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1.
《Physics letters. A》2020,384(15):126307
We introduce a procedure for separating periodic oscillations superposed on a stochastic signal. The procedure combines empirical mode decomposition (EMD) of a signal with tools of data analysis based on stochastic differential equations, namely nonlinear Langevin equations. Taking the set of modes retrieved from the EMD of the signal, our procedure is able to separate them into two groups, one composing the periodic signal and another composing the stochastic signal. The framework is robust for a broad family of localized oscillations, in the range of large frequencies. In particular, we show that, in this context, the EMD method outperforms a low-pass filter and is robust for a wide interval of different frequency ranges and amplitudes of the periodic oscillation, as well as for a broad family of different non-linear Langevin processes. 相似文献
2.
3.
4.
Frequency-sweep tests at various temperatures were conducted to study the asymmetric dynamic response of carbon black (CB) filled rubber. The master curves of storage modulus were constructed by use of time-temperature superposition (TTS), and the dynamic response of the material over a wide range of frequencies covering about 20 decades exhibits asymmetry. Based on the experimental results, the fractional Zener model and Prony series are verified to be unsuitable to reproduce the dynamicviscoelastic behavior. Therefore, a modified model by adding a spring-pot into the fractional Zener model is presented. The applicability of the modified model in describing the dynamic behavior of the CB-filled rubber is validated by the experimental results. 相似文献
5.
Quantum Bayesian computation is an emerging field that levers the computational gains available from quantum computers. They promise to provide an exponential speed-up in Bayesian computation. Our article adds to the literature in three ways. First, we describe how quantum von Neumann measurement provides quantum versions of popular machine learning algorithms such as Markov chain Monte Carlo and deep learning that are fundamental to Bayesian learning. Second, we describe quantum data encoding methods needed to implement quantum machine learning including the counterparts to traditional feature extraction and kernel embeddings methods. Third, we show how quantum algorithms naturally calculate Bayesian quantities of interest such as posterior distributions and marginal likelihoods. Our goal then is to show how quantum algorithms solve statistical machine learning problems. On the theoretical side, we provide quantum versions of high dimensional regression, Gaussian processes and stochastic gradient descent. On the empirical side, we apply a quantum FFT algorithm to Chicago house price data. Finally, we conclude with directions for future research. 相似文献
6.
In this paper the analytical solutions of the impact of a particle on Timoshenko beams with four kinds of different boundary
conditions are obtained according to Navier's idea, which is further developed. The initial values of the impact forces are
exactly determined by the momentum conservation law. The propagation of the longitudinal and transverse waves along the beam,
especially, the effects of boundary conditions on the characteristics of the reflected waves, are investigated in detail.
Some results are compared with those by MSC/NASTRAN. 相似文献
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9.
局部透射边界和叠加边界的精度分析与比较 总被引:5,自引:0,他引:5
本文研究了出平面和平面内波动在局部透射边界和叠加边界的反射系数,在研究中考虑了时空离散化的影响及反射波本身对反射系数的影响.采用一维有限元离散模型讨论了两种边界的阶数对反射系数的影响.通过比较这两种边界的反射系数得出以下结论:局部透射边界在有限元波动模拟中的精度高于叠加边界,且其优越性随着边界阶数的增加而提高。 相似文献
10.
The rheology of tetrafluoroethylene/hexafluoropropylene (TFE/HFP) copolymers, also known as Teflon FEP polymers, having different
molecular weight and composition (HFP content) was studied by means of a parallel-plate rheometer. Two groups of polymers
having different molecular weights with nearly constant polydispersity (around 2.5) were considered; namely, one group having
a relatively low melting temperature (amorphous with a high content of HFP) and a second group having a higher melting point
(semi-crystalline with a lower content of HFP). The relaxation time spectrum, H(λ), calculated by use of the BSW model (developed for monodisperse linear polymers) followed a scaling relationship in the
terminal zone with scaling exponent of 0.13. However, at higher frequencies the model fails to predict adequately the experimental
data. The longest relaxation time calculated from both the BSW model and discrete relaxation spectra (λ
i
,g
i
), which was determined by use of a parsimonious fitting software, depends on the molecular weight in a similar way as the
zero-shear viscosity does with the well-established scaling factor of 3.4. The critical molecular weight for the onset of
entanglements, M
c
, was found to be about 100000, a value much higher than those previously reported in literature for other polymers. The rheology
of resins in the second group (higher melting point) was found to exhibit a strong dependence on thermal history during oscillatory-shear
measurements. The data obtained in experiments at different temperatures without a preheating to a certain value (330°C) exhibited
a violation of the time-temperature superposition principle and no well-defined values of the zero-shear viscosity. This is
attributed to residual crystallinity even at temperatures well above their melting point (260°C). However, the same experiments
with preheating and subsequent cooling to desired temperature resulted into a very good time-temperature scaling.
Received: 13 January 1998 Accepted: 6 April 1998 相似文献