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171.
172.
本文利用Gibbs抽样法得到了CE模型下指数分布场合步进应力加速寿命试验的多层Bayes参数估计,最后通过模拟比较表明多层Bayes估计比最大似然估计更加有效而实用。 相似文献
173.
A. G. D’yakonov 《Computational Mathematics and Mathematical Physics》2008,48(5):866-876
It is shown that, in the pattern recognition problem with two nonoverlapping classes, the matrices of estimates of the object closeness are described by a metric. The transition to the algebraic closure of the model of recognizing operators of finite degree corresponds to the application of a special transformation of this metric. It is proved that the minimal degree correct algorithm can be found as a polynomial of a special form. A simple criterion for testing classification implementations is obtained. 相似文献
174.
He Shuyuan 《中国科学A辑(英文版)》1999,42(3):238-245
Two-dimensional hidden periodic model is an important model in random fields. The model is used in the field of two-dimensional
signal processing, prediction and spectral analysis. A method of estimating the parameters for the model is designed. The
strong consistency of the estimators is proved.
Project supported by the National Natural Science Foundation of China (Grant No. 19571002). 相似文献
175.
176.
177.
This paper addresses the development of a new algorithm forparameter estimation of ordinary differential equations. Here,we show that (1) the simultaneous approach combined with orthogonalcyclic reduction can be used to reduce the estimation problemto an optimization problem subject to a fixed number of equalityconstraints without the need for structural information to devisea stable embedding in the case of non-trivial dichotomy and(2) the Newton approximation of the Hessian information of theLagrangian function of the estimation problem should be usedin cases where hypothesized models are incorrect or only a limitedamount of sample data is available. A new algorithm is proposedwhich includes the use of the sequential quadratic programming(SQP) GaussNewton approximation but also encompassesthe SQP Newton approximation along with tests of when to usethis approximation. This composite approach relaxes the restrictionson the SQP GaussNewton approximation that the hypothesizedmodel should be correct and the sample data set large enough.This new algorithm has been tested on two standard problems. 相似文献
178.
Wenbin Lu 《Annals of the Institute of Statistical Mathematics》2008,60(3):545-574
The proportional hazards cure model generalizes Cox’s proportional hazards model which allows that a proportion of study subjects
may never experience the event of interest. Here nonparametric maximum likelihood approach is proposed to estimating the cumulative
hazard and the regression parameters. The asymptotic properties of the resulting estimators are established using the modern
empirical process theory. And the estimators for the regression parameters are shown to be semiparametric efficient. 相似文献
179.
In this paper it is argued that all multivariate estimation methods, such as OLS regression, simultaneous linear equations systems and, more widely, what are known as LISREL methods, have merit as geometric approximation methods, even if the observations are not drawn from a multivariate normal parent distribution and consequently cannot be viewed as ML estimators. It is shown that for large samples the asymptotical distribution of any estimator, being a totally differentiable covariance function, may be assessed by the δ method. Finally, we stress that the design of the sample and a priori knowledge about the parent distribution may be incorporated to obtain more specific results. It turns out that some fairly traditional assumptions, such as assuming some variables to be non-random, fixed over repeated samples, or the existence of a parent normal distribution, may have dramatic effects on the assessment of standard deviations and confidence bounds, if such assumptions are not realistic. The method elaborated by us does not make use of such assumptions. 相似文献
180.
James J. Sheng 《Transport in Porous Media》2009,77(3):507-527
To determine the permeabilities from a vertical interference test, earlier investigators proposed correlations or type curves
based on point source solutions or partially penetrated well solutions. However, it is impossible for these correlations or
type curves to cover all possible scenarios in the real world. In more recent years, people use regression analysis to simultaneously
match the pressure responses at the source interval and the observation point. With regression analysis, we face the problem
of non-unique solutions. Sometimes, estimated permeability could be outside a reasonable range when analyzing noisy data from
real tests. In this paper, a new technique is presented to estimate horizontal and vertical permeabilities from the time-delayed
response in a wireline vertical interference test. In a vertical test, a pressure drawdown test period is followed by a pressure
buildup test period. Because of the delay in response, the pressure at the observation probe continues to drop for some time
while the pressure at the source interval is being built up. The maximum pressure drop at the observation probe with regard
to the maximum pressure drop in the source interval is time-delayed. Using this time delay and the maximum pressure drop at
the observation probe, vertical and horizontal permeabilities can be estimated. A novel numerical scheme is used. The new
technique is compared with the previous methods, and it shows its superiority in accuracy. In addition, it can be used in
different test configurations. Application issues in real testing conditions are discussed. Finally, two field tests are analyzed
using this technique, while an earlier effort to analyze the tests using a conventional method was not successful due to poor
data quality. 相似文献