全文获取类型
收费全文 | 7226篇 |
免费 | 154篇 |
国内免费 | 1篇 |
专业分类
化学 | 4321篇 |
晶体学 | 35篇 |
力学 | 134篇 |
数学 | 1525篇 |
物理学 | 1366篇 |
出版年
2021年 | 51篇 |
2020年 | 55篇 |
2019年 | 73篇 |
2018年 | 147篇 |
2017年 | 141篇 |
2016年 | 220篇 |
2015年 | 171篇 |
2014年 | 228篇 |
2013年 | 510篇 |
2012年 | 333篇 |
2011年 | 450篇 |
2010年 | 253篇 |
2009年 | 217篇 |
2008年 | 369篇 |
2007年 | 371篇 |
2006年 | 353篇 |
2005年 | 264篇 |
2004年 | 237篇 |
2003年 | 183篇 |
2002年 | 182篇 |
2001年 | 119篇 |
2000年 | 102篇 |
1999年 | 86篇 |
1998年 | 69篇 |
1997年 | 71篇 |
1996年 | 67篇 |
1995年 | 71篇 |
1994年 | 54篇 |
1993年 | 54篇 |
1992年 | 77篇 |
1991年 | 61篇 |
1990年 | 62篇 |
1989年 | 68篇 |
1988年 | 59篇 |
1987年 | 65篇 |
1986年 | 60篇 |
1985年 | 85篇 |
1984年 | 96篇 |
1983年 | 74篇 |
1982年 | 84篇 |
1981年 | 56篇 |
1980年 | 81篇 |
1979年 | 70篇 |
1978年 | 93篇 |
1977年 | 62篇 |
1976年 | 76篇 |
1975年 | 69篇 |
1974年 | 83篇 |
1973年 | 74篇 |
1972年 | 58篇 |
排序方式: 共有7381条查询结果,搜索用时 15 毫秒
1.
2.
3.
Simen Gjelseth Antonsen Arne Joakim C. Bunkan Tomas Mikoviny Yngve Stenstrøm Armin Wisthaler 《Molecular physics》2020,118(15)
The kinetics of the O3, OH and NO3 radical reactions with diazomethane were studied in smog chamber experiments employing long-path FTIR and PTR-ToF-MS detection. The rate coefficients were determined to be k CH2NN+O3?=?(3.2?±?0.4)?×?10?17 and k CH2NN+OH?=?(1.68?±?0.12)?×?10?10 cm3 molecule?1 s?1 at 295?±?3?K and 1013?±?30 hPa, whereas the CH2NN?+?NO3 reaction was too fast to be determined in the static smog chamber experiments. Formaldehyde was the sole product observed in all the reactions. The experimental results are supported by CCSD(T*)-F12a/aug-cc-pVTZ//M062X/aug-cc-pVTZ calculations showing the reactions to proceed exclusively via addition to the carbon atom. The atmospheric fate of diazomethane is discussed. 相似文献
4.
5.
6.
Boban Marinković 《Mathematical Methods of Operations Research》2006,63(3):513-524
We present local sensitivity analysis for discrete optimal control problems with varying endpoints in the case when the customary regularity of boundary conditions can be violated. We study the behavior of the optimal solutions subject to parametric perturbations of the problem. 相似文献
7.
N. S. Simonović 《Few-Body Systems》2006,38(2-4):139-145
In agreement with the Kohn theorem the relative motion (rel) of three electrons in a two-dimensional parabolic trap separates
from the centre-of-mass (CM) motion. By introducing new coordinates the Hamiltonian for relative motion in the approximation
of non-interacting electrons can be taken to the normal form. The eigenstates of the normalized Hamiltonian are products of
the Fock-Darwin states for normal modes. The energy levels for relative motion are obtained by diagonalizing the exact Hamiltonian
in the eigenbasis for the non-interacting case. In this basis the interaction matrix elements can be obtained in the analytical
form. Since the rank of the Hamiltonian matrix is significantly reduced, the calculations are faster and more accurate than
those for the full (CM + rel) motion. This advantage is especially important for the calculations of excited states and the
analysis of energy spectra. 相似文献
8.
9.
Veličković Jelena Đ. Andrić Deana Roglić Goran Tešic Živoslav Lj. Milojković-Opsenica Dušanka M. 《平面色谱法杂志一现代薄层色谱法》2004,17(4):255-260
JPC – Journal of Planar Chromatography – Modern TLC - The chromatographic behavior of fourteen 1-arylpiperazine derivatives has been studied by thin-layer chromatography on both silica... 相似文献
10.
The new techniques and ideas in quantum interferometry with neutrons, photons, atoms, electrons, and Bose condensates that fluorished in the last two decades have influenced in a decisive way the thinking and the research in the foundations and interpretation of quantum mechanics. The controversies existing among different schools on the reality of matter waves of quantum theory, the postulates of quantum measurement theory, and the (in)completeness of quantum mechanics have to be approached now in a new way. Our argumentation follows the spirit of the Paris school. 相似文献