中山什么原因引起肛瘘中山市肛肠需要多少钱,中山肛旁脓肿的治疗技术,中山拉血很多鲜红的血,中山为什么老是拉屎出血,中山痔疮 疼,中山屁眼有个大肉疙瘩,中山做一次肛门镜多少钱

BEIJING, July 27 (Xinhuanet) -- Amazon.com’s e-book reader Kindle 3G with special offers is now the company’s top-selling e-book device, according to media reports on Wednesday.Amazon revealed in its quarterly earnings report that the ad-supported version costs 139 U.S. dollars,  50 dollars cheaper than the comparable Kindle 3G, and costs the same as a Kindle with Wi-Fi connectivity. Many believe Kindle is the most popular dedicated e-book device on the market today.The advertisements will appear only in screensavers (which appear when the reader is in an idle state) and at the bottom of the home screen, so they don’t interrupt readers.“Since AT&T agreed to sponsor screensavers, Kindle 3G with Special Offers is now our bestselling Kindle device,” Amazon’s press release said.Having zoomed past the earlier Sony Reader, and kicked off a wave of competition including the Barnes & Noble Nook and the Kobo E-Reader, Kindle is believed the most popular dedicated e-book device on the market today.

BEIJING, Aug. 22 (Xinhuanet) -- U.S. presidential candidate Rick Perry's controversial stem-cell treatment may inspire desperate patients to follow his lead while causing medical and legal concerns, according to media reports Monday.The Texas governor underwent a procedure on July 1 where stem cells, made from fat taken from his body, were put into his bloodstream to see if they might find their way to fix a bad back.The treatment carries potential risks ranging from blood clots to infection to cancer and may even run afoul of federal rules, doctors say. File photo of U.S. Republican presidential candidate Texas Governor Rick Perry."As a highly influential person of power, Perry’s actions have the unfortunate potential to push desperate patients into the clinic of quacks,” Harvard’s stem cell expert George Daley told the Associated Press.Worries about the safety and wisdom of this treatment are widespread among stem cell researchers as such a treatment has not been thoroughly vetted by researchers or approved by the FDA.

BEIJING, Sept. 25 (Xinhua) -- As China's economy has soared to the second place in the world, the country's scientific strength has also surged -- if only measured by the numbers.Chinese researchers published more than 1.2 million papers from 2006 to 2010 -- second only to the United States but well ahead of Britain, Germany and Japan, according to data recently published by Elsevier, a leading international scientific publisher and data provider. This figure represents a 14 percent increase over the period from 2005 to 2009.The number of published academic papers in science and technology is often seen as a gauge of national scientific prowess.But these impressive numbers mask an uncomfortable fact: most of these papers are of low quality or have little impact. Citation per article (CPA) measures the quality and impact of papers. China's CPA is 1.47, the lowest figure among the top 20 publishing countries, according to Elsevier's Scopus citation database.China's CPA dropped from 1.72 for the period from 2005 to 2009, and is now below emerging countries such as India and Brazil. Among papers lead-authored by Chinese researchers, most citations were by domestic peers and, in many cases, were self-citations."While quantity is an important indicator because it gives a sense of scientific capacity and the overall level of scientific activity in any particular field, citations are the primary indicator of overall scientific impact," said Daniel Calto, Director of SciVal Solutions at Elsevier North America.Calto attributed China's low CPA to a "dilution effect.""When the rise in the number of publications is so rapid, as it has been in China -- increasing quantity does not necessarily imply an overall increase in quality," said Calto.He noted the same pattern in a variety of rapidly emerging research countries such as India, Brazil, and earlier in places like the Republic of Korea."Chinese researchers are too obsessed with SCI (Science Citation Index), churning out too many articles of low quality," said Mu Rongping, Director-General of the Institute of Policy and Management at the Chinese Academy of Sciences, China's major think tank.SCI is one of the databases used by Chinese researchers to look-up their citation performance. The alternative, Scopus, provides a wider coverage worldwide."Chinese researchers from a wide range of areas and institutions are vying for publication, as it is a key criterion for academic appraisal in China, if not the only one. As a result, the growth of quality pales in comparison to that of quantity," said Mu, an expert on China's national science policy and competitiveness.On the other hand, China also falls behind the United States in multidisciplinary research, which is a core engine for scientific advance and research excellence.From 2006 to 2010, China published 1,229,706 papers while the United States churned out 2,082,733. According to a new metric introduced by Elsevier's Spotlight research assessment solution, China generated 885 competencies while the United States had 1,817.In other words, China's total research output is more than half that of the United States, while the number of competencies showing China's strength in multidisciplinary research is less than half that of the United States.Cong Cao, an expert on China's science and technology, put it more bluntly in an article he wrote: "When the paper bubble bursts, which will happen sooner or later, one may find that the real situation of scientific research in China probably is not that rosy."China has been investing heavily in scientific research and technological development in recent years to strengthen its innovative capacity, The proportion of GDP spent on R&D grew from 0.9 percent in 2000 to 1.4 percent in 2007, according to the World Bank.An IMF forecast in 2010 says China now ranks second globally in R&D spending. The IMF calculates China's R&D expenditure at 150 billion U.S. dollars when based on Purchasing Power Parity, a widely used economic concept that attempts to equalize differences in standard of living among countries.By this measure, China surpassed Japan in R&D spending in 2010.Many see China's huge investment in R&D as the momentum behind the country's explosive increase in research papers."Getting published is, in some ways, an improvement over being unable to get published," Mu said. "But the problem is, if the papers continue to be of low quality for a long time, it will be a waste of resources."In China, academic papers play a central role in the academic appraisal system, which is closely related to degrees and job promotions.While acknowledging the importance of academic papers in research, Mu believes a more balanced appraisal system should be adopted. "This is a problem with science management. If we put too much focus on the quantity of research papers, we leave the job of appraisal to journal editors."In China, the avid pursuit of publishing sometimes gives rise to scientific fraud. In the most high-profile case in recent years, two lecturers from central China's Jinggangshan University were sacked in 2010 after a journal that published their work admitted 70 papers they wrote over two years had been falsified."This is one of the worst cases. These unethical people not only deceived people to further their academic reputations, they also led academic research on the wrong path, which is a waste of resources," Mu said.A study done by researchers at Wuhan University in 2010 says more than 100 million U.S. dollars changes hands in China every year for ghost-written academic papers. The market in buying and selling scientific papers has grown five-fold in the past three years.The study says Chinese academics and students often buy and sell scientific papers to swell publication lists and many of the purported authors never write the papers they sign. Some master's or doctoral students are making a living by churning out papers for others. Others mass-produce scientific papers in order to get monetary rewards from their institutions.A 2009 survey by the China Association for Science and Technology (CAST) of 30,078 people doing science-related work shows that nearly one-third of respondents attributed fraud to the current system that evaluates researchers' academic performance largely on the basis of how many papers they write and publish.Despite rampant fraud, China will continue to inject huge money into science. According to the latest national science guideline, which was issued in 2006 by the State Council, the investment in R&D will account for 2.5 percent of GDP in 2020."If China achieves its stated goal of investing 2.5 percent of its GDP in R&D in 2020, and sustains its very fast economic growth over the next decade, it would quite likely pass the U.S. in terms of total R&D investment sometime in the late 2010s," said Calto, adding that it is also quite likely that at some point China will churn out more papers than the United States.According to Calto, China does mostly applied research, which helps drive manufacturing and economic growth, while basic research only accounts for 6 percent, compared with about 35 percent in Germany, Britain, and the United States, and 16 percent in Japan."In the long term, in order to really achieve dominance in any scientific area, I think it will be necessary to put significant financial resources into fundamental basic research -- these are the theoretical areas that can drive the highest level of innovation," Calto said.

CANBERRA, Sept. 24 (Xinhua) -- Australian scientists on Saturday said a satellite due to re-enter Earth poses a negligible threat to life and property on Earth.U.S. National Aeronautics and Space Administration's Upper Atmosphere Research Satellite (UARS), which weighs more than five tons, is expected to re-enter the Earth's atmosphere at 1058 (AEST) on Saturday. The U.S.-based Center for Orbital and Re-entry Debris Studies estimates that re-entry could occur up to seven hours before or after this time.According to Nonathan Nally, a former editor of two space magazines and currently editor of the Australian Space News website, the satellite poses a negligible threat to life and property on Earth."Most of the satellite will burn up on re-entry, with perhaps as many as 26 stronger or harder small pieces surviving to reach the surface," Nally said in a statement."But with the majority of the Earth comprising oceans or uninhabited (or very sparsely populated) remote regions, the chances are overwhelming that any pieces of UARS that survive re- entry will fall harmlessly and never be seen again."Since the spacecraft is no longer powered, U.S. National Aeronautics and Space Administration has no control over where it comes down, but Nally said there is a small chance that debris from the satellite could land in Australia.Debris from SkyLab, another satellite which plunged to Earth, was scattered over parts of Western Australia in 1979. Skylab weighed about 77 tonnes, many times more than the UARS.?Dr Alice Gorman, a lecturer in the Department of Archaeology, specializing in space archaeology, at Flinders University in South Australia, said the UARS satellite re-entry is very reminiscent of Skylab in 1979."There is the same exaggeration of the hazard through the media, public anxiety as the advance warning allows for speculation, and a lack of understanding of what the risks actually are," he said in a statement."Should it land in Australia, we might expect the same rush for souvenirs as we saw with Skylab, as anything that has been in space has a special meaning on Earth."?UARS was launched on 12 September 1991 and decommissioned on 15 December 2005. Its total dry mass is about 5.5 tonnes. UARS is one of the largest NASA satellites to plunge back to Earth uncontrolled in the last 30 years.Since the beginning of the Space Age in the late-1950s, there have been no confirmed reports of an injury resulting from re- entering space objects.? Nor is there a record of significant property damage resulting from a satellite re-entry.

SAN FRANCISCO, July 15 (Xinhua) -- U.S. microblogging platform Twitter on Friday marked its fifth anniversary since public debut."Twitter, then called Twttr, opened to the public five years ago today," the company said in a Tweet, a short message within 140 characters users are allowed to communicate on the website."Twttr is a new mobile service that helps groups of friends bounce random thoughts around with SMS," co-founder Biz Stone described the service in a blog post on July 13, 2006, two days before its public debut."There were 224 Tweets sent on July 15, 2006. Today, users send that many Tweets in less than a tenth of a second," said the San Francisco-based company.Twitter said more than 600,000 new users signed up on Thursday while it took it more than 16 months to reach the first 600,000 Twitter accounts.The tipping point for the service's popularity was the 2007 South by Southwest festival, a set of film, interactive and music festivals and conferences that take place every March in Austin, Texas. During the event, the Tweets sent per day grew from 20,000 to 60,000.With an estimated user base of 200 million worldwide, some 200 million Tweets are generated and 1.6 billion search queries are handled every day, the company said.According to research firm EMarketer, advertising sales on Twitter is expected to reach 150 million U.S. dollars this year. SharesPost, a secondary market for privately held companies, has assessed Twitter's current worth at 6.8 billion dollars.