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991.
With uncorrelated Gaussian factors extended to mutually independent factors beyond Gaussian, the conventional factor analysis is extended to what is recently called independent factor analysis. Typically, it is called binary factor analysis (BFA) when the factors are binary and called non-Gaussian factor analysis (NFA) when the factors are from real non-Gaussian distributions. A crucial issue in both BFA and NFA is the determination of the number of factors. In the literature of statistics, there are a number of model selection criteria that can be used for this purpose. Also, the Bayesian Ying-Yang (BYY) harmony learning provides a new principle for this purpose. This paper further investigates BYY harmony learning in comparison with existing typical criteria, including Akaik’s information criterion (AIC), the consistent Akaike’s information criterion (CAIC), the Bayesian inference criterion (BIC), and the cross-validation (CV) criterion on selection of the number of factors. This comparative study is made via experiments on the data sets with different sample sizes, data space dimensions, noise variances, and hidden factors numbers. Experiments have shown that for both BFA and NFA, in most cases BIC outperforms AIC, CAIC, and CV while the BYY criterion is either comparable with or better than BIC. In consideration of the fact that the selection by these criteria has to be implemented at the second stage based on a set of candidate models which have to be obtained at the first stage of parameter learning, while BYY harmony learning can provide not only a new class of criteria implemented in a similar way but also a new family of algorithms that perform parameter learning at the first stage with automated model selection, BYY harmony learning is more preferred since computing costs can be saved significantly. 相似文献
992.
In this paper, we investigate the isolated closed orbits of two types of cubic vector fields in R3 by using the idea of central projection transformation, which sets up a bridge connecting the vector field X(x) in R3 with the planar vector fields. We have proved that the cubic vector field in R3 can have two isolated closed orbits or one closed orbit on the invariant cone. As an application of this result, we have shown that a class of 3-dimensional cubic system has at least 10 isolated closed orbits located on 5 invariant cones, and another type of 3-dimensional cubic system has at least 26 isolated closed orbits located on 13 invariant cones or 26 invariant cones. 相似文献
993.
Zaharie Moldovan Nicolae Palibroda Monica Culea Ioan FeneAn Andrei Hantz 《Journal of mass spectrometry : JMS》1989,24(2):81-85
This paper presents the mass spectra, fragmentation pathways and structures of ions obtained by electron impact from methyl cyclohexyl phosphinomorpholinylamidothioate (1), cyclohexyl phosphonomorpholinylamidochloridothioate (2), cyclohexyl morpholinylamidophosphonothioic acid (3) and O-methyl cyclohexyl phosphonomorpholinylamidothioate (4). The fragmentation pathways and ion structures were established by exact mass determinations on compound 1 and by metastable transitions of all the compounds. 相似文献
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995.
研究机器带有多次速率改变行为的单机排序问题.机器可以通过不超过t个时段的中断来调整加工速度, 即每个工件在每次中断时段前后加工的加工时间可能不同.因此问题就需要决定是否中断,以及何时中断,使得最大完工时间、完工时间总和、加权完工时间总和等尽可能小.对任意固定的t,关于最大完工时间和完工时间总和目标分别给出了多项式时间最优算法,对满足正则假设的加权完工时间总和目标也给出了一个多项式时间最优算法. 相似文献
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997.
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999.
光子晶体中缺陷的色散导致的群速度降低 总被引:8,自引:4,他引:4
利用传输矩阵方法计算了包含色散媒质缺陷的一维光子晶体的复透射系数,其中色散媒质用洛仑兹振子模型描述。计算了由复透射系数定义的等效复折射率并由此研究了频谱位于缺陷模频率附近的光脉冲的群速度。结果发现,由于缺陷模附近的透射谱敏感地依赖于缺陷层的光学厚度,而缺陷层的色散使缺陷层光学厚度随频率变化而改变,从而使包含缺陷的光子晶体的等效色散性质明显地依赖于缺陷的色散行为。由于光脉冲是由多种频率成分的单色场迭加构成的,透射脉冲由各单色场透射后重新迭加构成,因此波包的传播由介质的等效色散性质决定。与包含无色散缺陷的光子晶体相比,缺陷的色散可导致极慢的群速度。通过改变振子强度,群速度可从极慢光速转变为超光速(superluminal)。 相似文献
1000.
C.Y. Kim H.W. Kim J.W. Chung K.S. An C.Y. Park A. Kimura A. Kakizaki 《Applied Physics A: Materials Science & Processing》1997,64(6):597-602
Received: 14 October 1996/Accepted: 17 December 1996 相似文献