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Früh-Green GL Kelley DS Bernasconi SM Karson JA Ludwig KA Butterfield DA Boschi C Proskurowski G 《Science (New York, N.Y.)》2003,301(5632):495-498
Strontium, carbon, and oxygen isotope data and radiocarbon ages document at least 30,000 years of hydrothermal activity driven by serpentinization reactions at Lost City. Serpentinization beneath this off-axis field is estimated to occur at a minimum rate of 1.2 x 10(-4) cubic kilometers per year. The access of seawater to relatively cool, fresh peridotite, coupled with faulting, volumetric expansion, and mass wasting processes, are crucial to sustain such systems. The amount of heat produced by serpentinization of peridotite massifs, typical of slow and ultraslow spreading environments, has the potential to drive Lost City-type systems for hundreds of thousands, possibly millions, of years. 相似文献
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Histocompatibility antigens on murine tumors 总被引:11,自引:0,他引:11
Recent advances in tumor immunology suggest that the expression of the histocompatibility antigens, encoded by the major histocompatibility complex, is important in controlling the metastatic growth of certain murine tumors. The anomalous expression of histocompatibility antigens in many neoplasms appears to be associated with the ability of these cells to evade the immune system and progress to metastasis. This review examines some of the underlying molecular and immunobiological interactions that might determine the metastatic outcome of cellular transformation. 相似文献
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Wahlen M Tanaka N Henry R Deck B Zeglen J Vogel JS Southon J Shemesh A Fairbanks R Broecker W 《Science (New York, N.Y.)》1989,245(4915):286-290
Measurements of carbon-14 in small samples of methane from major biogenic sources, from biomass burning, and in "clean air" samples from both the Northern and Southern hemispheres reveal that methane from ruminants contains contemporary carbon, whereas that from wetlands, pat bogs, rice fields, and tundra is somewhat, depleted in carbon-14. Atmospheric (14)GH(4) seems to have increased from 1986 to 1987, and levels at the end of 1987 were 123.3 +/- 0.8 percent modern carbon (pMC) in the Northern Hemisphere and 120.0 +/- 0.7 pMC in the Southern Hemisphere. Model calculations of source partitioning based on the carbon-14 data, CH(4) concentrations, and delta(13)C in CH(4) indicate that 21 +/- 3% of atmospheric CH(4) was derived from fossil carbon at the end of 1987. The data also indicate that pressurized water reactors are an increasingly important source of (14)CH(4). 相似文献
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Vogel KS Klesse LJ Velasco-Miguel S Meyers K Rushing EJ Parada LF 《Science (New York, N.Y.)》1999,286(5447):2176-2179
Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder characterized by increased incidence of benign and malignant tumors of neural crest origin. Mutations that activate the protooncogene ras, such as loss of Nf1, cooperate with inactivating mutations at the p53 tumor suppressor gene during malignant transformation. One hundred percent of mice harboring null Nf1 and p53 alleles in cis synergize to develop soft tissue sarcomas between 3 and 7 months of age. These sarcomas exhibit loss of heterozygosity at both gene loci and express phenotypic traits characteristic of neural crest derivatives and human NF1 malignancies. 相似文献
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Vogel G 《Science (New York, N.Y.)》2000,288(5474):2119-2120
BOULDER, COLORADO--Nearly 600 scientists gathered at the base of the Flatirons to discuss the growth and patterning of organisms including plants, worms, fruit flies, fish, and mice at the 59th annual meeting of the Society for Developmental Biology. Among the highlights were clues about how blind cave fish lost their eyes and how a gene that influences cell movement might help cancer spread. 相似文献
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