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The ultrashort intense laserplasma interaction has been a rapidly evolving field for last decade known as highfield physics among many other research frontiers.…… 《中国科学基金(英文版)》2007,15(2):16-17
The ultrashort intense laserplasma interaction has been a rapidly evolving field for last decade, known as highfield physics among many other research frontiers. 相似文献
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Alexander V. Kolobov a) onleavefromA .F .IoffePhysico TechnicalInstitute StPetersburg Russia 《中国科学技术大学学报》2001,31(3):282-288
Thelatticemismatchbetweenthesubstrateandtheovergrownlayerallowstheformationofself as sembledquantumdots (QDs)throughtheStranski Krastanovmechanism[1,2 ] .Thistechniquehasbeensuccessfullyappliedtovarioussemiconductorsystems,andinparticulartoGe/Siquantumdots(Q… 相似文献
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基于模拟退火遗传算法的电液伺服马达超低速性能 总被引:1,自引:0,他引:1
针对电液伺服马达超低速运行时局部爬行及振荡现象,分析了密闭工作容腔内流量及压力的连续特性,采用了自适应改进模拟退火遗传算法,对马达超低速性能结构进行寻优解算,得出马达定子预过渡曲线及其包角范围和配油三角缓冲槽理论公式及最佳尺寸.通过仿真及实验研究,结果表明,该方法可以将遗传算法全局规划能力与模拟退火法局部优化特性进行有效结合,并具有良好的邻域特性和初值鲁棒性,其优化结果能够保证新型连续回转电液伺服马达跟踪0.001 °/s超低速斜坡信号和满足0.001 °的公差带要求. 相似文献
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采用有限元法研究用于视神经视觉假体铂铱合金微电极阵列的电场分布情况,在单极和双极电流刺激条件下,分析不同长度微电极的空间电场分布,通过在体动物实验验证了铂铱合金微电极阵列在体工作的有效性.结果表明,经过100μA的单极和双极电流刺激后,铂铱合金电极的最大电场强度均发生在电极材料和绝缘材料的交界处.以电场强度最大点为原点,单极和双极电流刺激的有效半径分别约为21和24μm. 相似文献
128.
低渗储层的流体渗流具有明显的非达西渗流特性,在试油过程中,即使地层没有受到污染,流体也需要克服一定的阻力之后才能开始流动。因此,对于低渗油气藏的试油,不仅准确求取产能难度大,而且获取稳定的地层压力和储层参数更是十分困难。通过有针对性的测试工艺技术研究,采用合理分配测试时间方案、积极推广分层跨隔测试技术、利用测试技术进行压裂效果评价等,圆满地解决了低渗透储层试油测试中获取资料困难的问题。 相似文献
129.
Welsh WF Orosz JA Carter JA Fabrycky DC Ford EB Lissauer JJ Prša A Quinn SN Ragozzine D Short DR Torres G Winn JN Doyle LR Barclay T Batalha N Bloemen S Brugamyer E Buchhave LA Caldwell C Caldwell DA Christiansen JL Ciardi DR Cochran WD Endl M Fortney JJ Gautier TN Gilliland RL Haas MR Hall JR Holman MJ Howard AW Howell SB Isaacson H Jenkins JM Klaus TC Latham DW Li J Marcy GW Mazeh T Quintana EV Robertson P Shporer A Steffen JH Windmiller G Koch DG Borucki WJ 《Nature》2012,481(7382):475-479
Most Sun-like stars in the Galaxy reside in gravitationally bound pairs of stars (binaries). Although long anticipated, the existence of a 'circumbinary planet' orbiting such a pair of normal stars was not definitively established until the discovery of the planet transiting (that is, passing in front of) Kepler-16. Questions remained, however, about the prevalence of circumbinary planets and their range of orbital and physical properties. Here we report two additional transiting circumbinary planets: Kepler-34 (AB)b and Kepler-35 (AB)b, referred to here as Kepler-34 b and Kepler-35 b, respectively. Each is a low-density gas-giant planet on an orbit closely aligned with that of its parent stars. Kepler-34 b orbits two Sun-like stars every 289?days, whereas Kepler-35 b orbits a pair of smaller stars (89% and 81% of the Sun's mass) every 131?days. The planets experience large multi-periodic variations in incident stellar radiation arising from the orbital motion of the stars. The observed rate of circumbinary planets in our sample implies that more than ~1% of close binary stars have giant planets in nearly coplanar orbits, yielding a Galactic population of at least several million. 相似文献
130.
Beck PG Montalban J Kallinger T De Ridder J Aerts C García RA Hekker S Dupret MA Mosser B Eggenberger P Stello D Elsworth Y Frandsen S Carrier F Hillen M Gruberbauer M Christensen-Dalsgaard J Miglio A Valentini M Bedding TR Kjeldsen H Girouard FR Hall JR Ibrahim KA 《Nature》2012,481(7379):55-57
When the core hydrogen is exhausted during stellar evolution, the central region of a star contracts and the outer envelope expands and cools, giving rise to a red giant. Convection takes place over much of the star's radius. Conservation of angular momentum requires that the cores of these stars rotate faster than their envelopes; indirect evidence supports this. Information about the angular-momentum distribution is inaccessible to direct observations, but it can be extracted from the effect of rotation on oscillation modes that probe the stellar interior. Here we report an increasing rotation rate from the surface of the star to the stellar core in the interiors of red giants, obtained using the rotational frequency splitting of recently detected 'mixed modes'. By comparison with theoretical stellar models, we conclude that the core must rotate at least ten times faster than the surface. This observational result confirms the theoretical prediction of a steep gradient in the rotation profile towards the deep stellar interior. 相似文献