全文获取类型
收费全文 | 313326篇 |
免费 | 3001篇 |
国内免费 | 1340篇 |
专业分类
化学 | 152472篇 |
晶体学 | 4505篇 |
力学 | 15620篇 |
综合类 | 61篇 |
数学 | 48043篇 |
物理学 | 96966篇 |
出版年
2019年 | 1900篇 |
2018年 | 10885篇 |
2017年 | 11746篇 |
2016年 | 7529篇 |
2015年 | 3228篇 |
2014年 | 3659篇 |
2013年 | 8997篇 |
2012年 | 11727篇 |
2011年 | 21134篇 |
2010年 | 13311篇 |
2009年 | 13232篇 |
2008年 | 18795篇 |
2007年 | 22185篇 |
2006年 | 8560篇 |
2005年 | 13926篇 |
2004年 | 10109篇 |
2003年 | 9326篇 |
2002年 | 7326篇 |
2001年 | 6860篇 |
2000年 | 5371篇 |
1999年 | 3707篇 |
1998年 | 3086篇 |
1997年 | 3028篇 |
1996年 | 3189篇 |
1995年 | 2722篇 |
1994年 | 2809篇 |
1993年 | 2658篇 |
1992年 | 2894篇 |
1991年 | 2967篇 |
1990年 | 2776篇 |
1989年 | 2695篇 |
1988年 | 2648篇 |
1987年 | 2586篇 |
1986年 | 2596篇 |
1985年 | 3389篇 |
1984年 | 3466篇 |
1983年 | 2900篇 |
1982年 | 3136篇 |
1981年 | 2905篇 |
1980年 | 2699篇 |
1979年 | 2896篇 |
1978年 | 3112篇 |
1977年 | 3063篇 |
1976年 | 3124篇 |
1975年 | 2847篇 |
1974年 | 2957篇 |
1973年 | 3047篇 |
1972年 | 2357篇 |
1971年 | 1871篇 |
1968年 | 1761篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
L. A. Beklaryan 《Journal of Mathematical Sciences》2004,124(4):5098-5109
In the paper we study infinite-dimensional dynamic systems with the Frenkel–Kontorova potentials. For such systems we describe their traveling-wave-type solutions, which are solutions for the corresponding boundary-value problem with nonlocal conditions. Describing the mentioned solutions is equivalent to describing the space of solutions for a functional differential equation that can be canonically derived from the original dynamic system. The stability of traveling-wave-type solutions is also investigated. 相似文献
992.
993.
Summary The solubility parameters of cationic surfactants were obtained using the inverse gas chromatographic technique. The surfactants
didodecyl dimethyl ammonium bromide, dioctadecyl dimethyl ammonium bromide and dodecyl pyridinium chloride were used as stationary
phase and retention data of different probe solutes were measured at different temperatures. The results were analysed by
the combination of Flory-Huggins and Hildebrand theories, and the solubility parameters of the surfactants were obtained in
a range of temperatures between 80–120°C. 相似文献
994.
L.G. Casado I. García T. Csendes V.G. Ruíz 《Journal of Optimization Theory and Applications》2003,118(1):27-43
Based on the investigation carried out in Ref. 1, this paper incorporates new studies about the properties of inclusion functions on subintervals while a branch-and-bound algorithm is solving global optimization problems. It is found that the relative place of the global minimum value within the inclusion function value of the objective function at the current interval indicates mostly whether the given interval is close to a minimizer point. This information is used in a heuristic interval rejection rule that can save a considerable amount of computation. Illustrative examples are discussed and an extended numerical study shows the advantages of the new approach. 相似文献
995.
996.
G. Kocher-Oberlehner W. Jantsch L. Palmetshofer A. Ulyashin 《Physica E: Low-dimensional Systems and Nanostructures》2003,16(3-4):347
Erbium (Er)- and oxygen (O)-doped Cz–Si was additionally doped with hydrogen, using plasma enhanced chemical vapour deposition. Photoluminescence (PL) spectra show a large enhancement especially for samples treated with solid phase epitaxy before hydrogenation and annealing at 900°C later. Secondary ion mass spectroscopy measurements give evidence for an enhanced diffusion of O and Er at this temperature towards the surface. Etching shows that the PL does not stem from the heavily doped surface layer but from a deeper region with lower Er concentration. This conclusion is supported by the appearance of the so-called “cubic” centre with low solubility. Comparing the PL yield of the hydrogenated samples to that of samples with similar Er volume concentration but without hydrogenation still gives a large enhancement. We thus conclude that hydrogen can enhance the solubility of the cubic centre in Si:Er,O. 相似文献
997.
I. V. Bodnar 《Technical Physics》2003,48(5):587-591
The thermal expansion coefficients and the thermal conductivity of Bridgman-grown crystals of CuGa1−x
InxTe2 solid solutions are investigated. It is found that the thermal expansion coefficient varies with x linearly, while the thermal conductivity is minimal when x=0.5. The Debye temperature and the rms dynamic atomic displacements are calculated from experimental data. It is shown that
the Debye temperature decreases and the rms displacements in the crystal lattice sharply increase as the In content in the
solid solutions grows. 相似文献
998.
We prove that all invariant distances on the universal Teichmuller space agree and are determined by the Grunsky coefficients of the naturally related conformal maps. This fact yields various important consequences; in particular, we obtain solutions of certain well-known geometric problems in complex analysis and related fields. 相似文献
999.
A. N. Bogolyubov A. L. Delitsyn A. G. Sveshnikov 《Computational Mathematics and Modeling》2003,14(1):64-73
Radiation conditions are posed for an electromagnetic waveguide with a nonhomogeneous filling. The existence of a solution in a certain functional class is proved. A near-zone solution is obtained. 相似文献
1000.
E. Sh. Gutshabash 《JETP Letters》2003,78(11):740-744
The integration procedure based on the generalized Darboux transform is suggested for the Ishimori magnet model. Exact solutions are constructed for the model on the background of spiral structures. The possibility of phase transition in the system is hypothesized. 相似文献