全文获取类型
收费全文 | 83篇 |
免费 | 3篇 |
专业分类
化学 | 46篇 |
晶体学 | 1篇 |
力学 | 1篇 |
数学 | 19篇 |
物理学 | 19篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 1篇 |
2013年 | 6篇 |
2012年 | 9篇 |
2011年 | 4篇 |
2010年 | 1篇 |
2009年 | 1篇 |
2008年 | 7篇 |
2007年 | 5篇 |
2006年 | 6篇 |
2005年 | 5篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 5篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1988年 | 1篇 |
排序方式: 共有86条查询结果,搜索用时 0 毫秒
51.
We show that for a polynomial map, the size of the Jordan blocks for the eigenvalue 1 of the monodromy at infinity is bounded by the multiplicity of the reduced divisor at infinity of a good compactification of a general fiber. The existence of such Jordan blocks is related to global invariant cycles of the graded pieces of the weight filtration. These imply some applications to period integrals. We also show that such a Jordan block of size greater than 1 for the graded pieces of the weight filtration is the restriction of a strictly larger Jordan block for the total cohomology group. If there are no singularities at infinity, we have a more precise statement on the monodromy. 相似文献
52.
53.
Image super-resolution based on local self-similarity 总被引:4,自引:0,他引:4
A new image super-resolution method based on a codebook mapping is proposed. The codebook mapping represents the internal
relationship between low-and high-frequency image components, and is used for the estimation of highfrequency image components
lost in the sampling process. In the proposed method, codebooks are first generated by the low-and high-frequency image components
of the original image itself that is to be processed. Then, a resultant superresolution image, that is, an enlarged image,
is obtained by combining the estimated high-frequency image components with the low-frequency ones obtained by a typical interpolation-based
method. The effectiveness of the proposed method is verified by comparing it against some conventional methods. 相似文献
54.
We investigated the effects that the visual field has on the perception of heading speed. The stimulus was a radial flow pattern simulating a translational motion through a cylindrical tunnel. Observers evaluated the perception of heading speed by using a temporal two-alternative forced choice (2AFC) staircase method. In the first experiment, we manipulated the stimulus area by cutting the visual field along the longitudinal direction. The results showed that the perceived heading speed increases with the stimulus area. In the second experiment, we manipulated both the stimulus area and the eccentricity by cutting the visual field along the longitudinal direction. The results showed that the perception of heading speed increases when the stimulus occupies a large portion of the peripheral visual field. These findings suggest that the effect of eccentricity is a consequence of an incorrect translation of two-dimensional visual information into three-dimensional scaling. 相似文献
55.
Saida Debbih-Boustila Ioana Fechete Rabeh Kerbachi Francois Garin 《Comptes Rendus Chimie》2018,21(3-4):419-426
Co-KIT-6 mesoporous materials with Ia3d symmetry and Si/Co ratios of 50, 25, and 10 were prepared using hydrothermal one-pot synthesis. The Co-KIT-6 mesoporous materials were characterized by X-ray diffraction, N2 adsorption–desorption isotherms, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy. The physicochemical characterization results show that all of the samples have well-ordered cubic mesostructures and that the structural integrity is preserved for nSi/nCo ratios as high as 10. It was found that most of the cobalt ions exist as isolated framework species, but for Co-KIT-6 with an nSi/nCo ratio of 10, the presence of extra-framework species/small cobalt oxide clusters cannot be excluded. The ability of these catalysts was tested by examining the conversion of the reaction of methylcyclopentane with hydrogen at atmospheric pressure and temperatures between 200 and 450 °C. The catalytic results show that their catalytic activity increases significantly with increasing cobalt content. The active sites, tetrahedrally coordinated Co and isolated atomic Co sites, were responsible for the endocyclic CC bond rupture between substituted secondary–tertiary carbon atoms, whereas the small clusters serve as active sites for the successive CC bond rupture. The ring-opening selectivity can be improved by increasing the density of isolated cobalt atom sites at low reaction temperatures. 相似文献
56.
57.
The morphology evolution of silver islands on silicone oil surfaces is measured and the microstructure of the islands is studied. The deposited Ag atoms diffuse and aggregate on the oil surface and then Ag islands with the width of the order of 102-nm form. After the samples are removed from the vacuum chamber, the immediate measurement shows that the apparent Ag coverage of the total area decays with the magnitude up to (23.0±3.8)% in few minutes. In the following two hours, the samples are kept in the ambient atmosphere and several unexpected results are detected: 1) as the topological structure of the islands evolves, the total area of each island decreases gradually and the maximum decrement measured is around 20%; 2) if an island breaks and becomes two small pieces, the total area decreases obviously; 3) however, if two small islands meet and stick together, a sudden increment of the total area is observed. These phenomena, mirroring the evolution process of the island microstructure, are resulted from both the diffusion of the atoms and the combination of the defects inside the islands. 相似文献
58.
This note presents a commutant lifting theorem (CLT) with initial data a finite set of (test) functions and a compatible reproducing
kernel k on a set X. This covers the CLT of Ball, Li, Timotin, and Trent [9] for the polydisc, but in general no analyticity is required, rather
statements and proofs use the language and techniques of reproducing kernel Hilbert spaces. Uniqueness of the de Branges–Rovnyak
construction like found in Agler [1] and Ambrozie, Englis, and Müller [5] and an abstract Beurling Theorem in the present
context are of independent interest.
Received: October 12, 2006. Accepted: May 8, 2007. 相似文献
59.
Previous studies demonstrated that color categorical perception (CP; better cross-category than within-category discrimination)
was reduced by verbal interference, suggesting that CP is mediated by verbal labeling. Here, we examined chromatic generality
and experience-dependency of verbal interference in CP using the Stroop effect. We employed a simultaneous two-alternative
forced choice discrimination task. Congruent or incongruent words were presented prior to discrimination. In experiment 1,
incongruent color names reduced CP regardless of color boundary pairs. Next, we used noncolor words that seemed to be associated
with color through experience. The results showed that the tested noncolor words did not modify CP (experiment 2). However,
combined presentation of color and shape produced Stroop interference (experiment 3). Our finding suggests that familiarity
or mastery of categorized information through experience may be evaluated by verbal interference. 相似文献
60.
Asymmetric Y junctions allow the development of a new class of optical frequency mixers that utilize higher-order waveguide modes for signal processing. We measure high-contrast (>30 dB) mode sorting in asymmetric Y junctions by use of a novel technique: efficient TM00, TM10, and TM20 mode mixing in a periodically poled lithium niobate waveguide. We also demonstrate an odd-to-even mode wavelength converter capable of spectral inversion without offset or bidirectional wavelength conversion. 相似文献