全文获取类型
收费全文 | 117篇 |
免费 | 14篇 |
国内免费 | 1篇 |
专业分类
化学 | 86篇 |
晶体学 | 1篇 |
力学 | 1篇 |
数学 | 23篇 |
物理学 | 21篇 |
出版年
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 3篇 |
2015年 | 7篇 |
2014年 | 4篇 |
2013年 | 9篇 |
2012年 | 9篇 |
2011年 | 11篇 |
2010年 | 5篇 |
2009年 | 2篇 |
2008年 | 3篇 |
2007年 | 9篇 |
2006年 | 4篇 |
2005年 | 4篇 |
2004年 | 5篇 |
2003年 | 1篇 |
2002年 | 5篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1992年 | 1篇 |
1989年 | 2篇 |
1985年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1972年 | 4篇 |
1971年 | 3篇 |
1970年 | 1篇 |
1964年 | 2篇 |
1963年 | 2篇 |
1961年 | 1篇 |
1958年 | 1篇 |
1954年 | 1篇 |
1949年 | 1篇 |
1940年 | 1篇 |
1932年 | 1篇 |
1929年 | 1篇 |
排序方式: 共有132条查询结果,搜索用时 453 毫秒
1.
Whitten AE Dittrich B Spackman MA Turner P Brown TC 《Dalton transactions (Cambridge, England : 2003)》2004,(1):23-29
High-resolution X-ray diffraction data have been collected on the cubic polymorph of antimony(III) oxide (senarmontite) to determine the charge distribution in the crystal. The results are in quantitative agreement with crystal Hartree-Fock calculations for this polymorph, and have been compared with theoretical calculations on the orthorhombic polymorph (valentinite). Information about the nature of bonding and relative bond strengths in the two polymorphs has been extracted in a straightforward manner via topological analysis of the electron density. All the close contacts in both polymorphs are found to be similar in nature based on the value of the Laplacian, the magnitude of the electron density and the local energy density at the bond critical points, and these characterise the observed interactions as substantially polar covalent, similar to molecular calculation results on Si-O and Ge-O. Electrostatic potential isosurfaces reveal the octopolar nature of this function for senarmontite, and shed light on the observed packing arrangement of Sb4O6 molecules in the crystal. 相似文献
2.
3.
4.
5.
Niels Olaf Østerberg Torben Smith Sørensen Jørgen Birger Jensen 《Journal of Electroanalytical Chemistry》1981,119(1):93-108
The emf of electrochemical cells containing various sorts of salt bridges between various concentrations has been measured. The net diffusion potential over a salt bridge has been treated theoretically. An expression to calculate the net diffusion potential has been derived and tested on values estimated from the emf measurements. A merit factor has been calculated for a saturated KCl bridge separating two HCl solutions and compared with the merit factor estimated from emf measurements on the cell:Pt|Ag|AgCl, HCl(c1)|KCl(sat)|HCl(c2), AgCl|Ag|Pt The practical performance of two commonly used reference electrodes with salt bridges has been tested on emf measurements on KBr solutions. 相似文献
6.
Anatol P. Spork Stefan Koppermann Birger Dittrich Regine Herbst-Irmer Christian Ducho 《Tetrahedron: Asymmetry》2010,21(7):763-766
The reaction of protected uridine 5′-aldehydes with sulfur ylides has been reinvestigated. Further transformation of the resulting epoxide product provided a compound of which a single crystal for X-ray diffraction was obtained. As a consequence from the elucidated structure, the stereochemical configuration of the epoxide furnished by the sulfur ylide reaction was revised. Based on these results, an efficient synthesis of the core structure of the naturally occurring muraymycin and caprazamycin nucleoside antibiotics was developed. 相似文献
7.
8.
Rennies J Brand T Kollmeier B 《The Journal of the Acoustical Society of America》2011,130(5):2999-3012
Reverberation usually degrades speech intelligibility for spatially separated speech and noise sources since spatial unmasking is reduced and late reflections decrease the fidelity of the received speech signal. The latter effect could not satisfactorily be predicted by a recently presented binaural speech intelligibility model [Beutelmann et al. (2010). J. Acoust. Soc. Am. 127, 2479-2497]. This study therefore evaluated three extensions of the model to improve its predictions: (1) an extension of the speech intelligibility index based on modulation transfer functions, (2) a correction factor based on the room acoustical quantity "definition," and (3) a separation of the speech signal into useful and detrimental parts. The predictions were compared to results of two experiments in which speech reception thresholds were measured in a reverberant room in quiet and in the presence of a noise source for listeners with normal hearing. All extensions yielded better predictions than the original model when the influence of reverberation was strong, while predictions were similar for conditions with less reverberation. Although model (3) differed substantially in the assumed interaction of binaural processing and early reflections, its predictions were very similar to model (2) that achieved the best fit to the data. 相似文献
9.
10.
Stepwise Halide‐Triggered Double and Triple Catenation of Self‐Assembled Coordination Cages 下载免费PDF全文
Rongmei Zhu Jens Lübben Priv.‐Doz. Dr. Birger Dittrich Prof. Dr. Guido H. Clever 《Angewandte Chemie (International ed. in English)》2015,54(9):2796-2800
A simple self‐assembled [Pd2 L 4] coordination cage consisting of four carbazole‐based ligands was found to dimerize into the interpenetrated double cage [3 X@Pd4 L 8] upon the addition of 1.5 equivalents of halide anions (X=Cl?, Br?). The halide anions serve as templates, as they are sandwiched by four PdII cations and occupy the three pockets of the entangled cage structure. The subsequent addition of larger amounts of the same halide triggers another structural conversion, now yielding a triply catenated link structure in which each PdII node is trans‐coordinated by two pyridine donors and two halide ligands. This simple system demonstrates how molecular complexity can increase upon a gradual change of the relative concentrations of reaction partners that are able to serve different structural roles. 相似文献