郑州眼科医生免费咨询郑州近视眼手术的价格,郑州近视能不能当兵,郑州高度近视是指多少度,郑州近视激光手术疼吗,郑州近视眼激光手术好还是,郑州郑州眼科附属医院,郑州全飞秒 手术

BEIJING, Sept. 14 (Xinhuanet) -- Scientists had discovered the fossils of a new species of ancient carnivorous fish, National Geographic reported Monday.The newly-found ancient fish, "Laccognathus embryi", is a 1.8-meter-long predator, which was "waiting to lunge out to grab whatever was in front of it," said study co-author Ted Daeschler, a vertebrate zoologist at the Academy of Natural Sciences in Philadelphia, the U.S..It had a jaw filled with sharp teeth that were 1.5 inches long, the Journal of Vertebrate Paleontology described.The fish lived in the Devonian period, 415 to 360 million years ago, which "was a fish-eats-fish kind of world," Daeschler said. "There was a real arms race going. If you didn't have good armor on your body, you were very vulnerable.""It's not just finding the animal - it's also placing the animal in its evolutionary crucible," Daeschler added.Its closest living relative is the lungfish which can survive in the drought, scientists said.Scientists hope the finding can help in their study on the revolution of fishes as well as other species.

BEIJING, Sept. 6 (Xinhuanet) -- The amount of space junks floating in Earth's orbit has reached a critical level, warned scientists.The future space missions may become too dangerous to fly for a risk of colliding with space junks, said a report released recently by the U.S. National Research Council (NRC).The kinds of space junks range from huge, the report said, there are thousands of discarded satellites and rocket boosters and countless tiny pieces of daily gabages from space missions.The debris are traveling in orbit at 17,500mph, at such a speed even a tiny clash can destroy a spacecraft.The NRC recommended that NASA should launch a plan to clean up the floating debris and called on other major space nations' cooperation."The current space environment is growing increasingly hazardous to spacecraft and astronauts," said Kessler, an ex-NASA researcher, "NASA needs to determine the best path forward for tackling the multifaceted problems caused by meteoroids and orbital debris that put human and robotic space operations at risk."

SAN FRANCISCO, Aug. 15 (Xinhua) -- Facebook and Yahoo on Monday started to test "six degrees of separation," an iconic social experiment in the 1960s that showed everyone is on average approximately six steps away from any other person on earth.The current Facebook-Yahoo "small world" experiment, based on more than 750 million active Facebook users, is expected to determine the social path length between two strangers.Anyone with a Facebook account can participate by going to smallworld.sandbox.yahoo.com and will be assigned a "target person. " The participant will be asked to select one of his or her Facebook friends, whom will be forwarded a message and then pass the message from friend to friend so that the participant will get a message to the "target person" in as few steps as possible.The study is intended as academic social research and will be published in peer-reviews scientific journal, Duncan Watts, Yahoo' s principal research scientist who is leading the experiment, told San Jose Mercury News.In the 1960s, American social psychologist Stanley Milgram and other researchers conducted several experiments to examine the average path length for social networks of people in the United States, suggesting that human society is a small world type network by around 5.5 people steps or about six people on average.It is now currently accepted that there were potential flaws in the so-called "small world experiment" because the conclusions were based on relatively small number of research samples.

URUMQI, Sept. 5 (Xinhua) -- The first China-Eurasia Expo that concluded Monday in Urumqi, capital of northwest China's Xinjiang Uygur Autonomous Region, has clinched trade and technical cooperation contracts worth about 130 billion U.S. dollars, expo organizer said.Among all contracts, 5.5 billion dollars are clinched between Chinese and foreign companies, while 124 billion dollars are among Chinese companies, the organizer said.About 50,000 officials and business people from China and about 30 countries, regions and international organizations attended the trade fair, which also attracted an audience of more than 300,000 people.The event was upgraded from the 19-year-old China Urumqi Foreign Economic Relations and Trade Fair, a regional trade fair, last year.The fair covered an area of nearly 80,000 square meters for its more than 4,000 exhibition booths, according to the organizer.