全文获取类型
收费全文 | 19173篇 |
免费 | 743篇 |
国内免费 | 99篇 |
专业分类
化学 | 13104篇 |
晶体学 | 120篇 |
力学 | 420篇 |
数学 | 2930篇 |
物理学 | 3441篇 |
出版年
2023年 | 122篇 |
2022年 | 174篇 |
2021年 | 269篇 |
2020年 | 377篇 |
2019年 | 398篇 |
2018年 | 234篇 |
2017年 | 237篇 |
2016年 | 602篇 |
2015年 | 559篇 |
2014年 | 646篇 |
2013年 | 1025篇 |
2012年 | 1118篇 |
2011年 | 1253篇 |
2010年 | 745篇 |
2009年 | 659篇 |
2008年 | 1035篇 |
2007年 | 1024篇 |
2006年 | 952篇 |
2005年 | 886篇 |
2004年 | 773篇 |
2003年 | 639篇 |
2002年 | 609篇 |
2001年 | 310篇 |
2000年 | 291篇 |
1999年 | 277篇 |
1998年 | 242篇 |
1997年 | 232篇 |
1996年 | 266篇 |
1995年 | 250篇 |
1994年 | 221篇 |
1993年 | 211篇 |
1992年 | 199篇 |
1991年 | 174篇 |
1990年 | 176篇 |
1989年 | 174篇 |
1988年 | 150篇 |
1987年 | 126篇 |
1986年 | 115篇 |
1985年 | 169篇 |
1984年 | 161篇 |
1983年 | 127篇 |
1982年 | 154篇 |
1981年 | 159篇 |
1980年 | 133篇 |
1979年 | 141篇 |
1978年 | 160篇 |
1977年 | 116篇 |
1976年 | 101篇 |
1975年 | 118篇 |
1974年 | 90篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
V.A. Khoze A.D. Martin M.G. Ryskin 《The European Physical Journal C - Particles and Fields》2002,24(3):459-468
The rich structure of photon-exchange processes at hadron colliders is studied. We discuss central vector meson production
, W production and production. Each process has distinct, and large, soft pp rescattering effects, which can be directly observed by detecting the outgoing protons. This allows a probe of the optical
density of the proton, which plays a crucial role in the evaluation of the rapidity gap survival probabilities in diffractive-like
processes at hadron colliders. We note that an alternative mechanism for production is odderon, instead of photon, exchange; and that the ratio of odderon to photon contributions is enhanced (suppressed)
for vector meson production.
Received: 1 February 2002 / Revised version: 4 April 2002 / Published online: 22 May 2002 相似文献
52.
Motivated by Gauss's first proof of the Fundamental Theorem of Algebra, we study the topology of harmonic algebraic curves.
By the maximum principle, a harmonic curve has no bounded components; its topology is determined by the combinatorial data
of a noncrossing matching. Similarly, every complex polynomial gives rise to a related combinatorial object that we call a
basketball, consisting of a pair of noncrossing matchings satisfying one additional constraint. We prove that every noncrossing
matching arises from some harmonic curve, and deduce from this that every basketball arises from some polynomial. 相似文献
53.
Andrew S. Zektzer Gary E. Martin Raymond N. Castle 《Journal of heterocyclic chemistry》1987,24(3):879-884
Phenanthro[3,4:3′,4′]phenanthro[2,1-b]thiophene ( 1 ) served as the model system to evaluate two-dimensional proton zero quantum coherence nmr in order to establish the vicinal proton-proton connectivities. The utility of the two-dimensional proton zero quantum nmr experiment has been compared with the utility of the traditional autocorrelated proton-proton (COSY) experiment. In the case of a molecule such as 1 , where the proton chemical shifts are so highly congested, the zero quantum coherence experiment provides data not obtainable from the COSY experiment. 相似文献
54.
We give a self‐contained proof of the preservation theorem for proper countable support iterations known as “tools‐preservation”, “Case A” or “first preservation theorem” in the literature. We do not assume that the forcings add reals. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
55.
D. Abbaneo P. Antilogus T. Behnke S.C. Blyth M. Elsing R. Faccini R.W.L. Jones K. Mönig S. Petzold R. Tenchini 《The European Physical Journal C - Particles and Fields》1998,4(2):185-191
Measurements of the forward-backward production asymmetry of heavy quarks in Z decays provide a precise determination of
. The asymmetries are sensitive to QCD effects, in particular hard gluon radiation. In this paper QCD corrections for and are discussed. The interplay between the experimental techniques used to measure the asymmetries and the QCD effects is
investigated using simulated events. A procedure to estimate the correction needed for experimental measurements is proposed,
and some specific examples are given.
Received: 26 February 1998 / Published online: 2 June 1998 相似文献
56.
57.
We prove that the Mellin transform of a function log-concave (convex) is, after division by (+1), where is the argument of the transform, itself log-concave (convex) in . This theorem is first applied to the moments of the ground state wave function of the Schrödinger equation where the Laplacian of the central potential has a given sign, and generalized to other situations. This is used to derive inequalities linking thel
th derivative of the ground state wave function at the origin for angular momentuml and the expectation value of the kinetic energy, and applied to quarkonium physics. A generalization to higher radial excitations is shown to be plausible by using the WKB approximation. Finally, new bounds on ground-state energies in power potentials are obtained. 相似文献
58.
Martin Bordemann 《Communications in Mathematical Physics》1990,135(1):201-216
We generalize the usual Lax equationd/dt L=[M, L] byd/dt L=–(M)L, where is an arbitrary representation of a Lie algebra g (the values ofM) in a representation spaceV (the values ofL). The usual classicalr-matrix programme for Hamiltonian integrable systems is generalized tor-matrices taking values in gV. Ther-matrices are then considered as left invariant torsion-free covariant derivatives on a Lie groupK (with Lie algebraV
*). The Classical Yang-Baxter Equation (CYBE) is equivalent to the flatness ofK whereas the Modified CYBE implies thatK is an affine locally symmetric space. An example is discussed. 相似文献
59.
60.
Anjos JC Appel JA Bean A Bracker SB Browder TE Cremaldi LM Duboscq JE Elliott JR Escobar CO Gibney MC Hartner GF Karchin PE Kumar BR Losty MJ Luste GJ Mantsch PM Martin JF McHugh S Menary SR Morrison RJ Nash T Ong P Pinfold J Punkar G Purohit MV Santoro AF Sidhu JS Sliwa K Sokoloff MD Souza MH Spalding WJ Streetman ME Stundia AB Witherell MS 《Physical review letters》1990,64(24):2885-2888