全文获取类型
收费全文 | 2000篇 |
免费 | 99篇 |
国内免费 | 5篇 |
专业分类
化学 | 1647篇 |
晶体学 | 22篇 |
力学 | 17篇 |
数学 | 90篇 |
物理学 | 328篇 |
出版年
2023年 | 11篇 |
2022年 | 17篇 |
2021年 | 26篇 |
2020年 | 34篇 |
2019年 | 44篇 |
2018年 | 31篇 |
2017年 | 27篇 |
2016年 | 63篇 |
2015年 | 58篇 |
2014年 | 84篇 |
2013年 | 93篇 |
2012年 | 148篇 |
2011年 | 148篇 |
2010年 | 69篇 |
2009年 | 66篇 |
2008年 | 152篇 |
2007年 | 147篇 |
2006年 | 136篇 |
2005年 | 116篇 |
2004年 | 108篇 |
2003年 | 80篇 |
2002年 | 80篇 |
2001年 | 23篇 |
2000年 | 17篇 |
1999年 | 21篇 |
1998年 | 24篇 |
1997年 | 23篇 |
1996年 | 22篇 |
1995年 | 26篇 |
1994年 | 16篇 |
1993年 | 10篇 |
1992年 | 22篇 |
1991年 | 14篇 |
1990年 | 9篇 |
1989年 | 11篇 |
1987年 | 9篇 |
1986年 | 12篇 |
1985年 | 15篇 |
1984年 | 6篇 |
1983年 | 9篇 |
1982年 | 11篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 8篇 |
1978年 | 9篇 |
1977年 | 5篇 |
1976年 | 11篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1973年 | 7篇 |
排序方式: 共有2104条查询结果,搜索用时 461 毫秒
141.
The effect of molecular vibrations on electronic transport is investigated with the smallest fullerene C20 bridge, utilizing the Keldysh nonequilibrium Green's function techniques combined with the tight-binding molecular-dynamics method. Large discontinuous steps appear in the differential conductance when the applied bias voltage matches particular vibrational energies. The magnitude of the step is found to vary considerably with the vibrational mode and to depend on the local electronic states besides the strength of electron-vibration coupling. On the basis of this finding, a novel way to control the molecular motion by adjusting the gate voltage is proposed. 相似文献
142.
Spatiotemporal correlations of earthquakes are studied numerically on the basis of the one-dimensional spring-block (Burridge-Knopoff) model. As large events approach, the frequency of smaller events gradually increases, while, just before the mainshock, it is dramatically suppressed in a close vicinity of the epicenter of the upcoming mainshock, a phenomenon closely resembling the "Mogi doughnut." 相似文献
143.
We introduce Hilbert phase microscopy (HPM) as a novel optical technique for measuring high transverse resolution quantitative phase images associated with optically transparent objects. Because of its single-shot nature, HPM is suitable for investigating rapid phenomena that take place in transparent structures such as biological cells. The potential of this technique for studying biological systems is demonstrated with measurements of red blood cells, and its ability to quantify dynamic processes on a millisecond scale is exemplified with measurements of evaporating micrometer-sized water droplets. 相似文献
144.
We study a square-lattice three-state Potts antiferromagnet with a staggered polarization field at finite temperature. Numerically treating the transfer matrices, we determine two phase boundaries separating the model-parameter space into three parts. We confirm that one of them belongs to the ferromagnetic three-state Potts criticality, which is in accord with a recent prediction, and another to the Ising-type; these are both corresponding to the massless renormalization-group flows stemming from the Gaussian fixed points. We also discuss a field theory to describe the latter Ising transition. 相似文献
145.
An equilateral-triangular shape of three alpha clusters surrounded by excess neutrons is suggested for 14C, based on the molecular-orbit model. It is found that the attractive interaction between an excess neutron and an alpha particle stabilizes the K(pi)=0(+) and 3(-) rotational bands, which demonstrates an equilateral-triangular symmetry. This K(pi)=3(-) band at 3 MeV below the 10Be+alpha threshold energy corresponds to the experimentally observed band built on top of the second 3(-) state. A positive-parity rotational band (0(+), 2(+), 4(+)) arises similarly. These two bands suggest a molecular 3-alpha structure stabilized by the excess neutrons and can be viewed as a realization of the alpha crystallization in the dilute nuclear medium. 相似文献
146.
Kuriyama M Soeta T Hao X Chen Q Tomioka K 《Journal of the American Chemical Society》2004,126(26):8128-8129
A catalytic asymmetric arylation of sterically tuned imines with arylboroxines was developed by using N-Boc-l-valine-connected amidomonophosphane rhodium(I) catalyst in n-PrOH. The TMS group used for the steric tuning of imines is convertible to other functionalities that are applicable as a key foothold for the carbon-carbon bond-forming coupling reactions. 相似文献
147.
The universal features of quantized thermal conductance of carbon nanotubes (CNTs) are revealed through a theoretical analysis based on the Landauer theory of heat transport. The phonon-derived thermal conductance of semiconducting CNTs exhibits a universal quantization in the low-temperature limit, independent of the radius or atomic geometry. The temperature dependence follows a single curve given in terms of temperature scaled by the phonon energy gap. The thermal conductance of metallic CNTs has an additional contribution from electronic states, which also exhibits quantized behavior up to room temperature. 相似文献
148.
Takahiro Hosokawa Hiromi NakanoKazuto Takami Kazuya KobiroAkinobu Shiga 《Tetrahedron letters》2003,44(6):1175-1177
Treatment of rubrene (5,6,11,12-tetraphenylnaphthacene) with trifluoroacetic acid in dichloromethane gives 4b,9,10-triphenyl-4b,9-dihydroindeno[1,2,3-fg]naphthacene (1) as the sole isolable product. Paired interacting orbital (PIO) analysis indicates that the reaction is initiated by preferential attack of H+ at C(11) position of rubrene. 相似文献
149.
Yajima T Wakabayashi N Uchida H Watanabe M 《Chemical communications (Cambridge, England)》2003,(7):828-829
Adsorbed water molecules which promote the methanol oxidation reaction (MOR) at Pt-Ru alloy electrode are clearly detected by in-situ FTIR spectroscopy with the attenuated total reflection configuration, which directly supports the "bi-functional mechanism" for the MOR. 相似文献
150.