全文获取类型
收费全文 | 33133篇 |
免费 | 840篇 |
国内免费 | 750篇 |
专业分类
化学 | 6819篇 |
晶体学 | 959篇 |
力学 | 491篇 |
综合类 | 48篇 |
数学 | 21383篇 |
物理学 | 5023篇 |
出版年
2023年 | 79篇 |
2022年 | 255篇 |
2021年 | 197篇 |
2020年 | 232篇 |
2019年 | 637篇 |
2018年 | 681篇 |
2017年 | 447篇 |
2016年 | 487篇 |
2015年 | 492篇 |
2014年 | 911篇 |
2013年 | 2392篇 |
2012年 | 902篇 |
2011年 | 2304篇 |
2010年 | 1997篇 |
2009年 | 2119篇 |
2008年 | 2358篇 |
2007年 | 2324篇 |
2006年 | 1729篇 |
2005年 | 1401篇 |
2004年 | 1249篇 |
2003年 | 1015篇 |
2002年 | 955篇 |
2001年 | 640篇 |
2000年 | 646篇 |
1999年 | 679篇 |
1998年 | 658篇 |
1997年 | 536篇 |
1996年 | 629篇 |
1995年 | 636篇 |
1994年 | 590篇 |
1993年 | 478篇 |
1992年 | 497篇 |
1991年 | 347篇 |
1990年 | 312篇 |
1989年 | 330篇 |
1988年 | 217篇 |
1987年 | 231篇 |
1986年 | 187篇 |
1985年 | 276篇 |
1984年 | 244篇 |
1983年 | 132篇 |
1982年 | 208篇 |
1981年 | 233篇 |
1980年 | 164篇 |
1979年 | 113篇 |
1978年 | 165篇 |
1977年 | 128篇 |
1976年 | 121篇 |
1975年 | 53篇 |
1974年 | 50篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
In this paper we relate the operators in the operator representations of a generalized Nevanlinna function N(z) and of the function −N(z)−1 under the assumption that z=∞ is the only (generalized) pole of nonpositive type. The results are applied to the Q-function for S and H and the Q-function for S and H∞, where H is a self-adjoint operator in a Pontryagin space with a cyclic element w, H∞ is the self-adjoint relation obtained from H and w via a rank one perturbation at infinite coupling, and S is the symmetric operator given by S=H∩H∞. 相似文献
72.
Vinod Kumar Pragya Das R.P. Singh S. Muralithar R.K. Bhowmik 《The European Physical Journal A - Hadrons and Nuclei》2003,17(2):153-157
The fusion evaporation reaction 122Sn(14N, 4n)132La was used to populate the high-spin states of 132La at the beam energy of 60 MeV. A new band consisting of mostly E2 transitions has been discovered. This band has the interesting links to the ground state 2- and the isomeric state 6-. A new transition of energy 351 keV connecting the low-spin states of the positive-parity band based on the πh
11/2 ⊗ νh
11/2 particle configuration, has been found. This has played a very important role in resolving the existing ambiguities and inconsistencies
in the spin assignment of the band head.
Received: 12 August 2002 / Accepted: 18 March 2003 / Published online: 7 May 2003 相似文献
73.
M Gubinelli 《Journal of Functional Analysis》2004,216(1):86-140
We formulate indefinite integration with respect to an irregular function as an algebraic problem which has a unique solution under some analytic constraints. This allows us to define a good notion of integral with respect to irregular paths with Hölder exponent greater than 1/3 (e.g. samples of Brownian motion) and study the problem of the existence, uniqueness and continuity of solution of differential equations driven by such paths. We recover Young's theory of integration and the main results of Lyons’ theory of rough paths in Hölder topology. 相似文献
74.
D. Ruiz 《Journal of Differential Equations》2004,199(1):96-114
In this paper we study the existence of positive solutions for a nonlinear Dirichlet problem involving the m-Laplacian. The nonlinearity considered depends on the first derivatives; in such case, variational methods cannot be applied. So, we make use of topological methods to prove the existence of solutions. We combine a blow-up argument and a Liouville-type theorem to obtain a priori estimates. Some Harnack-type inequalities which are needed in our reasonings are also proved. 相似文献
75.
R. Bairava Ganesh Hitoshi Matsuo Takahiro Kawamura Yoshihiro Kangawa Koji Arafune Yoshio Ohshita Masafumi Yamaguchi Koichi Kakimoto 《Journal of Crystal Growth》2008,310(11):2697-2701
Multicrystalline silicon was grown by unidirectional solidification method using the accelerated crucible rotation technique. The application of the accelerated crucible rotation technique in unidirectional solidification method induced growth striations across the axial direction of the grown crystal. This striation pattern was observed from carbon concentration distribution, obtained by using Fourier transform infrared spectroscopy. The generated striation pattern was found to be weak and discontinuous. Some striations were absent, probably due to back melting, caused during each crucible rotation. From the growth striations and applied time period in crucible rotation, the growth rate was estimated by using Fourier transformation analysis. 相似文献
76.
77.
Operators on manifolds with corners that have base configurations with geometric singularities can be analysed in the frame of a conormal symbolic structure which is in spirit similar to the one for conical singularities of Kondrat'ev's work. Solvability of elliptic equations and asymptotics of solutions are determined by meromorphic conormal symbols. We study the case when the base has edge singularities which is a natural assumption in a number of applications. There are new phenomena, caused by a specific kind of higher degeneracy of the underlying symbols. We introduce an algebra of meromorphic edge operators that depend on complex parameters and investigate meromorphic inverses in the parameter-dependent elliptic case. Among the examples are resolvents of elliptic differential operators on manifolds with edges. 相似文献
78.
Peter Clifford 《Annals of Combinatorics》2005,9(3):281-291
Motivated by recent results of Stanley, we generalize the rank of a partition λ to the rank of a shifted partition S(λ). We show that the number of bars required in a minimal bar tableau of S(λ) is max(o, e + (ℓ(λ) mod 2)), where o and e are the number of odd and even rows of λ. As a consequence we show that the irreducible projective characters of Sn vanish on certain conjugacy classes. Another corollary is a lower bound on the degree of the terms in the expansion of Schur’s
Qλ symmetric functions in terms of the power sum symmetric functions.
Received November 20, 2003 相似文献
79.
《Magnetic resonance in chemistry : MRC》2003,41(1):37-41
The oxidation of symmetrical disulfides [D ,L ‐cystine ( 1 ) and 3,3′‐dithiobis(propionic acid) ( 2 )] with hydrogen peroxide in D2O–NaOH solution (pH 10–11) was studied by NMR spectroscopy. Assignments of the proton and carbon NMR signals of starting materials ( 1 and 2 ) and products of oxidation are based on conventional 1D NMR methods (DEPT, selective spin decoupling). Formation of C—S bond cleavage products or, in case of 2 , partially oxidized intermediates was not detected. The accelerating effect of Cu2+ cations, but not Fe3+ cations, on the oxidation rate of 1 in basic medium was demonstrated. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
80.
Extending to r > 1 a formula of the authors, we compute the expected reflection distance of a product of t random reflections in the complex reflection group G(r, 1, n). The result relies on an explicit decomposition of the reflection distance function into irreducible G(r, 1, n)-characters and on the eigenvalues of certain adjacency matrices.Received December 8, 2003 相似文献