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The Cascadia subduction zone is thought to be capable of generating major earthquakes with moment magnitude as large as M(w) = 9 at an interval of several hundred years. The seismogenic portion of the plate interface is mostly offshore and is currently locked, as inferred from geodetic data. However, episodic surface displacements-in the direction opposite to the long-term deformation motions caused by relative plate convergence across a locked interface-are observed about every 14 months with an unusual tremor-like seismic signature. Here we show that these tremors are distributed over a depth range exceeding 40 km within a limited horizontal band. Many occurred within or close to the strong seismic reflectors above the plate interface where local earthquakes are absent, suggesting that the seismogenic process for tremors is fluid-related. The observed depth range implies that tremors could be associated with the variation of stress field induced by a transient slip along the deeper portion of the Cascadia interface or, alternatively, that episodic slip is more diffuse than originally suggested. 相似文献
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Genomics: massively parallel sequencing 总被引:1,自引:0,他引:1
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Event-horizon-scale structure in the supermassive black hole candidate at the Galactic Centre 总被引:1,自引:0,他引:1
Doeleman SS Weintroub J Rogers AE Plambeck R Freund R Tilanus RP Friberg P Ziurys LM Moran JM Corey B Young KH Smythe DL Titus M Marrone DP Cappallo RJ Bock DC Bower GC Chamberlin R Davis GR Krichbaum TP Lamb J Maness H Niell AE Roy A Strittmatter P Werthimer D Whitney AR Woody D 《Nature》2008,455(7209):78-80
The cores of most galaxies are thought to harbour supermassive black holes, which power galactic nuclei by converting the gravitational energy of accreting matter into radiation. Sagittarius A* (Sgr A*), the compact source of radio, infrared and X-ray emission at the centre of the Milky Way, is the closest example of this phenomenon, with an estimated black hole mass that is 4,000,000 times that of the Sun. A long-standing astronomical goal is to resolve structures in the innermost accretion flow surrounding Sgr A*, where strong gravitational fields will distort the appearance of radiation emitted near the black hole. Radio observations at wavelengths of 3.5 mm and 7 mm have detected intrinsic structure in Sgr A*, but the spatial resolution of observations at these wavelengths is limited by interstellar scattering. Here we report observations at a wavelength of 1.3 mm that set a size of 37(+16)(-10) microarcseconds on the intrinsic diameter of Sgr A*. This is less than the expected apparent size of the event horizon of the presumed black hole, suggesting that the bulk of Sgr A* emission may not be centred on the black hole, but arises in the surrounding accretion flow. 相似文献
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L. J. Rogers J. V. Zappia S. P. Bullock 《Cellular and molecular life sciences : CMLS》1985,41(11):1447-1449
Summary Asymmetry of eye function has been demonstrated in the young chicken. Precocious copulation following intramuscular treatment with testosterone can be elicited by presentation of an appropriate stimulus to the left eye, but not to the right eye. 相似文献
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Initial sequencing and comparative analysis of the mouse genome 总被引:2,自引:0,他引:2
Mouse Genome Sequencing Consortium Waterston RH Lindblad-Toh K Birney E Rogers J Abril JF Agarwal P Agarwala R Ainscough R Alexandersson M An P Antonarakis SE Attwood J Baertsch R Bailey J Barlow K Beck S Berry E Birren B Bloom T Bork P Botcherby M Bray N Brent MR Brown DG Brown SD Bult C Burton J Butler J Campbell RD Carninci P Cawley S Chiaromonte F Chinwalla AT Church DM Clamp M Clee C Collins FS Cook LL Copley RR Coulson A Couronne O Cuff J Curwen V Cutts T Daly M David R Davies J 《Nature》2002,420(6915):520-562
The sequence of the mouse genome is a key informational tool for understanding the contents of the human genome and a key experimental tool for biomedical research. Here, we report the results of an international collaboration to produce a high-quality draft sequence of the mouse genome. We also present an initial comparative analysis of the mouse and human genomes, describing some of the insights that can be gleaned from the two sequences. We discuss topics including the analysis of the evolutionary forces shaping the size, structure and sequence of the genomes; the conservation of large-scale synteny across most of the genomes; the much lower extent of sequence orthology covering less than half of the genomes; the proportions of the genomes under selection; the number of protein-coding genes; the expansion of gene families related to reproduction and immunity; the evolution of proteins; and the identification of intraspecies polymorphism. 相似文献
20.
Mary Anne Rogers 《西北部美国博物学家》2011,51(2)
Geographic and nongeographic variation in morphology was examined in Thomomys townsendii . A univariate analysis of external and cranial characters from a large population sample (66 adults; fusion of cranial sutures used as aging criteria) was used to assess variation among three adult age classes and between sexes. Only minor variation is apparent among age classes; however, sexual dimorphism is pronounced. Univariate and multivariate techniques were used to analyze external and cranial measurements and pelage characters for adults throughout the species range. These analyses show little to support the seven subspecific designations recognized by Davis (1937). The general pattern is one of homogeneity throughout the range of Thomomys townsendii . With the possible exception of T. t. nevadensis samples, current subspecies are not defined as morphological units. In fact, differentiation is found among populations within some subspecies. The most apparent pattern seen in these analyses is the divergence between the Humboldt River (including Honey Lake Valley samples) and Snake River systems. These results will be considered with those of a companion paper on the genetic variation in this species to more adequately assess the patterns of differentiation in Thomomys townsendii . 相似文献