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904.
Dhananjay Kumar J. P. Gaur 《Environmental science and pollution research international》2014,21(17):10279-10285
The present study explores the tolerance and metal removal response of a well-developed 2-week-old Phormidium mat after long-term exposure to Cu2+-enriched medium. Cu2+ enrichment inhibited increase in mat biomass in a concentration-dependent manner. Mat area and the number of entrapped air bubbles decreased as Cu2+ concentration increased in the medium. Decrease in number of air bubbles obviously reflects the adverse effect of Cu2+ on photosynthetic performance of the mat. Metal enrichment did not substantially alter the amount of pigments, such as chlorophyll a, chlorophyll b, carotenoids, and phycocyanin, in the mat. Enhancement of Cu2+ concentration in the medium led to changes in species composition of the test mat; however, Phormidium bigranulatum always remained the dominant organism. Relative share of green algae and some cyanobacterial taxa, namely, Lyngbya sp. and Oscillatoria tenuis, in the mat were increased by Cu2+ enrichment. The mat successfully removed 80 to 94 % Cu2+ from the growth medium containing 10 to 100 μM Cu2+. Extracellular polysaccharides, whose share increased in the mat community after metal addition, seem to have contributed substantially to metal binding by the mat biomass. 相似文献
905.
A. K. Singh L. J. Bordoloi Manoj Kumar S. Hazarika Brajendra Parmar 《Environmental monitoring and assessment》2014,186(4):2013-2024
Quantitative assessment of soil quality is required to determine the sustainability of land uses in terms of environmental quality and plant productivity. Our objective was to identify the most appropriate soil quality indicators and to evaluate the impact of six most prevalent land use types (natural forestland, cultivated lowland, cultivated upland terrace, shifting cultivation, plantation land, and grassland) on soil quality in eastern Himalayan region of India. We collected 120 soil samples (20 cm depth) and analyzed them for 29 physical, chemical, and biological soil attributes. For selection of soil quality indicators, principal component analysis (PCA) was performed on the measured attributes, which provided four principal components (PC) with eigenvalues >1 and explaining at least 5 % of the variance in dataset. The four PCs together explained 92.6 % of the total variance. Based on rotated factor loadings of soil attributes, selected indicators were: soil organic carbon (SOC) from PC-1, exchangeable Al from PC-2, silt content from PC-3, and available P and Mn from PC-4. Indicators were transformed into scores (linear scoring method) and soil quality index (SQI) was determined, on a scale of 0–1, using the weighting factors obtained from PCA. SQI rating was the highest for the least-disturbed sites, i.e., natural forestland (0.93) and grassland (0.87), and the lowest for the most intensively cultivated site, i.e., cultivated upland terrace (0.44). Ratings for the other land uses were shifting cultivation (0.60)?>?cultivated low land (0.57)?>?plantation land (0.54). Overall contribution (in percent) of the indicators in determination of SQI was in the order: SOC (58 %)?>?exch. Al (17.1 %)?>?available P (8.9 %)?>?available Mn (8.2 %)?>?silt content (7.8 %). Results of this study suggest SOC and exch. Al as the two most powerful indicators of soil quality in study area. Thus, organic C and soil acidity management holds the key to improve soil quality under many exploitatively cultivated land use systems in eastern Himalayan region of India. 相似文献
906.
Lilibeth A. Acosta-Michlik K. S. Kavi Kumar Richard J. T. Klein Sabine Campe 《Regional Environmental Change》2008,8(4):151-160
By combining the concepts of environmental stress, state susceptibility and environmental crisis, “Security Diagram” (SD)
provides a quantitative approach to assessing environmental change and human security. The SD is a tool that clearly presents
in a diagram the security situation of a population or region affected by a particular environmental crisis. Its underlying
concept emphasises that the higher the level of environmental stress and socio-economic susceptibility, the higher the probability
of the occurrence of crisis. Focusing on drought, this study analyses the susceptibility of case study regions in India, Portugal,
and Russia from a socio-economic perspective. A conceptual framework of socio-economic susceptibility is developed based on
the economic development theories of modernisation and dependency. Fuzzy set theory is used to generate susceptibility indices
from a range of national and sub-national indicators, including financial resources, agricultural dependency and infrastructure
development (for economic susceptibility), and health condition, educational attainment and gender inequality (for social
susceptibility). Results indicate that socio-economic susceptibility over the period 1980–1995 was highest in India, followed
by Russia and (since 1989) lowest in Portugal. Globalisation is likely to contribute to changes in the level of socio-economic
susceptibility over time. Moreover, specific social and economic structures unique in each country (e.g., the role of women
in society in India, the socialist legacy in Russia) may explain differences in susceptibility between the case study regions.
相似文献
Sabine CampeEmail: |
907.
908.
Pankaj Kumar Manish Kumar A. L. Ramanathan Maki Tsujimura 《Environmental geochemistry and health》2010,32(2):129-146
Arsenic contamination in groundwater is of increasing concern because of its high toxicity and widespread occurrence. This
study is an effort to trace the factors responsible for arsenic enrichment in groundwater of the middle Gangetic Plain of
India through major ion chemistry, arsenic speciation, sediment grain-size analyses, and multivariate statistical techniques.
The study focuses on the distinction between the contributions of natural weathering and anthropogenic inputs of arsenic with
its spatial distribution and seasonal variations in the plain of the state Bihar of India. Thirty-six groundwater and one
sediment core samples were collected in the pre-monsoon and post-monsoon seasons. Various graphical plots and statistical
analysis were carried out using chemical data to enable hydrochemical evaluation of the aquifer system based on the ionic
constituents, water types, hydrochemical facies, and factors controlling groundwater quality. Results suggest that the groundwater
is characterized by slightly alkaline pH with moderate to strong reducing nature. The general trend of various ions was found
to be Ca2+ > Na+ > Mg2+ > K+ > NH4
+; and HCO3
− > Cl− > SO4
2− > NO3
− > PO4
3− > F− in both seasons. Spatial and temporal variations showed a slightly higher arsenic concentration in the pre-monsoon period
(118 μg/L) than in the post-monsoon period (114 μg/L). Results of correlation analyses indicate that arsenic contamination
is strongly associated with high concentrations of Fe, PO4
3−, and NH4
+ but relatively low Mn concentrations. Further, the enrichment of arsenic is more prevalent in the proximity of the Ganges
River, indicating that fluvial input is the main source of arsenic. Grain size analyses of sediment core samples revealed
clay (fine-grained) strata between 4.5 and 7.5 m deep that govern the vertical distribution of arsenic. The weathering of
carbonate and silicate minerals along with surface-groundwater interactions, ion exchange, and anthropogenic activities seem
to be the processes governing groundwater contamination, including with arsenic. Although the percentage of wells exceeding
the permissible limit (50 μg/L) was less (47%) than that reported in Bangladesh and West Bengal, the percentage contribution
of toxic As(III) to total arsenic concentration is quite high (66%). This study is vital considering that groundwater is the
exclusive source of drinking water in the region and not only makes situation alarming but also calls for immediate attention. 相似文献
909.
D. N. Kumar 《Die Naturwissenschaften》1964,51(12):286-286
910.
This paper studies the effect of environmental regulation on the productive efficiency of water polluting industries in India. The panel data of 92 firms belonging to sugar industry of India during the period 1996-99 are used to test the Porter hypothesis of having win-win opportunities for the firms subjected to the regulation. The main empirical result is that the technical efficiency of firms increases with the degree of compliance of firms to the environmental regulation and the water conservation efforts there by supporting the Porter hypothesis. 相似文献