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1.
The seeding of an expanse of surface waters in the equatorial Pacific Ocean with low concentrations of dissolved iron triggered a massive phytoplankton bloom which consumed large quantities of carbon dioxide and nitrate that these microscopic plants cannot fully utilize under natural conditions. These and other observations provide unequivocal support for the hypothesis that phytoplankton growth in this oceanic region is limited by iron bioavailability.  相似文献   
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For about 20 years Richard P. Erwin collected amphibians and reptiles in southwestern Idaho. This report is an attempt to indicate some of his herpetological activities, and to list the numerous individuals, universities, and museums that were recipients of his collections.  相似文献   
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In this report emphasis is placed on the dorsal skull characters of the genus Spea and the three species, bombifrons , hammondii , and intermontana . Spea hammondii is a polytypic species with at least three subspecies, hammondii , multiplicatus , and stagnalis , each of which is described and the distribution indicated. Drawings and photographs of skulls are provided for each species, with hammondii and intermontana receiving special consideration.  相似文献   
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Ghez AM  Morris M  Becklin EE  Tanner A  Kremenek T 《Nature》2000,407(6802):349-351
Recent measurements of the velocities of stars near the centre of the Milky Way have provided the strongest evidence for the presence of a supermassive black hole in a galaxy, but the observational uncertainties poorly constrain many of the black hole's properties. Determining the accelerations of stars in their orbits around the centre provides much more precise information about the position and mass of the black hole. Here we report measurements of the accelerations of three stars located approximately 0.005 pc (projected on the sky) from the central radio source Sagittarius A* (Sgr A*); these accelerations are comparable to those experienced by the Earth as it orbits the Sun. These data increase the inferred minimum mass density in the central region of the Galaxy by an order of magnitude relative to previous results, and localize the dark mass to within 0.05 +/- 0.04 arcsec of the nominal position of Sgr A*. In addition, the orbital period of one of the observed stars could be as short as 15 years, allowing us the opportunity in the near future to observe an entire period.  相似文献   
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Miloderes allredi, from Utah, and M. tingi, from California, are described as new to science.  相似文献   
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A general survey of the information presently available on the osteology and myology of the hyobranchial apparatus. Included in the survey are examples of the hyobranchial skeleton of the major groups of reptiles, including the Chelonia, Crocodilia, Rhynchocephalia, and Squamata. The myology treats the muscles directly associated with the hyoid as well as those associated with the functioning of the apparatus, but not arising or inserted directly on or from the hyoid. The innervation of the hyobranchial apparatus is reviewed and briefly discussed based on the information available in a few major studies. An attempt is made to cite all pertinent literature references, and in Tables 1 and 2 the references to basic areas are indicated. Twenty - nine plates and figures are included, some of which represent original research.  相似文献   
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Miloderes allredi, from Utah, and M. tingi, from California, are described as new to science.  相似文献   
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Reproduction in L. pyromelana infralabialis Tanner is reported. Eggs were measured and weighed and incubation time and hatching reported. Hatchlings were measured and weighed, and feeding was observed.  相似文献   
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