نتایج جستجو برای: 000 years of earth
تعداد نتایج: 21198985 فیلتر نتایج به سال:
The genus Flavivirus includes some of the most important human viral pathogens, and its members are found in all parts of the populated world. The temporal origin of diversification of the genus has long been debated due to the inherent problems with dating deep RNA virus evolution. A generally accepted hypothesis suggests that Flavivirus emerged within the last 10 000 years. However, it has be...
We employed Bayesian coalescent modeling of samples of mitochondrial control region sequences in two species of shorebird, Red Knots (Calidris canutus) and Dunlins (Calidris alpina) to estimate evolutionary effective population size, population divergence times, and time to most recent common ancestor of genes in the samples. The gene trees for the two species contrast sharply: knot haplotypes ...
Estimation of pathogen-specific causes of child diarrhea deaths is needed to guide vaccine development and other prevention strategies. We did a systematic review of articles published between 1990 and 2011 reporting at least one of 13 pathogens in children <5 years of age hospitalized with diarrhea. We included 2011 rotavirus data from the Rotavirus Surveillance Network coordinated by WHO. We ...
Abstract Located in the eastern section of ancient Silk Road, Hexi Corridor is a crucial area where and western civilizations met. Previous studies mainly explore human-nature interactions at particular period, there lack phased interaction long time scales. Here we present relationships patterns between humans nature region over past 10 000 years distinguish stages mechanisms interaction, whic...
BACKGROUND The 7-valent pneumococcal conjugate (PCV7) vaccine's impact on invasive pneumococcal disease (IPD) is well described, but few reports exist on the additional impact of the 13-valent vaccine (PCV13). METHODS We calculated the IPD incidence across all ages in a surveillance project following implementation of PCV7 (in September 2006) and PCV13 (in April 2010) in children aged <2 year...
در این پژوهش به منظور درک سن و محیط رسوبی سازند آسماری در برش کوه شجبیل، شمال غرب یاسوج به ضخامت 375 متر 171 نمونه برداشت گردیده است. سازند آسماری در برش مورد مطالعه با معیارهای سنگ شناختی به سه واحد مشخص تفکیک شده است. این واحد ها با داشتن شمای آهک های مسیو، ضخیم، متوسط و نازک لایه، آهک های نازک لایه ی مارنی و بعضاً مارن مشخص می گردد. در این برش تعداد 18 جنس و 29 گونه از فرامینیفرهای بنتیک شنا...
The catalytic reduction of carbon dioxide is of great interest for its potential as a hydrogen storage method and to use carbon dioxide as C-1 feedstock. In an effort to replace expensive noble metal-based catalysts with efficient and cheap earth-abundant counterparts, we report the first example of Mn(i)-catalysed hydrogenation of CO2 to HCOOH. The hydride Mn(i) catalyst [Mn(PNPNH-iPr)(H)(CO)2...
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