نتایج جستجو برای: population decrease

تعداد نتایج: 967835  

Journal: :Astronomy and Astrophysics 2023

Surveys of star-forming regions reveal that the dust mass protoplanetary discs decreases by several orders magnitude on a timescale few million years. This decrease in budget solids is likely due to gas-drag-induced radial drift mm-sized solids, called pebbles. However, quantifying evolution this component young stellar clusters difficult inherent large spread masses and formation times. Theref...

Journal: :محیط شناسی 0
منصور زیبایی آذر شیخ زین الدین

in this study an attempt has been made to empirically examine the relationship between biodiversity and economic growth using indicators of species diversity and income per capita as proxies for biodiversity and economic growth, respectively.also the effects of agricultural value added as a percentage of gdp, trade freedom index, exchange rate, population, percantage of land developed for agric...

Journal: :Proceedings of the Royal Society B: Biological Sciences 2014

Abstract Introduction: population aging refers to an age imbalance of the population so that the ratio of young population decreases while aged population grows. Decrease in fertility rate and growing life expectancy are the two key factors in emergence of population aging. The macro economy effects of population aging on economic growth was examined based on the effects of two factors includ...

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