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排序方式: 共有183条查询结果,搜索用时 31 毫秒
91.
Mitchell T. Irwin Patricia C. Wright Paul Loiselle Daniel Rakotondravony Jonah Ratsimbazafy 《Biological conservation》2010,143(10):2351-2362
Five main conclusions arise from this review of the responses of species to anthropogenic disturbance in Madagascar: First, species’ reactions to anthropogenic disturbance are generally negative, but remain poorly known. Our knowledge is patchy among and within higher taxonomic groups; we are still largely gathering case studies. Second, taxonomic groups vary considerably in which proximate factors are most important. Third, several groups show differing responses within different ecoregions. Whether these differences are consistent across groups requires further testing. Fourth, related species often have divergent reactions to disturbance, even within lower taxonomic groupings (families or genera). Thus, we cannot rely on phylogenetic relatedness or even ecological similarity to infer similarity in responses. Finally, disturbance typically reduces species diversity (especially of native and/or endemic species), but also causes species turnover, typically with forest specialists replaced by grassland generalists, and endemics replaced by non-endemics (including invasives). Given these knowledge gaps, we stress the urgency of applied studies that assess species’ ecology, behaviour and health across disturbance gradients, including purely anthropogenic landscapes. Remaining natural vegetation and protected areas will be unable to preserve Madagascar’s biodiversity under the impact of climatic change; we must understand responses of plants and animals to disturbance in order to create buffer zones and corridors combining secondary, degraded and natural habitats. 相似文献
92.
Extract Sir, — Regulations in this country require sheep lungs to be inspected after slaughter, then either passed for processing into petfood by recognised plants, or to be condemned. One reason for this is the high prevalence of parasitic infection. 相似文献
93.
Gerlânia de O. LeiteLaura H.I. Leite Renata de S. SampaioMariana Késsia A. Araruna Irwin Rose A. de MenezesJosé Galberto M. da Costa Adriana R. Campos 《Fitoterapia》2011,82(2):208-211
The study examined the antiinflammatory and antinociceptive effects of the sesquiterpene (−)-α-bisabolol (BISA). The antiinflammatory effect was evaluated on acute models of dermatitis induced by Croton oil, arachidonic acid, phenol and capsaicin, respectively, in mouse ear. BISA inhibited the dermatitis induced by all noxious agents, except capsaicin. BISA was assessed in two established mouse models of visceral nociception. Mice were pretreated orally with BISA, and the pain-related behavioral responses to intraperitoneal cyclophosphamide or to intracolonic mustard oil were analyzed. BISA showed a dose-unrelated significant antinociception. Collectively, the results suggest that BISA may be an topical antiinflammatory and visceral antinociceptive agent. 相似文献
94.
Kunde VG Flasar FM Jennings DE Bézard B Strobel DF Conrath BJ Nixon CA Bjoraker GL Romani PN Achterberg RK Simon-Miller AA Irwin P Brasunas JC Pearl JC Smith MD Orton GS Gierasch PJ Spilker LJ Carlson RC Mamoutkine AA Calcutt SB Read PL Taylor FW Fouchet T Parrish P Barucci A Courtin R Coustenis A Gautier D Lellouch E Marten A Prangé R Biraud Y Ferrari C Owen TC Abbas MM Samuelson RE Raulin F Ade P Césarsky CJ Grossman KU Coradini A 《Science (New York, N.Y.)》2004,305(5690):1582-1586
The Composite Infrared Spectrometer observed Jupiter in the thermal infrared during the swing-by of the Cassini spacecraft. Results include the detection of two new stratospheric species, the methyl radical and diacetylene, gaseous species present in the north and south auroral infrared hot spots; determination of the variations with latitude of acetylene and ethane, the latter a tracer of atmospheric motion; observations of unexpected spatial distributions of carbon dioxide and hydrogen cyanide, both considered to be products of comet Shoemaker-Levy 9 impacts; characterization of the morphology of the auroral infrared hot spot acetylene emission; and a new evaluation of the energetics of the northern auroral infrared hot spot. 相似文献
95.
McCall JW Baker CF Mather TN Chester ST McCall SD Irwin JP Young SL Cramer LG Pollmeier MG 《Veterinary parasitology》2011,179(4):335-342
Healthy, purpose-bred laboratory beagle dogs that had not been exposed to ticks and were seronegative for Borrelia burgdorferi and Anaplasma phagocytophilum were randomly assigned to four groups of eight dogs each. Control group 1 was not treated. Groups 2, 3 and 4 were treated with a single topical application of a new formulation of fipronil, amitraz and (S)-methoprene (CERTIFECT?, Merial Limited, GA, USA) at 28, 21 or 14 days prior to tick infestation, respectively. Each dog was infested with 25 female and 25 male field-collected adult Ixodes scapularis ticks that had infection rates of 66% for B. burgdorferi sensu stricto and 23% for A. phagocytophilum, as determined by polymerase chain reaction. Two and five days after tick infestation, control dogs had an average of 9.5 and 13.9 attached adult female ticks, respectively, whilst the 24 treated dogs remained tick-free aside from a single tick on the 2nd day after infestation. Serial serological tests demonstrated that the ticks successfully infected 8/8 control dogs with B. burgdorferi and co-infected 6/8 with A. phagocytophilum. B. burgdorferi infection also was confirmed in most control dogs by culture (6/8) and PCR (7/8) of skin biopsies. In contrast, CERTIFECT protected all 24 treated dogs against infection by both B. burgdorferi and A. phagocytophilum, as demonstrated by their negative serological tests throughout the study and the absence of any positive skin biopsy culture or PCR in these dogs. 相似文献
96.
97.
Fletcher LN Hesman BE Irwin PG Baines KH Momary TW Sanchez-Lavega A Flasar FM Read PL Orton GS Simon-Miller A Hueso R Bjoraker GL Mamoutkine A del Rio-Gaztelurrutia T Gomez JM Buratti B Clark RN Nicholson PD Sotin C 《Science (New York, N.Y.)》2011,332(6036):1413-1417
Saturn's slow seasonal evolution was disrupted in 2010-2011 by the eruption of a bright storm in its northern spring hemisphere. Thermal infrared spectroscopy showed that within a month, the resulting planetary-scale disturbance had generated intense perturbations of atmospheric temperatures, winds, and composition between 20° and 50°N over an entire hemisphere (140,000 kilometers). The tropospheric storm cell produced effects that penetrated hundreds of kilometers into Saturn's stratosphere (to the 1-millibar region). Stratospheric subsidence at the edges of the disturbance produced "beacons" of infrared emission and longitudinal temperature contrasts of 16 kelvin. The disturbance substantially altered atmospheric circulation, transporting material vertically over great distances, modifying stratospheric zonal jets, exciting wave activity and turbulence, and generating a new cold anticyclonic oval in the center of the disturbance at 41°N. 相似文献
98.
Ring species, which consist of two reproductively isolated forms connected by a chain of intergrading populations, have often been described as examples of speciation despite gene flow between populations, but this has never been demonstrated. We used amplified fragment length polymorphism (AFLP) markers to study gene flow in greenish warblers (Phylloscopus trochiloides). These genetic markers show distinct differences between two reproductively isolated forms but gradual change through the ring connecting these forms. These findings provide the strongest evidence yet for "speciation by force of distance" in the face of ongoing gene flow. 相似文献
99.
100.
The seeds of forbs, grass, and woody halophytes were collected from a cool moist temperate habitat of North America and subtropical maritime desert conditions of Karachi, Pakistan. Sodium, potassium, calcium, magnesium, and chloride concentrations as well as total ash content were determined. Ion concentrations of seeds are expressed both as relative values and on a dry weight basis. Plants were found to vary in the total ash content of seeds and the relative distribution of ions. In general, temperate forbs and grasses had lower ion content of seeds and several tropical shrub species had the highest ionic content. 相似文献