全文获取类型
收费全文 | 41523篇 |
免费 | 1440篇 |
国内免费 | 147篇 |
专业分类
化学 | 21954篇 |
晶体学 | 205篇 |
力学 | 1155篇 |
综合类 | 5篇 |
数学 | 7032篇 |
物理学 | 12759篇 |
出版年
2023年 | 273篇 |
2021年 | 357篇 |
2020年 | 523篇 |
2019年 | 401篇 |
2018年 | 554篇 |
2017年 | 556篇 |
2016年 | 1134篇 |
2015年 | 863篇 |
2014年 | 999篇 |
2013年 | 2041篇 |
2012年 | 1931篇 |
2011年 | 2086篇 |
2010年 | 1405篇 |
2009年 | 1158篇 |
2008年 | 1948篇 |
2007年 | 1797篇 |
2006年 | 1730篇 |
2005年 | 1560篇 |
2004年 | 1352篇 |
2003年 | 1096篇 |
2002年 | 963篇 |
2001年 | 873篇 |
2000年 | 737篇 |
1999年 | 509篇 |
1998年 | 458篇 |
1997年 | 434篇 |
1996年 | 534篇 |
1995年 | 482篇 |
1994年 | 503篇 |
1993年 | 523篇 |
1992年 | 571篇 |
1991年 | 392篇 |
1990年 | 408篇 |
1989年 | 367篇 |
1988年 | 336篇 |
1987年 | 350篇 |
1986年 | 323篇 |
1985年 | 511篇 |
1984年 | 496篇 |
1983年 | 414篇 |
1982年 | 438篇 |
1981年 | 439篇 |
1980年 | 437篇 |
1979年 | 419篇 |
1978年 | 406篇 |
1977年 | 398篇 |
1976年 | 378篇 |
1975年 | 362篇 |
1974年 | 350篇 |
1973年 | 295篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
121.
Michael Demuth Peter Stollmann Günter Stolz Jan van Casteren 《Integral Equations and Operator Theory》1995,23(2):145-153
We give trace norm estimates for products of integral operators and for diffusion semigroups. These are applied to differences of heat semigroups. A natural example of an integral operator with finite trace which is not trace class is given. 相似文献
122.
Yanfei Lü 《中国光学快报(英文版)》2007,5(6)
A new resonator design for doubly resonant continuous-wave (CW) intracavity sum-frequency mixing (SFM) is reported. 1.12 W of coherent radiation at 588 nm is generated by mixing 1062-nm Nd:GdVO4laser and 1319-nm Nd:YAG laser. The optical-to-optical conversion efficiency is up to 3.7%. 相似文献
123.
Let Top
0
be the category of topological T
0-spaces, QU
0
the category of quasi-uniform T
0-spaces, T : QU
0
→ Top
0
the usual forgetful functor and K : QU
0
→ QU
0
the bicompletion reflector with unit k : 1 → K. Any T-section F : Top
0
→ QU
0
is called K-true if KF = FTKF, and upper (lower)
K-true if KF is finer (coarser) than FTKF. The literature considers important T-sections F that enjoy all three, or just one, or none of these properties. It is known that T(K,k)F is well-pointed if and only if F is upper K-true. We prove the surprising fact that T(K,k)F is the reflection to Fix(TkF) whenever it is idempotent. We also prove a new characterization of upper K-trueness. We construct examples to set apart some natural cases. In particular we present an upper K-true F for which T(K,k)F is not idempotent, and a K-true F for which the coarsest associated T-preserving coreflector in QU
0
is not stable under K.
We dedicate this paper to the memory of Sérgio de Ornelas Salbany (1941–2005). 相似文献
124.
125.
126.
The synthesis of indole ring-fused benzazepinone series as latonduine derivatives has been developed via an intramolecular Heck reaction. The scope has been enlarged not only to indole moiety but also to pyrrolo and benzo[b]thiophene nuclei. Several derivatives prepared have been evaluated in vitro for their antiproliferative activities on breast cancer cell lines. Some of them showed promising cytotoxic activities. 相似文献
127.
Sedimentation and erosion processes in sedimentary basins can be modeled by a parabolic equation with a limiter on the fluxes and a constraint on the time variation.This limiter happens to satisfy a stationary scalar hyperbolic inequality,within a constraint,for which the authors prove the existence and the uniqueness of the solution.Actually,this solution is shown to be the maximal element of a convenient convex set of functions.The existence proof is obtained thanks to the use of a numerical scheme. 相似文献
128.
The FRS-ESR facility at GSI provides one of the most efficient methods for direct mass measurements. In the present experiment,
exotic nuclei were produced via fragmentation of 152Sm projectiles in a thick beryllium target at 500-600 MeV/u, separated in-flight with the fragment separator FRS, and injected
into the storage-cooler ring ESR. Time-resolved Schottky Mass Spectrometry was applied for mass measurements of stored and
electron-cooled bare and few-electron ions. 373 different nuclides were identified by means of the spectra of their revolution
frequencies. Masses for 18 nuclides (84Zr, 92Ru, 94Rh, 107,108,110Sb, 111,112,114I, 118Ba, 122,123La, 124Ce, 127Pr, 129Nd, 132Pm, 134Sm, 137Eu) have been determined for the first time. Masses for 111,112I and 113Xe have been obtained via known α-decay energies. The experiment and first results will be presented. 相似文献
129.
J. -R. Chazottes P. Collet C. Külske F. Redig 《Probability Theory and Related Fields》2007,137(1-2):201-225
We present a new and simple approach to concentration inequalities in the context of dependent random processes and random
fields. Our method is based on coupling and does not use information inequalities. In case one has a uniform control on the
coupling, one obtains exponential concentration inequalities. If such a uniform control is no more possible, then one obtains
polynomial or stretched-exponential concentration inequalities. Our abstract results apply to Gibbs random fields, both at
high and low temperatures and in particular to the low-temperature Ising model which is a concrete example of non-uniformity
of the coupling.
相似文献
130.
Langevin approach implemented in the inelastic cross-sections measured for the low-energy electrons colliding with metallic
clusters points out that statical form of the polarizability dominate at energies less than 1.25 eV. The dynamical form comes
into play at energies around 1.3 eV. The form of the polarizabilities indicates that polarizability of the metallic clusters
is energy-dependent. 相似文献