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1.
Summary. We introduce linear semi-implicit complementary volume numerical scheme for solving level set like nonlinear degenerate diffusion
equations arising in image processing and curve evolution problems. We study discretization of image selective smoothing equation
of mean curvature flow type given by Alvarez, Lions and Morel ([3]). Solution of the level set equation of Osher and Sethian
([26], \[30]) is also included in the study. We prove and estimates for the proposed scheme and give existence of its (generalized) solution in every discrete time-scale step. Efficiency
of the scheme is given by its linearity and stability. Preconditioned iterative solvers are used for computing arising linear
systems. We present computational results related to image processing and plane curve evolution.
Received April 25, 2000 / Revised version received June 11, 2001 / Published online November 15, 2001 相似文献
2.
JPC – Journal of Planar Chromatography – Modern TLC - 相似文献
3.
Liu L John VT McPherson G Maskos K Bose A 《Langmuir : the ACS journal of surfaces and colloids》2005,21(9):3795-3801
A viscous reverse hexagonal surfactant mesophase containing bis(2-ethylhexyl) sodium sulfosuccinate (AOT) and alpha-phosphatidylcholine (lecithin), with comparable volume fractions of isooctane and water, was characterized by Fourier transform (31)P and (1)H NMR spectroscopy. Shear alignment was reflected through both (31)P NMR and (1)H NMR spectra. A complicated (31)P spectrum was observed as a result of superposition of chemical shifts according to the distribution of crystalline domains prior to shear. The initially disordered samples with polydomain structures become macroscopically aligned after Couette shear. (31)P NMR chemical shift anisotropy characteristics are used to elucidate orientation of the hexagonal phase. Interestingly, (1)H NMR spectra exhibit spectral changes upon shear alignment closely corresponding with that of (31)P NMR spectra. These observations complement the findings of mesophase alignment obtained using SANS and imply that (31)P and (1)H NMR spectroscopy can be used as probes to define microstructure and monitor orientation changes in this binary surfactant system. This is especially beneficial if these mesophases are used as templates for materials synthesis. 相似文献
4.
On relatively short and long sides of convex pentagons 总被引:1,自引:0,他引:1
By the relative distance of pointsa andb of a convex bodyC we mean the ratio of the Euclidean distance ofa andb to the half of the Euclidean distance ofa, b C such thatab is a longest chord ofC parallel to the segmentab. We say that a sideab of a convexn-gon is relatively short (respectively: relatively long) if the relative distance ofa andb is at most (respectively: at least) the relative distance of two consecutive vertices of the regularn-gon. We show that every convexn-gon, wheren 5, has a relatively short side and a relatively long side, and that it is affine-regular if and only if all its sides are of equal relative lengths.Research supported in part by Komitet Bada Naukowych (Committee of Scientific Research), grant number 2 2005 92 03. 相似文献
5.
The mass spectra of some tertiary aliphatic nitroaldehydes, nitroketones, nitroesters, nitronitriles and related nitrocarbonyl compounds are discussed and compared with those of some analogous nitro compounds lacking the carbonyl function. The M+˙ ? NO2˙ and in several cases M+˙ ? HNO2 fragmentation seem to be the most characteristic features of all tertiary aliphatic nitro compounds. In the presence of the primary nitro group, the loss of NHO2 is always observed. 相似文献
6.
Karol Jankowski Danuta Rutkowska Andrzej Rutkowski 《Theoretical chemistry accounts》1978,48(2):119-125
It is shown that the Galerkin-Petrov method if applied in a controlled way yields reliable results for excited states of the
same symmetry classifications as the ground state. Computations are performed for the 21
S and 31
S states of He. The problem of optimizing nonlinear parameters of the basis functions by means of the GP method is discussed.
A special optimization scheme is suggested and numerically illustrated for someS states of He. 相似文献
7.
Chaudhuri RK Freed KF Hose G Piecuch P Kowalski K Włoch M Chattopadhyay S Mukherjee D Rolik Z Szabados A Tóth G Surján PR 《The Journal of chemical physics》2005,122(13):134105
Tests have been made to benchmark and assess the relative accuracies of low-order multireference perturbation theories as compared to coupled cluster (CC) and full configuration interaction (FCI) methods. Test calculations include the ground and some excited states of the Be, H(2), BeH(2), CH(2), and SiH(2) systems. Comparisons with FCI and CC calculations show that in most cases the effective valence shell Hamiltonian (H(v)) method is more accurate than other low-order multireference perturbation theories, although none of the perturbative methods is as accurate as the CC approximations. We also briefly discuss some of the basic differences among the multireference perturbation theories considered in this work. 相似文献
8.
We introduce a dynamical system, for which it is possible to get such a large number of eigenvalues that deviations from Wigner's surmise are visible. The obtained level-spacing distribution agrees much better with the distribution derived from random matrix theory. 相似文献
9.
Teobald Kupka Roman Wrzalik Gra
yna Pasterna Karol Pasterny 《Journal of Molecular Structure》2002,616(1-3):17-32
The results of extended MO calculations using density functional theory (DFT) approximation supported by experimental Raman, 1H and 13C NMR studies on thiophene are reported. Raman spectra of liquid thiophene were re-examined and the performance of a hybrid B3PW91 density functional was compared with the ab initio restricted Hartree–Fock (RHF) method. With the basis sets of the 6-311++G** quality, the DFT calculated bond lengths, dipole moments and harmonic vibrations were predicted in a very good agreement with available experimental data.
Additionally, the results on thiophene were extended by calculations on 3-methylthiophene and selenophene. In this case, a significant change in geometry and charge distribution in thiophene ring due to a methyl group substituent or replacement of sulphur by selene atom was observed.
A linear correlation between the predicted harmonic vibrational frequencies (scaled using SQM method) and experimental ones for thiophene, selenophene and 3-methylthiophene was shown. The theoretically calculated spectra have satisfactorily reproduced the available experimental spectra for thiophene and selenophene. 相似文献
10.
Lazny R Nodzewska A Sienkiewicz M Wolosewicz K 《Journal of combinatorial chemistry》2005,7(1):109-116
A new approach to polymeric supports useful for the immobilization of aldehydes and ketones via hydrazone linkers is reported. The new strategy gives supports with better properties and is effective for the synthesis of all supports previously used for the alkylation of ketones anchored as hydrazones. In contrast to other approaches, the new strategy also provided a polymer with an economical C2 spacer linker. The supports were used for immobilization of ketones 3-pentanone, acetone, N-benzylpiperidone, and aldehydes hexanal and 3-phenylpropanal in the form of their hydrazones. The polymer-supported hydrazones were subjected to alpha-alkylation (LDA/RX) followed by acidic, reductive, or oxidative cleavage/workup procedures to provide alpha-alkylated aldehydes or ketones as well as corresponding primary amines, alcohols, nitriles or acids. 相似文献