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991.
We study numerically the nature of the diffusion process on a honeycomb and a quasi-lattice, where a point particle, moving along the bonds of the lattice, scatters from randomly placed scatterers on the lattice sites according to strictly deterministic rules. For the honeycomb lattice fully occupied by fixed rotators two (symmetric) isolated critical points appear to be present, with the same hyperscaling relation as for the square and the triangular lattices. No such points appear to exist for the quasi-lattice. A comprehensive comparison is made with the behavior on the previously studied square and triangular lattices. A great variety of diffusive behavior is found, ranging from propagation, superdiffusion, normal, quasi-normal, and anomalous, to absence of diffusion. The influence of the scattering rules as well as of the lattice structure on the diffusive behavior of a point particle moving on the all lattices studied so far is summarized. 相似文献
992.
The total miscibility method is applied to study the recently discovered mesophases of disc-like molecules, benzene-hexa-n-alkanoates. These compounds do not form continuous solid solutions, but are totally miscible in the liquid and mesomorphic
states. The virtual mesophase-isotropic transition temperature for the hexanoate compound derived from the miscibility diagram
is in excellent accord with that obtained from the previously reported pressure-temperature phase diagram. With simplifying
assumptions, it is possible to predict with acceptable reliability the isobaric binary phase diagrams of any two members of
the series. The real and virtual mesophase-liquid transition temperatures are linear functions of the molecular weight. On
the other hand, a plot of the crystal-liquid transition temperatures versus the molecular weight exhibits a minimum. Total
miscibility in the mesomorphic state is not observed for two members of different discogenic series, but the existence of
different mesophase types is not proved. Lyotropic mesomorphism for a disc-like mesophase is established. 相似文献
993.
Ivan Gutman 《Theoretical chemistry accounts》1979,50(4):287-297
A graph-theoretical analysis of certain -electron properties of alternant molecules with one heteroatom is given. Topological formulas for total -electron energy, -electron charge density, bond order and various polarizabilities are derived. The main results of the paper are summarized in Rules 1-7. 相似文献
994.
The partition of the canonical entropy (invariant of motion) into a thermodynamic part 5th and a nonthermodynamic oneS
nonth, respectively increasing and decreasing functions of time for a system approaching equilibrium, was proposed by Prigogine and co-workers. This viewpoint is critically examined in the special case of an initially uncorrelated gas of hard disks. BothSth and the leading term ofS
nonth are evaluated for finite assemblies of 400,1600, and 6400 disks, by the method of molecular dynamics. There is good evidence that, in the limit of an infinite system, the Prigogine scheme is verified.On leave of absence from the University of Brussels, Belgium. 相似文献
995.
Gunnar Karlström 《Theoretical chemistry accounts》1977,44(2):165-169
A new method to perform variational CI calculations on systems containing non-interacting molecules is presented. 相似文献
996.
Water-like lattice gases on the triangular and body-centered cubic lattices are investigated. Molecules may reside on the lattice sites in either of two possible orientations, a hydrogen bond being formed between molecules on neighboring sites if they have the proper orientation with respect to one another. For a range of chemical potential at sufficiently low temperatures, the models are shown to have an ordered phase consisting of an open, hydrogen-bonded, icelike structure. The models are shown to be transitionfree at sufficiently high temperature, indicating the existence of a critical point.Research supported in part by the U.S. National Science Foundation, Grant CHE-7726177, and by The Robert A. Welch Foundation, Grant P-446. 相似文献
997.
Cyanobacteria and myxobacteria use slime secretion for gliding motility over surfaces. The slime is produced by the nozzle-like pores located on the bacteria surface. To understand the mechanism of gliding motion and its relation to slime polymerization, we have performed molecular dynamics simulations of a molecular nozzle with growing inside polymer chains. These simulations show that the compression of polymer chains inside the nozzle is a driving force for propulsion. There is a linear relationship between the average nozzle velocity and the chain polymerization rate with a proportionality coefficient dependent on the geometric characteristics of the nozzle such as its length and friction coefficient. This minimal model of the molecular engine was used to explain the gliding motion of bacteria over surfaces. 相似文献
998.
A.?N.?IvanovEmail author M.?Cargnelli M.?Faber H.?Fuhrmann V.?A.?Ivanova J.?Marton N.?I.?Troitskaya J.?Zmeskal 《The European Physical Journal A - Hadrons and Nuclei》2005,25(3):329-338
We argue that due to isospin and U-spin invariance of strong low-energy interactions the S-wave scattering lengths a
0
0 and a
1
0 of ˉN scattering with isospin I = 0 and I = 1 satisfy the low-energy theorem a
0
0 +3a
1
0 = 0 valid to leading order in chiral expansion. In the model of strong low-energy ˉN interactions at threshold (Eur. Phys. J. A 21, 11 (2004)) we revisit the contribution of the Σ(1750) resonance, which does not saturate the low-energy theorem a
0
0 +3a
1
0 = 0, and replace it by the baryon background with properties of an SU(3) octet. We calculate the S-wave scattering amplitudes of K-N and K-d scattering at threshold. We calculate the energy level displacements of the ground states of kaonic hydrogen and deuterium.
The result obtained for kaonic hydrogen agrees well with recent experimental data by the DEAR Collaboration. We analyse the
cross-sections for elastic and inelastic K-p scattering for laboratory momenta 70MeV/c < p
K < 150MeV/c of the incident K--meson. The theoretical results agree with the available experimental data within two standard deviations. 相似文献
999.
LI Zhihui ZHANG Hanxin & FU Song ⒈ National Laboratory for CFD Hypervelocity Aerodynamics Institute China Aerodynamics Research Development Center Mianyang China .Department of Engineering Mechanics Tsinghua University Beijing China 《中国科学G辑(英文版)》2005,48(4):496-512
~~Gas kinetic algorithm for flows in Poiseuille-like microchannels using Boltzmann model equation1. Feynman, R., There's plenty of room at the bottom, Journal of Microelectromechanical Systems, 1992, 1: 60 -66.
2. Piekos, E. S., Breuer, K. S., Numerical modeling of micromechanical devices using the direct simulation Monte Carlo method, Transactions of the ASME, Journal of Fluids Engineering, 1996, 118: 464-469.
3. Beskok, A., Karniadakis, G. E., Trimmer, W., Rarefaction and … 相似文献
1000.
A. V. Latyshev V. N. Popov A. A. Yushkanov 《Journal of Applied Mechanics and Technical Physics》2004,45(1):17-22
The slip velocity of a rarefied gas with inhomogeneous temperature and mass velocity on a solid spherical surface is calculated with the use of a twomoment boundary condition in the linear approximation in terms of the Knudsen number. The dependence of the slip velocity on accommodation coefficients of the two first moments of the distribution function is studied. 相似文献