全文获取类型
收费全文 | 507篇 |
免费 | 15篇 |
国内免费 | 7篇 |
专业分类
化学 | 266篇 |
晶体学 | 4篇 |
力学 | 6篇 |
数学 | 81篇 |
物理学 | 172篇 |
出版年
2022年 | 9篇 |
2021年 | 10篇 |
2020年 | 3篇 |
2019年 | 8篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 13篇 |
2015年 | 13篇 |
2014年 | 16篇 |
2013年 | 42篇 |
2012年 | 25篇 |
2011年 | 45篇 |
2010年 | 23篇 |
2009年 | 28篇 |
2008年 | 35篇 |
2007年 | 33篇 |
2006年 | 17篇 |
2005年 | 18篇 |
2004年 | 20篇 |
2003年 | 20篇 |
2002年 | 23篇 |
2001年 | 10篇 |
2000年 | 12篇 |
1999年 | 11篇 |
1998年 | 12篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1981年 | 2篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1975年 | 5篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1961年 | 1篇 |
1948年 | 2篇 |
1947年 | 2篇 |
1943年 | 3篇 |
排序方式: 共有529条查询结果,搜索用时 46 毫秒
61.
62.
C. Ristoscu E. Gyorgy I.N. Mihailescu A. Klini V. Zorba C. Fotakis 《Applied Physics A: Materials Science & Processing》2004,79(4-6):927-929
AlN thin films with a thickness in the nanometer range were prepared by pulsed laser deposition technique. We investigated the effect of laser wavelength, pulse duration, and ambient gas pressure on the composition and morphology of the deposited films. In all experiments we used AlN targets. We worked with three laser sources generating pulses of 34 ns@248 nm (source A), 450 fs@248 nm (source B), and 50 fs@800 nm (source C). XRD, SEM, and profilometric measurements were performed on the obtained AlN thin films. We have demonstrated that duration of the laser pulse is an important parameter for the quality and performances of AlN structures obtained by pulsed laser deposition. PACS 81.05.Ea; 81.15.Fg; 61.10.Nz 相似文献
63.
Ion Irimescu und Eugenia Chirnoag 《Fresenius' Journal of Analytical Chemistry》1943,125(1-2):32-37
Ohne Zusammenfassung 相似文献
64.
We determine the rank generating function, the zeta polynomial and the M?bius function for the poset NC
(B)
(p, q) of annular non-crossing partitions of type B, where p and q are two positive integers. We give an alternative treatment of some of these results in the case q = 1, for which this poset is a lattice. We also consider the general case of multiannular noncrossing partitions of type
B, and prove that this reduces to the cases of non-crossing partitions of type B in the annulus and the disc. 相似文献
65.
Claudia Lar Gheorghe-Doru Roiban Romina Mariana Crăsneanu Ilişca Mihalca Elena Bogdan Anamaria Terec Ion Grosu 《Central European Journal of Chemistry》2011,9(2):218-223
The synthesis and photophysical properties of several 6,6″ symmetrically substituted 4′-aryl-2,2′:6′,2″-terpyridine derivatives
are reported herein. The UV-Vis spectra in acetonitrile as well as in dichloromethane show two intense bands in the UV areas
252–262 nm and 275–290 nm while the fluorescence emission spectra are only slightly influenced by chemical derivatization. 相似文献
66.
Vitalie Stavila Ion Bulimestru Aurelian Gulea Adam C. Colson Kenton H. Whitmire 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(3):m65-m68
The title complexes, hexaaquacobalt(II) bis(μ‐pyridine‐2,6‐dicarboxylato)bis[(pyridine‐2,6‐dicarboxylato)bismuthate(III)] dihydrate, [Co(H2O)6][Bi2(C7H4NO4)4]·2H2O, (I), and hexaaquanickel(II) bis(μ‐pyridine‐2,6‐dicarboxylato)bis[(pyridine‐2,6‐dicarboxylato)bismuthate(III)] dihydrate, [Ni(H2O)6][Bi2(C7H4NO4)4]·2H2O, (II), are isomorphous and crystallize in the triclinic space group P. The transition metal ions are located on the inversion centre and adopt slightly distorted MO6 (M = Co or Ni) octahedral geometries. Two [Bi(pydc)2]− units (pydc is pyridine‐2,6‐dicarboxylate) are linked via bridging carboxylate groups into centrosymmetric [Bi2(pydc)4]2− dianions. The crystal packing reveals that the [M(H2O)6]2+ cations, [Bi2(pydc)4]2− anions and solvent water molecules form multiple hydrogen bonds to generate a supramolecular three‐dimensional network. The formation of secondary Bi...O bonds between adjacent [Bi2(pydc)4]2− dimers provides an additional supramolecular synthon that directs and facilitates the crystal packing of both (I) and (II). 相似文献
67.
Wolfgang Muessel Helmut Strobel Maxime Joos Eike Nicklas Ion Stroescu Jiří Tomkovič David B. Hume Markus K. Oberthaler 《Applied physics. B, Lasers and optics》2013,113(1):69-73
We report on the optimization of high-intensity absorption imaging for small Bose–Einstein condensates. The imaging calibration exploits the linear scaling of the quantum projection noise with the mean number of atoms for a coherent spin state. After optimization for atomic clouds containing up to 300 atoms, we find an atom number resolution of $\varDelta_{\rm det}= 3.7$ atoms, mainly limited by photon shot noise and radiation pressure. 相似文献
68.
69.
The process of drying a paint made of a dispersion of a polymer in a solvent is experimentally and theoretically studied at various constant temperatures. The diffusion of the solvent through the paint and evaporation from the surface is considered, as well as the subsequent shrinkage. From measurements made at the beginning and at the end of the drying operation on the kinetics of drying, the diffusivity is found to largely depend on the solvent concentration. An exponential relationship of the diffusivity versus the concentration is thus found and successfully tested for the whole process of drying, the diffusivity increasing with the solvent concentration. 相似文献
70.
R. Alexandrescu J. Morjan C. Grigoriu I. N. Mihailescu Z. Bastl J. Tlaskal R. Mayer J. Pola 《Applied Physics A: Materials Science & Processing》1988,46(4):275-279
Infrared multiphoton decomposition of monosilane in the presence of methyl methacrylate results in the formation of gaseous methane, acetylene, butenes and carbon monoxide along with a solid polymer whose chemical mechanism of formation is discussed in line of the poly(dimethylsiloxane) structure inferred from ESCA and IR spectral analysis. 相似文献