全文获取类型
收费全文 | 11377篇 |
免费 | 373篇 |
国内免费 | 32篇 |
专业分类
化学 | 7554篇 |
晶体学 | 73篇 |
力学 | 332篇 |
综合类 | 6篇 |
数学 | 1450篇 |
物理学 | 2367篇 |
出版年
2023年 | 82篇 |
2022年 | 183篇 |
2021年 | 358篇 |
2020年 | 256篇 |
2019年 | 278篇 |
2018年 | 271篇 |
2017年 | 223篇 |
2016年 | 470篇 |
2015年 | 340篇 |
2014年 | 392篇 |
2013年 | 718篇 |
2012年 | 788篇 |
2011年 | 825篇 |
2010年 | 622篇 |
2009年 | 602篇 |
2008年 | 746篇 |
2007年 | 695篇 |
2006年 | 555篇 |
2005年 | 451篇 |
2004年 | 391篇 |
2003年 | 341篇 |
2002年 | 285篇 |
2001年 | 220篇 |
2000年 | 173篇 |
1999年 | 121篇 |
1998年 | 115篇 |
1997年 | 101篇 |
1996年 | 98篇 |
1995年 | 73篇 |
1994年 | 87篇 |
1993年 | 81篇 |
1992年 | 82篇 |
1991年 | 67篇 |
1990年 | 49篇 |
1989年 | 37篇 |
1988年 | 45篇 |
1987年 | 35篇 |
1986年 | 37篇 |
1985年 | 55篇 |
1984年 | 42篇 |
1983年 | 37篇 |
1982年 | 30篇 |
1981年 | 37篇 |
1980年 | 40篇 |
1979年 | 32篇 |
1978年 | 38篇 |
1977年 | 18篇 |
1976年 | 23篇 |
1975年 | 25篇 |
1973年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
A. F. G. Monte M. A. G. Soler S. W. da Silva B. B. D. Rodrigues P. C. Morais A. A. Quivy J. R. Leite 《Physica E: Low-dimensional Systems and Nanostructures》2004,23(3-4):466
We have investigated the influence of vicinal GaAs substrates on the optical and electronic properties of InGaAs/GaAs quantum wells (QWs). A single In0.10Ga0.90As QW was grown by molecular-beam epitaxy on a vicinal GaAs(0 0 1) substrate with a miscut angle of 0° (nominal), 2°, 4° and 6° towards [1 1 0]. The carrier diffusion was obtained by a micro-photoluminescence scan technique that permits to observe the effective diffusion length characterized by the lateral spread of carriers in the QW followed by radiative recombination. The carrier diffusion length was obtained parallel (L||) and perpendicular (L) to the atomic steps. The diffusion length decreases as the temperature increases up to 100 K. Above this temperature we found different behaviours that depend on the sample miscut angle. 相似文献
63.
Isabel Brandariz José L. Barriada Teresa Vilari?o Manuel E. Sastre de Vicente 《Monatshefte für Chemie / Chemical Monthly》2004,343(6):1475-1488
Several reported procedures for calibrating glass electrodes in proton concentration are compared. Some recommendations for non-experts are also given. The examined procedures can be classified into two broad categories, namely: those based on direct potential difference measurements of solutions of known proton concentration and those that use one or several pH standards to calibrate the electrode and subsequently measure the pH of solutions containing known proton concentrations. With a single buffer, the two types of procedures lead to equivalent results. However, if two pH buffers are used, the slope of the calibration graph in proton concentration will differ from the real electrode slope to an extent proportional to the difference between the liquid junction potentials of the two buffers. Therefore, any other method is preferable under these circumstances. 相似文献
64.
65.
J. G. Cardoso 《International Journal of Theoretical Physics》1997,36(7):1641-1649
A set of simple identities is utilized to build up new projective twistor diagrams for massless free fields of arbitrary spin
in real Minkowski space. It is effectively shown that the inner structure of the configurations which arise out of implementing
the relevant techniques has characteristics that are different from those of the conventional diagrams associated with the
Kirchoff-D'Adhemar-Penrose integral expressions. A nonhomogeneous version of the configurations is also provided. 相似文献
66.
Some basic concepts about curvature collineations are reviewed and the existing results on this topic are applied to the case of perfect fluids, giving a characterization of those amongst them which admit proper curvature collineations. 相似文献
67.
R. Arnaldi R. Averbeck K. Banicz J. Castor B. Chaurand C. Cicalo A. Colla P. Cortese S. Damjanovic A. David A. De Falco A. Devaux A. Drees L. Ducroux H. En’yo A. Ferretti M. Floris A. Foerster P. Force N. Guettet A. Guichard H. Gulkanian J. Heuser M. Keil L. Kluberg J. Lozano C. Lourenço F. Manso A. Masoni P. Martins A. Neves H. Ohnishi C. Oppedisano P. Parracho P. Pillot G. Puddu E. Radermacher P. Ramalhete P. Rosinsky E. Scomparin J. Seixas S. Serci R. Shahoyan P. Sonderegger H.J. Specht R. Tieulent G. Usai R. Veenhof H.K. Wöhri 《The European Physical Journal C - Particles and Fields》2007,49(1):235-241
The NA60 experiment at the CERN SPS has studied low-mass muon pairs in 158 A GeV In–In collisions. A strong excess of pairs
is observed above the yield expected from neutral meson decays. The unprecedented sample size close to 400000 events and the
good mass resolution of about 2% made it possible to isolate the excess by subtraction of the decay sources. The shape of
the resulting mass spectrum shows some non-trivial centrality dependence, but is largely consistent with a dominant contribution
from π+π-→ϱ→μ+μ- annihilation. The associated ϱ spectral function exhibits considerable broadening, but essentially no shift in mass. The
pT-differential mass spectra show the excess to be much stronger at low pT than at high pT. The results are compared to theoretical model predictions; they tend to rule out models linking hadron masses directly to
the chiral condensate.
PACS 25.75.-q; 12.38.Mh; 13.85.Qk 相似文献
68.
Siripon Anantawaraskul João B. P. Soares Preechathorn Jirachaithorn Jumras Limtrakul 《Journal of Polymer Science.Polymer Physics》2006,44(19):2749-2759
Four polyethylene samples (PE) with different molecular weight distributions (MWD) were analyzed by crystallization analysis fractionation (Crystaf) at several cooling rates to investigate the effect of MWD and cooling rate on their Crystaf profiles. Using these results, we developed a mathematical model for Crystaf that considers crystallization kinetic effects, which are ignored in all previous Crystaf models. The Crystaf model we proposed can fit the experimental Crystaf profiles of the 4 polyethylene resins very well. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2749–2759, 2006 相似文献
69.
The algebras of Kleinian type are finite-dimensional semisimple rational algebras A such that the group of units of an order in A is commensurable with a direct product of Kleinian groups. We classify the Schur algebras of Kleinian type and the group algebras of Kleinian type. As an application, we characterize the group rings RG, with R an order in a number field and G a finite group, such that the group of units of RG is virtually a direct product of free-by-free groups. 相似文献
70.