排序方式: 共有28条查询结果,搜索用时 15 毫秒
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S Peña-Llopis S Vega-Rubín-de-Celis A Liao N Leng A Pavía-Jiménez S Wang T Yamasaki L Zhrebker S Sivanand P Spence L Kinch T Hambuch S Jain Y Lotan V Margulis AI Sagalowsky PB Summerour W Kabbani SW Wong N Grishin M Laurent XJ Xie CD Haudenschild MT Ross DR Bentley P Kapur J Brugarolas 《Nature genetics》2012,44(9):1072
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John R. Spence 《西北部美国博物学家》2011,65(1)
Symphyotrichum expansum (Puepp ex Spreng.) Nesom is reported new to Utah from the Escalante River drainage. A major range extension is reported for Aralia racemosa L. in the Escalante drainage, and additional populations are reported of the rare species Imperata brevifolia Vasey in Utah, including the 1st record for the Grand Staircase--Escalante National Monument. Heterotheca grandiflora Nutt. is reported new to north central Arizona. New locations and notes on an additional 22 rare species in Glen Canyon National Recreation Area are listed. 相似文献
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John R. Spence 《西北部美国博物学家》2011,45(1)
Symphyotrichum expansum (Puepp ex Spreng.) Nesom is reported new to Utah from the Escalante River drainage. A major range extension is reported for Aralia racemosa L. in the Escalante drainage, and additional populations are reported of the rare species Imperata brevifolia Vasey in Utah, including the 1st record for the Grand Staircase--Escalante National Monument. Heterotheca grandiflora Nutt. is reported new to north central Arizona. New locations and notes on an additional 22 rare species in Glen Canyon National Recreation Area are listed. 相似文献
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G. E. Spence A. A. Hoffmann P. A. Parsons 《Cellular and molecular life sciences : CMLS》1984,40(7):763-765
Summary We have found that males of the sibling speciesD. melanogaster andD. simulans are preferentially attracted to sites marked by the residual odors of conspecific females, especially if non-virgin. In natural populations, this could enhance sexual selection among males, and cause some isolation at the microhabitat level. 相似文献
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Acetaldehyde: a low-concentration resource and larval attractant in 3Drosophila species 总被引:1,自引:0,他引:1
Summary Acetaldehyde is used as an energy source and attracts larvae up to low concentrations where it becomes a stress and a larval repellant, inD. melanogaster, D. simulans, andD. immigrans. This result is expected, since acetaldehyde is an intermediary compound between ethanol and acetic acid, both of which are utilized as resources and attract larvae to varying thresholds according to species and genotype.We thank Jan Clarke for assistance, and the Australian Research Grants Committee for partial financial support. 相似文献
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IJ Simpson MP Sulbaek Andersen S Meinardi L Bruhwiler NJ Blake D Helmig FS Rowland DR Blake 《Nature》2012,488(7412):490-494
After methane, ethane is the most abundant hydrocarbon in the remote atmosphere. It is a precursor to tropospheric ozone and it influences the atmosphere's oxidative capacity through its reaction with the hydroxyl radical, ethane's primary atmospheric sink. Here we present the longest continuous record of global atmospheric ethane levels. We show that global ethane emission rates decreased from 14.3 to 11.3 teragrams per year, or by 21 per cent, from 1984 to 2010. We attribute this to decreasing fugitive emissions from ethane's fossil fuel source--most probably decreased venting and flaring of natural gas in oil fields--rather than a decline in its other major sources, biofuel use and biomass burning. Ethane's major emission sources are shared with methane, and recent studies have disagreed on whether reduced fossil fuel or microbial emissions have caused methane's atmospheric growth rate to slow. Our findings suggest that reduced fugitive fossil fuel emissions account for at least 10-21 teragrams per year (30-70 per cent) of the decrease in methane's global emissions, significantly contributing to methane's slowing atmospheric growth rate since the mid-1980s. 相似文献
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Howell DA Sullivan M Nugent PE Ellis RS Conley AJ Le Borgne D Carlberg RG Guy J Balam D Basa S Fouchez D Hook IM Hsiao EY Neill JD Pain R Perrett KM Pritchet CJ 《Nature》2006,443(7109):308-311
The accelerating expansion of the Universe, and the need for dark energy, were inferred from observations of type Ia supernovae. There is a consensus that type Ia supernovae are thermonuclear explosions that destroy carbon-oxygen white dwarf stars that have accreted matter from a companion star, although the nature of this companion remains uncertain. These supernovae are thought to be reliable distance indicators because they have a standard amount of fuel and a uniform trigger: they are predicted to explode when the mass of the white dwarf nears the Chandrasekhar mass of 1.4 solar masses (M(o)). Here we show that the high-redshift supernova SNLS-03D3bb has an exceptionally high luminosity and low kinetic energy that both imply a super-Chandrasekhar-mass progenitor. Super-Chandrasekhar-mass supernovae should occur preferentially in a young stellar population, so this may provide an explanation for the observed trend that overluminous type Ia supernovae occur only in 'young' environments. As this supernova does not obey the relations that allow type Ia supernovae to be calibrated as standard candles, and as no counterparts have been found at low redshift, future cosmology studies will have to consider possible contamination from such events. 相似文献
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J. Gillman Christine Gilbert Isobel Spence 《Cellular and molecular life sciences : CMLS》1955,11(4):157-158
Zusammenfassung Die Entstehung von Reticulosarkom bei Ratten nach mehrmaliger Injektion von Trypanblau kann unterdrückt werden durch Entkräftung, Verabreichung anti-thyreoidaler Mittel und durch alle andern Faktoren, welche den Stoffwechsel herabsetzen. 相似文献
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