全文获取类型
收费全文 | 532篇 |
免费 | 0篇 |
国内免费 | 2篇 |
专业分类
化学 | 372篇 |
晶体学 | 1篇 |
力学 | 8篇 |
数学 | 100篇 |
物理学 | 53篇 |
出版年
2021年 | 6篇 |
2017年 | 3篇 |
2015年 | 3篇 |
2013年 | 10篇 |
2012年 | 14篇 |
2011年 | 12篇 |
2010年 | 10篇 |
2009年 | 4篇 |
2008年 | 17篇 |
2007年 | 13篇 |
2006年 | 13篇 |
2005年 | 8篇 |
2004年 | 16篇 |
2003年 | 16篇 |
2002年 | 5篇 |
2001年 | 3篇 |
1999年 | 8篇 |
1998年 | 11篇 |
1997年 | 12篇 |
1996年 | 11篇 |
1995年 | 13篇 |
1994年 | 11篇 |
1993年 | 22篇 |
1992年 | 7篇 |
1991年 | 11篇 |
1990年 | 12篇 |
1989年 | 7篇 |
1988年 | 9篇 |
1987年 | 10篇 |
1986年 | 13篇 |
1985年 | 13篇 |
1984年 | 6篇 |
1983年 | 12篇 |
1982年 | 13篇 |
1981年 | 6篇 |
1980年 | 17篇 |
1979年 | 10篇 |
1978年 | 11篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1975年 | 17篇 |
1974年 | 9篇 |
1973年 | 10篇 |
1972年 | 10篇 |
1971年 | 14篇 |
1970年 | 19篇 |
1969年 | 10篇 |
1966年 | 4篇 |
1964年 | 4篇 |
1963年 | 4篇 |
排序方式: 共有534条查询结果,搜索用时 140 毫秒
31.
Karl-Heinz Thunemann Sigrid D. Peyerimhoff Robert J. Buenker 《Journal of Molecular Spectroscopy》1978,70(3):432-448
Large-scale configuration interaction calculations (including energy extrapolation) are reported for the various states of ozone and its positive ion. The first four dipole-forbidden electronic transitions in the O3 spectrum are calculated to occur at 1.20, 1.44, 1.59, and 1.72 eV, respectively, while the corresponding low-energy-allowed species known as the Chappuis, Huggins, and Hartley bands are predicted to possess vertical excitation energies of 1.95, 3.60, and 4.97 eV, respectively. These results all appear to fit in quite well with the observed location of the pertinent spectral features, with respect to both energy and intensity. The 5- to 8-eV region of the ozone spectrum is found to be characterized by a series of double-excitation transitions out of the highest three occupied orbitals to the lowest unoccupied 2b1(π*) species. The strong features observed at 9.3 and 10.2 eV are thereupon calculated to result primarily from transitions into the 7a1 (σ*) MO (calculated 9.29 and 10.05 eV) and in the former case also from the 3s members of the various O3 Rydberg series (calculated 9.21 and 9.38 eV). Finally the order of the first three ip's is found to be 6a1, 4b2, and 1a2, while the feature in the neighborhood of 16 eV is attributed to a shake-up state of 2B1 symmetry. 相似文献
32.
33.
Karl-Heinz Helwig 《Mathematische Zeitschrift》1966,91(2):152-168
Ohne ZusammenfassungGefördert durch National Science Foundation grant GP-3750. 相似文献
34.
Ohne ZusammenfassungGefördert durch National Science Foundation Grant GP-3750 相似文献
35.
We have investigated the formation and motion of copper adatoms and addimers on Ag(111) between 6 and 25 K with low-temperature scanning tunneling microscopy. The presence of atoms and dimers alters the motion of atoms and dimers via the long-range interaction mediated by the electrons in the two-dimensional surface state band. Above 16 K, dimers show quantum rotor behavior with altered rotational behavior in the presence of an additional adatom. The most favorable diffusional motion of the dimer is identified in combination with molecular dynamics calculations to be a zigzag out-of-cell motion starting above 24 K. 相似文献
36.
A novel scanning tunneling microscope manipulation scheme for a controlled molecular transport of weakly adsorbed molecules is demonstrated. Single sexiphenyl molecules adsorbed on a Ag(111) surface at 6 K are shot towards single silver atoms by excitation with the tip. To achieve atomically straight shooting paths, an electron resonator consisting of linear standing-wave fronts is constructed. The sexiphenyl manipulation signals reveal a pi ring flipping as the molecule moves from the hcp to fcc site. Ab initio calculations show an incorporation of the Ag atom below the center of a pi ring. 相似文献
37.
The directionality patterns of sound emission in domestic dogs were measured in an anechoic environment using a microphone array. Mainly long-distance signals from four dogs were investigated. The radiation pattern of the signals differed clearly from an omnidirectional one with average differences in sound-pressure level between the frontal and rear position of 3-7 dB depending from the individual. Frequency dependence of directionality was shown for the range from 250 to 3200 Hz. The results indicate that when studying acoustic communication in mammals, more attention should be paid to the directionality pattern of sound emission. 相似文献
38.
Moresco F Gross L Alemani M Rieder KH Tang H Gourdon A Joachim C 《Physical review letters》2003,91(3):036601
A crucial problem in molecular electronics is the control of the electronic contact between a molecule and its electrodes. As a model system, we investigated the contact between the molecular wire group of a C90H98 (Lander) molecule and the edge of a Cu(111) monatomic step. The reproducible contact and decontact of the wire was obtained by manipulating the Lander with a low temperature scanning tunneling microscope. The electronic standing wave patterns on the Cu(111) surface serve to monitor the local electronic perturbation caused by the interaction of the wire end with the step edge, giving information on the quality of the contact. 相似文献
39.
Köhler S Hiller KH Griswold M Bauer WR Haase A Jakob PM 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2003,161(2):252-257
The purpose of this paper is to demonstrate that a fully balanced gradient echo technique (TrueFISP) can be used for microscopic experiments at high static magnetic field strengths. TrueFISP experiments were successfully performed on homogeneous and inhomogeneous objects at 11.75T. High-resolution TrueFISP images were obtained from phantoms, plants, formalin-fixed samples, and from an isolated beating rat heart with an in-plane resolution of 78 micro m and a slice thickness of 500 micro m. The signal-to-noise ratio (SNR) gain of TrueFISP compared to conventional gradient echo or spin echo sequences will allow faster acquisition times or an improvement in spatial resolution for microscopic experiments. 相似文献
40.
Roth KM Yasseri AA Liu Z Dabke RB Malinovskii V Schweikart KH Yu L Tiznado H Zaera F Lindsey JS Kuhr WG Bocian DF 《Journal of the American Chemical Society》2003,125(2):505-517
Redox kinetics were measured for two electroactive molecules attached to Si(100) surfaces, a ferrocene (Fc-BzOH) and a Zn(II) trimesitylporphyrin (Por-BzOH). Each molecule was derivatized with a benzyl alcohol linker for attachment to the Si surface via the formation of a Si-O bond. A complete protocol was developed for the preparation of stable Si(100) surfaces derivatized with the electroactive molecules. The redox-kinetic measurements were performed on the resulting Fc-BzOH and Por-BzOH monolayers to probe (1) the rate of electron transfer (k0) for oxidation in the presence of applied potentials and (2) the rate of charge dissipation after the applied potential is disconnected (in the form of a charge-retention half-life t1/2). The k0 values for the two types of monolayers were found to be similar to one another as were the t1/2 values. Perhaps more importantly, the electron-transfer rates for both the Fc-BzOH and the Por-BzOH monolayers differ from the charge-dissipation rates by approximately 6 orders of magnitude and are strongly dependent on the surface concentration of the electroactive species. For the Por-BzOH monolayers on Si(100), the k0 and t1/2 values and their trends as a function of surface coverage were determined to be similar to those previously measured for the analogous thiol-derivatized molecule assembled on Au(111). In contrast, the Fc-BzOH monolayers on Si(100) were found to exhibit much slower electron-transfer and charge-dissipation rates than those in the corresponding thiol-Au(111) case. Two alternative hypotheses are advanced to explain both the diminution in rates with increased surface coverage and the contrasting behavior with the analogous thiols on Au, one based on space-charge effects at the monolayer-solution interface, and a second relying on changes in distance of the redox centers from the surface as modulated by the orientation of the linking chains. Collectively, the ability to prepare and study stable, electroactive molecular media on Si(100) is likely to be key in the development of hybrid molecular/semiconductor devices. 相似文献