全文获取类型
收费全文 | 13180篇 |
免费 | 882篇 |
国内免费 | 558篇 |
专业分类
化学 | 4076篇 |
晶体学 | 42篇 |
力学 | 825篇 |
综合类 | 80篇 |
数学 | 6492篇 |
物理学 | 3105篇 |
出版年
2024年 | 18篇 |
2023年 | 192篇 |
2022年 | 290篇 |
2021年 | 365篇 |
2020年 | 469篇 |
2019年 | 449篇 |
2018年 | 447篇 |
2017年 | 498篇 |
2016年 | 431篇 |
2015年 | 397篇 |
2014年 | 735篇 |
2013年 | 1532篇 |
2012年 | 706篇 |
2011年 | 736篇 |
2010年 | 573篇 |
2009年 | 862篇 |
2008年 | 869篇 |
2007年 | 723篇 |
2006年 | 606篇 |
2005年 | 554篇 |
2004年 | 443篇 |
2003年 | 346篇 |
2002年 | 314篇 |
2001年 | 182篇 |
2000年 | 232篇 |
1999年 | 224篇 |
1998年 | 191篇 |
1997年 | 173篇 |
1996年 | 150篇 |
1995年 | 103篇 |
1994年 | 97篇 |
1993年 | 82篇 |
1992年 | 74篇 |
1991年 | 49篇 |
1990年 | 36篇 |
1989年 | 40篇 |
1988年 | 35篇 |
1987年 | 30篇 |
1986年 | 23篇 |
1985年 | 62篇 |
1984年 | 62篇 |
1983年 | 34篇 |
1982年 | 37篇 |
1981年 | 32篇 |
1980年 | 24篇 |
1979年 | 23篇 |
1978年 | 17篇 |
1977年 | 12篇 |
1976年 | 11篇 |
1973年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
91.
The theoretical investigation of the image states in front of an ultrathin iron film grown on copper has been performed by means of the embedding method and a recently developed procedure for the inclusion of the image potential tail in a first principle calculation. From the electronic response to an applied electric field, the image plane position has been evaluated. This also allows one to obtain useful information about the spin dependent screening properties of the system. Exchange splitting, effective mass, and lifetime of such surface states result in good agreement with recently performed two-photon photoemission experiments [see A.B. Schmidt, M. Pickel, M. Wiemhöfer, M. Donath, M. Weinelt, Phys. Rev. Lett. 95 (2005) 107402]. 相似文献
92.
1846年,刘维尔在自己主办的杂志“纯粹与应用数学杂志”首次出版了伽罗瓦的数学研究,这对于伽罗瓦理论的传播与发展是具有决定意义的事件.伽罗瓦去世14年后,刘维尔发表伽罗瓦数学研究的原因是什么?采用数学历史文献分析法,得出四个重要原因:①伽罗瓦的朋友和弟弟的请求;②力图弥补科学院曾经造成的不公正;③刘维尔积极扶持年轻人的高贵品质使然;④刘维尔与利布里学术论战的促进. 相似文献
93.
Eiji Yanagida 《Journal of Dynamics and Differential Equations》2007,19(4):895-914
This paper is concerned with the irregular behavior of solutions for Fisher’s equation when initial data do not decay in a
regular way at the spatial infinity. In the one-dimensional case, we show the existence of a solution whose profile and average
speed are not convergent. In the higher-dimensional case, we show the existence of expanding fronts with arbitrarily prescribed
profiles. We also show the existence of irregularly expanding fronts whose profile varies in time. Proofs are based on some
estimate of the difference of two distinct solutions and a comparison technique.
Dedicated to Professor Pavol Brunovsky on his 70th birthday. 相似文献
94.
Steven G. From 《Annals of the Institute of Statistical Mathematics》1991,43(1):167-179
In this paper, a family of estimators for estimating means when mixing two independent Poisson samples is proposed. This family is based on the probability-generating function of the Poisson distribution and is offered as an alternative to the maximum likelihood estimators, which have some drawbacks. These estimators include the method of moments estimators as a special limiting case. 相似文献
95.
Olav Kallenberg 《Stochastic Processes and their Applications》1992,40(2):199-223
From the predictable reduction of a marked point process to Poisson, we derive a similar reduction theorem for purely discontinuous martingales to processes with independent increments. Both results are then used to examine the existence of stochastic integrals with respect to stable Lévy processes, and to prove a variety of time change representations for such integrals. The Knight phenomenon, where possibly dependent but orthogonal processes become independent after individual time changes, emerges as a general principle. 相似文献
96.
We show by general considerations that it is not possible to test violation of the existing versions of Bell’s inequality
in entangled neutral kaons system using experimentally accessible thin regenerators. We point out the loophole in the recent
argument (A Bramon and M Nowakowski, Phys. Rev. Lett.
83, 1 (1999)) that claimed such a test to be possible. 相似文献
97.
Lin Zhengyan 《数学年刊B辑(英文版)》1998,19(3):281-292
§1.IntroductionandResultsLet{Xn,n1}beasequenceofrandomvariableswithacommondistributionfunctionF(x)andletXn1Xn2…Xnnbetheor... 相似文献
98.
99.
Derived Brackets 总被引:3,自引:1,他引:2
Yvette Kosmann-Schwarzbach 《Letters in Mathematical Physics》2004,69(1-3):61-87
We survey the many instances of derived bracket construction in differential geometry, Lie algebroid and Courant algebroid theories, and their properties. We recall and compare the constructions of Buttin and of Vinogradov, and we prove that the Vinogradov bracket is the skew-symmetrization of a derived bracket. Odd (resp., even) Poisson brackets on supermanifolds are derived brackets of canonical even (resp., odd) Poisson brackets on their cotangent bundle (resp., parity-reversed cotangent bundle). Lie algebras have analogous properties, and the theory of Lie algebroids unifies the results valid for manifolds on the one hand, and for Lie algebras on the other. We outline the role of derived brackets in the theory of Poisson structures with background'. 相似文献
100.
Hiroshi Ito Masaki Okazaki Dolores C. Miller 《Journal of polymer science. Part A, Polymer chemistry》2004,42(6):1478-1505
Radical copolymerizations of electron‐deficient 2‐trifluoromethylacrylic (TFMA) monomers, such as 2‐trifluoromethylacrylic acid and t‐butyl 2‐trifluoromethylacrylate (TBTFMA), with electron‐rich norbornene derivatives and vinyl ethers with 2,2′‐azobisisobutyronitrile as the initiator were investigated in detail through the analysis of the kinetics in situ with 1H NMR and through the determination of the monomer reactivity ratios. The norbornene derivatives used in this study included bicyclo[2.2.1]hept‐2‐ene (norbornene) and 5‐(2‐trifluoromethyl‐1,1,1‐trifluoro‐2‐hydroxylpropyl)‐2‐norbornene. The vinyl ether monomers were ethyl vinyl ether, t‐butyl vinyl ether, and 3,4‐dihydro‐2‐H‐pyran. Vinylene carbonate was found to copolymerize with TBTFMA. Although none of the monomers underwent radical homopolymerization under normal conditions, they copolymerized readily, producing a copolymer containing 60–70 mol % TFMA. The copolymerization of the TFMA monomer with norbornenes and vinyl ethers deviated from the terminal model and could be described by the penultimate model. The copolymers of TFMA reported in this article were evaluated as chemical amplification resist polymers for the emerging field of 157‐nm lithography. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1478–1505, 2004 相似文献