全文获取类型
收费全文 | 16913篇 |
免费 | 131篇 |
国内免费 | 112篇 |
专业分类
安全科学 | 415篇 |
废物处理 | 745篇 |
环保管理 | 1852篇 |
综合类 | 3340篇 |
基础理论 | 3938篇 |
环境理论 | 11篇 |
污染及防治 | 4772篇 |
评价与监测 | 1113篇 |
社会与环境 | 896篇 |
灾害及防治 | 74篇 |
出版年
2022年 | 227篇 |
2021年 | 245篇 |
2020年 | 128篇 |
2019年 | 160篇 |
2018年 | 386篇 |
2017年 | 375篇 |
2016年 | 533篇 |
2015年 | 374篇 |
2014年 | 541篇 |
2013年 | 1254篇 |
2012年 | 619篇 |
2011年 | 807篇 |
2010年 | 573篇 |
2009年 | 618篇 |
2008年 | 763篇 |
2007年 | 789篇 |
2006年 | 680篇 |
2005年 | 555篇 |
2004年 | 560篇 |
2003年 | 520篇 |
2002年 | 454篇 |
2001年 | 505篇 |
2000年 | 358篇 |
1999年 | 246篇 |
1998年 | 138篇 |
1997年 | 146篇 |
1996年 | 128篇 |
1995年 | 184篇 |
1994年 | 177篇 |
1993年 | 137篇 |
1992年 | 150篇 |
1991年 | 166篇 |
1990年 | 139篇 |
1989年 | 142篇 |
1988年 | 147篇 |
1987年 | 125篇 |
1986年 | 104篇 |
1985年 | 111篇 |
1984年 | 137篇 |
1983年 | 137篇 |
1982年 | 142篇 |
1981年 | 106篇 |
1980年 | 106篇 |
1979年 | 112篇 |
1978年 | 97篇 |
1977年 | 93篇 |
1976年 | 89篇 |
1975年 | 98篇 |
1974年 | 104篇 |
1965年 | 86篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
991.
Degassing of H/He, CFCs and SF6 by denitrification: Measurements and two-phase transport simulations
Ate Visser Joris D. Schaap Hans Peter Broers Marc F.P. Bierkens 《Journal of contaminant hydrology》2009,103(3-4):206-218
The production of N2 gas by denitrification may lead to the appearance of a gas phase below the water table prohibiting the conservative transport of tracer gases required for groundwater dating. We used a two-phase flow and transport model (STOMP) to study the reliability of 3H/3He, CFCs and SF6 as groundwater age tracers under agricultural land where denitrification causes degassing. We were able to reproduce the amount of degassing (R2 = 69%), as well as the 3H (R2 = 79%) and 3He (R2 = 76%) concentrations observed in a 3H/3He data set using simple 2D models. We found that the TDG correction of the 3H/3He age overestimated the control 3He/3He age by 2.1 years, due to the accumulation of 3He in the gas phase. The total uncertainty of degassed 3H/3He ages of 6 years (± 2 σ) is due to the correction of degassed 3He using the TDG method, but also due to the travel time in the unsaturated zone and the diffusion of bomb peak 3He. CFCs appear to be subject to significant degradation in anoxic groundwater and SF6 is highly susceptible to degassing. We conclude that 3H/3He is the most reliable method to date degassed groundwater and that two-phase flow models such as STOMP are useful tools to assist in the interpretation of degassed groundwater age tracer data. 相似文献
992.
A.A.L. Oiffer J.F. Barker F.M. Gervais K.U. Mayer C.J. Ptacek D.L. Rudolph 《Journal of contaminant hydrology》2009,108(3-4):89-106
An anaerobic plume of process-affected groundwater was characterized in a shallow sand aquifer adjacent to an oil sands tailings impoundment. Based on biological oxygen demand measurements, the reductive capacity of the plume is considered minimal. Major dissolved components associated with the plume include HCO3, Na, Cl, SO4, and naphthenic acids (NAs). Quantitative and qualitative NA analyses were performed on groundwater samples to investigate NA fate and transport in the subsurface. Despite subsurface residence times exceeding 20 years, significant attenuation of NAs by biodegradation was not observed based on screening techniques developed at the time of the investigation. Relative to conservative tracers (i.e., Cl), overall NA attenuation in the subsurface is limited, which is consistent with batch sorption and microcosm studies performed by other authors. Insignificant biological oxygen demand and low concentrations of dissolved As (< 10 µg L− 1) in the plume suggest that the potential for secondary trace metal release, specifically As, via reductive dissolution reactions driven by ingress of process-affected water is minimal. It is also possible that readily leachable As is not present in significant quantities within the sediments of the study area. Thus, for similar plumes of process-affected groundwater in shallow sand aquifers which may occur as oil sands mining expands, a reasonable expectation is for NA persistence, but minimal trace metal mobilization. 相似文献
993.
Plaza C Xing B Fernández JM Senesi N Polo A 《Environmental pollution (Barking, Essex : 1987)》2009,157(1):257-263
Binding of two model polycyclic aromatic hydrocarbons (PAHs), phenanthrene and pyrene, by humic acids (HAs) isolated from an organic substrate at different stages of composting and a soil was investigated using a batch fluorescence quenching method and the modified Freundlich model. With respect to soil HA, the organic substrate HA fractions were characterized by larger binding affinities for both phenanthrene and pyrene. Further, isotherm deviation from linearity was larger for soil HA than for organic substrate HAs, indicating a larger heterogeneity of binding sites in the former. The composting process decreased the binding affinity and increased the heterogeneity of binding sites of HAs. The changes undergone by the HA fraction during composting may be expected to contribute to facilitate microbial accessibility to PAHs. The results obtained also suggest that bioremediation of PAH-contaminated soils with matured compost, rather than with fresh organic amendments, may result in faster and more effective cleanup. 相似文献
994.
Spohn P Hirsch C Hasler F Bruinink A Krug HF Wick P 《Environmental pollution (Barking, Essex : 1987)》2009,157(4):1134-1139
Since the discovery of fullerenes in 1985, these carbon nanospheres have attracted attention regarding their physico/chemical properties. Despite little knowledge about their impact on the environment and human health, the production of fullerenes has already reached an industrial scale. However, the toxicity of C60 is still controversially discussed.The aim of this study was to clarify the biological effects of tetrahydrofuran (THF) suspended C60 fullerene in comparison to water stirred C60 fullerene suspensions. Beyond that, we analyzed the effects on the Crustacea Daphnia magna an indicator for ecotoxicological effects and the human lung epithelial cell line A549 as a simplified model for the respiratory tract.We could demonstrate that water-soluble side products which were formed in THF nC60 suspension were responsible for the observed acute toxic effects, whereas fullerenes themselves had no negative effect regardless of the preparative route on either A549 cell in vitro or D. magna in vivo. 相似文献
995.
Charles A. Young Marisa I. Escobar‐Arias Martha Fernandes Brian Joyce Michael Kiparsky Jeffrey F. Mount Vishal K. Mehta David Purkey Joshua H. Viers David Yates 《Journal of the American Water Resources Association》2009,45(6):1409-1423
Young, Charles A., Marisa I. Escobar‐Arias, Martha Fernandes, Brian Joyce, Michael Kiparsky, Jeffrey F. Mount, Vishal K. Mehta, David Purkey, Joshua H. Viers, and David Yates, 2009. Modeling the Hydrology of Climate Change in California’s Sierra Nevada for Subwatershed Scale Adaptation. Journal of the American Water Resources Association (JAWRA) 45(6):1409‐1423. Abstract: The rainfall‐runoff model presented in this study represents the hydrology of 15 major watersheds of the Sierra Nevada in California as the backbone of a planning tool for water resources analysis including climate change studies. Our model implementation documents potential changes in hydrologic metrics such as snowpack and the initiation of snowmelt at a finer resolution than previous studies, in accordance with the needs of watershed‐level planning decisions. Calibration was performed with a sequence of steps focusing sequentially on parameters of land cover, snow accumulation and melt, and water capacity and hydraulic conductivity of soil horizons. An assessment of the calibrated streamflows using goodness of fit statistics indicate that the model robustly represents major features of weekly average flows of the historical 1980‐2001 time series. Runs of the model for climate warming scenarios with fixed increases of 2°C, 4°C, and 6°C for the spatial domain were used to analyze changes in snow accumulation and runoff timing. The results indicated a reduction in snowmelt volume that was largest in the 1,750‐2,750 m elevation range. In addition, the runoff center of mass shifted to earlier dates and this shift was non‐uniformly distributed throughout the Sierra Nevada. Because the hydrologic model presented here is nested within a water resources planning system, future research can focus on the management and adaptation of the water resources system in the context of climate change. 相似文献
996.
Jessica Nihlén Fahlquist 《Journal of Agricultural and Environmental Ethics》2009,22(2):109-124
The actions performed by individuals, as consumers and citizens, have aggregate negative consequences for the environment.
The question asked in this paper is to what extent it is reasonable to hold individuals and institutions responsible for environmental
problems. A distinction is made between backward-looking and forward-looking responsibility. Previously, individuals were
not seen as being responsible for environmental problems, but an idea that is now sometimes implicitly or explicitly embraced
in the public debate on environmental problems is that individuals are appropriate targets for blame when they perform actions
that are harmful to the environment. This idea is criticized in this paper. It is argued that instead of blaming individuals
for performing actions that are not environmentally friendly we should ascribe forward-looking responsibility to individuals,
a notion that focuses more on capacity and resources than causation and blameworthiness. Furthermore, it is important to emphasize
that a great share of forward-looking responsibility should also be ascribed to institutional agents, primarily governments
and corporations. The urge to ascribe forward-looking responsibility to institutional agents is motivated by the efficiency
aim of responsibility distributions. Simply put, if responsibility is ascribed to governments and corporations there is a
better chance of creating a society in which the opportunities to act in an environmentally friendly way increase. 相似文献
997.
Júlio F. Carneiro 《International Journal of Greenhouse Gas Control》2009,3(4):431-443
The double porosity model for fissured rocks, such as limestones and dolomites, has some features that may be relevant for carbon sequestration. Numerical simulations were conducted to study the influence of matrix diffusion on the trapping mechanisms relevant for the long-term fate of CO2 injected in fissured rocks. The simulations show that, due to molecular diffusion of CO2 into the rock matrix, dissolution trapping and hydrodynamic trapping are more effective in double porosity aquifers than in an equivalent porous media. Mineral trapping, although assessed indirectly, is also probably more relevant in double porosity aquifers due to the larger contact surface and longer contact time between dissolved CO2 and rock minerals. However, stratigraphic/structural trapping is less efficient in double porosity media, because at short times CO2 is stored only in the fissures, requiring large aquifer volumes and increasing the risk associated to the occurrence of imperfections in the cap-rock through which leakage can occur. This increased risk is also a reality when considering storage in aquifers with a regional flow gradient, since the CO2 free-phase will move faster due to the higher flow velocities in fissured media and discharge zones may be reached sooner. 相似文献
998.
Niwagaba C Nalubega M Vinnerås B Sundberg C Jönsson H 《Waste management (New York, N.Y.)》2009,29(2):585-589
In urine-diverting toilets, urine and faeces are collected separately so that nutrient content can be recycled unmixed. Faeces should be sanitized before use in agriculture fields due to the presence of possible enteric pathogens. Composting of human faeces with food waste was evaluated as a possible method for this treatment. Temperatures were monitored in three 78-L wooden compost reactors fed with faeces-to-food waste substrates (F:FW) in wet weight ratios of 1:0, 3:1 and 1:1, which were observed for approximately 20 days. To achieve temperatures higher than 15 degrees C above ambient, insulation was required for the reactors. Use of 25-mm thick styrofoam insulation around the entire exterior of the compost reactors and turning of the compost twice a week resulted in sanitizing temperatures (>or=50 degrees C) to be maintained for 8 days in the F:FW=1:1 compost and for 4 days in the F:FW=3:1 compost. In these composts, a reduction of >3 log(10) for E. coli and >4 log(10) for Enterococcus spp. was achieved. The F:FW=1:0 compost, which did not maintain >or=50 degrees C for a sufficiently long period, was not sanitized, as the counts of E. coli and Enterococcus spp. increased between days 11 and 15. This research provides useful information on the design and operation of family-size compost units for the treatment of source-separated faeces and starchy food residues, most likely available amongst the less affluent rural/urban society in Uganda. 相似文献
999.
Machado SL Carvalho MF Gourc JP Vilar OM do Nascimento JC 《Waste management (New York, N.Y.)》2009,29(1):153-161
This paper deals with the use of simplified methods to predict methane generation in tropical landfills. Methane recovery data obtained on site as part of a research program being carried out at the Metropolitan Landfill, Salvador, Brazil, is analyzed and used to obtain field methane generation over time. Laboratory data from MSW samples of different ages are presented and discussed; and simplified procedures to estimate the methane generation potential, Lo, and the constant related to the biodegradation rate, k are applied. The first order decay method is used to fit field and laboratory results. It is demonstrated that despite the assumptions and the simplicity of the adopted laboratory procedures, the values Lo and k obtained are very close to those measured in the field, thus making this kind of analysis very attractive for first approach purposes. 相似文献
1000.
The Effect of Masterbatch Addition on the Mechanical, Thermal, Optical and Surface Properties of Poly(lactic acid) 总被引:1,自引:0,他引:1
F. Byrne P. G. Ward J. Kennedy N. Imaz D. Hughes D. P. Dowling 《Journal of Polymers and the Environment》2009,17(1):28-33
There has been considerable interest in the use of the biodegradable polymer poly(lactic acid) (PLA) as a replacement for
petroleum derived polymers due to ease of processability and its high mechanical strength. Other material properties have
however limited its wider application. These include its brittle properties, low impact strength and yellow tint. In an attempt
to overcome these drawbacks, PLA was blended with four commercially available additives, commonly known as masterbatches.
The effect of the addition of 1.5 wt% of the four masterbatches on the mechanical, thermal, optical and surface properties
of the polymer was evaluated. All four masterbatches had a slight negative effect on the tensile strength of PLA (3–5% reduction).
There was a four fold increase in impact resistance however with the addition of one of the masterbatches. Differential scanning
calorimetry demonstrated that this increase corresponded to a decrease in the polymer crystallinity. However there was an
associated increase in polymer haze with the addition of this masterbatch. The clarity of PLA was improved through the addition
of an optical brightener masterbatch, but the impact resistance remained low. The glass transition and melting temperatures
of PLA were not affected by the addition of the masterbatches, and no change was observed in surface energy. Some delay in
PLA degradation, in a PBS degradation medium at 50 °C, was observed due to blending with these masterbatches. 相似文献