全文获取类型
收费全文 | 254篇 |
免费 | 6篇 |
专业分类
化学 | 103篇 |
力学 | 2篇 |
数学 | 26篇 |
物理学 | 129篇 |
出版年
2023年 | 4篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 2篇 |
2014年 | 1篇 |
2013年 | 5篇 |
2012年 | 10篇 |
2011年 | 8篇 |
2010年 | 12篇 |
2009年 | 7篇 |
2008年 | 10篇 |
2007年 | 20篇 |
2006年 | 19篇 |
2005年 | 28篇 |
2004年 | 18篇 |
2003年 | 14篇 |
2002年 | 24篇 |
2001年 | 5篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 5篇 |
1996年 | 1篇 |
1995年 | 4篇 |
1994年 | 6篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1971年 | 3篇 |
1967年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有260条查询结果,搜索用时 29 毫秒
181.
Gershon Wolansky 《Journal of Dynamics and Differential Equations》1994,6(2):247-276
We consider the Burgers equation with a nonhomogeneous drift term, in the limit of small dissipation. A finite-dimensional manifold of slowly varying shock-like solutions is described, and a formal derivation of the dynamics on this manifold, in terms of a system of ordinary differential equations, is given. We also discuss the interpretation of the stationary solutions to the Burgers equation imbedded on the slow manifold. 相似文献
182.
183.
The Dirichlet problem for elliptic systems of the second order with constant real and complex coefficients in the half-space k + = {x = (x 1,…,xk ): xk > 0} is considered. It is assumed that the boundary values of a solution u = (u 1,…,u m) have the form ψ 1 ξ 1 + · · · + ψ n ξ n, 1 ≤ n ≤ m, where ξ 1,· · ·,ξ n is an orthogonal system of m-component normed vectors and ψ 1,· · ·,ψ n are continuous and bounded functions on ? k +. We study the mappings [C(? k +)] n ? (ψ 1,…,ψ n) → u(x) ? m and [C(? k +)] n ? (ψ 1,…,ψ n) → u(x) ? m generated by real and complex vector valued double layer potentials. We obtain representations for the sharp constants in inequalities between |u(x)| or |(z, u(x))| and ∥u| xk =0∥, where z is a fixed unit m-component vector, | · | is the length of a vector in a finite-dimensional unitary space or in Euclidean space, and (·,·) is the inner product in the same space. Explicit representations of these sharp constants for the Stokes and Lamé systems are given. We show, in particular, that if the velocity vector (the elastic displacement vector) is parallel to a constant vector at the boundary of a half-space and if the modulus of the boundary data does not exceed 1, then the velocity vector (the elastic displacement vector) is majorised by 1 at an arbitrary point of the half-space. An analogous classical maximum modulus principle is obtained for two components of the stress tensor of the planar deformed state as well as for the gradient of a biharmonic function in a half-plane. 相似文献
184.
The crystal structure of K[BF3(CN)] (Pbcn (Nr. 60) with a = 13.3486(15) b = 6.5239(7) c = 10.0085(11) Å, and eight formula units per unit cell) has been determined and the one of K[BF2(CN)2] was confirmed and improved. The different networks in the complete series of borates K[BFx(CN)4–x], x = 0–4 are compared and discussed. 相似文献
185.
Reaction of nickel(II) thiocyanate and pyridazine (pdz) as organic spacer ligand leads to the formation of the ligand‐rich 1:2 (1:2 = metal to ligand ratio) trinuclear nickel(II) complex of composition [Ni3(NCS)6(pdz)6]. Depending on the reaction solvent, different polymorphic modifications are obtained: Reaction in acetonitrile leads to the formation of the new modification 1I and reaction in ethanol leads to the formation of modification 1II reported recently. In their crystal structures discrete [Ni3(NCS)6(pdz)6] units are found, in which each of the Ni2+ cations exhibits a NiN6 distorted octahedral arrangement. The central Ni2+ cation is coordinated by four bridging pdz ligands and two thiocyanato anions in trans positions. Both thiocyanato anions exhibit the end‐on bridging mode. The peripheral Ni2+ cations are bridged by one thiocyanato anion and by two pdz ligands with the central Ni2+ cation. Further they are coordinated by two terminal N‐bonded thiocyanato anions and one terminal N‐bonded pdz ligand. The structure of 1I was determined by X‐ray single crystal structure investigation and emphasized by infrared spectroscopy. Magnetic measurements revealed a quasi Curie behavior with net ferromagnetic interactions for 1I and net antiferromagnetic interactions for 1II . Solvent‐mediated conversion experiments clearly show that modification 1I represents the thermodynamic most stable form at room temperature and that modification 1II is metastable. On thermal decomposition, both modification transform quantitatively in a new ligand‐deficient intermediate. Elemental analysis revealed a 3:4 compound of composition [Ni3(NCS)6(pdz)4]. A structure model supported by IR spectroscopic investigations was assumed, in which three coordination modes of the thiocyanato anion exist, resulting in a 2D polymeric network. 相似文献
186.
Huang HC Abe K Abe K Abe T Adachi I Aihara H Akatsu M Aso T Aulchenko V Aushev T Bakich AM Ban Y Banas E Bay A Bedny I Behera PK Bizjak I Bondar A Bozek A Bracko M Browder TE Casey BC Chang P Chao Y Chen KF Cheon BG Chistov R Choi Y Choi YK Danilov M Dong LY Drutskoy A Eidelman S Eiges V Enari Y Fukunaga C Gabyshev N Garmash A Gershon T Golob B Guo R Haba J Handa F Hara T Hastings NC Hayashii H Hazumi M Hinz L Hokuue T Hoshi Y Hou WS Hsiung YB Igarashi Y Iijima T Inami K Ishikawa A Itoh R 《Physical review letters》2003,91(24):241802
We report evidence for the decay mode B-->phiphiK based on an analysis of 78 fb(-1) of data collected with the Belle detector at KEKB. This is the first example of a b-->sssss transition. The branching fraction for this decay is measured to be B(B+/--->phiphiK+/-)=(2.6(+1.1)(-0.9)+/-0.3)x10(-6) for a phiphi invariant mass below 2.85 GeV/c(2). Results for other related charmonium decay modes are also reported. 相似文献
187.
Abe K Abe K Abe N Abe R Abe T Ahn BS Aihara H Akatsu M Asano Y Aso T Aulchenko V Aushev T Bakich AM Ban Y Behera PK Bizjak I Bondar A Bozek A Bracko M Browder TE Casey BC Chang MC Chang P Chao Y Cheon BG Chistov R Choi Y Choi YK Danilov M Dong LY Drutskoy A Eidelman S Eiges V Enari Y Fang F Fujii H Fukunaga C Gabyshev N Garmash A Gershon T Golob B Gordon A Guo R Haba J Hara T Harada Y Hayashii H Hazumi M Heenan EM Higuchi I Higuchi T Hinz L Hokuue T Hoshi Y Hou SR Hou WS Hsu SC Huang HC Igaki T 《Physical review letters》2003,90(13):131803
We report studies of the Cabibbo-suppressed decay B+/--->D(CP)K+/-, where D(CP) denotes CP eigenstates of the D0-D0; system. The analysis is based on a 29.1 fb(-1) sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e(+)e(-) storage ring. We measure ratios of branching fractions, relative to Cabibbo-favored B+/--->D(CP)pi(+/-), of B(B--->D1K-)/B(B--->D1pi(-))=0.125+/-0.036+/-0.010 and B(B--->D2K-)/B(B--->D2pi(-))=0.119+/-0.028+/-0.006; the index 1 (2) denotes the CP=+1 (-1) eigenstate. We also extract the partial rate asymmetries for B+/--->D(CP)K+/-, finding A(1)=0.29+/-0.26+/-0.05 and A(2)=-0.22+/-0.24+/-0.04. 相似文献
188.
Gabyshev N Kichimi H Abe K Abe K Abe R Abe T Adachi I Aihara H Akatsu M Asano Y Aso T Aulchenko V Aushev T Bakich AM Ban Y Banas E Bay A Bedny I Bizjak I Bondar A Bozek A Bracko M Brodzicka J Browder TE Casey BC Chang MC Chang P Chao Y Chen KF Cheon BG Chistov R Choi SK Choi Y Choi YK Danilov M Dong LY Dragic J Drutskoy A Eidelman S Eiges V Enari Y Fang F Fukunaga C Garmash A Gershon T Golob B Haba J Hagner C Handa F Hara T Hasuko K Hayashii H Hazumi M Higuchi I Hinz L Hojo T Hokuue T Hoshi Y 《Physical review letters》2003,90(12):121802
We report the measurement of the charmed baryonic decay B(0)-->Lambda(+)(c)p with a branching fraction of (2.19(+0.56)(-0.49)+/-0.32+/-0.57)x10(-5) and a statistical significance of 5.8 sigma. The errors are statistical, systematic, and the error of the Lambda(+)(c)-->pK(-)pi(+) decay branching fraction. This is the first observation of a two-body baryonic B decay. The analysis is based on 78.2 fb(-1) of data accumulated at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e(+)e(-) collider. 相似文献
189.
Summary A direct scan technique employing quantitative thin-layer chromatography for color samples of chlorpromazine and its metabolites by spectro-photometric method with the use of double-beam spectrodensitometer is described. Chlorpromazine and 17 metabolites have been analyzed qualitatively and quantitatively. This method can be applied for the assay of phenothiazines in both human plasma and urine. Extraction procedures for chlorpromazine and its metabolites in blood plasma and urine are presented. Advantages and disadvantages of this technique are discussed.
This work was supported by USPHS Grant MH 17968. 相似文献
Zusammenfassung Ein direktes Abtastverfahren für quantitative Dünnschichtchromatogramme von Chlorpromazin und seinen Metaboliten mit Hilfe eines Doppelstrahl-Spektrodensitometers wurde beschrieben. Chlorpromazin und 17 seiner Metaboliten wurden qualitativ und quantitativ analysiert. Das Verfahren eignet sich zur Phenothiazinbestimmung in Plasma und Harn. Extraktionsmethoden wurden angegeben. Vor- und Nachteile des beschriebenen Verfahrens wurden besprochen.
This work was supported by USPHS Grant MH 17968. 相似文献
190.
The effect of the lattice periodicity on the radiation emitted by a positron channeled along the 〈100〉 axis of copper is investigated. We show that the periodic nature of the potential along the channel axis gives rise to new features in the spectrum and therefore cannot be neglected. 相似文献