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951.
952.
The isomorphism problem for centrally nilpotent loops can be tackled by methods of cohomology. We develop tools based on cohomology and linear algebra that either lend themselves to direct count of the isomorphism classes (notably in the case of nilpotent loops of order 2q, q a prime), or lead to efficient classification computer programs. This allows us to enumerate all nilpotent loops of order less than 24. 相似文献
953.
In this paper, we define the generalized Kato spectrum of an operator, and obtain that the generalized Kato spectrum differs from the semi-regular spectrum on at most countably many points. We study the localized version of the single-valued extension property at the points which are not limit points of the approximate point spectrum, as well as of the surjectivity spectrum. In particular, we shall characterize the single-valued extension property at a point λ0∈C in the case that λ0I−T admits a generalized Kato decomposition. From this characterization we shall deduce several results on cluster points of some distinguished parts of the spectrum. 相似文献
954.
B.P. Duggal 《Journal of Mathematical Analysis and Applications》2009,359(2):631-636
A Banach space operator T∈B(X) satisfies Browder's theorem if the complement of the Weyl spectrum σw(T) of T in σ(T) equals the set of Riesz points of T; T is polaroid if the isolated points of σ(T) are poles (no restriction on rank) of the resolvent of T. Let Φ(T) denote the set of Fredholm points of T. Browder's theorem transfers from A,B∈B(X) to S=LARB (resp., S=A⊗B) if and only if A and B∗ (resp., A and B) have SVEP at points μ∈Φ(A) and ν∈Φ(B) for which λ=μν∉σw(S). If A and B are finitely polaroid, then the polaroid property transfers from A∈B(X) and B∈B(Y) to LARB; again, restricting ourselves to the completion of X⊗Y in the projective topology, if A and B are finitely polaroid, then the polaroid property transfers from A∈B(X) and B∈B(Y) to A⊗B. 相似文献
955.
Let K⊂L be a commutative field extension. Given K-subspaces A,B of L, we consider the subspace 〈AB〉 spanned by the product set . If dimKA=r and dimKB=s, how small can the dimension of 〈AB〉 be? In this paper we give a complete answer to this question in characteristic 0, and more generally for separable extensions. The optimal lower bound on dimK〈AB〉 turns out, in this case, to be provided by the numerical function
956.
Mabrouk Ben Nasr 《Monatshefte für Mathematik》2009,158(1):97-102
An extension of integral domains is said to have the “finite length of intermediate chains of domains” property (for short FICP) if each chain of intermediate
rings between R and S is finite. The main purpose of this paper is to characterize when has FICP in case R
* (the integral closure of R in S) is a finite dimensional semilocal domain. This generalizes a theorem due to Gilmer, in which S is the quotient field of R. Examples illustrating the sharpness and the limits of our results are settled.
相似文献
957.
Catarina A. Carvalho 《Semigroup Forum》2009,79(1):145-158
We say that a class of monoids satisfies the property ℘ if every monoid in that class that admits a finitely presented Bruck–Reilly
extension is finitely generated. We show that completely (0-)simple semigroups satisfy ℘, and that the direct product of two
monoids in a class that satisfy ℘ also satisfies ℘ subject to a certain condition on the endomorphisms of the direct product.
As a consequence of this result we obtain a new class of bands and a new class of completely regular semigroups that satisfy
property ℘. 相似文献
958.
Stanisawa Kanas 《Applied mathematics and computation》2009,215(6):2275-2282
A quasiconformal extension for the class of k-uniformly convex functions, denoted , and for the class of k-starlike functions, denoted is provided. Also, estimation of the norm of pre-Schwarzian derivative in is given. 相似文献
959.
The notion of a relatively uniform convergence (ru-convergence) has been used first in vector lattices and then in Archimedean
lattice ordered groups.
Let G be an Archimedean lattice ordered group. In the present paper, a relative uniform completion (ru-completion) of G is dealt with. It is known that exists and it is uniquely determined up to isomorphisms over G. The ru-completion of a finite direct product and of a completely subdirect product are established. We examine also whether
certain properties of G remain valid in . Finally, we are interested in the existence of a greatest convex l-subgroup of G, which is complete with respect to ru-convergence.
This work was supported by Science and Technology Assistance Agency under the contract No. APVT-20-004104. Supported by Grant
VEGA 1/3003/06. 相似文献
960.
Much of General Topology addresses this issue: Given a function fC(Y,Z) with YY′ and ZZ′, find , or at least , such that ; sometimes Z=Z′ is demanded. In this spirit the authors prove several quite general theorems in the context Y′=(XI)κ=∏iIXi in the κ-box topology (that is, with basic open sets of the form ∏iIUi with Ui open in Xi and with Ui≠Xi for <κ-many iI). A representative sample result, extending to the κ-box topology some results of Comfort and Negrepontis, of Noble and Ulmer, and of Hušek, is this. Theorem Let ωκα (that means: κ<α, and [β<α and λ<κ]βλ<α) with α regular, be a set of non-empty spaces with each d(Xi)<α, π[Y]=XJ for each non-empty JI such that |J|<α, and the diagonal in Z be the intersection of <α-many regular-closed subsets of Z×Z. Then (a) Y is pseudo-(α,α)-compact, (b) for every fC(Y,Z) there is J[I]<α such that f(x)=f(y) whenever xJ=yJ, and (c) every such f extends to . 相似文献