نتایج جستجو برای: کربن 14

تعداد نتایج: 368965  

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2017
Xinxin Zuo Houyuan Lu Leping Jiang Jianping Zhang Xiaoyan Yang Xiujia Huan Keyang He Can Wang Naiqin Wu

Phytolith remains of rice (Oryza sativa L.) recovered from the Shangshan site in the Lower Yangtze of China have previously been recognized as the earliest examples of rice cultivation. However, because of the poor preservation of macroplant fossils, many radiocarbon dates were derived from undifferentiated organic materials in pottery sherds. These materials remain a source of debate because o...

2008

Very soon after the discovery of radioactivity, measurements of the heavy radioactive elements existing in nature were undertaken to determine the age of rocks (Rutherford 1904), but only when Professor Willard Libby in an evening lecture during the first United Nations Conference on the Peaceful Uses of Atomic Energy in Geneva in 1955 described how he and his research team had evolved the carb...

2014
Hideyuki Takahashi Naoko Adachi Toshihiko Shirafuji Sally Danno Takehiko Ueyama Michele Vendruscolo Anton N. Shuvaev Takuya Sugimoto Takahiro Seki Daizo Hamada Kazuhiro Irie Hirokazu Hirai Norio Sakai Naoaki Saito

Biosignal Research Center, Kobe University, Kobe 657-8501, Japan, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK, Department of Neurophysiology, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan, Department of C...

Journal: :Science 2001
G Siani M Paterne E Michel R Sulpizio A Sbrana M Arnold G Haddad

Sea surface reservoir ages must be known to establish a common chronological framework for marine, continental, and cryospheric paleoproxies, and are crucial for understanding ocean-continent climatic relationships and the paleoventilation of the ocean. Radiocarbon dates of planktonic foraminifera and tephra contemporaneously deposited over Mediterranean marine and terrestrial regions reveal th...

Journal: :Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association 2010
Myriam Coulet Jean-Charles Leblanc R Woodrow Setzer

Sudan I is generally considered mutagenic based on various in vitro and in vivo tests and is carcinogenic in the rat. Dose-response modelling of the data for hepatocellular adenomas in male rats gave a BMDL(10) of 7.3mg/kg-bw/day. Sudan I is an unauthorised substance that might be present in food intermittently. The great variability and uncertainties in the human exposure data which are countr...

ژورنال: :نشریه حفاظت منابع آب و خاک (علمی - پژوهشی) 2013
سیده محبوبه موسوی فرد حمید رضا ممتاز حبیب خداوردیلو

طراحی و اجرای برنامه های حفاظت خاک نیازمند پهنه بندی دقیق و بهینه ویژگی های خاک است. از جمله عوامل بسیار موثر در پهنه بندی ویژگی های خاک، روش درون یابی کاربردی است. هدف از این پژوهش، ارزیابی کارایی شماری از روش های رایج درون یابی به منظور تخمین و پهنه بندی برخی ویژگی های کیفی خاک سطحی شامل درصد رس، هدایت الکتریکی، درصد کربنات کلسیم معادل و کربن آلی در اراضی زراعی منطقه نقده واقع در استان آذربای...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شهید باهنر کرمان 1390

در این تحقیق سنتز آزمایشگاهی کربن فعال به روش فیزیکی در راکتور دوار با استفاده از گازهای اکسید کننده دی اکسید کربن و بخار آ ب از پوست سخت پسته به عنوان ماده اولیه مورد بررسی قرار گرفت اثر سه پارامتر دمای فعالسازی،زمان ماندودبی گاز اکسید کننده بر روی عددیدی و burn-offبا استفاده از طراحی آزمایش به روش ccd مورد بررسی قرار گرفت. این پارامتر ها دردو سطح بالا وپایین که به ترتیب برای دمای فعالسازی،زما...

Journal: :The Biochemical journal 1974
I H White J Jeffery

Kinetic measurements were made with cortisone reductase (20-dihydrocortisone-NAD(+) oxidoreductase, EC 1.1.1.53) and a series of substrates which differed in shape, size and electronic character in the region adjacent to C-11, C-14 and C-18. Structural changes at C-11 in these substrates resulted in up to 660-fold changes in the apparent K(m) value, up to 200-fold changes in the apparent V(max....

Journal: :Science 2009
Vasilii V Petrenko Andrew M Smith Edward J Brook Dave Lowe Katja Riedel Gordon Brailsford Quan Hua Hinrich Schaefer Niels Reeh Ray F Weiss David Etheridge Jeffrey P Severinghaus

The cause of a large increase of atmospheric methane concentration during the Younger Dryas-Preboreal abrupt climatic transition (approximately 11,600 years ago) has been the subject of much debate. The carbon-14 (14C) content of methane (14CH4) should distinguish between wetland and clathrate contributions to this increase. We present measurements of 14CH4 in glacial ice, targeting this transi...

2013
Walter E. Brown

Although this paper is self-contained, it logically follows our discussion, begun several years ago in N1706 and continued in N1891, of a feature oft-requested for C++: an opaque typedef , sometimes termed a strong typedef . The earlier of those works was presented to WG21 on 2004-10-20 during the Redmond meeting, and the later work was presented during the Berlin meeting on 2005-04-06. Both pr...

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