| 单词 | carbon 14 |
| 例句 | This method is based on the slow decay of radioactive carbon 14, a very minor component of carbon, the ubiquitous building block of life, into the nonradioactive isotope nitrogen 14. Guns, Germs, and Steel: The Fates of Human Societies 1997-03-01T00:00:00Z Today, nearly 40 years after those early dates for pottery in Japan were measured, archaeologists are still reeling from the carbon 14 shock, as it is termed. Guns, Germs, and Steel: The Fates of Human Societies 1997-03-01T00:00:00Z Hence the age of material from an archaeological site can be calculated from the material’s carbon 14/carbon 12 ratio. Guns, Germs, and Steel: The Fates of Human Societies 1997-03-01T00:00:00Z Trees with unusual spikes in carbon 14 can also indicate a Miyake event. Traces of Oldest and Largest Solar Storm Found in Buried French Forest 2023-10-19T04:00:00Z Her goal was to measure the amount of carbon 14—a radioactive isotope of carbon commonly used to date archaeological artifacts. Mystery of Ancient Space Superstorms Deepens 2023-03-06T05:00:00Z Only a fleeting fraction is radioactive carbon 14, also called radiocarbon. Vikings were in the Americas exactly 1,000 years ago 2021-10-21T04:00:00Z In the case of carbon, the solar activity can form carbon 14, which is absorbed by tree rings as they grow. Solar ‘Superflares’ Rocked Earth Less Than 10,000 Years Ago—and Could Strike Again 2021-09-13T04:00:00Z All living things absorb carbon 14, a radioactive carbon isotope that decays at a regular rate over time. Long-Awaited Update Arrives for Radiocarbon Dating 2020-09-11T04:00:00Z They found that both carbon 14 and beryllium 10 shot up at the same time. Traces of Oldest and Largest Solar Storm Found in Buried French Forest 2023-10-19T04:00:00Z Tipped off by earlier research suggesting a pronounced increase in atmospheric carbon 14 some time in the late eighth century, Miyake began examining individual tree rings dating from C.E. Mystery of Ancient Space Superstorms Deepens 2023-03-06T05:00:00Z They ruled out earlier and later Miyake events based on the carbon 14 to carbon 12 ratios measured in the wood, which vary in known ways over centuries. Vikings were in the Americas exactly 1,000 years ago 2021-10-21T04:00:00Z Poring through them for events such as carbon 14 spikes is time-consuming, however. Solar ‘Superflares’ Rocked Earth Less Than 10,000 Years Ago—and Could Strike Again 2021-09-13T04:00:00Z For human or animal remains and artifacts from the past 50,000 years or so, researchers look at levels of carbon 14 in the sample. How Do Scientists Determine the Ages of Human Ancestors, Fossilized Dinosaurs and Other Organisms? 2020-08-04T04:00:00Z At death, the carbon 14 in living creatures begins to decay. Oscars, Boris Nemtsov, Nokia: Your Monday Briefing 2017-02-27T05:00:00Z Miyake’s efforts paid off, however, when the data revealed an anomalously large increase in the concentration of carbon 14 precisely in the year C.E. Mystery of Ancient Space Superstorms Deepens 2023-03-06T05:00:00Z All living things absorb tiny amounts of the radioactive isotope carbon 14 during their lives but this process halts upon death. Dating dispute over 'oldest Koran' - BBC News 2016-02-08T05:00:00Z The researchers followed up with tree rings and saw a corresponding spike of carbon 14. Solar ‘Superflares’ Rocked Earth Less Than 10,000 Years Ago—and Could Strike Again 2021-09-13T04:00:00Z While alive, animals and plants tend to contain the same levels of carbon 14 as their environment. How Do Scientists Determine the Ages of Human Ancestors, Fossilized Dinosaurs and Other Organisms? 2020-08-04T04:00:00Z A coral collected from a certain reef in Hawaii in 1975, for example, would provide a marker of carbon 14 levels for that place and year. Old Nuclear Fallout Proves Useful for Sea Turtle Clues 2016-01-25T05:00:00Z The carbon dating, done by a lab in Florida, found that the logs Yunker uncovered were living trees in the 1950s because they contained extra carbon 14, released during thermo-nuclear bomb testing in that era. Washburn man believes have might have found Fort Mandan 2015-10-18T04:00:00Z They then calculated age and accumulation rates using carbon 14 dating. Carbon tomb buried deep under Chinese desert 2015-08-05T04:00:00Z Studying carbon 14 data in tree rings from this era, the team found another spike. Solar ‘Superflares’ Rocked Earth Less Than 10,000 Years Ago—and Could Strike Again 2021-09-13T04:00:00Z The amount of carbon 14 in a dead organism decays exponentially, falling to one half of its initial value after about 5,730 years. How Do Scientists Determine the Ages of Human Ancestors, Fossilized Dinosaurs and Other Organisms? 2020-08-04T04:00:00Z In the mid-20th century, the United States and several other countries began conducting open-air nuclear tests that significantly increased concentrations of carbon 14, a radioactive isotope, in the atmosphere. Old Nuclear Fallout Proves Useful for Sea Turtle Clues 2016-01-25T05:00:00Z The Nobel Committee cited him “for his method to use carbon 14 for age determination in archaeology, geology, geophysics and other branches of science.” Digging Up the Root of Carbon Dating 2015-04-20T04:00:00Z In this case, though, the FSU team used carbon 14 as an “inverse tracer” to find the oil. Yet More BP Oil Found at Bottom of Gulf 2015-02-04T05:00:00Z When it decays, however, carbon 14 releases an electron that creates a flash of light very similar to that of a pp neutrino. Strange Neutrinos from the Sun Detected for the First Time 2014-08-27T04:00:00Z The dating method takes advantage of unstable, radioactive carbon 14 atoms produced from the bombardment of the atmosphere by cosmic rays from outer space. Neanderthals in Europe Died Out Thousands of Years Sooner Than Some Thought, Study Says 2014-08-20T04:00:00Z When the U.S. and Soviet Union conducted nuclear bomb tests during the Cold War, the sparring nations doubled the amount of radioactive carbon 14 in Earth's atmosphere. How Nuclear Fallout Casts Doubt on Renewal of Some Adult Brain Cells 2012-06-07T16:15:02.790Z Radiocarbon dating depends on measuring the radioactive isotope of carbon known as carbon 14, which is ingested during a person’s lifetime and steadily decays after death. Neanderthals and Early Humans May Not Have Mingled Much 2011-05-09T20:41:24Z Their secret weapon, they wrote, was carbon 14, a radioactive isotope often used to date ancient artifacts. Yet More BP Oil Found at Bottom of Gulf 2015-02-04T05:00:00Z Once it is part of the battle rhythm, it has the persistence of carbon 14. Colonel kicked out of war for hating PowerPoint 2010-08-27T18:15:00Z But as soon as they die, they absorb no additional radioactive carbon, and the carbon 14 disappears over time. Neanderthals in Europe Died Out Thousands of Years Sooner Than Some Thought, Study Says 2014-08-20T04:00:00Z They were able to determine that he was born between 1955 and 1960 by looking at the carbon 14 in the victim's teeth. The Radioactive Clock In Your Teeth 2010-05-21T16:00:00Z With plastic cards yet to be invented, customers put cheques impregnated with carbon 14, a mildly radioactive substance, into the machine which paid out a maximum of £10. Inventor of the cash machine dies 2010-05-19T23:38:00Z It works this way: Oil doesn’t contain carbon 14, so any sediment that did contain the isotope would become evident in their search. Yet More BP Oil Found at Bottom of Gulf 2015-02-04T05:00:00Z The heat of combustion of hydrogen being 62,032 units, that of carbon 14,544 units, it follows that 4.265 times the weight of hydrogen will represent an equivalent amount of carbon. Scientific American Supplement, No. 441, June 14, 1884. This happens at low rates; there's about one carbon 14 for every trillion carbon 12s. The Radioactive Clock In Your Teeth 2010-05-21T16:00:00Z But cosmic rays streaming into our atmosphere occasionally smash into the abundant nitrogen in our atmosphere and create a form of carbon with two extra neutrons called carbon 14. The Radioactive Clock In Your Teeth 2010-05-21T16:00:00Z |
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