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61.
62.
Shofner WP Whitmer WM Yost WA 《The Journal of the Acoustical Society of America》2005,118(5):3187-3197
Behavioral responses obtained from chinchillas trained to discriminate a cosine-phase harmonic tone complex from wideband noise indicate that the perception of 'pitch' strength in chinchillas is largely influenced by periodicity information in the stimulus envelope. The perception of 'pitch' strength was examined in chinchillas in a stimulus generalization paradigm after animals had been retrained to discriminate infinitely iterated rippled noise from wideband noise. Retrained chinchillas gave larger behavioral responses to test stimuli having strong fine structure periodicity, but weak envelope periodicity. That is, chinchillas learn to use the information in the fine structure and consequently, their perception of 'pitch' strength is altered. Behavioral responses to rippled noises having similar periodicity strengths, but large spectral differences were also tested. Responses to these rippled noises were similar, suggesting a temporal analysis can be used to account for the behavior. Animals were then retested using the cosine-phase harmonic tone complex as the expected signal stimulus. Generalization gradients returned to those obtained originally in the na?ve condition, suggesting that chinchillas do not remain "fine structure listeners," but rather revert back to being "envelope listeners" when the periodicity strength in the envelope of the expected stimulus is high. 相似文献
63.
Patterson RD Yost WA Handel S Datta AJ 《The Journal of the Acoustical Society of America》2000,107(3):1578-1588
Iterated rippled noise (IRN) is constructed by delaying a random noise by d ms, adding it back to the same noise, and repeating the process iteratively. When two IRNs with the same power but slightly different delays are added together, the perceptual tone/noise ratio of the "merged" IRN is markedly reduced with respect to that of either of the component IRNs. In this paper, the reduction in the perceptual tone/noise ratio is measured for IRNs in which one of the delays is always 16 ms and the other is either 16 +/- 0.1 ms or 16 +/- 1.1 ms. The component IRNs have the same number of iterations, and the number varies across conditions from 4 to 256. The perceptual tone/noise ratio is measured using a discrimination matching procedure developed for single IRNs; each merged IRN is compared with a range of "standard" stimuli having varying proportions of a complex tone and a broadband noise [Patterson et al., J. Acoust. Soc. Am. 100, 3286-3294 (1996)]. For single IRNs, the function relating the signal-to-noise ratio of the matching standard to the number of iterations in the IRN was found to be essentially straight. This relationship was explained in terms of the height of the first peak in the autocorrelation of the stimulus wave, or by the first peak in the summary autocorrelogram produced by a time-domain auditory model. For the merged IRNs in the current experiment, the matching-point functions are found to have pronounced downward curvature, in addition to being well below the function for single IRNs. To account for the reduction in the perceptual tone/noise ratio of merged IRNs, the autocorrelation model was extended to include a simple rule for combining adjacent peaks in the autocorrelation function of the wave, and the autocorrelogram model was revised to improve the simulation of the "loss of phase locking" at higher frequencies in the autocorrelogram. 相似文献
64.
W A Yost 《The Journal of the Acoustical Society of America》1978,63(4):1166-1175
A random-interval pulse train or wide-band noise when delayed (tau) and added back to itself (cos+) produces a stimulus with a consinusoidally varying (or trippled) power spectrum. The spacing between the peaks in the spectrum is equal to the reciprocal of the delay (1/tau). If the stimulus is delayed and added back at 180 degrees phase reversal (cos-), then a cosinusoidally varying power spectrum is generated whose spectral peaks are separated by 1/tau, but whose peaks are displaced by 1/2tau relative to the power spectrum of the cos+ stimulus generated with the same day, tau. These stimuli yield a pitch, such that the pitch of the cos+ stimulus is equal to approximately 1/tau and the pitches of the cos- stimuli are equal to approximately 0.9/tau and 1.1/tau. These pitch matching results were studied using a variety of matching stimuli and conditions. Following the identification of the pitches, a method of limits and a same-different procedure were used to study the pitch discriminability of both the cos+ and cos- stimuli. Delays (tau) ranging from 1 to 10 ms were studied covering a pitch range of 90-1100 Hz. The pitch discriminations associated with the cos+ and cos- stimuli were essentially the same for both the random-interval pulse train and the wide-band stimuli. These pitch-discrimination results are compared to those associated with a periodic pulse train. The research is also discussed in terms of discriminations of delayed sounds in reverberant environments. These are consistent with assumptions concerning the autocorrelation of the rippled stimuli within the dominant frequency region for pitch perception. 相似文献
65.
66.
The φ meson productions in Au+Au and/or Pb+Pb collisions at AGS, SPS,
RHIC, and LHC energies have been studied systematically with a hadron and
string cascade model LUCIAE. After considering the energy dependence of the
model parameter α in string fragmentation function and adjusting it
to the experimental data of charged multiplicity to a certain extent,
the model predictions for φ meson yield, rapidity, and
transverse mass distributions are compatible with the experimental data at
AGS, SPS and RHIC energies. A calculation for Pb+Pb collisions at LHC energy
is given as well. The obtained fractional variable in string fragmentation
function shows a saturation in energy dependence. It is discussed that the
saturation of fractional variable in string fragmentation function might be a
qualitative representation of the energy dependence of nuclear transparency. 相似文献
67.
The energy and centrality dependencies of charged particle pseudorapidity density in relativistic nuclearcollisions were studied using a hadron and string cascade model, JPCIAE. Both the relativistic p+p experimental dataand the PHOBOS and PHENIX Au+Au data at RHIC energy could be fairly reproduced within the framework ofJPCIAE model and without retuning the model parameters. The predictions for Pb + Pb collisions at the LHC energywere also given. We computed the participant nucleon distributions using different methods. It was found that thenumber of participant nucleons is not a well defined variable both experimentally and theoretically. Thus it may beinappropriate to use the charged particle pseudorapidity density per participant pair .as a function of the number ofparticipant nucleons for distinguishing various theoretical models. 相似文献
68.
69.
70.
GUY BOUCHITTÉ IRENE FONSECA GIOVANNI LEONI LUÍSA MASCARENHAS 《Archive for Rational Mechanics and Analysis》2002,165(3):187-242
An integral representation formula for a class of functionals defined on and in (the space of special functions of bounded variation) is obtained without requiring the regularity conditions usually imposed
in the literature. The approach is based on the general results of [10] and on a Poincaré-Wirtinger type inequality introduced
by DE GIORGI, CARRIERO & LEACI [25]. Applications to relaxation problems and dimension-reduction problems in brittle thin
films are presented.
(Accepted May 8, 2002) Published online October 18, 2002
Communicated by L. Ambrosio 相似文献