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51.
Stone R 《Science (New York, N.Y.)》1991,254(5034):929
52.
Stone R 《Science (New York, N.Y.)》2002,295(5556):777-779
53.
An overview of the Voyager 2 encounter with Uranus is presented, inclding a brief discussion of the trajectory and the planned observations as well as the highlights of the results described in the 11 companion papers. 相似文献
54.
Stone EC Cummings AC McDonald FB Heikkila BC Lal N Webber WR 《Science (New York, N.Y.)》2005,309(5743):2017-2020
Voyager 1 crossed the termination shock of the supersonic flow of the solar wind on 16 December 2004 at a distance of 94.01 astronomical units from the Sun, becoming the first spacecraft to begin exploring the heliosheath, the outermost layer of the heliosphere. The shock is a steady source of low-energy protons with an energy spectrum approximately E(-1.41 +/- 0.15) from 0.5 to approximately 3.5 megaelectron volts, consistent with a weak termination shock having a solar wind velocity jump ratio r=2.6(-0.2)(+0.4). However, in contradiction to many predictions, the intensity of anomalous cosmic ray (ACR) helium did not peak at the shock, indicating that the ACR source is not in the shock region local to Voyager 1. The intensities of approximately 10-megaelectron volt electrons, ACRs, and galactic cosmic rays have steadily increased since late 2004 as the effects of solar modulation have decreased. 相似文献
55.
56.
Self-incompatibility, the rejection of self pollen, is the most widespread mechanism by which flowering plants prevent inbreeding. In Brassica, the S receptor kinase (SRK) has been implicated in the self-incompatibility response, but the molecular mechanisms involving SRK are unknown. One putative downstream effector for SRK is ARC1, a protein that binds to the SRK kinase domain. Here it is shown that suppression of ARC1 messenger RNA levels in the self-incompatible Brassica napus W1 line is correlated with a partial breakdown of self-incompatibility, resulting in seed production. This provides strong evidence that ARC1 is a positive effector of the Brassica self-incompatibility response. 相似文献
57.
The local effects of isolated magnetic adatoms on the electronic properties of the surface of a superconductor were studied with a low-temperature scanning tunneling microscope. Tunneling spectra obtained near magnetic adsorbates reveal the presence of excitations within the superconductor's energy gap that can be detected over a few atomic diameters around the impurity at the surface. These excitations are locally asymmetric with respect to tunneling of electrons and holes. A model calculation based on the Bogoliubov-de Gennes equations can be used to understand the details of the local tunneling spectra. 相似文献
58.
DR Link G Natale R Shao JE Maclennan NA Clark E Korblova DM Walba 《Science (New York, N.Y.)》1997,278(5345):1924-1927
A smectic liquid-crystal phase made from achiral molecules with bent cores was found to have fluid layers that exhibit two spontaneous symmetry-breaking instabilities: polar molecular orientational ordering about the layer normal and molecular tilt. These instabilities combine to form a chiral layer structure with a handedness that depends on the sign of the tilt. The bulk states are either antiferroelectric-racemic, with the layer polar direction and handedness alternating in sign from layer to layer, or antiferroelectric-chiral, which is of uniform layer handedness. Both states exhibit an electric field-induced transition from antiferroelectric to ferroelectric. 相似文献
59.
PM Lundquist R Wortmann C Geletneky RJ Twieg M Jurich VY Lee CR Moylan DM Burland 《Science (New York, N.Y.)》1996,274(5290):1182-1185
The performance of amorphous organic photorefractive (PR) materials in applications such as optical data storage is generally limited by the concentration of active molecules (chromophores) that can be incorporated into the host without forming a crystalline material with poor optical quality. In polymeric PR systems described previously, performance has been limited by the necessity of devoting a large fraction of the material to inert polymer and plasticizing components in order to ensure compositional stability. A new class of organic PR materials composed of multifunctional glass-forming organic chromophores is described that have long-term stability and greatly improved PR properties. 相似文献
60.
Stone R 《Science (New York, N.Y.)》2011,331(6024):1507