全文获取类型
收费全文 | 1677篇 |
免费 | 18篇 |
国内免费 | 41篇 |
专业分类
安全科学 | 22篇 |
废物处理 | 113篇 |
环保管理 | 177篇 |
综合类 | 143篇 |
基础理论 | 295篇 |
环境理论 | 2篇 |
污染及防治 | 559篇 |
评价与监测 | 316篇 |
社会与环境 | 105篇 |
灾害及防治 | 4篇 |
出版年
2023年 | 60篇 |
2022年 | 173篇 |
2021年 | 116篇 |
2020年 | 25篇 |
2019年 | 46篇 |
2018年 | 83篇 |
2017年 | 90篇 |
2016年 | 110篇 |
2015年 | 49篇 |
2014年 | 81篇 |
2013年 | 180篇 |
2012年 | 76篇 |
2011年 | 93篇 |
2010年 | 73篇 |
2009年 | 59篇 |
2008年 | 73篇 |
2007年 | 57篇 |
2006年 | 66篇 |
2005年 | 38篇 |
2004年 | 26篇 |
2003年 | 23篇 |
2002年 | 29篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1988年 | 3篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1979年 | 2篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1966年 | 2篇 |
1965年 | 2篇 |
1964年 | 2篇 |
1962年 | 2篇 |
1961年 | 4篇 |
1958年 | 3篇 |
1957年 | 3篇 |
1956年 | 2篇 |
1955年 | 4篇 |
排序方式: 共有1736条查询结果,搜索用时 15 毫秒
651.
Richa Sharma Aniruddha Ghosh Pawan Kumar Joshi 《Environmental monitoring and assessment》2013,185(4):3313-3325
Urbanisation is a ubiquitous phenomenon with greater prominence in developing nations. Urban expansion involves land conversions from vegetated moisture-rich to impervious moisture-deficient land surfaces. The urban land transformations alter biophysical parameters in a mode that promotes development of heat islands and degrades environmental health. This study elaborates relationships among various environmental variables using remote sensing dataset to study spatio-temporal footprint of urbanisation in Surat city. Landsat Thematic Mapper satellite data were used in conjugation with geo-spatial techniques to study urbanisation and correlation among various satellite-derived biophysical parameters, [Normalised Difference Vegetation Index, Normalised Difference Built-up Index, Normalised Difference Water Index, Normalised Difference Bareness Index, Modified NDWI and land surface temperature (LST)]. Land use land cover was prepared using hierarchical decision tree classification with an accuracy of 90.4 % (kappa?=?0.88) for 1990 and 85 % (kappa?=?0.81) for 2009. It was found that the city has expanded over 42.75 km2 within a decade, and these changes resulted in elevated surface temperatures. For example, transformation from vegetation to built-up has resulted in 5.5?±?2.6 °C increase in land surface temperature, vegetation to fallow 6.7?±?3 °C, fallow to built-up is 3.5?±?2.9 °C and built-up to dense built-up is 5.3?±?2.8 °C. Directional profiling for LST was done to study spatial patterns of LST in and around Surat city. Emergence of two new LST peaks for 2009 was observed in N–S and NE–SW profiles. 相似文献
652.
Ajit Kumar Verma Suresh Kumar Gupta Rajendra Kumar Isaac 《Environmental Modeling and Assessment》2014,19(1):45-55
Soil–Water–Atmosphere–Plant (SWAP) version 2.0 was evaluated for its capability to simulate crop growth and salinity profiles at Agra (India) located in a semi-arid region having deep water table and monsoon climate. The data of 12 conjunctive use treatment combinations simulating cyclic and mixing modes of fresh and saline water for wheat were used to calibrate and validate the model. Absolute deviations between the SWAP simulated and observed relative yields during calibration ranged from 2.5 to 2.9 %. A close agreement in the trend and values of measured and simulated soil salinity profiles was observed. Scenario building simulations carried out with the validated SWAP revealed that the maximum crop yields varied from 97 to 99 % with the best available water (EC 3.6 dS m?1) while the minimum ranged from 65 to 79 % in the treatment with all saline water. Other than this, the relative yield varied from 80 to 98 % in 10 other cyclic and mixing mode treatments. It was established that notwithstanding the seasonal build-up of salts due to saline water use, there would be no long-term build-up of salts as leaching during the monsoon season would render the soil profile salt free at the time of sowing of rabi (winter) crops. Thus, short-term field observations could be used in conjunction with SWAP to show that there seems to be an assured long-term sustainability when saline water is used in conjunctive mode with fresh water in monsoon climatic conditions with deep water table. These results are in conformity with the observation that many farmers in India are using saline and fresh water in conjunctive mode on a long-term basis. 相似文献
653.
The emissions of greenhouse gas (GHG) from soils are of significant importance for global warming. The biological and physico-chemical characteristics of soil affect the GHG emissions from soils of different land use types. Methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) production rates from six forest and agricultural soil types in the Koteshwar hydropower reservoir catchments located in the Uttarakhand, India, were estimated and their relations with physico-chemical characteristics of soils were examined. The samples of different land use types were flooded and incubated under anaerobic condition at 30 °C for 60 days. The cumulative GHG production rates in reservoir catchment are found as 1.52 ± 0.26, 0.13 ± 0.02, and 0.0004 ± 0.0001 μg g soil?1 day?1 for CO2, CH4, and N2O, respectively, which is lower than global reservoirs located in the same eco-region. The significant positive correlation between CO2 productions and labile organic carbon (LOC), CH4 and C/N ratio, while N2O and N/P ratio, while pH of soils is negatively correlated, conforms their key role in GHG emissions. Carbon available as LOC in the reservoir catchment is found as 3–14% of the total ?C” available in soils and 0–23% is retained in the soil after the completion of incubation. The key objective of this study to signify the C, N, and P ratios, LOC, and pH with GHG production rate by creating an incubation experiment (as in the case of benthic soil/sediment) in the lab for 60 days. In summary, the results suggest that carbon, as LOC were more sensitive indicators for CO2 emissions and significant C, N, and P ratios, affects the GHG emissions. This study is useful for the hydropower industry to know the GHG production rates after the construction of reservoir so that its effect could be minimized by taking care of catchment area treatment plan. 相似文献
654.
Thawale P Ghosh T Kumar Singh S Singh S Kulkarni A 《Environmental monitoring and assessment》2012,184(4):2575-2591
Feasibility of an irrigation project is evaluated by two criteria viz., reservoir capacity to irrigate its command area and
economic returns by incremental crop production versus capital investment for dam construction. The annual water requirement
of different crops in the command area is estimated and compared with the availability of water from the dam for irrigation
purpose. The annual crop water requirement is estimated as the sum of evapotranspiration for crops and transmission and other
losses. Evapotranspiration is estimated by modified Penman formula. Economics of crop production is analyzed by first estimating
the monetary value of existing crop production under current rain fed conditions and then estimating the incremental production
of irrigated command area for the proposed crop pattern. The proposed cropping pattern is prepared so as to maximize the benefit
of crop production and fodder requirement while maintaining a better crop rotation to improve and maintain physical, chemical,
and biological conditions of the soil. The dam is to be used for irrigation and water supply only. Command area served by
this reservoir will be 76,500 ha. The existing annual agricultural return is Rs. 2995.56 lakhs and with the proposed irrigation
scheme, it is estimated as Rs. 1,77,91.90 lakhs. The incremental annual return would be Rs. 1,47,96.35 lakhs i.e., 642.68%
increase in annual return. 相似文献
655.
This paper presents an analysis using temporal moments to study multi-species radionuclide transport along a single fracture with variable fracture aperture in a fracture-skin-matrix system. In the present study, a decay chain having three elements is considered and transport of each member in the decay chain is modeled by solving a coupled system of partial differential equations for fracture, fracture-skin, and rock matrix using explicit finite difference method. Having obtained the concentration distribution, lower order temporal moments of radionuclide distribution are computed to analyze the effective velocity and macro-dispersion coefficient of radionuclides in the fracture. In the present study, effect of varying fracture aperture on transport characteristics of radionuclides is also analyzed. It is found that the fracture aperture variation profile has significant impact on radionuclide distribution along the fracture. Sensitivity analysis is carried out in a fracture-skin-matrix system with sinusoidal fracture aperture to study the effect of various parameters like fracture aperture thickness, fracture-skin porosity, fracture-skin diffusion coefficient, flow rate, radioactive decay constant, and Freundlich sorption isotherm exponent on transport characteristics of radionuclide. The results suggest that the above mentioned parameters significantly influence concentration, distribution, mobility, and effective macro-dispersion coefficient of radionuclides along the fracture. 相似文献
656.
A multivariate time series approach vector autoregression (VAR) along with impulse response function and variance decomposition
technique has been employed to look into the interrelationship among O3, NO, NO2, and volatile organic compounds (VOCs, namely, benzene, ethylbenzene, toluene, and xylene in the present study) using 3 months
long continuous time series data of 1 h average concentration of these pollutants at one of the traffic sites in Delhi, India.
It is found that the VAR of order 2 (i.e., past two lagged values of 1 h interval) is sufficient to represent the observed
time series at the station studied. The impulse response function and variance decomposition analysis indicate that O3 concentration shows an immediate rise and persists for a longer duration (typically 8–10 h) once the impulse of NO2, benzene, ethylbenzene, or xylene is given in the ambient environment. However, in case of toluene, the reverse effect has
been observed. Since O3 forms in the troposphere due to photolysis of NO2, it is not surprising that its impulse triggers O3 formation in the ambient environment. However, in case of VOCs, this has been attributed to their tendency to show higher
inclination toward intermediary reactions leading to the formation of O3 rather than their (VOCs) reaction with O3. Among VOCs, only toluene has been observed to show higher inclination toward its reaction with O3. Apart from this, variance decomposition technique also reveals that the relation of NO with NO2 is more important than the relation of NO with O3 creating a conducive atmosphere for O3 formation in the present scenario. Thus, the multivariate time series approach provides significant insight about the role
played by the dominant individual VOCs and NO
x
in influencing the O3 concentration in ambient urban atmosphere whereas a photochemical modeling approach gives an overall view of NO
x
and VOCs behavior with respect to O3 by using the O3 isopleth technique. 相似文献
657.
M. H. Sayadi M. R. G. Sayyed Suyash Kumar 《Environmental monitoring and assessment》2010,162(1-4):465-473
In modern civilization, numerous anthropogenic activities release a variety of pollutants into the environment and with anomalous enrichment of heavy metals it causes surface and subsurface contamination. The aquatic sediments provide pertinent tools for the quality assessment of urban and industrial environments in large cities. The present study reveals short-term accumulative trends of heavy metals (Co, Cd, and Pb) in the sand and silt dominated riverbed sediments from Chitgar industrial area (Tehran, Iran) between the period of May 2007 and May 2008. Lead demonstrates highest concentration in residential areas, cadmium in and around industrial areas, whereas cobalt shows least variability. Geo-accumulation index implies moderately to highly polluted sediments with respect to Cd and Pb. With few exceptions, all three metals at different sampling stations display short-term increasing trends, independent of seasonal variability with urban and industrial distends along the river being the chief sources of contamination. 相似文献
658.
Nepal C. Mondal Ananda V. Rao Vijay P. Singh 《Environmental monitoring and assessment》2010,168(1-4):103-114
The accumulation of fluoride (F) in groundwater is a common phenomenon in India and worldwide. Its location can be identified through a direct hydrochemical analysis, which was carried out in Kurmapalli watershed (located 60 km SE of Hyderabad city), Nalgonda district, Andhra Pradesh, India affected by F contamination. The results of the hydrochemical analysis showed that F varied from 0.71 to 19.01 mg/l and its concentration exceeded the permissible limit (i.e., 1.5 mg/l) in 78% of the total 32 samples analyzed. The highest F value (19.01 mg/l) was found near Madnapur village, which is located in the central part of the watershed. Resistivity and induced polarization (IP) surveys were also carried out to reveal the zones where elevated F-contaminated groundwater exists. The objective of this paper was to highlight the utility of resistivity and IP surveys, using hydrochemical constituents as constraint, for the successful delineation of such contaminated/polluted groundwater zones in the granite area. 相似文献
659.
Assessment of daily intake of trace elements by Kakrapar adult population through ingestion pathway 总被引:1,自引:0,他引:1
Akhaya Kumar Patra S. S. Wagh A. K. Jain A. G. Hegde 《Environmental monitoring and assessment》2010,169(1-4):267-272
Concentration of trace elements such as Fe, Cu, Ni, and Zn were measured in cereals, pulses, vegetables, fish, meat, milk, egg, and water samples collected around Kakrapar, Gujarat, India. A wide variation of the trace element concentration was observed among all the dietary matrices. The concentration of Fe is comparatively more in all the dietary matrices. The concentrations of these elements are translated into intake rates through ingestion pathways. Daily intake (milligrams/day) of Fe, Cu, Ni, and Zn by adult population of Kakrapar, Gujarat were 16.5 ± 6.2, 3.3 ± 1.2, 1.8 ± 1.0, and 3.6 ± 1.3, respectively. Dietary sources of Fe, Cu, and Ni by Kakrapar adult population are comparable with RDA. In case of Zn, the daily dietary intake is comparatively lower than that of RDA. 相似文献
660.
Arveti N Reginald S Kumar KS Harinath V Sreedhar Y 《Environmental monitoring and assessment》2012,184(4):2295-2306
Termite mounds are abundant components of Tummalapalle area of uranium mineralization of Cuddapah District of Andhra Pradesh,
India. The systematic research has been carried out on the application of termite mound sampling to mineral exploration in
this region. The distribution of chemical elements Cu, Pb, Zn, Ni, Co, Cr, Li, Rb, Sr, Ba, and U were studied both in termite
soils and adjacent surface soils. Uranium accumulations were noticed in seven termite mounds ranging from 10 to 36 ppm. A
biogeochemical parameter called “Biological Absorption Coefficient” of the termite mounds indicated the termite affected soils
contained huge amounts of chemical elements than the adjacent soils. 相似文献