全文获取类型
收费全文 | 29920篇 |
免费 | 203篇 |
国内免费 | 46篇 |
专业分类
化学 | 13389篇 |
晶体学 | 549篇 |
力学 | 1068篇 |
综合类 | 11篇 |
数学 | 4380篇 |
物理学 | 10772篇 |
出版年
2022年 | 295篇 |
2021年 | 491篇 |
2020年 | 455篇 |
2019年 | 655篇 |
2018年 | 1097篇 |
2017年 | 1202篇 |
2016年 | 1457篇 |
2015年 | 693篇 |
2014年 | 1291篇 |
2013年 | 2096篇 |
2012年 | 1797篇 |
2011年 | 1884篇 |
2010年 | 2022篇 |
2009年 | 1949篇 |
2008年 | 1982篇 |
2007年 | 1878篇 |
2006年 | 1660篇 |
2005年 | 1063篇 |
2004年 | 805篇 |
2003年 | 534篇 |
2002年 | 492篇 |
2001年 | 433篇 |
2000年 | 714篇 |
1999年 | 428篇 |
1998年 | 533篇 |
1997年 | 494篇 |
1996年 | 167篇 |
1995年 | 116篇 |
1994年 | 84篇 |
1993年 | 52篇 |
1992年 | 67篇 |
1991年 | 45篇 |
1990年 | 73篇 |
1989年 | 58篇 |
1988年 | 58篇 |
1987年 | 56篇 |
1986年 | 61篇 |
1985年 | 77篇 |
1984年 | 93篇 |
1983年 | 59篇 |
1982年 | 57篇 |
1981年 | 67篇 |
1980年 | 67篇 |
1979年 | 39篇 |
1978年 | 51篇 |
1977年 | 57篇 |
1976年 | 52篇 |
1975年 | 46篇 |
1974年 | 38篇 |
1973年 | 37篇 |
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
191.
A. I. Burkhanov P. V. Bondarenko S. I. Raevskaya A. V. Shil’nikov I. P. Raevskiĭ 《Physics of the Solid State》2006,48(6):1114-1116
The dielectric properties of a ceramic and a single crystal of the same composition 0.9NaNbO3-0.1Gd1/3NbO3 (NNG10) with different prehistories of the material are investigated in the low-and infralow-frequency ranges. It is revealed that the dielectric aging of the material based on the NaNbO3 antiferroelectric with a smeared phase transition differs in character from similar phenomena observed in relaxor ferroelectrics. 相似文献
192.
We study applications of the theory of quadratic differentials to the solution of new extremal problems of nonoverlapping
domains with free poles on rays and generalize known results to a certain class of open sets.
__________
Translated from Neliniini Kolyvannya, Vol. 10, No. 4, pp. 435–442, October–December, 2007. 相似文献
193.
V. M. Nagirnyi R. D. Apostolova E. M. Shembel’ 《Russian Journal of Applied Chemistry》2006,79(9):1443-1446
The surface morphology of V2O5, Co2O3, and MnO2 electroplated under different electrolysis conditions was studied. The nature of the electrocrystallization of these materials was suggested on the basis of the analysis results. 相似文献
194.
I. P. Dobrovol’skaya M. K. Mokeev Yu. N. Sazanov A. V. Gribanov T. E. Sukhanova 《Russian Journal of Applied Chemistry》2006,79(7):1178-1180
Changes in the supramolecular structure of heat-resistant fibers based on polyimide PM were studied by X-ray diffraction analysis and NMR spectroscopy. 相似文献
195.
Reactions between polypyromellitamido acid and component materials of microelectronic articles were examined by thermogravimetric analysis. Modes of modification of the surfaces of semiconductor structures to be used in formation of a system of interconnections with polyimide as interlayer insulator to obtain a high adhesion between the layers via their chemical reactions. 相似文献
196.
197.
B. V. Pal’tsev I. I. Chechel’ 《Computational Mathematics and Mathematical Physics》2006,46(5):820-847
The convergence rate of a fast-converging second-order accurate iterative method with splitting of boundary conditions constructed by the authors for solving an axisymmetric Dirichlet boundary value problem for the Stokes system in a spherical gap is studied numerically. For R/r exceeding about 30, where r and R are the radii of the inner and outer boundary spheres, it is established that the convergence rate of the method is lower (and considerably lower for large R/r) than the convergence rate of its differential version. For this reason, a really simpler, more slowly converging modification of the original method is constructed on the differential level and a finite-element implementation of this modification is built. Numerical experiments have revealed that this modification has the same convergence rate as its differential counterpart for R/r of up to 5 × 103. When the multigrid method is used to solve the split and auxiliary boundary value problems arising at iterations, the modification is more efficient than the original method starting from R/r ~ 30 and is considerably more efficient for large values of R/r. It is also established that the convergence rates of both methods depend little on the stretching coefficient η of circularly rectangular mesh cells in a range of η that is well sufficient for effective use of the multigrid method for arbitrary values of R/r smaller than ~ 5 × 103. 相似文献
198.
Orotic acid (vitamin B13) is a key intermediate in biosynthesis of the pyrimidine nucleotides in living organisms, moreover, it may serve as the biological carrier for some metal ions. cis-Diammine(orotato)platinum(II), cis-[Pt(C5H2N2O4)(NH3)2] can be considered as a new potential cisplatin analogue. The FT-Raman and FT-IR spectra of the title complex are reported, for the first time. The molecular structure, vibrational frequencies, and the theoretical infrared and Raman intensities have been calculated by the density functional mPW1PW91 method. The detailed vibrational assignment has been made on the basis of the calculated potential energy distribution. The theoretically predicted IR and Raman spectra show very good agreement with experiment. Natural bond orbital (NBO) analyses were performed for cisplatin, carboplatin and the title complex. The results provided new data on the nature of platinum–ligand bonding in these compounds. Strong intramolecular hydrogen bond between the orotate ligand and the coordinated ammonia group stabilizes the structure of the platinum(II) complex. Thus, it is suggested that the orotate ligand in the title complex is more inert to the substitution reactions than the chloride ligands in cisplatin. 相似文献
199.
I. V. Kuchin N. B. Ur’ev 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2007,81(3):349-353
The main rules governing the redistribution of microparticles in disperse systems were revealed by computer simulation. These rules predetermine the character and properties of the structure being formed, which opens up the possibility to control the properties of disperse materials, including sorbents and catalysts based on high-dispersity solid phases. 相似文献
200.
A. V. Smol’yakov 《Acoustical Physics》2006,52(3):331-337
A model is developed for the statistical characteristics of the turbulent pressure field in a boundary layer. It is shown that the coherence scales are limited at low frequencies by the finiteness of the boundary layer thickness and at high frequencies by the effect of viscous forces acting in the flow. A relationship between the behavior of the coherence scales and that of the power spectra is demonstrated. The model is characterized by convertibility, which allows changes from cross spectra to wavenumber-frequency spectra and back via Fourier transformations. Calculations performed using the proposed model agree well with experimental results. 相似文献