全文获取类型
收费全文 | 5933篇 |
免费 | 150篇 |
国内免费 | 8篇 |
专业分类
化学 | 3795篇 |
晶体学 | 62篇 |
力学 | 158篇 |
数学 | 794篇 |
物理学 | 1282篇 |
出版年
2023年 | 31篇 |
2022年 | 33篇 |
2021年 | 52篇 |
2020年 | 81篇 |
2019年 | 59篇 |
2018年 | 61篇 |
2017年 | 52篇 |
2016年 | 126篇 |
2015年 | 128篇 |
2014年 | 128篇 |
2013年 | 275篇 |
2012年 | 338篇 |
2011年 | 391篇 |
2010年 | 215篇 |
2009年 | 174篇 |
2008年 | 278篇 |
2007年 | 290篇 |
2006年 | 273篇 |
2005年 | 285篇 |
2004年 | 268篇 |
2003年 | 214篇 |
2002年 | 203篇 |
2001年 | 105篇 |
2000年 | 78篇 |
1999年 | 67篇 |
1998年 | 60篇 |
1997年 | 64篇 |
1996年 | 60篇 |
1995年 | 64篇 |
1994年 | 36篇 |
1993年 | 38篇 |
1992年 | 58篇 |
1991年 | 39篇 |
1990年 | 41篇 |
1989年 | 42篇 |
1988年 | 53篇 |
1987年 | 48篇 |
1985年 | 45篇 |
1984年 | 35篇 |
1983年 | 32篇 |
1982年 | 39篇 |
1981年 | 53篇 |
1980年 | 42篇 |
1979年 | 32篇 |
1978年 | 42篇 |
1977年 | 33篇 |
1976年 | 42篇 |
1975年 | 36篇 |
1974年 | 33篇 |
1973年 | 28篇 |
排序方式: 共有6091条查询结果,搜索用时 15 毫秒
31.
A. Lacourt J. Derkosch M. Sobotka M. K. Zacherl W. Stöckl F. Wessely 《Mikrochimica acta》1955,43(1):212-216
Ohne Zusammenfassung 相似文献
32.
The acidic properties of a series of TiO2–SiO2 catalysts with different Ti/Si mole ratios have been studied. In order to determine the amount of acid centers and the acid strength distribution, the Benesi method of discontinuous titration has been used. Thermogravimetric measurements were also carried out.
TiO2–SiO2 Ti/Si. , - . .相似文献
33.
D. Dubbers H. Ackermann M. Grupp P. Heitjans H. -J. Stöckmann 《Zeitschrift für Physik B Condensed Matter》1976,25(4):363-368
An experimental method is presented which allows the determination of the sign of nuclear electric quadrupole interactions in solids. Activated target nuclei with a purely dipolar spin polarization are produced by capture of polarized thermal neutrons. The quadrupole coupling of the nuclei to the electric field gradient tensor in the target crystal converts this (dipolar) polarization partly into a (quadrupolar) alignment, which can be measured by the anisotropy of the-ray emission in a succeeding nuclear transition. The sign of the alignment created in this reorientation process depends on the sign of the electric quadrupole interaction. The reorientation effect can be enhanced by selective induction of nuclear magnetic resonance transitions. The method has been applied to measure the sign of the crystal electric field gradient (efg) in tetragonal MgF2. Further, the sign of an efg in cubic CaF2 originating from a19F interstitial adjacent to the activated20F probe nucleus has been determined. The method is in principle applicable to a considerable number of nuclides. 相似文献
34.
35.
36.
Abstract Taking advantage of the same configuration present at C-5 and C-5′ in sucrose, 6,6′-diprotected sucrose derivatives were transformed into enantiomerically pure glycerol derivatives. This was achieved by oxidative ring cleavage of both the glucopyranosyl ring as well as the fructofuranosyl moiety followed by reduction of the resulting tetraaldehyde and subsequent per-O-protection of the resulting pentahydroxy compound. The obtained intermediate was hydrolysed under acidic conditions to furnish two equivalents of partially protected chiral glycerol derivative per molecule of starting material. The efficiencies of sodium metaperiodate and lead tetraacetate as oxidizing agents were compared and the side reactions observed in these procedures were investigated. 相似文献
37.
38.
39.
M. Jonker F. Udo J. V. Allaby U. Amaldi G. Barbiellini A. Capone W. Flegel M. Metcalf J. Meyer F. L. Navarria J. Panman A. M. Wetherell K. Winter F. W. Büsser H. Daumann P. D. Gall E. Metz F. Niebergall K. H. Ranitzsch P. Stähelin E. Grigoriev V. Kaftanov V. Khovansky A. Rosanov A. Baroncelli B. Borgia C. Bosio F. Ferroni E. Longo P. Monacelli F. de Notaristefani P. Pistilli C. Santoni V. Valente 《Zeitschrift fur Physik C Particles and Fields》1983,17(3):211-217
The question whether scalar-type interactions contribute to weak interactions at large momentum transfer has been investigated by a measurement of the longitudinal polarization of positive muons produced in charged-current interactions of high-energy antineutrinos with iron. At an average momentum transfer <Q 2>=4 GeV2 the muon spin is found to be oriented forward with respect to the muon momentum vector, with an average polarization of 1.10±0.24, consistent with positive helicity. A limit on scalar contributions of σs, p/σtot <7% at the 95% confidence level can be deduced. A search for violation of time reversal invariance which could manifest itself by a polarization component perpendicular to the muon production plane gave a limit of σtv/σtot <16% (95% c.l.). It is concluded that the weak leptonic charged current retains its dominant vector and axial vector structure at large momentum transfers. 相似文献
40.
J. Badalec J. Ďatlov K. Jakubka VI. Kopecký Š. Körbel L. Kryška P. Magula J. Stöckel F. Žáček S. Nanobashvili 《Czechoslovak Journal of Physics》1983,33(7):787-790
The work is devoted to the study of the LH wave effect on the peripheral plasma of the TM-1-MH tokamak. The observed enhancement of the ion saturated current in the limiter shadow is interpreted as heating of the peripheral ions by absorption of decay waves generated in this region due to the nonlinear wave-plasma interaction. 相似文献