全文获取类型
收费全文 | 42694篇 |
免费 | 1459篇 |
国内免费 | 137篇 |
专业分类
化学 | 22601篇 |
晶体学 | 215篇 |
力学 | 1104篇 |
综合类 | 5篇 |
数学 | 7078篇 |
物理学 | 13287篇 |
出版年
2023年 | 274篇 |
2021年 | 339篇 |
2020年 | 517篇 |
2019年 | 400篇 |
2018年 | 540篇 |
2017年 | 538篇 |
2016年 | 1132篇 |
2015年 | 866篇 |
2014年 | 981篇 |
2013年 | 2049篇 |
2012年 | 1915篇 |
2011年 | 2071篇 |
2010年 | 1378篇 |
2009年 | 1147篇 |
2008年 | 1926篇 |
2007年 | 1816篇 |
2006年 | 1702篇 |
2005年 | 1573篇 |
2004年 | 1333篇 |
2003年 | 1107篇 |
2002年 | 958篇 |
2001年 | 907篇 |
2000年 | 732篇 |
1999年 | 534篇 |
1998年 | 454篇 |
1997年 | 455篇 |
1996年 | 565篇 |
1995年 | 514篇 |
1994年 | 528篇 |
1993年 | 555篇 |
1992年 | 610篇 |
1991年 | 425篇 |
1990年 | 429篇 |
1989年 | 393篇 |
1988年 | 364篇 |
1987年 | 374篇 |
1986年 | 347篇 |
1985年 | 539篇 |
1984年 | 525篇 |
1983年 | 438篇 |
1982年 | 476篇 |
1981年 | 466篇 |
1980年 | 451篇 |
1979年 | 449篇 |
1978年 | 448篇 |
1977年 | 435篇 |
1976年 | 404篇 |
1975年 | 402篇 |
1974年 | 380篇 |
1973年 | 320篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
Jürg Kramer 《Elemente der Mathematik》2002,57(3):115-120
72.
The contributions to the coefficient functions of the quark and the mixed quark-gluon condensate to mesonic correlators are calculated for the first time to all orders in the quark masses, and to lowest order in the strong coupling constant. Existing results on the coefficient functions of the unit operator and the gluon condensate are reviewed. The proper factorization of short- and long-distance contributions in the operator product expansion is discussed in detail. It is found that to accomplish this task rigorously the operator product expansion has to be performed in terms ofnon-normal-ordered condensates. The resulting coefficient functions are improved with the help of the renormalization group. The scale invariant combination of dimension 5 operators, including mixing with the mass operator, which is needed for the renormalization group improvement, is calculated in the leading order.Supported by the German Bundesministerium für Forschung und Technologie, under the contract 06 TM 761 相似文献
73.
This author wants to express his thanks to the School of Information Engineering at Teesside Polytechnic, Middlesbrough, England, for its support and hospitality during a visiting appointment of 3 months in 1989, when this paper was written. 相似文献
74.
Correspondence is established between sigma models, minimal surfaces and the Monge–Ampére equation. The Lax pairs of the minimality condition of the minimal surfaces and the Monge–Ampére equations are given. Existence of infinitely many nonlocal conservation laws is shown and some Bäcklund transformations are also given. 相似文献
75.
S. Trebert Haeberlin F. Lux J. Karl T. Spruss H. Schönenberger 《Journal of Radioanalytical and Nuclear Chemistry》1987,113(2):461-467
As part of an examination of the cytostatic effects of 1,2-diarylethylenediamine-platinum(II)-complexes the contents of platinum and biologically essential trace elements of tumour tissue and different organs were determined. The activation analysis procedure — separation of32P, isolation of199Au and99Mo — is described. In the course of a pharmakokinetical experiment with tumourbearing rats (DMBA induced hormone-dependent tumours) the desired enrichment of the administered drug in the tumour tissue was found. Changes of the trace element level of tumour tissue were found for hormone-dependent MXT-mammary tumours on mice. 相似文献
76.
Mustafa Çelebier Ertan Şahin Nilgün Ancın Nurşen Altuntaş Öztaş Selma Gül Öztaş 《应用有机金属化学》2007,21(10):viii-viii
The article referenced above was first published online on 30 August 2007 with incorrect pagination; the pagination has now been corrected online and in print. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
77.
Let A be an algebra without unit. If ∥ ∥ is a complete regular norm on A it is known that among the regular extensions of ∥ ∥ to the unitization of A there exists a minimal (operator extension) and maximal (ℓ1-extension) which are known to be equivalent. We shall show that the best upper bound for the ratio of these two extensions
is exactly 3. This improves the results represented by A. K. Gaur and Z. V. Kovářík and later by T. W. Palmer.
The second author was partially supported by the grant No. 201/03/0041 of GAČR. 相似文献
78.
Bahattin Gümgüm Nermin Biricik Feyyaz Durap Ismail Özdemir Nevin Gürbüz Wee Han Ang Paul J. Dyson 《应用有机金属化学》2007,21(8):711-715
Palladium(II) complexes with N,N‐bis(diphenylphosphino)aniline ligands catalyse the Heck reaction between styrene and aryl bromides, affording stilbenes in good yield. The structures of two of the complexes used as pre‐catalysts have been determined by single‐crystal X‐ray diffraction. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
79.
Vlasov Yu. G. Murzina Yu. G. Legin A. V. Ermolenko Yu. E. Schubert J. Schüoning M. J. Lut H. 《Russian Journal of Applied Chemistry》2002,75(3):351-356
Methods of silicon planar technology and pulsed laser deposition were applied to fabricate fully solid-state chemical sensors for determining ions of copper, lead, cadmium, thallium, and also sulfide and chloride ions on the basis of thin chalcogenide films as ion-sensitive membranes. 相似文献
80.
We study a class of nonlinear Ito stochastic differential equations (with possibly state dependent diffusion coefficients), in which the variables can be divided into linearly damped (slaved) variables s and linearly undamped variablesu (order parameters). We devise a systematic and constructive procedure to eliminate the slaved variables. We take explicit time and chance dependence of the slaved variables into account, the latter via a family of diffusion processesZ
t
(v)
. These act as fluctuating coefficients of the Center Manifolds
t=s(u
t, t,Z
t
(v)
(v=2, 3, ...)) and appear explicitly in the elimination procedure. We show how in the Ito calculus fluctuating and deterministic coefficients of the Center Manifold are more completely separated than in the previously treated Stratonovich case [1]. The adiabatic approximation is defined as a partial summation of the elimination expansion and the stochastic generalization ofs=0 is derived. We show how thus ambiguity of stochastic calculi is removed. Closed form summations are given in two examples. We briefly indicate the potential use of perturbation theory techniques in the systematic elimination procedure. 相似文献