江西膝关节模型(湖南颈椎后路手术实训仿真人体) (今日更新中)

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.

WASHINGTON, Aug. 4 (Xinhua) -- Researchers have found a way to turn mouse embryonic stem cells into sperm and this finding opens up new avenues for infertility research and treatment, according to a study published Thursday in the online edition of journal Cell,A Kyoto University team coaxed mouse embryonic stem cells into sperm precursors, called primordial germ cells (PGCs), and shown that these cells can give rise to healthy sperm. The researchers say that such in vitro reconstitution of germ cell development represents one of the most fundamental challenges in biology.When transplanted into mice that were unable to produce sperm normally, the stem cell derived PGCs produced normal-looking sperm, which were then used to successfully fertilize eggs. These fertilized eggs, when transplanted into a recipient mother, produced healthy offspring that grew into fertile male and female adult mice. The same procedure could produce fertile offspring from induced pluripotent stem cells that are often derived from adult skin cells."Continued investigations aimed at in vitro reconstitution of germ cell development, including the induction of female primordial germ cell-like cells and their descendants, will be crucial for a more comprehensive understanding of germ cell biology in general, as well as for the advancement of reproductive technology and medicine," the researchers wrote.

MOSCOW, Sept. 13 (Xinhua) -- Russian federal space agency -- Roscosmos -- has announced that it would launch four more spacecraft in the forthcoming four months, including two Soyus manned spacecraft to the International Space Station (ISS).In accordance with the work schedule of Roscosmos, two cargo spaceships -- of the "Progress" type -- will be launched on Oct.30, 2011 and on Jan.26, 2012, while the two manned spacecraft will be blast off on Nov.12 and Dec.20.Roscosmos said on Tuesday it had been conducting consultations with NASA over updated plans of the upcoming expeditions to the ISS.According to Roscosmos, the new launch schedule has been drafted on the basis of an investigation into an abortive launch of a cargo spaceship on Aug. 24, when the Progress M-12M cargo spaceship failed to reach the orbit due to a rocket malfunction. Russia announced on the same day to delay its future launches of manned spaceship to ISS.After the retirement of the U.S. space shuttle fleet, Russia's Soyuz spacecraft has become the only way for astronauts to reach the ISS until at least the middle of this decade.

LOS ANGELES, June 5 (Xinhua) -- A latest study has found no evidence that screening for ovarian cancer may reduce the risk of dying from the disease, it was reported on Sunday.Screening, however, does increase the likelihood of unnecessary invasive procedures, according to researchers at the University of Utah.The researchers presented their findings at an on-going meeting of the American Society of Clinical Oncology in Chicago, The Los Angeles Times said.Researchers studied 78,216 women, ages 55 to 74, who participated in the National Cancer Institute's Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Half of the women received the usual care from their OB-gyns, and half received a CA 125 screening every year for six years and an ultrasound every year for four years. They were then followed for a maximum of 12 years.The researchers observed 212 ovarian cancers in the screened group and 176 in the normal care group. There were 118 ovarian cancer deaths in the screened group and 100 in the normal care group. The differences were not statistically significant. Overall, there were 2,924 deaths from all causes in the screened group and 2,914 in the normal care group.But the researchers also observed that 3,285 women had false- positive diagnoses from the screening. Among those, 1,080 underwent surgery that included an oophorectomy (surgical removal of one or both ovaries). Fifteen percent of those who had surgery developed major complications as a result. Overall, 1,771 women in the screened group (7.7 percent) had an oophorectomy, compared with 1,304 in the normal care group (5.8 percent)."We conclude that annual screening for ovarian cancer ... does not reduce disease-specific mortality in women at average risk for ovarian cancer but does increase invasive medical procedures and associated harms," the researchers said in the study.New data presented at the meeting also showed that the widely used cancer drug Avastin can improve treatment of ovarian cancer, The Times said.About 21,880 American women are diagnosed with ovarian cancer each year and about 13,850 die from it, according to the American Cancer Society. Because it produces few symptoms, the disease is typically not diagnosed until it has become advanced and spread throughout the body. As a result, five-year survival is only about 30 percent, and the disease is one of the five most deadly cancers among women. Being able to detect the cancer at an earlier stage when it might be more curable could thus, theoretically, improve the survival rate.The tests most commonly used to detect ovarian cancer include a transvaginal ultrasound to look for tumor masses and a blood test that screens for increased levels of a tumor marker called CA 125.

VIENNA, Sept. 22 (Xinhua) -- Climate change and rising temperature in the long term can lead to water shortages in the Alps region, international experts warned Thursday at the Water-Scarce Final Conference in the Austrian eastern city Graz.The Alpine region originally is rich in water resources due to a large number of glaciers, spring and abundant rainfall either in summer or winter. But global warming may change this situation which has been shown in the past years that the water reserve has reduced gradually due to climate change, warned the experts.Observation data have shown a significant decrease of 25 percent in groundwater recharge in the past 100 years which has also resulted in the reduction of mountain spring.Director of the Provincial Department of Water Resources of Styria Johann Wiedner point out, in 2003, droughts occurred in the eastern part of the Alps, including the state of Styria and water shortages were also found in other regions of the Alps. He said the phenomenon was giving a warning that people "have to do something."To this end, the European Union begun a project called "Alp Water Scarce" three years ago to observe water reserves, air temperature, water temperature and water table in this region and study the relationships among them.Wiedner also admitted that there is no shortage of water at least in the short term and water supply for the local residents is totally insured.

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