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21.
C. I. J. M. Stuart 《Foundations of Physics Letters》1991,4(5):493-497
Costa de Beauregard's reformulation of joint probability, in connection with retrocausality, reveals a mathematical paradox independent of time-reversal. That paradox is intrinsic to Bell's theorem and has a physical manifestation in the Orsay experiments. 相似文献
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Baxter P. Rogers Santosh B. Katwal Victoria L. Morgan Christopher L. Asplund John C. Gore 《Magnetic resonance imaging》2010
Connectivity refers to the relationships that exist between different regions of the brain. In the context of functional magnetic resonance imaging (fMRI), it implies a quantifiable relationship between hemodynamic signals from different regions. One aspect of this relationship is the existence of small timing differences in the signals in different regions. Delays of 100 ms or less may be measured with fMRI, and these may reflect important aspects of the manner in which brain circuits respond as well as the overall functional organization of the brain. The multivariate autoregressive time series model has features to recommend it for measuring these delays and is straightforward to apply to hemodynamic data. In this review, we describe the current usage of the multivariate autoregressive model for fMRI, discuss the issues that arise when it is applied to hemodynamic time series and consider several extensions. Connectivity measures like Granger causality that are based on the autoregressive model do not always reflect true neuronal connectivity; however, we conclude that careful experimental design could make this methodology quite useful in extending the information obtainable using fMRI. 相似文献
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过度自信是行为金融学中的一个重要假说。本文以证券市场整体为研究对象,采用可行的广义最小二乘法(FGLS)估计线性回归模型并结合格兰杰因果检验、指数自回归条件异方差模型(EGARCH)等对中国证券投资者过度自信情况进行实证研究。结果显示,中国投资者普遍存在着过度自信,且这种心理偏差对其投资行为产生了明显影响;与美国等成熟证券市场不同,中国投资者过度自信程度在牛市和熊市中并没有统计上的显著差别。 相似文献
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Hector Sabelli 《Complexity》2010,15(5):12-24
The waves recorded by the Laser Interferometer Gravitational‐Wave Observatory (LIGO) presumably represent gravitational waves. Time series analyses revealed chaotic characteristics (nonperiodic oscillations, causal generation) and features of creativity that characterize Bios: increasing diversity (as contrasted to convergence to an attractor); novelty (lesser recurrence than randomized copies); and temporal complexity (a succession of different time‐limited patterns). Bios is also observed in quantum, cosmological, biological, and economic processes. Bios can be generated mathematically by bipolar feedback. Finding features of creativity in gravitational waves indicates that gravitational interactions causally generate complex patterns. As the gravitational wave background dates from the trillionth‐of‐a‐second after the Big Bang, these results indicate that causal and creative processes were important in the early universe, in contrast to the presumed predominance of random oscillations. © 2009 Wiley Periodicals, Inc. Complexity, 2010 相似文献
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近二十年来,我国高等教育规模不断扩大,高校在校生数不断增加,其中武汉市位居全国前列.为了研究高校在校生数对当地经济发展的影响,本文利用武汉市1992—2012年在校大学生人数数据,通过建立合适的模型,来定量探讨武汉市在校大学生数与经济增长的内在关系.结果表明,武汉市经济增长与武汉在校大学生人数模型之间存在着长期均衡关系且互为格兰杰因果关系. 相似文献
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We propose a novel measure to assess causality through the comparison of symbolic mutual information between the future of one random quantity and the past of the other.This provides a new perspective that is different from the conventional conceptions.Based on this point of view,a new causality index is derived that uses the definition of directional symbolic mutual information.This measure presents properties that are different from the time delayed mutual information since the symbolization captures the dynamic features of the analyzed time series.In addition to characterizing the direction and the amplitude of the information flow,it can also detect coupling delays.This method has the property of robustness,conceptual simplicity,and fast computational speed. 相似文献
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This study employs a parametric approach based on TGARCH and GARCH models to estimate the VaR of the copper futures market and spot market in China. Considering the short selling mechanism in the futures market, the paper introduces two new notions: upside VaR and extreme upside risk spillover. And downside VaR and upside VaR are examined by using the above approach. Also, we use Kupiec’s [P.H. Kupiec, Techniques for verifying the accuracy of risk measurement models, Journal of Derivatives 3 (1995) 73-84] backtest to test the power of our approaches. In addition, we investigate information spillover effects between the futures market and the spot market by employing a linear Granger causality test, and Granger causality tests in mean, volatility and risk respectively. Moreover, we also investigate the relationship between the futures market and the spot market by using a test based on a kernel function. Empirical results indicate that there exist significant two-way spillovers between the futures market and the spot market, and the spillovers from the futures market to the spot market are much more striking. 相似文献
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