全文获取类型
收费全文 | 465161篇 |
免费 | 5560篇 |
国内免费 | 1599篇 |
专业分类
化学 | 257124篇 |
晶体学 | 6868篇 |
力学 | 19107篇 |
综合类 | 11篇 |
数学 | 52942篇 |
物理学 | 136268篇 |
出版年
2018年 | 3065篇 |
2016年 | 5922篇 |
2015年 | 4762篇 |
2014年 | 6467篇 |
2013年 | 20306篇 |
2012年 | 14770篇 |
2011年 | 18460篇 |
2010年 | 11677篇 |
2009年 | 11526篇 |
2008年 | 16936篇 |
2007年 | 17287篇 |
2006年 | 16606篇 |
2005年 | 15128篇 |
2004年 | 13642篇 |
2003年 | 12100篇 |
2002年 | 11878篇 |
2001年 | 13971篇 |
2000年 | 10739篇 |
1999年 | 8590篇 |
1998年 | 6867篇 |
1997年 | 6752篇 |
1996年 | 6803篇 |
1995年 | 6215篇 |
1994年 | 5982篇 |
1993年 | 5682篇 |
1992年 | 6542篇 |
1991年 | 6245篇 |
1990年 | 5933篇 |
1989年 | 5830篇 |
1988年 | 5995篇 |
1987年 | 5758篇 |
1986年 | 5508篇 |
1985年 | 7751篇 |
1984年 | 7869篇 |
1983年 | 6457篇 |
1982年 | 6890篇 |
1981年 | 6900篇 |
1980年 | 6561篇 |
1979年 | 6821篇 |
1978年 | 7005篇 |
1977年 | 6901篇 |
1976年 | 6765篇 |
1975年 | 6552篇 |
1974年 | 6342篇 |
1973年 | 6519篇 |
1972年 | 3942篇 |
1971年 | 3055篇 |
1968年 | 3398篇 |
1967年 | 3317篇 |
1966年 | 3009篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
111.
We study the induced measure obtained from a 1-step Markov measure, supported by a topological Markov chain, after the mapping of the original alphabet onto another one. We give sufficient conditions for the induced measure to be a Gibbs measure (in the sense of Bowen) when the factor system is again a topological Markov chain. This amounts to constructing, when it does exist, the induced potential and proving its Hölder continuity. This is achieved through a matrix method. We provide examples and counterexamples to illustrate our results. 相似文献
112.
Jeroen J. L. M. Cornelissen W. Sander Graswinckel Alan E. Rowan Nico A. J. M. Sommerdijk Roeland J. M. Nolte 《Journal of polymer science. Part A, Polymer chemistry》2003,41(11):1725-1736
The conformational properties of polymers derived from isocyanodipeptides have been investigated with a combination of model calculations, X‐ray diffraction, and circular dichroism spectroscopy. Depending on the configuration of the side chains, defined arrays of hydrogen bonds along the polymeric backbone are formed. This leads to a well‐defined conformation as, for example, expressed in the formation of lyotropic liquid‐crystalline phases and increased helical stability. Upon the disruption of the hydrogen bonds by a strong acid, a less well‐defined macromolecular conformation is observed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1725–1736, 2003 相似文献
113.
Hellweg T. Schemmel S. Rother G. Brlet A. Eckerlebe H. Findenegg G.H. 《The European physical journal. E, Soft matter》2003,12(1):1-4
The European Physical Journal E - The temperature-induced microphase separation of the binary liquid system iso-butyric acid+heavy water (iBA + D2O) in a mesoporous silica glass (CPG-10-75) of... 相似文献
114.
115.
M Lepère R Gobeille V.Malathy Devi M.A.H Smith B Aoaeh A.W Mantz 《Journal of Molecular Spectroscopy》2004,224(1):7-12
We have analyzed the methyl fluoride RQ(J,0)Q branch lines located near 1475 cm−1 using a simultaneous multi-spectrum fitting technique. In this analysis we have used previously recorded diode-laser data in which we collected many data points covering only one or two Q branch lines in a particular run. The analysis consists of simultaneously fitting 57 spectra collected with numerous pressure and path length conditions for all absorption lines. The data are concatenated to create one continuous spectrum of the Q branch. We have determined the intensity and self-broadened widths at 296 K for 23 RQ(J,0) lines. 相似文献
116.
The decomposition of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) molecules during evaporation of unpurified raw material in ultra high vacuum was studied. The fragments were identified by mass spectrometry and the influence of these fragments and further contaminations of the raw material on the electronic structure of PTCDA thin films was measured by photoemission spectroscopy. Annealing of contaminated PTCDA films was tested as cheap and easy to perform method for (partial) post deposition purification of the contaminated films. 相似文献
117.
Equilibrium Problems with Applications to Eigenvalue Problems 总被引:5,自引:0,他引:5
In this paper, we consider equilibrium problems and introduce the concept of (S)+ condition for bifunctions. Existence results for equilibrium problems with the (S)+ condition are derived. As special cases, we obtain several existence results for the generalized nonlinear variational inequality studied by Ding and Tarafdar (Ref. 1) and the generalized variational inequality studied by Cubiotti and Yao (Ref. 2). Finally, applications to a class of eigenvalue problems are given. 相似文献
118.
In a recent paper to this journal (Whitman A M et al 2003 Waves Random Media 13 269-86) we derived a set of coupled equations that describe the intermodal scattering of acoustic radiation in a duct whose speed of sound varies randomly in space and time. In the paper we were mainly interested in modes that were not near cutoff. Here we study the solution of these equations in the vicinity of the cutoff. We find that near cutoff almost all the energy is reflected back independent of the other duct parameters. In addition to presenting these results, we analyse the mathematical structure of the equations in these regions in order to elucidate the reason for this behaviour. 相似文献
119.
We show that there are close relations between extremal problems in dual Brunn-Minkowski theory and isotropic-type properties for some Borel measures on the sphere. The methods we use allow us to obtain similar results in the context of Firey-Brunn-Minkowski theory. We also study reverse inequalities for dual mixed volumes which are related with classical positions, such as ?-position or isotropic position. 相似文献
120.
A homologous series of azomesogens, 2″-[4-(4′-n-alkoxybenzoyloxy)-2-chlorophenylazo] naphthalenes, with lateral chloro groups was synthesised. All the homologues synthesized
exhibit enantiotropic nematic mesophase. The mesomorphic properties of the present series are compared with other structurally
related series to evaluate the effect of lateral chloro group and its position on mesomorphism
This paper was presented at the 10th National Conference on Liquid Crystals held at Bangalore, India during 9–11 October 2003. 相似文献