全文获取类型
收费全文 | 17989篇 |
免费 | 421篇 |
国内免费 | 203篇 |
专业分类
化学 | 7216篇 |
晶体学 | 400篇 |
力学 | 1062篇 |
综合类 | 15篇 |
数学 | 1697篇 |
物理学 | 8223篇 |
出版年
2023年 | 85篇 |
2022年 | 233篇 |
2021年 | 186篇 |
2020年 | 138篇 |
2019年 | 148篇 |
2018年 | 235篇 |
2017年 | 211篇 |
2016年 | 361篇 |
2015年 | 250篇 |
2014年 | 424篇 |
2013年 | 812篇 |
2012年 | 1019篇 |
2011年 | 1280篇 |
2010年 | 908篇 |
2009年 | 890篇 |
2008年 | 1017篇 |
2007年 | 1034篇 |
2006年 | 1035篇 |
2005年 | 846篇 |
2004年 | 726篇 |
2003年 | 569篇 |
2002年 | 548篇 |
2001年 | 955篇 |
2000年 | 662篇 |
1999年 | 540篇 |
1998年 | 351篇 |
1997年 | 380篇 |
1996年 | 305篇 |
1995年 | 246篇 |
1994年 | 240篇 |
1993年 | 187篇 |
1992年 | 207篇 |
1991年 | 173篇 |
1990年 | 164篇 |
1989年 | 139篇 |
1988年 | 111篇 |
1987年 | 102篇 |
1986年 | 95篇 |
1985年 | 94篇 |
1984年 | 63篇 |
1983年 | 53篇 |
1982年 | 45篇 |
1981年 | 38篇 |
1980年 | 32篇 |
1979年 | 32篇 |
1978年 | 28篇 |
1977年 | 41篇 |
1976年 | 40篇 |
1975年 | 45篇 |
1974年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Li Y. Shi W. H. Dong L. M. Xu S. X. Huang H. J. Yin J. R. 《Journal of Applied Spectroscopy》2022,89(3):534-541
Journal of Applied Spectroscopy - Sr3B2O6:Dy3+, Eu3+ single-matrix white-light-emitting materials are prepared using the high-temperature solid-state method. The microstructure, emission spectrum,... 相似文献
2.
3.
Su X. F. Zhang Y. L. Maximov A. L. Zhang K. Xin Q. Feng C. Q. Bai X. F. Wu W. 《Russian Journal of Applied Chemistry》2020,93(1):127-136
Russian Journal of Applied Chemistry - Nanoscale ZSM-5 (AlZ5-D) and Ga-substituted ZSM-5 zeolites ((Al,Ga)Z5-D and GaZ5-D) were synthesized by a green dry-gel conversion strategy. For comparison,... 相似文献
4.
5.
6.
Kinetics and Catalysis - A series of Cu-SSZ-13@CeO2 catalysts with surface modification with CeO2 was prepared by the modified self-resemble method based on the one-pot synthesized Cu-SSZ-13... 相似文献
7.
In this paper, the authors studied certain properties of the estimate of Liang and Krishnaiah (1985, J. Multivariate Anal. 16, 162–172) for multivariate binary density. An alternative shrinkage estimate is also obtained. The above results are generalized to general orthonormal systems. 相似文献
8.
A numerical procedure, with an exact strain-displacement relationship of twisted and curved cylindrical panels having variable thickness derived by considering the Green strain tensor on general shell theory, is presented using the principle of virtual work and the Rayleigh-Ritz method with algebraic polynomials as in-plane and transverse displacement functions. The accuracy and applicability of the procedure are verified by comparing the present results with previous experimental and theoretical results for several panels. The effects of variation ratio of thickness in chordwise and lengthwise directions, twist, and curvature both in two directions aforementioned on vibrations of cylindrical panels are studied in detail, and typical vibration mode shapes are plotted to demonstrate the effects. 相似文献
9.
Q. Sun Q. Wang X.G. Gong V. Kumar Y. Kawazoe 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(1):77-81
We report results of the atomic and electronic structures of Al7C cluster using ab initio molecular dynamics with ultrasoft pseudopotentials and generalized gradient approximation. The lowest energy structure is
found to be the one in which carbon atom occupies an interstitial position in Al7 cluster. The electronic structure shows that the recent observation [Chem. Phys. Lett. 316, 31 (2000)] of magic behavior of Al7C- cluster is due to a large highest occupied and lowest unoccupied molecular orbital (HOMO-LUMO) gap which makes Al7C- chemically inert. These results have further led us to the finding of a new neutral magic cluster Al7N which has the same number of valence electrons as in Al7C- and a large HOMO-LUMO gap of 1.99 eV. Further, calculations have been carried out on (Al7N)2 to study interaction between magic clusters.
Received 28 July 2001 相似文献
10.
A three-dimensional molecular dynamics (MD) model is utilized to investigate the effect of tool geometry on the deformation process of the workpiece and the nature of deformation process at the atomic-scale. Results show that different states exist between the atomic force microscope (AFM) pin tool and the workpiece surface, i.e. the non-wear state, the ploughing state, the state in which ploughing is dominant and the state in which cutting plays a key role. A relationship between the deformation process of the workpiece and the potential energy variation is presented. The potential energy variation of atoms in different deformed regions in the workpiece such as plastically deformed region, elastically deformed region and the mixed deformation region is different. The features of variations of potential energy are discussed. 相似文献