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101.
Michael J. Dick Brian J. Drouin Timothy J. Crawford John C. Pearson 《Journal of Quantitative Spectroscopy & Radiative Transfer》2009,110(9-10):628-638
A new spectroscopic experiment has been constructed at the Jet Propulsion Laboratory. This experiment employs the collisional cooling technique to study gases at temperatures below their condensation points. Specifically, the experiment has been designed to mimic the temperatures of the interstellar medium for the study of water under these conditions. The ultimate purpose is to measure state-to-state excitation rates under equilibrium conditions to provide insights into the interpretation of interstellar water spectra obtained from space-borne platforms such as the Herschel Space Observatory. This paper presents an overview of the new experiment including a discussion of its design and a detailed explanation of the system. In addition, we report a pressure broadening study of the J=5←4 transition of CO at 576 GHz used as a system validation. The new results are compared with measurements from the literature as a validation of the new experiment. In addition, the non-classical behavior of the pressure broadening of CO at low temperature observed in the measurements will be discussed. 相似文献
102.
103.
A previous calculation of Green's function (E-H)-1 for an interface Hamiltonian which interpolates between two and three dimensions is generalized to include scattering from perturbations both on and off the interface. 相似文献
104.
105.
Dick K. G. de Boer 《Waves in Random and Complex Media》1999,9(3):459-460
Recently, in this journal, Leskova and Maradudin published a new method for calculating x-ray scattering from a rough surface. In this comment their results will be compared with those obtained by other methods, especially the distorted-wave Born approximation. It is concluded that their results are useful in the limit of small transverse correlation length of the surface roughness. For intermediate values of the correlation length the results of both approximations are equivalent, being valid for small root-mean-square roughness and/or large incident perpendicular wavevector. In the case of large correlation length, neither approximation is correct. It is noted that the new method includes cross-polarization effects. 相似文献
106.
107.
This paper contributes to the state of the art in Cartesian-grid methods through development of new advection and reconstruction Volume-of-Fluid (VOF) algorithms which are applicable to two and three-dimensional flows. A computationally efficient and second-order VOF reconstruction method is presented which uses no inversions to determine the interface normal direction. Next, the lack of conservation of fluid volume in previous VOF advection methods are shown to be due to improper treatment of one-dimensional stretching in the velocity field. This paper uses simple explicit time stepping and a cell-center estimate of the volume fraction in the dilatation term to achieve a completely conservative advection method. The new methods are simple, robust and shown to out perform existing approaches for canonical test problems relevant to breaking wave flows. 相似文献
108.
High-resolution laser excitation spectroscopy has been used to record the A (2)E-X (2)A(1) electronic transition of SrCH(3) in a laser ablation/molecular jet source. Transitions arising from the K(')=1<--K(")=0, K(')=0<--K(")=1, and K(')=2<--K(")=1 subbands have been observed and assigned. The data were modeled with (2)E and (2)A(1) symmetric top Hamiltonian matrices in a Hund's case (a) basis, using a least squares fitting program. Rotational and fine structure parameters for the A (2)E state were determined. A comparison of the spin-orbit energy separation in the A (2)E state to other strontium containing free radicals showed that the Jahn-Teller effect is negligible. The spin-rotation constants for the A (2)E state were calculated using the pure precession model and were found to be in good agreement with the experimentally determined parameters. These calculations suggest that the A (2)E state of SrCH(3) is not entirely of p orbital character. The rotational constants were used to estimate the structural parameters of SrCH(3) in the A (2)E state. The strontium-carbon bond length was found to decrease by approximately 0.006 A, and the hydrogen-carbon-hydrogen bond angle opened by approximately 0.8 degrees compared to the X (2)A(1) state, similar to the geometry changes observed for CaCH(3). 相似文献
109.
Tushar S. Basu Baul Cheerfulman Masharing Eleonora Rivarola Robert Jirásko Dick de Vos 《Journal of organometallic chemistry》2006,691(5):952-965
Reactions of potassium β-{[(E)-1-(2-hydroxyaryl)alkylidene]amino}propionates (L1HK-L3HK) and potassium β-{[(2Z)-(3-hydroxy-1-methyl-2- butenylidene)]amino}propionate (L4HK) with R3SnCl (R = Ph and nBu) and nBu2SnCl2 yielded complexes of composition Ph3SnL1H (1), Ph3SnL2H (2), Ph3SnL4H (3), nBu3SnL1H (4), and {[nBu2Sn(L2H)]2O}2 (5) and {[nBu2Sn(L3H)]2O}2 (6), respectively. These complexes have been characterized by 1H, 13C, 119Sn NMR, ESI-MS, IR and 119mSn Mössbauer spectroscopic techniques in combination with elemental analyses. The crystal structures of 1, 4, 5 and 6 were determined. In the solid state, compound 1 is a one-dimensional polymer built from SnPh3 moieties bridged by single carboxylate ligands, but two alternating modes of bridging are present along the polymeric chain. Compound 4 is also a one-dimensional polymer built from SnBu3 moieties bridged by the two carboxylate O-atoms of a single ligand, but only one mode of bridging is present. Di-n-butyltin compounds 5 and 6 are centrosymmetric tetranuclear bis(dicarboxylatotetrabutyldistannoxane) complexes containing a planar Sn4O2 core in which two μ3-oxo O-atoms connect an Sn2O2 ring to two exocyclic Sn-atoms. The four carboxylate ligands display two different modes of coordination where both modes involve bridging of two Sn-atoms. The solution structures were predicted by 119Sn NMR spectroscopy. The in vitro cytotoxic activity of compound 5 against WIDR, M19 MEL, A498, IGROV, H226, MCF7 and EVSA-T human tumor cell lines is reported. 相似文献
110.
This paper describes a mild palladium-catalyzed method for the regioselective chlorination, bromination, and iodination of arene C-H bonds using N-halosuccinimides as oxidants. These transformations have been applied to a wide array of substrates and can provide products that are complementary to those obtained via conventional electrophilic aromatic substitution reactions. [reaction: see text] 相似文献