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排序方式: 共有264条查询结果,搜索用时 109 毫秒
101.
102.
Daniel Reker Michael Seet Max Pillong Christian P. Koch Petra Schneider Matthias C. Witschel Matthias Rottmann Cline Freymond Reto Brun Bernd Schweizer Boris Illarionov Adelbert Bacher Markus Fischer Franois Diederich Gisbert Schneider 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(27):7199-7204
103.
Alberto Gambi Marino Pedrali Manfred Winnewisser Guy Guelachvili 《Journal of Molecular Spectroscopy》1985,113(1):250-261
The Doppler-limited infrared spectrum of diazirine was recorded using a high-information Fourier transform spectrometer with a resolution of 0.0054 cm?1. The rovibrational structure of the ν9 fundamental (CH2 rocking) at 1124.9144 cm?1, which is a C-type band, was analyzed in detail with extensive use of spectrum simulation and correlation diagrams. The molecular constants for the upper energy level of this band were obtained from the overall rovibrational assignment of more than 2000 transitions, which cover the region from 1070 to 1220 cm?1. 相似文献
104.
The high resolution Fourier transform infrared spectra of thev
4-v
2 andv
7 band systems of tricarbon disulfide, SCCCS, were measured with a Bomem D A3.002 interferometer and an apodized resolution of 0.004 cm–1. The rotational structure of the bandsv
4-v
2, (v
4+v
7)–(v
2+v
7), (v
4+2v
7)–(v
2+2v
7) andv
7 could be resolved and assigned. The analysis confirmed that SCCCS displays the dynamics of a linear molecule. 相似文献
105.
Jun Nakagawa Koichi Yamada Manfred Bester Gisbert Winnewisser 《Journal of Molecular Spectroscopy》1985,110(1):74-85
Rotational transitions of CH3CCSiH3 have been observed in the millimeter-wave region using a computer-controlled source-frequency modulation spectrometer with a 1.8-m-long free space absorption cell. The observed spectrum clearly showed the effect of internal rotation with a small potential barrier. It has been analyzed by calculating the torsion-rotation energies on the basis of torsional wave functions obtained by diagonalizing the torsional part of the Hamiltonian. The least-squares analysis has yielded the rotational constant B = 2068.2817(4) MHz and a few centrifugal distortion constants. The barrier height to internal rotation has been determined to be 3.77(70) cm?1 from the contour map of the standard deviation. Also, the A rotational constant of the silyl group around the symmetry axis has been estimated by fixing the A constant of the methyl group to the value of CH3CCH. 相似文献
106.
107.
Jun Nakagawa Koichi M.T. Yamada Gisbert Winnewisser 《Journal of Molecular Spectroscopy》1985,112(1):127-141
Fifty-one sections of infrared diode-laser spectra of acetonitrile have been measured in the region from 2283.5 to 2235.7 cm?1. About 450 transitions belonging to the ν2 band have been assigned for K ≦ 7 and J ≦ 44. Anomalies found in the rotational structure have been proven to be due to five local resonances. Observed transition frequencies have been fitted by a least-squares method to a model which includes Fermi-type resonances (Δk = 0, Δ? = ± 3n) with ν6±1 + 2ν8±2 and ν4 + ν7±1 + ν8±1 states, x, y-type Coriolis resonances (Δk = ±1, Δ? = ?3n ± 1) with ν4 + ν6±1 and ν4 + ν7±1 + ν8±1 states, and a centrifugal-distortion-type resonance (Δk = ±2, Δ? = ?3n ± 2) with a 2ν70 + ν8±1 state. The 11 × 11 dimensional energy matrix has been diagonalized in order to obtain the perturbed energy levels. The standard deviation for the fit is 1.075 × 10?3 cm?1. The molecular constants determined are also listed. 相似文献
108.
The determination of a precise vibrational energy level scheme for the two-dimensional bending mode of tricarbon oxide sulfide (3-thioxo-1,2-propadiene-1-one), OCCCS, has been carried out by relative intensity measurements of rotational transitions up to the seventh excited vibrational state of ν7. The harmonic wavenumber ω7 was determined to be 84.50 ± 0.63 cm?1 while the anharmonicity constant χ77 was found to be ?0.62 ± 0.11 cm?1, respectively. A linear dependence of the expectation value of the electric dipole moment on the vibrational quantum number υ7 was found. All results confirm that in O CCCS the potential function describing the two-dimensional oscillator of ν7 is very harmonic without a perturbing barrier to linearity as was found in the case of OCCCO. 相似文献
109.
De novo design of molecular architectures by evolutionary assembly of drug-derived building blocks 总被引:3,自引:0,他引:3
Schneider G Lee ML Stahl M Schneider P 《Journal of computer-aided molecular design》2000,14(5):487-494
An evolutionary algorithm was developed for fragment-based de novo design of molecules (TOPAS, TOPology-Assigning System). This stochastic method aims at generating a novel molecular structure mimicking a template structure. A set of 25,000 fragment structures serves as the building block supply, which were obtained by a straightforward fragmentation procedure applied to 36,000 known drugs. Eleven reaction schemes were implemented for both fragmentation and building block assembly. This combination of drug-derived building blocks and a restricted set of reaction schemes proved to be a key for the automatic development of novel, synthetically tractable structures. In a cyclic optimization process, molecular architectures were generated from a parent structure by virtual synthesis, and the best structure of a generation was selected as the parent for the subsequent TOPAS cycle. Similarity measures were used to define `fitness', based on 2D-structural similarity or topological pharmacophore distance between the template molecule and the variants. The concept of varying library `diversity' during a design process was consequently implemented by using adaptive variant distributions. The efficiency of the design algorithm was demonstrated for the de novo construction of potential thrombin inhibitors mimicking peptide and non-peptide template structures. 相似文献
110.
The bending vibrations of linear, quasilinear, and bent molecules are qualitatively different phenomena. Each of these cases has been fully described by quantum mechanical formulations in the last half century, but important two-dimensional aspects of all three cases as well as the relationship between the three types of bending behavior remain difficult to visualize. Simple two-dimensional figures can help to provide an introduction to basic spatial and mathematical aspects of the bending problem. 相似文献