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491.
通过估计中国农村居民收入分配的lorenz曲线测算了2006、2007年中国农村贫困和收入不平等的状况,并运用shapley分解法对贫困指数的变动进行分解,分析物价水平、经济增长、收入分配对贫困变化的影响。研究结果表明:(1)2007年农村贫困发生率较2006年有所下降,但下降速度比较缓慢;(2)农村居民的收入差距逐渐在拉大,收入不平等程度有所加重;(3)经济增长减缓了农村贫困,但由于物价水平的上涨和收入分配的恶化,贫困人口整体的贫困状况不轻反重。 相似文献
492.
《Limnologica》2016
We elucidate the ecology of Recent Ostracoda from a deep brackish lake, Tangra Yumco (30°45′—31°22′N and 86°23′—86°49′E, 4595 m a.s.l.) and adjacent waters on the southern Tibetan Plateau. Ostracod associations (living and empty valves) in sixty-six sediment samples collected from diverse aquatic habitats (lakes, estuary-like water and lagoon-like water waters, rivers, ponds and springs) were quantitatively assessed.Eleven Recent Ostracoda were found (nine living and two as empty valves only). Cluster analysis established two significant (p < 0.05) habitat specific associations; (i) Leucocytherella sinensis, Limnocythere inopinata, Leucocythere? dorsotuberosa, Fabaeformiscandona gyirongensis and Candona xizangensis are lacustrine fauna. (ii) Tonnacypris gyirongensis, Candona candida, Ilyocypris sp., Heterocypris incongruens and Heterocypris salina are temporary water species.Ostracod distribution and abundance are significantly (p < 0.05) correlated to physico-chemical variables. The first two axes of a canonical correspondence analysis (CCA) explain 30.9% of the variation in the species abundance data. Conductivity and habitat types are the most influential ecological factors explaining the presence and abundance of ostracods. Spearman correlation analysis reveals that: (i) Two species, L.? dorsotuberosa (r = 0.25) and L. inopinata (r = 0.36) have a significant positive correlation with conductivity while one species, T. gyirongensis (r = −0.68) displays a significant negative correlation with conductivity. Limnocythere inopinata correlates significantly positive (r = 0.37) with alkalinity. Fabaeformiscandona gyirongensis correlates significantly positive (r = 0.28) with water depth.Key indicator living assemblages are: (i) L. sinensis dominates Ca-depleted brackish waters although ubiquitously distributed; (ii) L.? dorsotuberosa dwells in fresh to brackish waters; (iii) L. inopinata predominates in mesohaline to polyhaline waters; (iv) F. gyirongensis inhabits exclusively brackish-lacustrine deeper waters; (v) C. candida populates freshwaters; (vi) T. gyirongensis and Ilyocypris sp. are restricted to shallow temporary waters; (vii) H. incongruens occurs in ponds.Water depth indicators are F. gyirongensis and L.? dorsotuberosa, useful in ostracod assemblages for palaeo-water depth reconstruction.Our results expand the knowledge of the ecological significance of Recent Tibetan Ostracoda ecology. This is a new insight on habitat chacteristics of both living assemblages and sub-Recent associations of ostracods in mountain aquatic ecosystems. The new modern ostracod dataset can be used for the quantitative reconstruction of past environmental variables (e.g., conductivity) and types of water environment. The key indicator ostracods are relevant in palaeolimnological and climate research on the Tibetan Plateau. 相似文献
493.
Dušan Plut 《GeoJournal》2000,52(2):149-155
The state of the environment and environmental pressures in the EU Member States (EU15) and the Accession Countries (AC10) is discussed from the prospective of ecosystems and geopolitics. In the EU15, the reduction of the most acute kinds of pollution began in the 1970s, and at the beginning of the 1990s, an overall environmental development action program was made, aimed at sustainability. In the AC10, the state of the environment slightly improved in the 1990s, particularly thanks to the decline of industrial production and a general slump. Typical of the EU15 and the AC10 is the consumption of natural resources at an above-average level per inhabitant of the globe. The starting position in the EU15 with regard to a sustainable development is considerably more favourable than in the AC10.However, the EU15 are only in the phase of weak sustainability, with the emphasis laid on curative measures for eliminating some consequences of environmental pressures. To achieve the environmental and other goals of sustainable development of Europe and the planet, it is necessary to establish a strategic partnership on the basis of the equality of all European countries, to reduce radically the environmental pressures and consumption of natural resources per inhabitant, and to integrate the ecological principles into sectoral policies. The period of two-speed Europe should be as short as possible. 相似文献
494.
We have worked out a ’statistical algorithm’ for obtaining the posterior probability density of the deceleration parameter
q0 from quasars where there is a luminosity indicator available. We point out that the role of the luminosity indicator is to
provide asecond estimate of individual luminosities after a first estimate has been obtained from measured brightness and redshift together
with an assumed q0. Discrimination of q0 is to be sought in the statistical properties of the set of differences between the two estimates (the residuals). We show
that the variance of the residuals and their correlation with redshifts (further refined to luminosity distances) are two
independent test-statistics for q0, whose known distributions then lead to the probability density sought.
We have applied the above algorithm to a sample of flat-spectrum radio quasars with measured CIV, MgII and Ly α lines. A combined
Baldwin’s relation was used for all 3 lines. Our result is that log q0 is normally distributed with a mean value of + 0.270± 0.135 (s.d.), or, q0
= + 1.86 ± 0.135 dex. This result, we believe, is the sharpest result so far published on q0. 相似文献
495.
496.
497.
Neolithic site sections, natural sections and other proxy indicators like paleotrees and peat are collected for further understanding the environmental changes during the past 10,000 years in the Yangtze Delta region. The results indicate that cultural interruption in the Yangtze Delta was the result of water expansion induced by climatic changes like more precipitation. For fragile human mitigation to the natural hazards in the Neolithic cultural period, environmental changes usually exerted tremendous influences on human activities, havocking the human civilization, which is meaningful for human mitigation to natural hazards under the present global warming. At the same time, some uncertainties in reconstruction of paleo-environmental changes were discussed in the text. 相似文献
498.
以福建省永安市为例,探讨南方山区以集体林为主的县域森林可持续经营标准与指标,旨在为相类似区域森林可持续经营标准与指标研究提供借鉴。在借鉴国内外森林可持续经营标准与指标的基础上,根据南方山区县域和森林经营单位水平森林可持续经营的要求,从森林可持续经营的保障条件、森林资源状态、森林生态系统健康、森林生产、生物多样性、土壤和水及经济、社会和文化方面等七个方面,构建福建省永安市森林可持续经营标准与指标。 相似文献
499.
V. A. Parovyshny O. V. Veselov V. N. Senachin V. S. Kirienko 《Russian Journal of Pacific Geology》2008,2(4):283-293
Results of repeated geophysical observations above the Yuzhno-Lugovskoye gas field (southern Sakhalin) carried out from 2003 to 2006 are considered. It is shown that the gas field is a natural indicator of geodynamic processes occurring in the gas field and beyond it. A complex of methods and observations is offered to estimate the degree of productivity of the objects involved in prospecting drilling. They provide further development of the short-term forecast of seismic events by geophysical methods, because seismic pulses propagating from an external source cause sharp changes of the geophysical fields above the gas-containing structure. 相似文献
500.
Cyclic terpenoids of contemporary resinous plant detritus and of fossil woods, ambers and coals 总被引:3,自引:0,他引:3
Bernd R.T. Simoneit J.O. Grimalt T.G. Wang R.E. Cox P.G. Hatcher A. Nissenbaum 《Organic Geochemistry》1986,10(4-6)
Cyclic terpenoids present in the solvent extractable material of fossil woods, ambers and brown coals have been analyzed. The sample series chosen consisted of wood remains preserved in Holocene to Jurassic sediments and a set of of ambers from the Philippines (copalite), Israel, Canada and Dominican Republic. The brown coals selected were from the Fortuna Garsdorf Mine and Miocene formations on Fiji.The fossil wood extracts contained dominant diterpenoid or sesquiterpenoid skeletons, and aromatized species were present at high concentrations, with a major amount of two-ring aromatic compounds. Tricyclic diterpenoids were the predominant compounds in the ambers. Aromatized derivatives were the major components, consisting of one or two aromatic ring species with the abietane and occasionally pimarane skeletons. The saturated structures were comprised primarily of the abietane and pimarane skeletons having from three to five carbon (C1, C2, etc.) substituents. Kaurane and phyllocladane isomers were present in only minor amounts. Bicyclic sesquiterpenoids as saturated and partial or fully aromatized forms were also common in these samples, but only traces of sesterterpenoids and triterpenoid derivatives were found.The brown coal extracts were composed of major amounts of one- and two-ring aromatized terpenoids, with a greater proportion of triterpenoid derivatives than in the case of the woods and ambers. This was especially noticeable for the German coal, where the triterpenoids were predominant. Open C-ring aromatized structures were also present in this coal. Steroid compounds were not detectable, but some hopanes were found as minor components in the German brown coal.An overview of the skeletal structure classes identified in each sample, as well as the general mass spectrometric characteristics of the unknown compounds are included in the present paper. It can be concluded from these structural distributions that aromatization is the main process for the transformation of terrestrial cyclic terpenoids during diagenesis, constituting a general pathway for all terpenoids. 相似文献