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31.
32.
Takuya Hasebe Shotaro Nishitsuji Takashi Inoue Sadayuki Kobayashi 《Journal of Macromolecular Science: Physics》2013,52(11):2061-2069
Dumbbell specimens of common plastics—polyethylene, polypropylene, and polyamide—were uniaxially stretched and the surface temperature was measured by thermography. The surface temperature decreased at small strain below the yield point and then increased at larger strain. The endothermic deformation in the elastic regime was unexpected. It might be a characteristic of polymer material, which is possessed of free volume. The endotherm is interpreted by the volume increment with stretching as represented by Poisson's ratio. The temperature rise at larger strain is not surprising for plastic deformation over the yield point. The exotherm is interpreted in terms of the melting of crystallites and re-crystallization induced by large deformation. 相似文献
33.
The feasibility of applying temporal reference holography to detection of moving acoustic radiation sources are examined theoretically and experimentally. Temporal reference holography is proved to be used for the purpose if the width of amplitude spectrum of sound is within a certain range, because the point spread functions of temporal reference hologram coincide with amplitude spectra of sound waves used for recording them. 相似文献
34.
In addition to conventional optical elements, mechanically flexible optical fibers of 17 μm in diameter are successfully used as coherent optical probes for vibration measurements based on optical heterodyne techniques. This means a feasibility of mechanically flexible setup for vibration measurements. 相似文献
35.
Naoki Kobayashi Erning Wihardjo Sadayuki Ueha Jumpei Tsujiuchi 《Optics Communications》1982,43(5):308-312
An experimental study is presented of quasi real-time measurements of small vibration and deformation by using phase difference amplification through high order diffraction of thermoplastic holograms. An optimum recording condition for obtaining high diffraction efficiency of high order diffraction is obtained and the sensitivity becomes three times that of the conventional method. 相似文献
36.
Combined standing and propagating wave modes have previously been successfully used by the authors for simultaneous agglomeration and transportation of small particles suspended in still water. The present study of this method with flowing water, using a 120 x 350 x 13 mm3 agglomerator, confirmed that the proposed method is applicable with suspended SiO2 particles of varying size. The process was found to be most efficient at flow rates below a certain threshold, which varies with particle size. This threshold was found to be 5 ml/s for a particle size of 7.9 microns at an ultrasonic frequency of 2 MHz corresponding to 0.74 mm wavelength. The existence of a maximum particle transport velocity was demonstrated. 相似文献
37.
Non-contact transportation using near-field acoustic levitation 总被引:1,自引:0,他引:1
Near-field acoustic levitation, where planar objects 10 kg in weight can levitate stably near the vibrating plate, is successfully applied both to non-contact transportation of objects and to a non-contact ultrasonic motor. Transporting apparatuses and an ultrasonic motor have been fabricated and their characteristics measured. The theory of near-field acoustic levitation both for a piston-like sound source and a flexural vibration source is also briefly described. 相似文献
38.
39.
Cook AR Sreearunothai P Asaoka S Miller JR 《The journal of physical chemistry. A》2011,115(42):11615-11623
Data showing significant time-resolution-limited "step" capture of electrons following radiolysis by 7 - 10 ps electron pulses in a series of different length and different concentration conjugated polyfluorene polymers in tetrahydrofuran (THF) are presented. At the highest concentration, ~48 mM in repeat units for lengths from 20 to 133 fluorenes, ~30% of the electrons formed during pulse radiolysis were captured in the step, with a constant efficiency per repeat unit. Step capture per repeat unit (q = 6.9 M(-1)) is 60% of the presolvated electron capture efficiency previously reported for biphenyl in THF, giving capture per polymer molecule 12-80 times larger than that for biphenyl at the same concentration. This increase in capture efficiency is large compared to the rate constant per repeat unit for diffusion-limited electron attachment to the same molecules, which is 13% of that of a single unit of fluorene. Plausible mechanisms of this fast capture are explored. It is shown that both capture of quasi-free and localized presolvated electrons can adequately explain the observations. The large yield of radical anions at low concentration of polyfluorene enables observation of subsequent chemistry on the picosecond time scale in these systems, which would otherwise been limited by diffusional attachment to the nanosecond regime. 相似文献
40.
In this paper, we present the transmission characteristics of a polyurea ultrasonic transducer operating in water. In this study, we used a polyurea transducer with fundamental resonance at approximately 30 MHz. Firstly, acoustic pressure radiated from the transducer was measured using a hydrophone, which has a diameter of 0.2 mm. The transmission characteristics such as relative bandwidth, pulse width, and acoustic sensitivity were calculated from the experimental results. The results of the experiment showed a relative bandwidth of 50% and a pulse width of 0.061 μs. The acoustic sensitivity was 0.60 kPa/V with good linearity, where the correlation coefficient R in the fitting calculation was 0.996. A maximum pressure of 13.1 kPa was observed when the transducer was excited at a zero-to-peak voltage of 21 V. Moreover, we experimentally verified the results. The results of the pulse/echo experiment showed that the estimated diameters of the copper wires were 458 and 726 μm, where the differences between the actual and measured values were 15% and 4%, respectively. Acoustic streaming was also observed so that a particle velocity map was estimated by particle image velocimetry (PIV). The sound pressure calculated from the particle velocity obtained by PIV showed good agreement with the acoustic pressure measured using the hydrophone, where the differences between the calculated and measured values were 12–19%. 相似文献