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711.
Cécile Fauvelot Francesca Bertozzi Federica Costantini Laura Airoldi Marco Abbiati 《Marine Biology》2009,156(11):2313-2323
Human-made structures are increasingly found in marine coastal habitats. The aim of the present study was to explore whether
urban coastal structures can affect the genetic variation of hard-bottom species. We conducted a population genetic analysis
on the limpet Patella caerulea sampled in both natural and artificial habitats along the Adriatic coast. Five microsatellite loci were used to test for
differences in genetic diversity and structure among samples. Three microsatellite loci showed strong Hardy–Weinberg disequilibrium
likely linked with the presence of null alleles. Genetic diversity was significantly higher in natural habitat than in artificial
habitat. A weak but significant differentiation over all limpet samples was observed, but not related to the type of habitat.
While the exact causes of the differences in genetic diversity deserve further investigation, these results clearly point
that the expansion of urban structures can lead to genetic diversity loss at regional scales. 相似文献
712.
Gabriel Ramos-Fernández Denis Boyer Filippo Aureli Laura G. Vick 《Behavioral ecology and sociobiology》2009,63(7):999-1013
We use two novel techniques to analyze association patterns in a group of wild spider monkeys (Ateles geoffroyi) studied continuously for 8 years. Permutation tests identified association rates higher or lower than chance expectation,
indicating active processes of companionship and avoidance as opposed to passive aggregation. Network graphs represented individual
adults as nodes and their association rates as weighted edges. Strength and eigenvector centrality (a measure of how strongly
linked an individual is to other strongly linked individuals) were used to quantify the particular role of individuals in
determining the network's structure. Female–female dyads showed higher association rates than any other type of dyad, but
permutation tests revealed that these associations cannot be distinguished from random aggregation. Females formed tightly
linked clusters that were stable over time, with the exception of immigrant females who showed little association with any
adult in the group. Eigenvector centrality was higher for females than for males. Adult males were associated mostly among
them, and although their strength of association with others was lower than that of females, their association rates revealed
a process of active companionship. Female–male bonds were weaker than those between same-sex pairs, with the exception of
those involving young male adults, who by virtue of their strong connections both with female and male adults, appear as temporary
brokers between the female and male clusters of the network. This analytical framework can serve to develop a more complete
explanation of social structure in species with high levels of fission–fusion dynamics.
This contribution is part of the special issue “Social Networks: new perspectives” (Guest Editors: J. Krause, D. Lusseau and
R. James) 相似文献
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714.
Distinct mycorrhizal communities on new and established hosts in a transitional tropical plant community 总被引:3,自引:0,他引:3
Aldrich-Wolfe L 《Ecology》2007,88(3):559-566
The extent to which interspecific plants share mycorrhizal fungal communities depends on the specificity of the symbiosis. For tropical forest tree seedlings, colonization by mycorrhizal fungi associated with established vegetation could have important consequences for survival and growth. I used a novel molecular technique to assess the potential for sharing of mycorrhizas in forest and pasture in southern Costa Rica, by identifying arbuscular mycorrhizal (AM) fungi in roots of the forest canopy tree species Terminalia amazonia, pasture grasses Urochloa ruziziensis and U. decumbens, and seedlings of T. amazonia planted into experimental reforestation plots. I tested the hypotheses that experimental seedlings were colonized either by the AM fungal community of the forest T. amazonia (suggesting host specificity) or of Urochloa (suggesting absence of specificity/importance of local environment). After two years, pasture-grown T. amazonia seedlings were colonized by neither community, but rather by a species of Glomus that was rarely observed on the other plants. These results suggest that conspecific seedlings planted into existing vegetation generate a distinct mycorrhizal community that may influence competitive interactions and the relative costs and benefits of the AM fungal symbiosis at early stages in the life cycle of tropical trees. 相似文献
715.
Nolan F. Mangelson Laura Lewis Jyothi M. Joseph Wenxuan Cui James Machir Delbert J. Eatough 《Journal of the Air & Waste Management Association (1995)》2013,63(2):167-175
Abstract Air pollutants were collected in Logan, Cache County, UT, in February 1993 during two periods of atmospheric inversion accompanied by fog. The following atmospheric species were determined: (1) gaseous SO2, NO2 (semi-quantitatively),HNO3, NH3, and HF; (2) fine particulate SO4 =, NO3 -, NH4 +, F–, H+, C, Si, S, K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, Pb, Se, Br, and Sr, and; (3) fine particulate mass, which was calculated. The major components of fine particulate matter were carbonaceous material, ammonium nitrate, and ammonium sulfate, while the soil component was small. Calculated, fine particulate mass averaged 80 μg/m3 and reached concentrations as high as 120 μg/m3. SO2/Sox and NO2/NOy mole ratios generally varied between 0.2 and 0.1 during inversions. These ratios also showed moderate but consistent diurnal patterns. The emission inventory for Cache County indicates sources of SO2 and NOx but not significant amounts of primary sulfate and nitrate. The observations reported here indicate there is significant conversion of SO2 and NOx in the presence of excess oxidants to sulfuric and nitric acid that are neutralized by excess ammonia. 相似文献
716.
The concentrations of gas-phase PCBs were measured from March 2002 to June 2003 at two sites of the Venice Lagoon and at one site of the Euganei hills. The aims of this study were to evaluate the various gas-phase PCB sources, the spatial and temporal variability of PCB concentrations in the gas-phase that enter the Venice Lagoon atmosphere and the influence of the air temperature on PCB trends. The highest annual average concentration of summation PCBs was observed at the station directly influenced by "urban" sources with values about 3 and 1.5 times higher compared to the concentrations found at the stations where "marine" sources and "not subjected to direct local sources" were respectively sampled from. The temporal trends of summation PCBs concentrations were similar at the three sampling stations corresponding to seasonal temperature changes. Greater concentrations occurred in the summer and first autumn months while the lower ones occurred in late autumn and winter. The temperature dependences were investigated using plots of the natural logarithm of the summation PCBs concentrations vs. reciprocal mean temperatures. 相似文献
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