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11.
We examine the resource allocation problem of partitioning identical servers into two parallel pooling centers, and simultaneously
assigning job types to pooling centers. Each job type has a distinct Poisson arrival rate and a distinct holding cost per
unit time. Each pooling center becomes a queueing system with an exponential service time distribution. The goal is to minimize
the total holding cost. The problem is shown to be polynomial if a job type can be divided between the pooling centers, and
NP-hard if dividing job types is not possible. When there are two servers and jobs cannot be divided, we demonstrate that
the two pooling center configuration is rarely optimal. A heuristic which checks the single pooling center has an upper bound
on the relative error of 4/3. The heuristic is extended for the multiple server problem, where relative error is bounded above
by the number of servers.
相似文献
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The classical (non-quantum) cohomology of the Becchi-Rouet-Stora-Tyutin (BRST) symmetry in phase space is defined and worked out. No group action for the gauge transformations is assumed. The results cover, therefore, the general case of an open algebra and are valid off-shell. Each cohomology class contains all BRST invariant functions with fixed ghost number (an integer) which differ from each other by a BRST variation. If the ghost number is negative there is only the trivial class whose elements are equivalent to zero. If the ghost number is positive or zero there is a bijective correspondence between the BRST classes and those of the exterior derivative along the gauge orbits. These gauge orbits lie in the phase space surface on which the gauge generators are constrained to vanish. The BRST invariant functions of ghost numberp are then related to closedp-forms along the orbits. The addition of a BRST variation corresponds to the addition of an exact form. Some comments about the quantum case are included. The physical meaning of the classes with ghost number greater than zero is not discussed.Chercheur qualifié du Fonds National de la Recherche Scientifique (Belgium) 相似文献
15.
Finite dimensional representations of the quantum analog of the enveloping algebra of a complex simple Lie algebra 总被引:3,自引:0,他引:3
Marc Rosso 《Communications in Mathematical Physics》1988,117(4):581-593
Let
be a complex simple Lie algebra. We show that whent is not a root of 1 all finite dimensional representations of the quantum analogU
t
are completely reducible, and we classify the irreducible ones in terms of highest weights. In particular, they can be seen as deformations of the representations of the (classical)U
. 相似文献
16.
Summary A method for determining histamine in wine by precolumn derivatization with PITC (phenylisothiocyanate) with reversed-phase HPLC and UV detection is reported. Histamine can be determined together with the 24 amino acids within 40 min, or separately in a shorter time (less than 4 min) if a prior solid phase extraction clean-up is used. 相似文献
17.
Marc Halpern Yoel Sasson Itamar Willner Mordecai Rabinovitz 《Tetrahedron letters》1981,22(18):1719-1722
The effects of water molecules and quat structure are shown to be significant in determining the behavior of alkylation reactions of weakly acidic carbon acids under PTC/OH? conditions. 相似文献
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The role of search theory in the exploitation of natural resources is discussed in this paper. After a brief history and taxonomy of search problems, the mathematics of search is discussed. This includes underlying probability distributions, the differential equations of search, Bayesian use of search information and optimization problems in search theory. The theory is illustrated by applications in fisheries, pest control, animal foraging, and oil and mineral exploration. 相似文献
20.
Joyeux M 《The Journal of chemical physics》2005,122(7):074303
Vibrational energy localization and/or redistribution in hydrogen peroxide H2O2 is studied at about 4000 cm(-1) above the quantum mechanical ground state using the ab initio potential energy surface of Koput, Carter, and Handy [J. Phys. Chem. A 102, 6325 (1998)]. In this work, the recently derived canonical perturbation procedure for floppy molecules serves two purposes. First, from the quantum mechanical point of view, it is shown that the energies of the lowest 130 states are reproduced with an average error smaller than 1.5 cm(-1) by a two-dimensional Hamiltonian, which is a function of the torsion and OO-stretch coordinates and momenta, while the other four degrees of freedom contribute only through powers of good quantum numbers. Moreover, the canonical perturbation procedure is also used in classical mechanics calculations, in order to define meaningful local modes, for which the ingoing and outgoing energy flows are monitored. Almost all the individual trajectories launched on the ab initio surface display the same behavior, that is, the superposition of (a) rapid (few hundreds of femtoseconds) and quasiperiodic energy exchanges between the two OH stretches and between the torsion and OO-stretch, and (b) slower (few to several picoseconds) but erratic-looking energy flows between all degrees of freedom. When averaging over large numbers of trajectories with the same local mode energies at time t=0, one observes instead a smooth and irreversible energy flow between all degrees of freedom, which usually thermalize in the range of several tens of picoseconds, that is, on time scales larger than the 5 ps period associated with the quantum density of states. 相似文献