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941.
To estimate nutrient budgets,water samples were collected at 16 sites in Tapong lagoon from January 2004 through April 2005 and the parameters of water quality were analyzed immediately after collection.These data were used to build a box model for calculating nutrient budgets of the lagoon.We estimated the net amount of nutrient fluxes into (coming from creeks) and out (from tidal inlet) of the lagoon and calculated the total amount of nutrient that deposits into the sediment in a full tidal cycle.During J... 相似文献
942.
台湾可持续能源发展指标建构与耦合性分析 总被引:1,自引:0,他引:1
为应对全球气候变迁之冲击,以及迈向低碳社会,推动可持续能源发展,已成为本世纪各国政府施政的重点.依据国际可持续能源指标架构,建立"台湾可持续能源指标系统",并以Eview计量软件进行指标项目与架构之"单根"(unit root)、"共整合"(integration)、与"因果"(causality)检定,并据此建构的长期稳定关系与各方面耦合性(coupling)的可持续能源发展指标"压力-状态-响应"(Pressure,State,Response,PSR)架构系统.回顾了台湾近18年(1990-2007)来可持续能源发展绩效,获得结论如下:1)台湾能源发展已朝向可持续性,其中以环境保护方面绩效最佳,而能源安全与经济竞争力仍需改善;2)整体指标架构的状态与响应指标耦合度相当高,惟压力指标则呈现脱钩(decoupling)现象;3)权重模拟分析发现,适当调整权重,可以大幅提高经济竞争力与环境保障方面指标耦合性,显示权重具敏感性;惟能源安全指标方面的权重较不具敏感性. 相似文献
943.
944.
Global analysis of protein phosphorylation in yeast 总被引:1,自引:0,他引:1
945.
Guojiang?WanEmail author Wei?Yang Wang?Shilu Enyuan?Wan Fengchang?Wu S.?N.?Lee Changsheng?Wang Ronggui?Huang 《科学通报(英文版)》2005,50(16):1751-1756
A better understanding of the variation of 210Pb concentrations in the surface air is the key to trace lake sedimentation and catchment erosion, to establish and validate
the global diffusion model of contaminants, and to assess the impact of natural radiation on the ecological system. Basing
on the study progresses of the sedimentation, the atmospheric model and the unique environmental background in the Yunnan-Guizhou
Plateau, and starting from December 20, 2001, we made use of a 500 NE Type aerosol sampler to collect filter samples, once
a week in the past consecutive two years, in the surface air at Mt. Guanfeng, Guiyang City, China. Synchronous detailed γ-energy spectrometric observations of 210Pb concentrations at both Chinese and U.S. laboratories have shown that the average monthly 210Pb concentration displays a regular U-patterns distribution of annual variations, with high values appearing in winter and
low values in late spring and summer. The average annual 210Pb concentrations are estimated to be 2.77±0.63 mBq/m3, about 4 times the average maximum concentrations reported from quite a number of monitoring stations throughout the world.
The possible factors affecting the sources of 210Pb in the surface air in the central part of Guizhou Province are: Release of 222Rn from the U-Ra series enriched in the soils; chemical weathering of carbonate rocks; the exploitation, processing and utilization
of coal and phosphorous resources. The principal factor controlling the high 210Pb concentrations in the surface air in the central Guizhou and their annual U-pattern distribution is the release of 222Rn. The average monthly 210Pb concentrations show a good negative powerfunction relationship with increasing precipitation and also show a good negative
linear-function relationship with the rise of air temperature in month grouping. Group No.1 (June to November) reflects a
relatively low release of 222Rn from soils in relatively high temperature seasons; Group No.2 (December to May) mirrors a relatively high release of 222Rn from soils in relatively low temperature seasons. The average monthly 210Pb concentrations simulated in terms of the precipitation and air temperature are in good consistency with the measured values,
revealing that the regular U-pattern distribution characteristics of 210Pb concentrations in the surface air in the central Guizhou are controlled predominantly by regional precipitation and air
temperature. Meanwhile, it is also indicated that the magnitude of variation of air temperature and precipitation within the
same year also constrains the ratio of high values over low values of average monthly 210Pb concentrations. On a month time scale, precipitation and air temperature are a main factor affecting the release of 222Rn from soils (rocks). In this aspect strong evidence has been obtained. 相似文献
946.
Vassylyev DG Sekine S Laptenko O Lee J Vassylyeva MN Borukhov S Yokoyama S 《Nature》2002,417(6890):712-719
947.
Hole DG Whittingham MJ Bradbury RB Anderson GQ Lee PL Wilson JD Krebs JR 《Nature》2002,418(6901):931-932
House-sparrow populations have declined sharply in Western Europe in recent decades, but the reasons for this decline have yet to be identified, despite intense public interest in the matter. Here we use a combination of field experimentation, genetic analysis and demographic data to show that a reduction in winter food supply caused by agricultural intensification is probably the principal explanation for the widespread local extinctions of rural house-sparrow populations in southern England. We show that farmland populations exhibit fine-level genetic structuring and that some populations are unable to sustain themselves (sinks), whereas others act as sources. 相似文献
948.
The breast cancer susceptibility protein BRCA2 controls the function of RAD51, a recombinase enzyme, in pathways for DNA repair by homologous recombination. We report here the structure of a complex between an evolutionarily conserved sequence in BRCA2 (the BRC repeat) and the RecA-homology domain of RAD51. The BRC repeat mimics a motif in RAD51 that serves as an interface for oligomerization between individual RAD51 monomers, thus enabling BRCA2 to control the assembly of the RAD51 nucleoprotein filament, which is essential for strand-pairing reactions during DNA recombination. The RAD51 oligomerization motif is highly conserved among RecA-like recombinases, highlighting a common evolutionary origin for the mechanism of nucleoprotein filament formation, mirrored in the BRC repeat. Cancer-associated mutations that affect the BRC repeat disrupt its predicted interaction with RAD51, yielding structural insight into mechanisms for cancer susceptibility. 相似文献
949.
Zusammenfassung Nachweis der Absorption von Aflatoxin B1 durch die Rattenhaut. Die toxische Leberwirkung nach der Hautbepinselung entsprach den von anderen Autoren gefundenen Verhältnissen bei peroraler oder intraperitonealer Verabreichung. 相似文献
950.