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481.
We develop a flexible discrete-time hedging methodology that minimizes the expected value of any desired penalty function of the hedging error within a general regime-switching framework. A numerical algorithm based on backward recursion allows for the sequential construction of an optimal hedging strategy. Numerical experiments comparing this and other methodologies show a relative expected penalty reduction ranging between 0.9% and 12.6% with respect to the best benchmark. 相似文献
482.
We demonstrate a position-sensing technique that relies on the inherent sensitivity of chaos, where we illuminate a subwavelength object with a complex structured radio-frequency field generated using wave chaos and nonlinear feedback. We operate the system in a quasiperiodic state and analyze changes in the frequency content of the scalar voltage signal in the feedback loop. This allows us to extract the object's position with a one-dimensional resolution of ~λ/10,000 and a two-dimensional resolution of ~λ/300, where λ is the shortest wavelength of the illuminating source. 相似文献
483.
Jean-Philippe Gauthier Sébastien Cauet Pascal Martin 《Journal of sound and vibration》2011,330(24):5785-5790
This article presents a real-life application for the extremal harmonic active control of power [1] applied on a hybrid engine setup. The active control was adapted for a hybrid powertrain constituted of a one-cylinder diesel engine coupled with a permanent magnet synchronous machine. The problem was formulated in the harmonic domain and the control objective was to extremalize energetic criterions. Three criterions were considered: minimizing the speed ripple of the engine, maximizing the mechanical reactive power (mechanical impedance adaptation) and maximizing the active electric power for energy harvesting. The results show that, for the first and second orders of the ripple, speed oscillations can be completely cancelled and reactive power and active power can be optimized on-line. The implicit extremal controller converged rapidly, remaining stable even when the mean engine speed changed abruptly. These results confirm the robustness and the applicability of the extremal harmonic active control for industrial applications. 相似文献
484.
R. Chaplin D. MacManus F. Leopold T. Gauthier B. Martinez T. Birch 《Experiments in fluids》2011,50(2):491-507
Aerodynamic interference between high-speed slender bodies can detrimentally affect the force and moment characteristics.
This is investigated through a wind tunnel study using pressure sensitive paint and force measurements on a receiver body
placed adjacent to a generator body. The aim of this paper is to understand both the force and moment changes as well as the
underlying aerodynamics of the interference loads which are induced by the disturbance flowfield. The impact of receiver incidence
and the strength of the disturbance field are also assessed. The observed interference loads primarily depend on a complex
balance of static pressure footprints and tend to be bespoke to each configuration. As a result, overall trends are difficult
to extract, but in general the magnitude of the interference loads increases when the receiver is at incidence and also when
the strength of the imposed disturbance flowfield increases. 相似文献
485.
Abstract Ultrasonic (70 W, 20 kHz) solution (2% THF) degradations of polystyrene (PS), poly(α-methylstyrene) (PαMeS), poly(p-isopropyl α-methylstyrene) (PpiPrαMeS), poly(p-chlorostyrene) (PpCIS), poly(p-bromostyrene) (PpBrS), and poly(p-methoxystyrene) (PpOMeS) have been carried out in tetrahydrofuran at 27° C. The average number of chain scissions S (where S = [(M n)0/(M n)t] - 1), computed from the overall values of [(M n)0 and (M n)t, were found to be different from those of S' (where S' = α([(M n)0/(M n)t] - 1)) based on the component (only that part of the polymer which is involved in degradation) data of the weight fraction (α), (M n)0, and (M n)t), S' for polystyrene and substituted polystyrene follows the order PS gt; PpCIS gt; PpiPrαMeS gt; PpBrS gt; PpOMeS gt; PαMeS. In the case of PS where degradations were also carried out at -20°C, lowering of the temperature increased the weight fraction of polymer degraded as well as S. Based on the viscosity and GPC data, it is concluded that the ultrasonic solution degradation of PS does not lead to branched polymers. 相似文献
486.
Sébastien Gauthier Nikolay Vologdin Sylvain Achelle Alberto Barsella Bertrand Caro Françoise Robin-le Guen 《Tetrahedron》2013
This paper presents the synthesis of a series of push–pull and quadrupolar π-conjugated structures incorporating pro-aromatic methylenepyran electron-donor groups and various electron-attracting groups. Some of the methylenepyran derivatives were oxidized by I2 to give, after reduction by Na2S2O3, bismethylenepyran compounds via successive steps. 相似文献
487.
Sound field reproduction has applications in music reproduction, spatial audio, sound environment reproduction, and experimental acoustics. Sound field reproduction can be used to artificially reproduce the spatial character of natural hearing. The objective is then to reproduce a sound field in a real reproduction environment. Wave field synthesis (WFS) is a known open-loop technology which assumes that the reproduction environment is anechoic. The room response thus reduces the quality of the physical sound field reproduction by WFS. In recent research papers, adaptive wave field synthesis (AWFS) was defined as a potential solution to compensate for these quality reductions from which WFS objective performance suffers. In this paper, AWFS is experimentally investigated as an active sound field reproduction system with a limited number of reproduction error sensors to compensate for the response of the listening environment. Two digital signal processing algorithms for AWFS are used for comparison purposes, one of which is based on independent radiation mode control. AWFS performed propagating sound field reproduction better than WFS in three tested reproduction spaces (hemianechoic chamber, standard laboratory space, and reverberation chamber). 相似文献
488.
489.
Lucie Blondeau Suzy Surble Eddy Foy Hicham Khodja Magali Gauthier 《Journal of Energy Chemistry》2021,(4):124-128
A composite In-Pb:carbon was successfully synthetized by a two-step mechanochemical synthesis in order to obtain an adequate particles size and structure to investigate the electrochemical reactivity of the In-Pb solid solution towards Mg.A potential synergetic coupling of electroactive elements In and Pb was examined using electrochemical and ex situ X-ray diffraction analyses.The potential profile of the solid solution indicates the formation of Mg2Pb and Mg In.However,the diffraction study suggests a peculiar electrochemically-driven amorphization of Mg In during the magnesiation,in strong contrast to Mg In crystallization in In-based and In Bi-based electrodes reported in the literature.Combining In and Pb favors the amorphization of Mg In and a high first magnesiation capacity of about 550 m Ah g-1,but is thereafter detrimental to the material’s reversibility.These results emphasize the possible influence of electrochemically-driven amorphization and crystallization processes on electrochemical performance of battery materials. 相似文献
490.
Xiaoxuan Yang Shreya Mukherjee Thomas O'Carroll Prof. Yang Hou Prof. Meenesh R. Singh Prof. Joseph A. Gauthier Prof. Gang Wu 《Angewandte Chemie (International ed. in English)》2023,62(10):e202215938
Unrestrained anthropogenic activities have severely disrupted the global natural nitrogen cycle, causing numerous energy and environmental issues. Electrocatalytic nitrogen transformation is a feasible and promising strategy for achieving a sustainable nitrogen economy. Synergistically combining multiple nitrogen reactions can realize efficient renewable energy storage and conversion, restore the global nitrogen balance, and remediate environmental crises. Here, we provide a unique aspect to discuss the intriguing nitrogen electrochemistry by linking three essential nitrogen-containing compounds (i.e., N2, NH3, and NO3−) and integrating four essential electrochemical reactions, i.e., the nitrogen reduction reaction (N2RR), nitrogen oxidation reaction (N2OR), nitrate reduction reaction (NO3RR), and ammonia oxidation reaction (NH3OR). This minireview also summarizes the acquired knowledge of rational catalyst design and underlying reaction mechanisms for these interlinked nitrogen reactions. We further underscore the associated clean energy technologies and a sustainable nitrogen-based economy. 相似文献