全文获取类型
收费全文 | 399605篇 |
免费 | 3744篇 |
国内免费 | 1366篇 |
专业分类
化学 | 211879篇 |
晶体学 | 6795篇 |
力学 | 17635篇 |
综合类 | 5篇 |
数学 | 42194篇 |
物理学 | 126207篇 |
出版年
2018年 | 3847篇 |
2017年 | 3719篇 |
2016年 | 5900篇 |
2015年 | 3882篇 |
2014年 | 6087篇 |
2013年 | 16930篇 |
2012年 | 11963篇 |
2011年 | 14885篇 |
2010年 | 10397篇 |
2009年 | 10310篇 |
2008年 | 13654篇 |
2007年 | 13782篇 |
2006年 | 13096篇 |
2005年 | 11863篇 |
2004年 | 10984篇 |
2003年 | 9809篇 |
2002年 | 9587篇 |
2001年 | 11773篇 |
2000年 | 9031篇 |
1999年 | 7105篇 |
1998年 | 5843篇 |
1997年 | 5799篇 |
1996年 | 5586篇 |
1995年 | 5126篇 |
1994年 | 4998篇 |
1993年 | 4966篇 |
1992年 | 5525篇 |
1991年 | 5544篇 |
1990年 | 5311篇 |
1989年 | 5300篇 |
1988年 | 5251篇 |
1987年 | 5168篇 |
1986年 | 4869篇 |
1985年 | 6561篇 |
1984年 | 6777篇 |
1983年 | 5538篇 |
1982年 | 5820篇 |
1981年 | 5730篇 |
1980年 | 5557篇 |
1979年 | 5794篇 |
1978年 | 6135篇 |
1977年 | 5883篇 |
1976年 | 5910篇 |
1975年 | 5498篇 |
1974年 | 5500篇 |
1973年 | 5519篇 |
1972年 | 3773篇 |
1971年 | 3147篇 |
1968年 | 3333篇 |
1967年 | 3346篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
We consider the growth of a spherical crystal in a supersaturatedsolution. In the first part, existence and uniqueness resultsfor radially symmetric growth are obtained, provided that thesupersaturation is not too large; conversely, when the far-fieldsupersaturation exceeds a critical value, it is shown that theradially symmetric solution ceases to exist in finite time.In the second part, we examine the linear stability of a radiallysymmetric similarity solution (in which the radius grows ast?) to shape perturbations. The results are compared with previousquasi-static analyses, and, in particular, the critical radiusat which the crystal becomes unstable is found to be largerfor small supersaturations, but smaller for large supersaturations,than those predicted by the quasi-static analysis 相似文献
43.
44.
J. Maul I. Strachnov S. Karpuk P. Bernhard A. Oelsner G. Schönhense G. Huber 《Applied Physics A: Materials Science & Processing》2006,82(1):43-47
We report morphologic changes of metallic surfaces at the onset of ablation, starting from gentle ablation to the emergence of ablation craters. The evolution of both observed melting zones and of ablation craters therein are investigated in dependence of the ablation laser fluence for nanosecond ultraviolet laser pulses. Further, consequences of crater formation for cluster synthesis within the released atomic vapor are pointed out. PACS 52.38.Mf; 79.20.Ds; 65.40.De 相似文献
45.
Zarubitskii O. G. Budnik V. G. Omel'chuk A. A. Melekhin V. T. Opanasyuk V. P. Zakharchenko N. F. 《Russian Journal of Applied Chemistry》2002,75(4):558-561
Electrochemical separation of lead-silver alloys into the constituents by thin-layer electrolysis in molten electrolytes, with bismuth as metal separator, is studied. It is proposed to determine the extent of component recovery by potentiometry. 相似文献
46.
J. C. Fabris S. V. B. Gonçalves P. E. de Souza 《General Relativity and Gravitation》2002,34(12):2111-2126
The mass power spectrum for a Universe dominated by the Chaplygin gas is evaluated numerically from scales of the order of the Hubble horizon to 100 Mpc. The results are compared with a pure baryonic Universe and a cosmological constant model. In all three cases, the spectrum increases with k, the wavenumber of the perturbations. The slope of the spectrum is higher for the baryonic model and smaller for the cosmological constant model, the Chaplygin gas interpolating these two models. The results are analyzed in terms of the sound velocity of the Chaplygin gas and the moment the Universe begins to accelerate. 相似文献
47.
A numerical procedure, with an exact strain-displacement relationship of twisted and curved cylindrical panels having variable thickness derived by considering the Green strain tensor on general shell theory, is presented using the principle of virtual work and the Rayleigh-Ritz method with algebraic polynomials as in-plane and transverse displacement functions. The accuracy and applicability of the procedure are verified by comparing the present results with previous experimental and theoretical results for several panels. The effects of variation ratio of thickness in chordwise and lengthwise directions, twist, and curvature both in two directions aforementioned on vibrations of cylindrical panels are studied in detail, and typical vibration mode shapes are plotted to demonstrate the effects. 相似文献
48.
The Wheeler–DeWitt equation of arbitrary Hartle–Hawking factor ordering for several minisuperspace universe models, such as the pure gravity Friedmann–Robertson–Walker and Taub ones, is mapped onto the dynamics of corresponding classical oscillators. The latter ones are studied by the classical Ermakov invariant method, which is a natural approach in this context. For the more realistic case of a minimally coupled massive scalar field, one can study, within the same type of approach, the corresponding squeezing features as a possible means of describing cosmological evolution. Finally, we comment on the analogy with the accelerator physics. 相似文献
49.
A.-S. F. Obada M. Darwish H. H. Salah 《International Journal of Theoretical Physics》2002,41(9):1755-1768
In this paper a new state called odd-excited binomial state (OEBS) is introduced. It interpolates between the odd number state and the odd-excited coherent state. We discuss some statistical properties, such as the Glauber second-order correlation function and squeezing phenomenon (normal and amplitude-squared squeezing) for this state. The quasiprobability distribution functions (Husimi Q-function and Wigner W-function) are also examined. 相似文献
50.