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排序方式: 共有136条查询结果,搜索用时 15 毫秒
11.
《Surface Science Reports》2023,78(2):100596
Molecular switching has established itself as a key functionality of building blocks developed for addressable materials and surfaces over the last two decades. Many challenges in their use and characterisation have been presented by the wide variation in interfaces studied, these ranging from truly single-molecule devices to two-dimensional self-assembled monolayers and thin films that bridge the gap between surface and macroscopically bulk materials (polymers, MOFs, COFs), and further still to other interfaces (solid–liquid, liquid–air, etc.). The low number density of molecules on monolayer-coated interfaces as well as in thin films, for example, presents substantial challenges in the characterisation of the composition of modified interfaces. The switching of molecular structure with external stimuli such as light and electrode potential adds a further layer of complexity in the characterisation of function. Such characterisation “in action” is necessary to correlate macroscopic phenomena with changes in molecular structure. In this review, key classes of molecular switches that have been applied frequently to interfaces will be discussed in the context of the techniques and approaches used for their operando characterisation. In particular, we will address issues surrounding the non-innocence of otherwise information-rich techniques and show how model – non-switching – compounds are often helpful in confirming and understanding the limitations and quirks of specific techniques. 相似文献
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In this article, we develop a rigorous mathematical foundation of microscopic motors. The main characteristic is the combination of Brownian and Poisson noises. 相似文献
14.
Es wurde eine unter Betriebsverhältnissen anwendbare Prüfmethode für die Bestimmung der Verschleβeigenschaften von Verbrennungsmotoren mit Hilfe der Gammaspektrometrie der neutronenaktivierten Verschleiβprodukte ausgearbeitet und die die Lebensdauer begrenzende Wirkung des abrasiven Verschleiβes festgestellt. Durch Verbesserung der Luftfilterung konnte die potentielle Lebensdauer der Motoren gut angenähert, und es konnten die Verunreinigung des Schmieröls vermindert und die Dauer der Ölwechselperiode verdoppelt werden. 相似文献
15.
E. Weźranowski A. Kalicki A. Lutze-Birk S. Myczkowski 《Isotopes in environmental and health studies》2013,49(4):155-156
Es wurde eine X-X-Fluoreszensmethode (mit einer 30-mCi-238 Pu-Anregungsquelle und einem Proportionalzähler) zur Bestimmung von eisenhaltigen Verschleiβteilchen in Schmierölen für Schiffsmotoren erarbeitet. Die Methode ermöglicht eine schnelle Abschātzung des Verschleiβes von Miotorteilen. Die Empfindlichkeit der Methode beträgt ca. 0,005% Fe, der mittlere Fehler (nach dem Student-Test bei einer Zuverlässigkeit von 0,95) ca. ±5%. 相似文献
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The present paper investigates optimization rules and new design methodologies dealing with the contact mechanics in rotative travelling wave ultrasonic motors (TWUM). The proposed approaches focus on the design of the rotor, including the friction layer that is usually deposited onto its lower surface, while the stator is supposed to be preliminary designed. Contact aspects such as the transmission of mechanical power as well as the wear mechanism of the friction layer are investigated, according to the analysis of the stator–rotor contact mechanics in both hoop and radial directions. Considering a classical wear criterion in a preliminary step, a contact ratio, that allows the mechanical power to be optimized, is pointed out in the hoop direction. In a further step, the contact conditions in the radial direction are improved through the elastic fitting of the stator and rotor radial deflexions, therefore allowing the material's wear to be decreased. Some experimental tests, that have been recently performed, give a comparison of wear marks, which occur onto optimal and non-optimal rotor geometries. A first mechanism synthesis is finally proposed in such a way to allow the mechanical architecture of the rotor (including the friction layer) to be automatically designed according to a given set of mechanical constraints. 相似文献
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Chengtao Chen Zhengqing He Jie Wu Xueqing Zhang Qianfeng Xia Huangxian Ju 《化学:亚洲杂志》2019,14(14):2491-2496
Microshells are attractive in constructing bubble‐propelled micromotors due to the lower energy consumption for bubbles forming on a concave surface. In this work, enzyme‐powered microshell motors were fabricated on multimetallic (Au/Ag/Au) microshells along with the modification of catalase on its concave surface. The catalase triggered the decomposition of hydrogen peroxide to oxygen gas, hence propelling the autonomous motion of microshell motors. A size‐dependent motion behaviour was observed for the microshell motors in the form of slow tremble and fast translation motion for a size smaller and larger than 5 μm, respectively, according to the size, generation efficiency and ejection mechanism of bubbles and the intensity of Brownian motion. In addition, the effect of fuel concentration on the motion speed of microshells was dependent on whether the bubble generation was affected by the limited mass transfer in the microshell space. These findings play an important role for the design of microshell motors. 相似文献
20.
F. Ziebert M. Vershinin S. P. Gross I. S. Aranson 《The European physical journal. E, Soft matter》2009,28(4):401-409
We study the alignment of polar biofilaments, such as microtubules and actin, subject to the action of multiple molecular
motors attached simultaneously to more than one filament. Focusing on a paradigm model of only two filaments interacting with
multiple motors, we were able to investigate in detail the alignment dynamics. While almost no alignment occurs in the case
of a single motor, the filaments become rapidly aligned due to the collective action of the motors. Our analysis shows that
the alignment time is governed by the number of bound motors and the magnitude of the motors’ stepping fluctuations. We predict
that the time scale of alignment is in the order of seconds, much faster than that reported for passive crosslink-induced
bundling. In vitro experiments on the alignment of microtubules by multiple-motor covered beads are in qualitative agreement. We also discuss
another mode of fast alignment of filaments, namely the cooperation between motors and passive crosslinks. 相似文献