全文获取类型
收费全文 | 2314篇 |
免费 | 87篇 |
国内免费 | 16篇 |
专业分类
化学 | 1880篇 |
晶体学 | 37篇 |
力学 | 20篇 |
数学 | 85篇 |
物理学 | 395篇 |
出版年
2023年 | 9篇 |
2022年 | 13篇 |
2021年 | 22篇 |
2020年 | 30篇 |
2019年 | 37篇 |
2018年 | 27篇 |
2017年 | 12篇 |
2016年 | 49篇 |
2015年 | 58篇 |
2014年 | 52篇 |
2013年 | 115篇 |
2012年 | 110篇 |
2011年 | 137篇 |
2010年 | 75篇 |
2009年 | 64篇 |
2008年 | 124篇 |
2007年 | 148篇 |
2006年 | 146篇 |
2005年 | 106篇 |
2004年 | 135篇 |
2003年 | 102篇 |
2002年 | 101篇 |
2001年 | 78篇 |
2000年 | 49篇 |
1999年 | 53篇 |
1998年 | 34篇 |
1997年 | 31篇 |
1996年 | 32篇 |
1995年 | 20篇 |
1994年 | 21篇 |
1993年 | 22篇 |
1992年 | 25篇 |
1991年 | 22篇 |
1990年 | 20篇 |
1989年 | 17篇 |
1988年 | 19篇 |
1987年 | 21篇 |
1986年 | 15篇 |
1985年 | 42篇 |
1984年 | 28篇 |
1983年 | 22篇 |
1982年 | 17篇 |
1981年 | 28篇 |
1980年 | 17篇 |
1979年 | 18篇 |
1977年 | 11篇 |
1976年 | 13篇 |
1975年 | 17篇 |
1974年 | 7篇 |
1969年 | 7篇 |
排序方式: 共有2417条查询结果,搜索用时 93 毫秒
951.
Tsuyoshi Tsujioka Toshio Harada Minoru Kume Kazuhiko Kuroki Masahiro Irie 《Optical Review》1995,2(3):181-186
The possibility of a super-resolution optical memory using a photochromic mask layer was theoretically discussed. An equation which estimates the transmittance change of the mask layer was derived. The numerical simulation based on the equation showed that the reflectance increase of the layer by photo-irradiation is nonlinear when the optical density of the layer is high. The nonlinear response decreased the crosstalk in adjacent recording tracks and improved the MTF (modulation transfer function) characteristics, resulting in a higher recording density. 相似文献
952.
N. Momono T. Nakano A. Eida K. Chida Y. Miura M. Oda M. Ido 《Czechoslovak Journal of Physics》1996,46(Z3):1233-1234
The electronic specific heat Cel was studied at T≤10K on Ga- and Zn-doped La2−xSrxCuO4 (0.16≤x≤0.22). In pure La2−xSrxCuO4 (0.16≤x≤0.22), the Cel at T<Tc contains only a T2 component but no T-linear one, which is peculiar to a clean d-wave superconductor. Partial substitution of Ga or Zn for Cu
changes the T2-term of Cel into a quite different one described by the sum of a T-linear and a nearly T3 term. The coefficient of the T-linear term, γ, markedly increases with Zn-or Ga-content. The λ/λN vs. Tc/Tco relation for Zn-doped samples with x≥0.2 is in good agreement with the theoretical curve for resonant impurity scattering
in a d-wave superconductor, while those for Ga-doped samples and for Zn-doped samples with x<0.2 deviate slightly from the
theoretical curve. Such a deviation will be discussed in relation to the change in the magnetic properties of the present
system caused by impurity-doping. 相似文献
953.
Various esters are conveniently prepared by direct esterification of the corresponding carboxylic acids with alcohols catalyzed by a triphenylstibine oxide–phosphorus(V) sulfide combined system (Ph3SbO/P4S10) under mild conditions (25–80 °C). 相似文献
954.
Diketocarbene generated by rhodium(II) acetate-catalyzed decomposition of diazodimedone reacts with benzene at room temperature to give 5,5-dimetlryl-2-phenylcyclohexane-1,3-dione in 88% yield.Translated from Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 491–493, February, 1996 相似文献
955.
Junichi Goto Nobuharu Goto Fazel Shamsa Makoto Saito Sakae Komatsu Kazuhiko Suzaki Toshio Nambara 《Analytica chimica acta》1983
New highly sensitive and moderately reactive derivatization reagents for hydroxysteroids have been developed. Two derivatization reagents, 1-anthroyl nitrile and 9-anthroyl nitrile, were readily prepared from the corresponding anthracenecarboxylic acid in two steps. The hydroxysteroid was condensed with the anthroyl nitrile in the presence of triethylamine under mild conditions. The resulting ester showed a single peak of the theoretical shap on the chromatogram and provided excellent sensitivity. The detection limit of the C-21 ester formed from cortisol was 10 pg in normal-phase chromatorgraphy. 相似文献
956.
957.
958.
Takeo Ishidate Kuon Inoue Kazuhiko Tsuji Shigeru Minomura 《Solid State Communications》1982,42(3):197-200
The first studies on the pressure dependences of the first-order Raman spectra in plasma-deposited a-Si:H films are reported. With increasing pressure up to 25 kbar the TO optical phonon band shows a shift in peak to higher frequencies with a sharpening of width while the TA acoustic phonon band shows a shift in peak to lower frequencies with a broadening of width. The LO optical phonon band shows a shift in peak to higher frequencies whereas the LA acoustic phonon band remains unchanged. These pressure effects are discussed with changes in force constant and structural disorder. The alloying effect of H atoms on the Raman spectra is also discussed while comparing the pressure effects. 相似文献
959.
960.
We report the influence of external high-pressure (P up to 8 GPa) on the temperature (T) dependence of electrical resistivity (ρ) of a Yb-based Kondo lattice, YbPd2Si2, which does not undergo magnetic ordering under ambient pressure condition. There are qualitative changes in the ρ(T) behavior due to the application of external pressure. While ρ is found to vary quadratically below 15 K (down to 45 mK) characteristic of Fermi-liquids, a drop is observed below 0.5 K for P=1 GPa, signaling the onset of magnetic ordering of Yb ions with the application of P. The T at which this fall occurs goes through a peak as a function of P (8 K for P=2 GPa and about 5 K at high pressures), mimicking Doniach's magnetic phase diagram. We infer that this compound is one of the very few Yb-based stoichiometric materials, in which one can traverse from valence fluctuation to magnetic ordering by the application of external pressure. 相似文献