National Centers for Environmental Prediction Global Data Assimilation System (NCEP-GDAS) model. The dispersive ability of the atmosphere was tested through the vertical mixing coefficient (VMC) generated by NCEP-GDAS simulations. The VMC during the summer simulated case is approximately four times larger than the respective one during the winter case. Consequently, during the advection of winter sea breeze, a shallow dome less than 100 m is shaped and forms an obstacle to the air-pollutant dispersion. 相似文献
150.
Kishore?Kumar?MahatoEmail author Krishna?Dutta Bankim?Chandra?Ray 《Journal of Polymers and the Environment》2018,26(3):1024-1050
The study of static and dynamic behavior of environmentally conditioned fibre reinforced polymeric (FRP) composites is necessary and crucial to examine the durability, reliability and sustainability of these noble materials. FRP composites are being used all around the globe and substituting the conventional materials, starting from mini toys to large aerospace components. Present review has introduced to accumulate and understand the disseminate literature in concentrating the significance of understanding the static and dynamic behavior of FRPs with changing environmental conditionings (hygrothermal, low and high temperature, salt solution, freeze thaw, UV light) and with the interaction of different nano-fillers. Their stability and integrity in diverse service environments may be reformed by their reactions against different nature of loadings i.e. static or dynamic and the components such as fibre, matrix and fibre/matrix interfaces in those environments. The static and dynamic states of loading may come with a possible weaker region to encounter the durability and integrity of the composites. To understand the exact failure modes that correlates the position of environmentally conditioned interfaces and dynamic state of loadings, thus confusing the estimation of its overall performance and mechanical behavior. Interface reliability and durability is vital since in-service environments the degradation in the interfacial region leads to complete composite failure. Therefore, the study of combined effects of various in-service environmental conditions and the role of static and dynamic behavior on the interface will be a crucial part related to the multiaxial dynamic states of failures occurring in FRP’s. 相似文献