全文获取类型
收费全文 | 566篇 |
免费 | 6篇 |
国内免费 | 2篇 |
专业分类
化学 | 130篇 |
力学 | 351篇 |
数学 | 16篇 |
物理学 | 77篇 |
出版年
2020年 | 5篇 |
2019年 | 20篇 |
2018年 | 16篇 |
2017年 | 18篇 |
2016年 | 12篇 |
2015年 | 23篇 |
2014年 | 15篇 |
2013年 | 9篇 |
2012年 | 4篇 |
2011年 | 5篇 |
2010年 | 8篇 |
2009年 | 9篇 |
2008年 | 16篇 |
2007年 | 5篇 |
2006年 | 53篇 |
2005年 | 75篇 |
2004年 | 74篇 |
2003年 | 67篇 |
2002年 | 71篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1995年 | 1篇 |
1992年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 4篇 |
1980年 | 9篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 9篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 8篇 |
1972年 | 2篇 |
1957年 | 1篇 |
1948年 | 1篇 |
排序方式: 共有574条查询结果,搜索用时 15 毫秒
91.
In this paper, a differentially heated square/cubic cavity is studied by performing three-dimensional direct numerical simulations. The first bifurcation observed at is due to the 3D vortex structures generated at the end regions of vertical boundary layers near the median plane. The main results of this Note are that the flow returns to a steady state for higher values of the Rayleigh number (7×107 and 108 for example) still exhibiting these 3D vortex structures, and that multiple steady flows which differ by their symmetry properties, are obtained for . However, the flow reverts to unsteadiness for . In this latter case, the instability is due to the vertical boundary layers. To cite this article: G. de Gassowski et al., C. R. Mecanique 331 (2003). 相似文献
92.
The sloshing problem is considered in a half-space covered by a rigid dock with apertures. The dependence of the fundamental sloshing frequency on the shape of the free surface region is studied. It is proved that the inequality holds between the fundamental eigenvalues corresponding to two different regions if some conditions are fulfilled. These conditions are verified for particular classes of regions of a fixed area in order to demonstrate that the disk yields the maximum of the fundamental eigenvalue for each of these classes. On the other hand, examples of regions are constructed for which the fundamental eigenfrequency is larger than that for the circular aperture of the same area and even as large as one wishes. To cite this article: V. Kozlov, N. Kuznetsov, C. R. Mecanique 330 (2002) 723–728. 相似文献
93.
Nearly repetitive structures can present at least two kinds of vibration modes: localized modes and modulated ones. In this Note, the multiple scale method is applied to characterize a packet of modulated modes. In this respect, only small size problems are to be solved: periodic problems posed on a few basic cells and amplitude equations, which define a sort of homogenized model for this type of modes. It is established that the influence of the non-repetitive part of the structure is accounted by a boundary condition. To cite this article: E.M. Daya et al., C. R. Mecanique 331 (2003). 相似文献
94.
El Mostafa Daya Bouazza Braikat Noureddine Damil Michel Potier-Ferry 《Comptes Rendus Mecanique》2002,330(5):333-338
By homogenization theory, one can predict the vibrations of long repetitive structures in the low frequency range. Beyond this range, many modes have a modulated shape. Based on a multiple scale analysis, a continuum model is presented, that is able to account for this class of modes. This model involves a real coefficient that can be computed from the finite element resolution of problems defined on a few basic cells. An application in 2D elasticity is presented. To cite this article: E.M. Daya et al., C. R. Mecanique 330 (2002) 333–338. 相似文献
95.
Let T be an extension of a one to one normal operator A by a nilpotent operator N. In this paper we calculate the defect of reflexivity of T. We give a necessary and sufficient condition to insure the reflexivity of such extensions. In particular, it is shown that T is reflexive when N is reflexive. 相似文献
96.
Peter Heering 《Physics in Perspective (PIP)》2006,8(1):52-63
I discuss our replication of the wire-torsion experiments that Charles Augustin Coulomb (1736–1806) reported in a session
of the Paris Académie des Sciences in 1784. I first explain the nature and purpose of the replication method and then apply it to an analysis of Coulomb’s experiments.
I conclude by placing Coulomb’s presentation of his memoir into its specific historical contest. 相似文献
97.
Alexandre Delye de Clauzade de Mazieux Michel Marot Monique Becker 《Comptes Rendus Mecanique》2006,334(11):669-673
d-dominating sets in graphs are very important in system and network engineering. Their constructions is thus an important research topic. An heuristic which forms such sets by using a given criterion is proposed. We simplify the heuristic presented elsewhere. We extend it and prove the correctness of the extended heuristic. This heuristic has the advantage of being distributed and scalable. To cite this article: A. Delye de Clauzade de Mazieux et al., C. R. Mecanique 334 (2006). 相似文献
98.
W. van der Eijk 《Fresenius' Journal of Analytical Chemistry》1979,297(1):10-12
Summary In 1973 a research programme Community Bureau of Reference — BCR has been started in the Commission of the European Communities. Its task is to group, harmonize, dovetail and supplement national efforts in the field of reference materials and methods. Its terms of reference and working methods are explained. As a result of the BCR activities so far 26 CRMs are produced, covering several sectors of technical and scientific activities (e.g. ferrous and non-ferrous metallurgy, organic chemistry and clinical laboratory sciences). Organization of the measurement campaigns and the procedures for certification are outlined.
Die Aktivitäten des Europäischen Referenzbüros der Gemeinschaft — BCR
Zusammenfassung Im Jahre 1973 wurde von der Kommission der Europäischen Gemeinschaften ein Forschungsprogramm über Referenzmaterialien aufgestellt, das seinen Ausdruck im Europäischen Referenzbüro der Gemeinschaft (BCR) fand. Seine Aufgabe ist es, die nationalen Bemühungen auf diesem Gebiet zu stärken, zu harmonisieren und zu ergänzen. Zur Zeit sind 26 verschiedene Referenzmaterialien verfügbar, die mehrere technisch-wissenschaftliche Gebiete umfassen (Eisen- und Nichteisen-Metallurgie, organische Chemie, klinische Analyse). Organisation, Arbeitsprogramm und Zertifizierungsverfahren des Büros werden beschrieben.
Presented at Euroanalysis III conference, Dublin, August 20–25, 1978 相似文献
99.
Henri Gouin 《Comptes Rendus Mecanique》2004,332(4):285-292
Near the critical point, isothermal interfacial zones are investigated starting from a non-local density of energy. From the equations of motion of thermocapillary fluids, we point out a new kind of adiabatic waves propagating along the interfacial layers. The waves are associated with the second derivatives of densities and propagate with a celerity depending on the proximity of the critical point. To cite this article: H. Gouin, C. R. Mecanique 332 (2004). 相似文献
100.
P. Kocielniak S. Walas A. Parczewski 《Fresenius' Journal of Analytical Chemistry》1980,302(5):402-406
Summary The matrix effects in the determination of the main components of dolomite by flame emission (Na, K) and atomic absorption spectrometry (Ca, Mg, Fe, Mn) have been examined according to the methodology based on the theory of design of experiments. The influence of some auxiliary compounds added to a sample solution has been investigated. The determination of Fe and Mn proved to be specific. The matrix effect has been eliminated in the determination of K by adding a mixture of NaCl and H3PO4, in the determination of Na by KCl spectral buffer, in the determination of Mg by NaCl buffer and in the case of Ca by SrCl2 as a spectral buffer.
Untersuchung über den Matrixeffekt bei der Bestimmung der Hauptbestandteile von Dolomit durch Atomemissions- und -absorptionsspektrometrie
Zusammenfassung Mit Hilfe methodisch geplanter Versuche wurde der Einfluß der Matrix auf die Bestimmung von Na und K (Emission) sowie Ca, Mg, Fe und Mn (Absorption) untersucht. Ebenso wurde der Einfluß verschiedener Zusätze geprüft. Die Bestimmung von Fe und Mn erwies sich als spezifisch. In den anderen Fällen konnte die Matrixstörung durch folgende Zusätze behoben werden: Gemisch von NaCl und H3PO4 für K, KCl für Na, NaCl für Mg, SrCl2 für Ca.相似文献