全文获取类型
收费全文 | 1868篇 |
免费 | 93篇 |
国内免费 | 22篇 |
专业分类
化学 | 1374篇 |
晶体学 | 11篇 |
力学 | 17篇 |
数学 | 263篇 |
物理学 | 318篇 |
出版年
2023年 | 15篇 |
2022年 | 30篇 |
2021年 | 53篇 |
2020年 | 42篇 |
2019年 | 43篇 |
2018年 | 41篇 |
2017年 | 36篇 |
2016年 | 74篇 |
2015年 | 50篇 |
2014年 | 63篇 |
2013年 | 119篇 |
2012年 | 133篇 |
2011年 | 152篇 |
2010年 | 86篇 |
2009年 | 65篇 |
2008年 | 124篇 |
2007年 | 115篇 |
2006年 | 99篇 |
2005年 | 91篇 |
2004年 | 81篇 |
2003年 | 61篇 |
2002年 | 65篇 |
2001年 | 25篇 |
2000年 | 50篇 |
1999年 | 27篇 |
1998年 | 16篇 |
1997年 | 25篇 |
1996年 | 29篇 |
1995年 | 26篇 |
1994年 | 17篇 |
1993年 | 12篇 |
1992年 | 18篇 |
1991年 | 7篇 |
1990年 | 10篇 |
1989年 | 11篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1986年 | 9篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1934年 | 2篇 |
排序方式: 共有1983条查询结果,搜索用时 31 毫秒
131.
132.
R.?Morales H.?Rubio M.?VélezEmail author J. I.?Martín J. M.?Alameda 《The European Physical Journal B - Condensed Matter and Complex Systems》2005,47(3):337-340
The role of material microstructure in the magnetic
anisotropy of real nanostructures has been studied by the comparison of the
magnetic behavior of arrays of amorphous and polycrystalline
CoxSi1-x lines. From the experimental measurements of angular
dependences of remanences parallel and perpendicular to the applied field we
determine the angular dispersion of effective local easy axis of anisotropy.
We have proved that amorphous lines have a dispersion of effective
anisotropy axis much smaller than the polycrystalline samples. As a
consequence, amorphous lines have a better defined magnetic behaviour,
pointing the interest of the fabrication of nanostructures made of amorphous
materials. 相似文献
133.
Pabla?Aguirre Natalia?Mena Victoria?Tapia Miguel?Arredondo Marco?T?Nú?ezEmail author 《BMC neuroscience》2005,6(1):3
Background
Iron is necessary for neuronal function but in excess generates neurodegeneration. Although most of the components of the iron homeostasis machinery have been described in neurons, little is known about the particulars of their iron homeostasis. In this work we characterized the response of SH-SY5Y neuroblastoma cells and hippocampal neurons to a model of progressive iron accumulation. 相似文献134.
Bartholomy O Credé V van Pee H Anisovich AV Anton G Bantes R Beloglazov Y Bogendörfer R Castelijns R Ehmanns A Ernst J Fabry I Flemming H Fösel A Freiesleben H Fuchs M Funke Ch Gothe R Gridnev A Gutz E Höffgen SK Horn I Hössl J Joosten R Junkersfeld J Kalinowsky H Klein F Klempt E Koch H Konrad M Kopf B Krusche B Langheinrich J Löhner H Lopatin I Lotz J Matthäy H Menze D Messchendorp J Morales C Novinski D Ostrick M Radkov A Reinnarth J Sarantsev AV Schadmand S Schmidt Ch Schmieden H Schoch B 《Physical review letters》2005,94(1):012003
Single pi(0) photoproduction has been studied with the CB-ELSA experiment at Bonn using tagged photon energies between 0.3 and 3.0 GeV. The experimental setup covers a very large solid angle of approximately 98% of 4pi. Differential cross sections dsigma/dOmega have been measured. Complicated structures in the angular distributions indicate a variety of different resonances being produced in the s channel intermediate state gammap-->N(*)(Delta(*))-->ppi(0). A combined analysis including the data presented in this letter along with other data sets reveals contributions from known resonances and evidence for a new resonance N(2070)D15. 相似文献
135.
Locally periodic Timoshenko rod: experiment and theory 总被引:2,自引:0,他引:2
Díaz-de-Anda A Pimentel A Flores J Morales A Gutiérrez L Méndez-Sánchez RA 《The Journal of the Acoustical Society of America》2005,117(5):2814-2819
The flexural vibrations of a locally periodic rod, which consists of N unit cells, are discussed both from the experimental and theoretical points of view. Timoshenko's beam theory and the transfer matrix method are used to calculate the normal-mode frequencies and amplitudes. The theoretical values are then compared with the experimental ones, which are obtained using an electromagnetic acoustic transducer (EMAT). Good agreement between the numerical results and the experimental measurements is obtained. It is shown that as N grows, a band spectrum emerges. 相似文献
136.
González-Rojas C. H. Oprunenko Yu. F. Morales R. G. E. 《Russian Chemical Bulletin》2004,53(2):474-475
A method for the synthesis of diphenylacetylenes containing donor and acceptor groups in aryl substituents was proposed. 4"-Formyl-4-methoxydiphenylacetylene was synthesized as an example. 相似文献
137.
A particle-in-cell code is used to investigate the evolution of a density plume moving through a background plasma with supersonic speed directed along the confinement magnetic field. For scale lengths representative of laboratory and auroral phenomena, the major nonlinear effects identified by the present simulations are the formation of a bipolar current system from the ballistic electrons, the appearance of transient potential layers, and the carving of deep density cavities. A 3D magnetic topology is generated by the self-consistent ballistic and diamagnetic currents that accompany highly localized potential layers. 相似文献
138.
Walsh RD Bradner MW Fleischman aS Morales LA Moulton aB Rodríguez-Hornedo N Zaworotko MJ 《Chemical communications (Cambridge, England)》2003,(2):186-187
The carboxylic acid-pyridine supramolecular heterosynthon can be exploited to predictably generate binary crystalline phases involving rac-ibuprofen, rac-flurbiprofen or aspirin. 相似文献
139.
C. A. Morales 《Transactions of the American Mathematical Society》2003,355(2):735-745
Let be an Axiom A flow with a transverse torus exhibiting a unique orbit that does not intersect . Suppose that there is no null-homotopic closed curve in contained in either the stable or unstable set of . Then we show that has either an attracting periodic orbit or a repelling periodic orbit or is transitive. In particular, an Anosov flow with a transverse torus is transitive if it has a unique periodic orbit that does not intersect the torus.
140.
Let (X, F) be an Alexandroff space, let A(F) be the Boolean subalgebra of 2
X
generated by F, let G be a Hausdorff commutative topological lattice group and let rbaF(A(F), G) denote the set of all order bounded F-inner regular finitely additive set functions from A(F) into G. Using some special properties of the elements of rbaF(A(F), G), we extend to this setting the first decomposition theorem of Alexandroff. 相似文献