全文获取类型
收费全文 | 398423篇 |
免费 | 3493篇 |
国内免费 | 1332篇 |
专业分类
化学 | 201481篇 |
晶体学 | 6605篇 |
力学 | 18732篇 |
综合类 | 5篇 |
数学 | 45895篇 |
物理学 | 130530篇 |
出版年
2020年 | 3256篇 |
2019年 | 3691篇 |
2018年 | 4901篇 |
2017年 | 4750篇 |
2016年 | 6965篇 |
2015年 | 4330篇 |
2014年 | 6977篇 |
2013年 | 17635篇 |
2012年 | 13434篇 |
2011年 | 16479篇 |
2010年 | 11525篇 |
2009年 | 11361篇 |
2008年 | 14995篇 |
2007年 | 15149篇 |
2006年 | 14359篇 |
2005年 | 12978篇 |
2004年 | 12028篇 |
2003年 | 10665篇 |
2002年 | 10477篇 |
2001年 | 12007篇 |
2000年 | 9266篇 |
1999年 | 7290篇 |
1998年 | 5964篇 |
1997年 | 5884篇 |
1996年 | 5551篇 |
1995年 | 5090篇 |
1994年 | 4941篇 |
1993年 | 4923篇 |
1992年 | 5321篇 |
1991年 | 5432篇 |
1990年 | 5174篇 |
1989年 | 4956篇 |
1988年 | 5097篇 |
1987年 | 4948篇 |
1986年 | 4638篇 |
1985年 | 6234篇 |
1984年 | 6609篇 |
1983年 | 5380篇 |
1982年 | 5731篇 |
1981年 | 5633篇 |
1980年 | 5381篇 |
1979年 | 5571篇 |
1978年 | 5738篇 |
1977年 | 5705篇 |
1976年 | 5804篇 |
1975年 | 5363篇 |
1974年 | 5331篇 |
1973年 | 5537篇 |
1972年 | 3717篇 |
1971年 | 3029篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
31.
A. P. Voronov G. N. Babenko V. M. Puzikov A. D. Roshal’ V. I. Salo 《Crystallography Reports》2008,53(4):708-712
The features of doping of KDP crystals with cerium ions and organocerium complexes with alizarin complexon and arsenazo III have been investigated. It is established that “direct” doping by introducing cerium salts into the initial solution cannot be implemented. The effect of organometallic complexes of cerium on the crystal growth has been studied. Organocerium complexes predominantly enter the prismatic or pyramidal growth sectors. It is shown that the complex arsenazo III + Ce blocks the growth of the prismatic sector. Cerium-doped KDP crystals exhibit a photoluminescence band peaking at the wavelength λmax= 350 nm. 相似文献
32.
N. A. Anurova V. A. Blatov G. D. Ilyushin O. A. Blatova A. K. Ivanov-Shitz L. N. Demyanets 《Crystallography Reports》2008,53(6):930-936
A new method was developed for studying voids and channels in crystal structures based on the Voronoi-Dirichlet partition
of crystal space, and 822 structurally characterized ternary compounds Li
p
X
q
O
r
were analyzed for the first time. For these compounds, the dimensionality was determined and the migration patterns of channel
systems capable of providing lithium-ion transport were constructed. The calculated coordinates of lithium atoms in the centers
of the voids are consistent (within 0.4 ?) with the known structural data. Among these compounds, 113 compounds have infinite
channel systems, 60 compounds (18 structural types, STs) have been described earlier in the literature as solid electrolytes,
and 53 compounds (23 STs) can be considered as potential one-, two-, or three-dimensional ionic conductors (13, 3, and 7 STs,
respectively).
Original Russian Text ? N.A. Anurova, V.A. Blatov, G.D. Ilyushin, O.A. Blatova, A.K. Ivanov-Shitz, L.N. Dem’yanets, 2008,
published in Kristallografiya, 2008, Vol. 53, No. 6, pp. 987–993. 相似文献
33.
K. Morigaki K. Takeda H. Hikita C. Ogihara P. Roca i Cabarrocas 《Journal of Non》2008,354(19-25):2131-2134
Our model for light-induced defect creation in hydrogenated amorphous silicon is applied to its kinetics, i.e., the growing curve of light-induced dangling bond density as a function of illumination time, which is fitted to a stretched exponential function. Two parameters β and τ involved in the function are estimated as functions of saturated dangling bond density in terms of our model. These are compared with two experimental results, i.e., our results obtained from ESR measurements and Shimakawa et al.’s results obtained from photoconductivity measurements. The saturated dangling bond density is also measured as a function of the generation rate of free carriers. The experimental results are compared with calculated results and discussed. 相似文献
34.
I. D. Lomako M. I. Danil’kevich D. V. Karpinskiĭ I. I. Makoed 《Crystallography Reports》2008,53(2):278-284
The experimental and calculated values of the optical permittivity ε∞ have been analyzed and generalized with allowance for the oxygen concentration and possible valences of Fe and O ions in YIG single crystals. It is shown that the deficit of oxygen ions in the samples is accompanied by a decrease in ε∞. A decrease in the gradient of distribution of Ba ions over the sample thickness decreases the difference between the calculated and experimental values. It is revealed that the ratio of the number of valence electrons to the number of core electrons, with regard to their polarizabilities, is proportional to the ratio of the incoherent and coherent X-ray scattering intensities, nk/k. 相似文献
35.
We study parametric oscillations of linear systems with one degree of freedom for large values of the modulation coefficient. We use the classical analytic Lyapunov-Poincaré perturbation methods and an original numerically-analytic method of accelerated convergence to construct periodic solutions and the corresponding eigenvalues. We find the boundaries of stability and instability domains. We use specific models to illustrate the main properties of parametric oscillations of systems with singular character of the perturbation dependence on the modulation coefficient. We consider periodic boundary value problems for the modified Mathieu equation and the Kochin equation modeling crankshaft torsional vibrations and show that there are significant differences between weakly and essentially perturbed periodicmotions both for the lowest and arbitrary oscillation modes. We also describe the unusual properties of the boundaries in the domain of the system determining parameters. 相似文献
36.
J. Song H. Jiang Z.J. Liu D.Y. Khang Y. Huang J.A. Rogers C. Lu C.G. Koh 《International Journal of Solids and Structures》2008,45(10):3107-3121
A finite-deformation theory is developed to study the mechanics of thin buckled films on compliant substrates. Perturbation analysis is performed for this highly nonlinear system to obtain the analytical solution. The results agree well with experiments and finite element analysis in wavelength and amplitude. In particular, it is found that the wavelength depends on the strain. Based on the accurate wavelength and amplitude, the membrane and peak strains in thin films, and stretchability and compressibility of the system are also obtained analytically. 相似文献
37.
A. Ya. Samuilov L. A. Zenitova I. N. Bakirova Ya. D. Samuilov 《Russian Journal of Applied Chemistry》2008,81(8):1419-1422
Thermodynamic parameters of reactions of methyl and phenyl isocyanates with a series of compounds were determined by quantum-chemical calculations. The products of these reactions model for various functional groups present in commercial polyurethanes. The thermodynamic stability series for compounds formed from aliphatic and aromatic isocyanates were constructed. 相似文献
38.
39.
40.
S. A. Bulgakova A. I. Mashin I. A. Kazantseva D. E. Kashtanov M. M. Jones G. S. Tsepkov A. V. Korobkov A. V. Nezhdanov 《Russian Journal of Applied Chemistry》2008,81(8):1446-1451
Polymer films with a dispersed liquid crystal were prepared by photopolymerization of (meth)acrylic monomers. The electrooptical properties of these films were studied. The influence exerted by the composition of the monomer mixture, cross-linking agents, and chain-transfer agent on the liquid crystal drop size and on the transmission of the polymer-liquid crystal films was examined. 相似文献