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151.
152.
Water quality from forested landscapes tends to be very high but can deteriorate during and after silvicultural activities.
Practices such as forest harvesting, site preparation, road construction/use, and stream crossings have been shown to contribute
sediment, nutrients, and other pollutants to adjacent streams. Although advances in forest management accompanied with Best
Management Practices (BMPs) have been very effective at reducing water quality impacts from forest operations, projected increases
in demand for forest products may result in unintended environmental degradation. Through a review of the pertinent literature,
we identified several research gaps related to water yield, aquatic habitat, sediment source and delivery, and BMP effectiveness
that should be addressed for streams in the United States to better understand and address the environmental ramifications
of current and future levels of timber production. We explored the current understanding of these topics based on relevant
literature and the possible implications of increased demand for forest products in the United States. 相似文献
153.
Comparative studies on plant species richness, endemism, floristic composition, and structure between protected and unprotected
forests are few in the Eastern Arc Mountains, one of the most biodiverse ecosystems in Africa. This study from one mountain
range, the East Usambaras, examines floristic and structural tree data from 41–0.5 ha plots in four types of Eastern Arc forest:
active agroforests, recently abandoned agroforests, mature secondary forest, and natural forest. Active agroforests had significantly
lower tree species richness, endemic species richness, and stand density compared to natural and mature secondary forest.
Recently abandoned agroforests contained a higher tree species richness, density, and tree height than active agroforests.
Active and abandoned agroforests were dominated by an invasive tree, Maesopsis eminii. This tree species makes up a large percentage of the stems in active agroforests (26%), recently abandoned agroforests (32%),
and in the canopy of mature secondary forests ∼ 30 years post logging (30%). Through time the increasing dominance of this
non-native tree in active agroforests is a concern when considering the role of agroforests in a landscape scale conservation
strategy. 相似文献
154.
The international shelter response to the Jogjakarta earthquake in Indonesia in May 2006 is widely regarded as a success story, especially when compared with the response to the Indian Ocean tsunami 16 months earlier. This evaluation is largely in terms of the international aid system itself, which emphasises statistical measures of ‘success’ and internal coordination and efficiency. From the perspective of those closer to the ground, however, it was less successful, especially in terms of coordination and communication with and participation of local agencies and affected communities. This paper, by an aid worker resident in Jogjakarta and an anthropologist, examines the response from a perspective grounded both within and outside the aid system, local as well as global. It recognises the relative success of the response, but argues for an approach more grounded in local knowledge and responsive to local concerns, while also providing practical suggestions for improvement. 相似文献
155.
Allinson G Mispagel C Kajiwara N Anan Y Hashimoto J Laurenson L Allinson M Tanabe S 《Chemosphere》2006,64(9):1464-1471
In recent times, the apparent population decline of the southern bent-wing bat (Miniopterus schreibersii bassanii) at Bat Cave, Naracoorte has been ascribed to pesticide use in the region, following the finding of organochlorine and orgaonophosphate insecticide residues in bat guano. Adult southern bent-wing bats were collected from Bat Cave and Starlight Cave in 2003. Organochlorine contaminants were detected in all carcass samples: p,p'-DDE was by far the most dominant contaminant with concentrations ranging from 11,000 to 59,000ngg(-1), followed by p,p'-DDT (110-1600ngg(-1)), p,p'-DDD (35-620ngg(-1)), summation operatorPCBs (33-490ngg(-1)), summation operatorchlordane and related compounds (7.9-270ngg(-1)), HCB (1.6-120ngg(-1)), HP epox. (3.1-230ngg(-1)), TCPMOH (3.8-38ngg(-1)), summation operatorHCHs (1.4-9.6ngg(-1)), and TCPMe (0.1-4.2ngg(-1)) (all values on lipid-weight basis). No significant difference in DDE, DDD, DDT, summation operatorDDT, summation operatorPCB, trans-chlordane, heptachlor epoxide, trans-nonachlor, alpha-HCH, beta-HCH, gamma-HCH, TCPMOH or TCPMe concentrations were observed either between sexes within sites, or between sites (p>0.05). However, there were significant differences in HCB and oxychlordane concentrations between sexes and between sites (p<0.05), between site differences in cis-nonachlor concentrations in male bats (p<0.05), and cis-chlordane concentrations between sexes at Starlight Cave, and between males of each site (p<0.05). There were also significant differences in the liver concentrations of some metals between sexes within sites (Ag, Cd, Co, Cu, Pb, Se, Zn), and between sites (Ag, Cd, Co, Cu, Hg, Pb, Se, V, Zn). Clustering or grouping of sites was observed when the OC data was expressed on a lipid-weight basis. These inter-site differences in OC concentrations reflect local exposure over a period of time, and do not unambiguously support any suggestion that we are witnessing incipient speciation. However, for conservation purposes, it may be prudent to assume that there are two sub-populations of M. s. bassani feeding in different locations in this region of southern Australia, rather than the single homogeneous population suggested by genetic studies. 相似文献