全文获取类型
收费全文 | 1911篇 |
免费 | 43篇 |
国内免费 | 11篇 |
专业分类
化学 | 1171篇 |
晶体学 | 10篇 |
力学 | 63篇 |
综合类 | 1篇 |
数学 | 194篇 |
物理学 | 526篇 |
出版年
2020年 | 13篇 |
2019年 | 16篇 |
2017年 | 22篇 |
2016年 | 34篇 |
2015年 | 22篇 |
2014年 | 27篇 |
2013年 | 83篇 |
2012年 | 82篇 |
2011年 | 103篇 |
2010年 | 44篇 |
2009年 | 53篇 |
2008年 | 87篇 |
2007年 | 94篇 |
2006年 | 89篇 |
2005年 | 79篇 |
2004年 | 80篇 |
2003年 | 60篇 |
2002年 | 49篇 |
2001年 | 38篇 |
2000年 | 40篇 |
1999年 | 47篇 |
1998年 | 21篇 |
1997年 | 20篇 |
1996年 | 25篇 |
1995年 | 42篇 |
1994年 | 37篇 |
1993年 | 39篇 |
1992年 | 47篇 |
1991年 | 22篇 |
1990年 | 20篇 |
1989年 | 17篇 |
1988年 | 22篇 |
1987年 | 19篇 |
1986年 | 17篇 |
1985年 | 33篇 |
1984年 | 14篇 |
1983年 | 19篇 |
1982年 | 26篇 |
1981年 | 23篇 |
1980年 | 16篇 |
1979年 | 26篇 |
1978年 | 25篇 |
1977年 | 25篇 |
1976年 | 20篇 |
1975年 | 21篇 |
1974年 | 29篇 |
1973年 | 23篇 |
1972年 | 12篇 |
1971年 | 13篇 |
1934年 | 16篇 |
排序方式: 共有1965条查询结果,搜索用时 15 毫秒
51.
52.
53.
B. Gartner P. Ackerbauer M. Augsburger W.H. Breunlich M. Cargnelli D. Chatellard J.-P. Egger T. von Egidy F.J. Hartmann R. Jacot-Guillarmod E. Jeannet P. Kammel R.C. King A. Kosak B. Lauss J. Marton M. Mühlbauer F. Mulhauser C. Petitjean C. Piller W. Prymas L.A. Schaller L. Schellenberg H. Schneuwly W. Schott Y.A. Thalmann S. Tresch A. Werthmüller J. Zmeskal 《Hyperfine Interactions》1999,119(1-4):103-108
The energy and time distributions of the decay X-rays of excited, metastable, molecular (dμHe)*-resonances were measured. The comparison of the observed energy spectra with calculated ones suggests that decay from
the rotational state J = 1 dominates at the investigated conditions. The muon transfer rates from ground state deuterium to the helium isotopes
3He and 4He at low temperatures were determined from the time distributions of these spectra. Additionally, the temperature dependence
of the muon transfer rate was clearly established in deuterium / 4He mixtures.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
54.
Using the random cluster expansion, correlations of the Potts model on a graph can be expressed as sums over partitions of the vertices where the spins are fixed. For a planar graph, only certain partitions can occur in these sums. For example, when all fixed spins lie on the boundary of one face, only noncrossing partitions contribute. In this paper we examine the partitions which occur when fixed spins lie on the boundaries of two disjoint faces. We call these the annular partitions, and we establish some of their basic properties. In particular we demonstrate a partial duality for these partitions, and show some implications for correlations of the Potts model. 相似文献
55.
CM Silva MF Duarte ML Mira MH Florêncio K Versluis AJ Heck 《Rapid communications in mass spectrometry : RCM》1999,13(12):1098-1103
Fast atom bombardment, combined with high-energy collision-induced tandem mass spectrometry, has been used to investigate gas-phase metal-ion interactions with captopril, enalaprilat and lisinopril, all angiotensin-converting enzyme inhibitors.Suggestions for the location of metal-binding sites are presented. For captopril, metal binding occurs most likely at both the sulphur and the nitrogen atom. For enalaprilat and lisinopril, binding preferably occurs at the amine nitrogen. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
56.
J. Domscheit S. Trmnen B. Aengenvoort H. Hübel R. A. Bark M. Bergstrm A. Bracco R. Chapman D. M. Cullen C. Fahlander S. Frattini A. Grgen G. B. Hagemann A. Harsmann B. Herskind H. J. Jensen S. L. King S. Lenzi D. Napoli S. W.
degrd C. M. Petrache H. Ryde U. J. van Severen G. Sletten P. O. Tjm C. Ur 《Nuclear Physics A》1999,660(4):1211-392
High-spin states in 163Lu have been investigated using the Euroball spectrometer array. The previously known superdeformed band has been extended at low and high energies, and its connection to the normal-deformed states has been established. From its decay the mixing amplitude and interaction strength between superdeformed and normal states are derived. In addition, a new band with a similar dynamic moment of inertia has been found. The experimental results are compared to cranking calculations which suggest that the superdeformed bands in this mass region correspond to shapes with a pronounced triaxiality (γ≈±20°). 相似文献
57.
We derive production yields for massive pseudo-scalar and scalar axion-like-particles (ALPs), through non-linear Compton scattering of an electron in the background of low- and high-intensity electromagnetic fields. In particular, we focus on electromagnetic fields from Gaussian plane wave laser pulses. A detailed study of the angular distributions and effects of the scalar and pseudo-scalar masses is presented. It is shown that ultra-relativistic seed electrons can be used to produce scalars and pseudo-scalars with masses up to the order of the electron mass. We briefly discuss future applications of this work towards lab-based searches for light beyond-the-Standard-Model particles. 相似文献
58.
The chemisorption of CO on W(100) at ~ 100K has been studied using a combination of flash desorption and electron stimulated desorption (ESD) techniques. This is an extension of a similar study made for CO adsorption on W(100) at temperatures in the range 200–300K. As in the 200–300 K CO layer, both α1-CO and α2-CO are formed in addition to more strongly bound CO species upon adsorption at ~ 100K; the α-CO states yield CO+ and O+ respectively upon ESD. At low CO coverages, the α1 and α2-CO states are postulated to convert to β-CO or other strongly bound CO species upon heating. At higher CO coverages, α1-CO converts to α2-CO upon thermal desorption or electron stimulated desorption. There is evidence for the presence of other weakly-bound states in the low temperature CO layer having low surface concentration at saturation. The ESD behavior of the CO layer coadsorbed with hydrogen on W(100) is reported, and it is found that H(ads) suppresses either the concentration or the ionic cross section for α1 and α2-CO states. 相似文献
59.
S.R. Bare K. Griffiths P. Hofmann D.A. King G.L. Nyberg N.V. Richardson 《Surface science》1982,120(2):367-375
Using both synchrotron and HeII radiation the electronic and geometric structure of Pt{110}-(2×1)p1g1 CO was examined. The shape resonance for the 4σ orbital of CO is found to be peaked at 38 eV, while that for the 5σ orbital is peaked at 28 eV. No shape resonance is observed from the 1π orbital. The ordering is reversed from that of gas phase CO. Further evidence, from the polar intensity variation of the non-bonding 4σ orbital, is presented for the tilted CO structure proposed previously. 相似文献
60.
Simon A. King 《Transactions of the American Mathematical Society》2004,356(11):4519-4542
We introduce a numerical isomorphism invariant for any triangulation of . Although its definition is purely topological (inspired by the bridge number of knots), reflects the geometric properties of . Specifically, if is polytopal or shellable, then is ``small' in the sense that we obtain a linear upper bound for in the number of tetrahedra of . Conversely, if is ``small', then is ``almost' polytopal, since we show how to transform into a polytopal triangulation by local subdivisions. The minimal number of local subdivisions needed to transform into a polytopal triangulation is at least . Using our previous results [The size of triangulations supporting a given link, Geometry & Topology 5 (2001), 369-398], we obtain a general upper bound for exponential in . We prove here by explicit constructions that there is no general subexponential upper bound for in . Thus, we obtain triangulations that are ``very far' from being polytopal. Our results yield a recognition algorithm for that is conceptually simpler, although somewhat slower, than the famous Rubinstein-Thompson algorithm.