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排序方式: 共有129条查询结果,搜索用时 78 毫秒
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Ann Magee 《Asia Pacific viewpoint》2001,42(1):35-45
In New Zealand while women dominate leadership positions in constitutional, political and business areas, gender inequality remains entrenched. Despite significant gains in rights (employment, pay equity, property), as a group women earn less and perform more family care and unpaid work than men. In part these disparities result from the economic restructuring of the last 15 years which saw a loss in unskilled manufacturing jobs, less social support and greater rewards to business and public sector elites. Maori and Pacific Island women are the most disadvantaged groups. Labour/Alliance government initiatives to reduce poverty particularly among Maori and Pacific Island peoples by strengthening access to health and education services and supporting and replicating successful community initiatives are also likely to benefit other low income women. 相似文献
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RL Westemeier JD Brawn SA Simpson TL Esker RW Jansen JW Walk EL Kershner JL Bouzat KN Paige 《Science (New York, N.Y.)》1998,282(5394):1695-1698
Effects of small population size and reduced genetic variation on the viability of wild animal populations remain controversial. During a 35-year study of a remnant population of greater prairie chickens, population size decreased from 2000 individuals in 1962 to fewer than 50 by 1994. Concurrently, both fitness, as measured by fertility and hatching rates of eggs, and genetic diversity declined significantly. Conservation measures initiated in 1992 with translocations of birds from large, genetically diverse populations restored egg viability. Thus, sufficient genetic resources appear to be critical for maintaining populations of greater prairie chickens. 相似文献
25.
Contrary to the prediction of the Z-scheme model of photosynthesis, experiments demonstrated that mutants of Chlamydomonas containing photosystem II (PSII) but lacking photosystem I (PSI) can grow photoautotrophically with O2 evolution, using atmospheric CO2 as the sole carbon source. Autotrophic photosynthesis by PSI-deficient mutants was stable both under anaerobic conditions and in air (21 percent O2) at an actinic intensity of 200 microeinsteins per square meter per second. This PSII photosynthesis, which was sufficient to support cell development and mobility, may also occur in wild-type green algae and higher plants. The mutants can survive under 2000 microeinsteins per square meter per second with air, although they have less resistance to photoinhibition. 相似文献
26.
Waite JH Niemann H Yelle RV Kasprzak WT Cravens TE Luhmann JG McNutt RL Ip WH Gell D De La Haye V Müller-Wordag I Magee B Borggren N Ledvina S Fletcher G Walter E Miller R Scherer S Thorpe R Xu J Block B Arnett K 《Science (New York, N.Y.)》2005,308(5724):982-986
The Cassini Ion Neutral Mass Spectrometer (INMS) has obtained the first in situ composition measurements of the neutral densities of molecular nitrogen, methane, molecular hydrogen, argon, and a host of stable carbon-nitrile compounds in Titan's upper atmosphere. INMS in situ mass spectrometry has also provided evidence for atmospheric waves in the upper atmosphere and the first direct measurements of isotopes of nitrogen, carbon, and argon, which reveal interesting clues about the evolution of the atmosphere. The bulk composition and thermal structure of the moon's upper atmosphere do not appear to have changed considerably since the Voyager 1 flyby. 相似文献
27.
Sensitivity of boreal forest carbon balance to soil thaw 总被引:6,自引:0,他引:6
ML Goulden SC Wofsy JW Harden SE Trumbore PM Crill ST Gower T Fries BC Daube S Fan DJ Sutton A Bazzaz JW Munger 《Science (New York, N.Y.)》1998,279(5348):214-217
We used eddy covariance; gas-exchange chambers; radiocarbon analysis; wood, moss, and soil inventories; and laboratory incubations to measure the carbon balance of a 120-year-old black spruce forest in Manitoba, Canada. The site lost 0.3 +/- 0.5 metric ton of carbon per hectare per year (ton C ha-1 year-1) from 1994 to 1997, with a gain of 0.6 +/- 0.2 ton C ha-1 year-1 in moss and wood offset by a loss of 0.8 +/- 0.5 ton C ha-1 year-1 from the soil. The soil remained frozen most of the year, and the decomposition of organic matter in the soil increased 10-fold upon thawing. The stability of the soil carbon pool ( approximately 150 tons C ha-1) appears sensitive to the depth and duration of thaw, and climatic changes that promote thaw are likely to cause a net efflux of carbon dioxide from the site. 相似文献
28.
J Christensen-Dalsgaard W Dappen SV Ajukov ER Anderson HM Antia S Basu VA Baturin G Berthomieu B Chaboyer SM Chitre AN Cox P Demarque J Donatowicz WA Dziembowski M Gabriel DO Gough DB Guenther JA Guzik JW Harvey F Hill G Houdek CA Iglesias AG Kosovichev JW Leibacher P Morel CR Proffitt J Provost J Reiter EJ Rhodes FJ Rogers IW Roxburgh MJ Thompson RK Ulrich 《Science (New York, N.Y.)》1996,272(5266):1286-1292
Data from the Global Oscillation Network Group (GONG) project and other helioseismic experiments provide a test for models of stellar interiors and for the thermodynamic and radiative properties, on which the models depend, of matter under the extreme conditions found in the sun. Current models are in agreement with the helioseismic inferences, which suggests, for example, that the disagreement between the predicted and observed fluxes of neutrinos from the sun is not caused by errors in the models. However, the GONG data reveal subtle errors in the models, such as an excess in sound speed just beneath the convection zone. These discrepancies indicate effects that have so far not been correctly accounted for; for example, it is plausible that the sound-speed differences reflect weak mixing in stellar interiors, of potential importance to the overall evolution of stars and ultimately to estimates of the age of the galaxy based on stellar evolution calculations. 相似文献
29.
Waite JH Combi MR Ip WH Cravens TE McNutt RL Kasprzak W Yelle R Luhmann J Niemann H Gell D Magee B Fletcher G Lunine J Tseng WL 《Science (New York, N.Y.)》2006,311(5766):1419-1422
The Cassini spacecraft passed within 168.2 kilometers of the surface above the southern hemisphere at 19:55:22 universal time coordinated on 14 July 2005 during its closest approach to Enceladus. Before and after this time, a substantial atmospheric plume and coma were observed, detectable in the Ion and Neutral Mass Spectrometer (INMS) data set out to a distance of over 4000 kilometers from Enceladus. INMS data indicate that the atmospheric plume and coma are dominated by water, with significant amounts of carbon dioxide, an unidentified species with a mass-to-charge ratio of 28 daltons (either carbon monoxide or molecular nitrogen), and methane. Trace quantities (<1%) of acetylene and propane also appear to be present. Ammonia is present at a level that does not exceed 0.5%. The radial and angular distributions of the gas density near the closest approach, as well as other independent evidence, suggest a significant contribution to the plume from a source centered near the south polar cap, as distinct from a separately measured more uniform and possibly global source observed on the outbound leg of the flyby. 相似文献
30.
DO Gough AG Kosovichev J Toomre E Anderson HM Antia S Basu B Chaboyer SM Chitre J Christensen-Dalsgaard WA Dziembowski A Eff-Darwich JR Elliott PM Giles PR Goode JA Guzik JW Harvey F Hill JW Leibacher MJPFG Monteiro O Richard T Sekii H Shibahashi M Takata MJ Thompson S Vauclair SV Vorontsov 《Science (New York, N.Y.)》1996,272(5266):1296-1300
Global Oscillation Network Group data reveal that the internal structure of the sun can be well represented by a calibrated standard model. However, immediately beneath the convection zone and at the edge of the energy-generating core, the sound-speed variation is somewhat smoother in the sun than it is in the model. This could be a consequence of chemical inhomogeneity that is too severe in the model, perhaps owing to inaccurate modeling of gravitational settling or to neglected macroscopic motion that may be present in the sun. Accurate knowledge of the sun's structure enables inferences to be made about the physics that controls the sun; for example, through the opacity, the equation of state, or wave motion. Those inferences can then be used elsewhere in astrophysics. 相似文献