全文获取类型
收费全文 | 115篇 |
免费 | 1篇 |
专业分类
化学 | 38篇 |
晶体学 | 6篇 |
力学 | 21篇 |
数学 | 31篇 |
物理学 | 20篇 |
出版年
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 6篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 1篇 |
2014年 | 3篇 |
2013年 | 4篇 |
2012年 | 5篇 |
2011年 | 5篇 |
2010年 | 11篇 |
2009年 | 3篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 9篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 5篇 |
2002年 | 3篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1969年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有116条查询结果,搜索用时 15 毫秒
111.
Yuriko Aoki Oleksandr Loboda Kai Liu Marcin A. Makowski Feng Long Gu 《Theoretical chemistry accounts》2011,130(4-6):595-608
The elongation method, developed in our groups, is an ab initio method approaching order O(N) type scalability with high efficiency and high accuracy (error <10?8?au/atom in total energy compared to the conventional calculation) that can be applied to any one-dimensional (polymer), two-dimensional (surface) or three-dimensional (solid material) systems. For strongly delocalized systems, however, the accuracy of the original elongation method for the targeted entire systems declines by approximately two orders of magnitude in the total energy as compared to the value obtained by the earlier implemented version of the elongation method for nondelocalized systems. The relatively small differences (10?6?C10?8 au) between the elongation method and conventional method total energies have caused more serious errors in the second hyperpolarizability, ??, especially in nano-scale systems which have accompanying strong delocalization. In order to solve this problem, we have incorporated a simple correction technique based on an additional ??orbital basis?? to the ??region basis?? in our original elongation method procedures. Some not so-well-localized orbitals are incorporated into the interaction with the attacking molecule. This treatment has been applied to some model nano- and bio-systems that previously have shown strong delocalization, and the high accuracy in the energy obtained for nonstrongly delocalized systems was retained even for the strongly delocalized systems, both for the energies and for the second hyperpolarizabilities. This is a major breakthrough and now expands the systems for which the elongation method can be used to calculate and predict second-order nonlinear optical properties for delocalized systems. 相似文献
112.
Polycrystalline strontium-europium hydroxovanadates Sr10−xEux(VO4)6(OH)2−xOx were synthesized and studied by X-ray powder diffraction, infrared absorption and diffuse-reflectance spectroscopies and also thermogravimetry. The single-phase region of isomorphous substitution of Eu for Sr in hydroxovanadate has been found to lie in the compositional interval 0?x?0.18 at 800 °C. Refinement of X-ray diffraction (XRD) patterns by the Rietveld method shows that Eu substitutes for Sr preferentially at the Sr(1) sites of the apatite structure. The substitution results in a more uniform distribution of Sr-O bond lengths in coordination polyhedra both around Sr (1) and Sr (2) sites and also in a slight contraction of the vanadate anion VO43−. Synthetic Sr hydroxovanadates absorb a considerable amount of water in two forms: capillary condensed and chemically combined. The latter form may be absorbed at temperatures as high as 500 °C. 相似文献
113.
Mathematical Notes - Unitary transformations and canonical representatives of a family of real-valued harmonic fourth-degree polynomials in three complex variables are studied. The subject relates... 相似文献
114.
Shcherbyna SV Bohme DK Baranov VI Loboda A Swartz CR Anthony JE 《Journal of the American Society for Mass Spectrometry》2006,17(2):222-229
A high-performance orthogonal time-of flight (TOF) mass spectrometer, in combination with the matrix assisted laser desorption/ionization
(MALDI) source operating at elevated pressure (∼1 torr in N2), was used to perform MALDI-TOF analyses of pentacene and some of its derivatives with and without an added matrix. These
molecules are among the most interesting semiconductor materials for organic thin film transistor applications (OTFT). The
observation of ion-molecule reactions between “cold” analyte ions and neutral analyte molecules in the gas phase has provided
some insight into the mechanism of pentacene cluster formation and its functionalized derivatives. Furthermore, some of the
matrices employed to assist the desorption/ionization process of these compounds were observed to influence the outcome via
ion-molecule reactions of analyte ions and matrix molecules in the gas phase. The stability and reactivity of the compounds
and their clusters in the MALDI plume during gas-phase expansion were evaluated; possible structures of the resulting clusters
are discussed. The MALDI-TOF technique was also helpful in distinguishing between two isomeric forms of bis-[(triisopropylsilyl)-ethynyl]-pentacene. 相似文献
115.
A. I. Magunov T. A. Pikuz I. Yu. Skobelev A. Ya. Faenov F. Blasco F. Dorchies T. Caillaud C. Bonte F. Salin C. Stenz P. A. Loboda I. A. Litvinenko V. V. Popova G. V. Baidin G. C. Junkel-Vives J. Abdallah Jr. 《JETP Letters》2001,74(7):375-379
Line emission spectrum of a laser plasma produced in an argon cluster jet target was measured on the n 1 P1?11 S 0 (n=5–9) transitions of the helium-like Ar XVII ion for a pulse duration varying from 45 fs to 1.1 ps and a constant fluence of ~105 J/cm2. The independent modeling of the relative intensities of the transitions from the n=5,..., 10 levels, as well as of the 21 P 1? 12 S 0 and 23 P 1?12 S 0 lines and dielectronic satellites indicates that the electron temperature is anomalously low and that the electron density in emitting plasma increases with shortening the laser pulse. The excitation from the ground state by a small fraction of hot electrons is expected to be the main channel of populating the Ar XVII levels. 相似文献
116.