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31.
Quantification of the effect of fumigation on short- and long-term nitrogen mineralization and nitrification in different soils 总被引:2,自引:0,他引:2
The effect of soil fumigation on N mineralization and nitrification needs to be better quantified to optimize N fertilizer advice and predict NO(-)(3) concentrations in crops and NO(-)(3) leaching risks. Seven soils representing a range in soil texture and organic matter contents were fumigated with Cyanamid DD 95 (a mixture of 1,3-dichloropropane and 1,3-dichloropropene). After removal of the fumigant, the fumigated soils and unfumigated controls were incubated for 20 wk and N mineralization and nitrification were monitored by destructive sampling. The average short-term N mineralization rates (k(s)) were significantly larger in the fumigated than in the unfumigated soils (P = 0.025), but the differences in k(s) between fumigated and unfumigated soils could not be related to soil properties. The average long-term N mineralization rates (k(l)) were slightly larger in the fumigated soils but the difference with the unfumigated soils was not significant. Again, the differences in k(l) values could not be related to soil properties. Nitrification was inhibited completely for at least 3 wk in all soils, and an effect on nitrification could be observed up to 17 wk in one soil. An S-shaped function was fitted to the nitrification data corrected for N mineralization, and both the rate constant (gamma) and the time at which maximum nitrification was reached (t(max)) were strongly correlated to soil pH. However, since no correlations were found between the effect of fumigation on N mineralization and soil properties, taking into account the effects of fumigation in fertilizer advice and in the prediction of NO(-)(3) leaching risks will need further research. 相似文献
32.
Georges S.Zouain 《生态毒理学报》2001,23(1):77-78
城市遗产的保存和利用将都市管理的负责人置于艰难选择的境地 .下面的文字对城市的构成进行了简短的历史回顾,得出了在场所利用及其保存之间保持平衡发展条件 . 相似文献
33.
Major shifts in Amazon wildlife populations from recent intensification of floods and drought 下载免费PDF全文
Richard Bodmer Pedro Mayor Miguel Antunez Kimberlyn Chota Tula Fang Pablo Puertas Marlini Pittet Maire Kirkland Mike Walkey Claudia Rios Pedro Perez‐Peña Peter Henderson William Bodmer Andy Bicerra Joseph Zegarra Emma Docherty 《Conservation biology》2018,32(2):333-344
In the western Amazon Basin, recent intensification of river‐level cycles has increased flooding during the wet seasons and decreased precipitation during the dry season. Greater than normal floods occurred in 2009 and in all years from 2011 to 2015 during high‐water seasons, and a drought occurred during the 2010 low‐water season. During these years, we surveyed populations of terrestrial, arboreal, and aquatic wildlife in a seasonally flooded Amazonian forest in the Loreto region of Peru (99,780 km2) to study the effects of intensification of natural climatic fluctuations on wildlife populations and in turn effects on resource use by local people. Shifts in fish and terrestrial mammal populations occurred during consecutive years of high floods and the drought of 2010. As floods intensified, terrestrial mammal populations decreased by 95%. Fish, waterfowl, and otter (Pteronura brasiliensis) abundances increased during years of intensive floods, whereas river dolphin and caiman populations had stable abundances. Arboreal species, including, macaws, game birds, primates, felids, and other arboreal mammals had stable populations and were not affected directly by high floods. The drought of 2010 had the opposite effect: fish, waterfowl, and dolphin populations decreased, and populations of terrestrial and arboreal species remained stable. Ungulates and large rodents are important sources of food and income for local people, and large declines in these animals has shifted resource use of people living in the flooded forests away from hunting to a greater reliance on fish. 相似文献
34.
35.
Guillerme S Kumar BM Menon A Hinnewinkel C Maire E Santhoshkumar AV 《Environmental management》2011,48(2):351-364
Agroforestry systems are fundamental features of the rural landscape of the Indian state of Kerala. Yet these mixed species
systems are increasingly being replaced by monocultures. This paper explores how public policies on land tenure, agriculture,
forestry and tree growing on private lands have interacted with farmer preferences in shaping land use dynamics and agroforestry
practices. It argues that not only is there no specific policy for agroforestry in Kerala, but also that the existing sectoral
policies of land tenure, agriculture, and forestry contributed to promoting plantation crops, even among marginal farmers.
Forest policies, which impose restrictions on timber extraction from farmers’ fields under the garb of protecting natural
forests, have often acted as a disincentive to maintaining tree-based mixed production systems on farmlands. The paper argues
that public policies interact with farmers’ preferences in determining land use practices. 相似文献
36.
Katia Ballorain Stéphane Ciccione Jérôme Bourjea Henri Grizel Manfred Enstipp Jean-Yves Georges 《Marine Biology》2010,157(12):2581-2590
We investigated the habitat use in green turtles exploiting a 13-ha multispecific seagrass meadow at Mayotte Island, south-western
Indian Ocean. A phyto-ecological survey shows the occurrence of eight seagrass species, dominated by Halodule uninervis and Syringodium isoetifolium, distributed according to four distinct seagrass communities along the depth gradient. Direct underwater censuses show that
green turtles occurred all over the meadow. Yet when community relative surface area was taken into account green turtles
preferentially frequented the most seaward, biomass-richer S. isoetifolium-dominated community, suggesting that green turtles compensate for their intrinsically nutrient-poor herbivorous diet. Additionally,
smaller (<80 cm standard curved carapace length, SCCL) individuals also preferentially occurred in the most shoreward H. univervis-dominated community where no larger (>80 cm SCCL) individuals were sighted, suggesting habitat use is indicative of diet
selection and may reflect size-specific food requirements and physiology. 相似文献
37.
Hanitra Randrianaivo Georges Haddad Horatiu Roman Anne Lise Annick Toutain Martine Le Merrer Claude Moraine 《黑龙江环境通报》2002,22(9):806-810
An Erratum has been published for this article in Prenatal Diagnosis 22(13) 2002, 1241. Fibrochondrogenesis is a rare and lethal osteochondrodysplasia with an autosomal recessive mode of inheritance. We report a male fetus in which the diagnosis of lethal osteochondrodysplasia was suspected on prenatal ultrasound and radiological examinations during the second trimester of pregnancy. After termination of pregnancy, fibrochondrogenesis was diagnosed by radiological examination and histological study of fetal bones. Interwoven fibrous septa and fibroblastic degeneration of chondrocytes are pathognomonic. The recurrence rate is 25% and accurate diagnosis is necessary to enable genetic counselling. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
38.
Edouard Kauffmann Horatiu Roman Georges Barau Hervé Dumas Annick Laffitte Alain Fourmaintraux Marc Bintner Hanitra Randrianaivo 《黑龙江环境通报》2003,23(2):163-165
The Jarcho–Levin syndrome is a specific form of spondylocostal/spondylothoracic dysostosis. There have been various classifications of this syndrome. We present the case of a severe prenatal Jarcho–Levin syndrome, diagnosed by ultrasound examination during the first trimester of pregnancy in a family with no previous medical history of an affected child. X-ray exploration, high-resolution spiral computed tomography and autopsy confirmed the diagnosis. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
39.
Pedro Lorite Xulio Maside Olivia Sanllorente María I. Torres Georges Periquet Teresa Palomeque 《Die Naturwissenschaften》2012,99(12):1007-1020
To date, only three types of full-length mariner elements have been described in ants, each one in a different genus of the Myrmicinae subfamily: Sinvmar was isolated from various Solenopsis species, Myrmar from Myrmica ruginodis, and Mboumar from Messor bouvieri. In this study, we report the coexistence of three mariner elements (Tnigmar-Si, Tnigmar-Mr, and Tnigmar-Mb) in the genome of a single species, Tapinoma nigerrimum (subfamily Dolichoderinae). Molecular evolutionary analyses of the nucleotide sequence data revealed a general agreement between the evolutionary history of most the elements and the ant species that harbour them, and suggest that they are at the vertical inactivation stage of the so-called Mariner Life Cycle. In contrast, significantly reduced levels of synonymous divergence between Mboumar and Tnigmar-Mb and between Myrmar and Botmar (a mariner element isolated from Bombus terrestris), relative to those observed between their hosts, suggest that these elements arrived to the species that host them by horizontal transfer, long after the species?? split. The horizontal transfer events for the two pairs of elements could be roughly dated within the last 2 million years and about 14 million years, respectively. As would be expected under this scenario, the coding sequences of the youngest elements, Tnigmar-Mb and Mboumar, are intact and, thus, potentially functional. Each mariner element has a different chromosomal distribution pattern according to their stage within the Mariner Life Cycle. Finally, a new defective transposable element (Azteca) has also been found inserted into the Tnigmar-Mr sequences showing that the ant genomes have been invaded by at least four different types of mariner elements. 相似文献