全文获取类型
收费全文 | 324589篇 |
免费 | 3452篇 |
国内免费 | 923篇 |
专业分类
化学 | 161373篇 |
晶体学 | 4283篇 |
力学 | 15406篇 |
综合类 | 7篇 |
数学 | 38294篇 |
物理学 | 109601篇 |
出版年
2021年 | 3001篇 |
2020年 | 3329篇 |
2019年 | 3760篇 |
2018年 | 5198篇 |
2017年 | 5438篇 |
2016年 | 7368篇 |
2015年 | 4139篇 |
2014年 | 7028篇 |
2013年 | 15905篇 |
2012年 | 12374篇 |
2011年 | 14824篇 |
2010年 | 11012篇 |
2009年 | 10913篇 |
2008年 | 13233篇 |
2007年 | 13191篇 |
2006年 | 12137篇 |
2005年 | 10520篇 |
2004年 | 9832篇 |
2003年 | 8685篇 |
2002年 | 8113篇 |
2001年 | 10130篇 |
2000年 | 7298篇 |
1999年 | 5570篇 |
1998年 | 4643篇 |
1997年 | 4516篇 |
1996年 | 4161篇 |
1995年 | 3753篇 |
1994年 | 3727篇 |
1993年 | 3607篇 |
1992年 | 4005篇 |
1991年 | 4223篇 |
1990年 | 3999篇 |
1989年 | 3907篇 |
1988年 | 3692篇 |
1987年 | 3848篇 |
1986年 | 3615篇 |
1985年 | 4560篇 |
1984年 | 4621篇 |
1983年 | 3828篇 |
1982年 | 3907篇 |
1981年 | 3640篇 |
1980年 | 3591篇 |
1979年 | 3878篇 |
1978年 | 3862篇 |
1977年 | 3881篇 |
1976年 | 3861篇 |
1975年 | 3639篇 |
1974年 | 3591篇 |
1973年 | 3623篇 |
1972年 | 2583篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Semigroup Forum - It is known that if a cancellative monoid M is left amenable then the monoid ring K[M] satisfies the Ore condition, that is, there exist nontrivial common right multiples for the... 相似文献
92.
Siberian Mathematical Journal - We give a simple proof of one assertion used in solving Waring’s problem. 相似文献
93.
Svetlakova A. V. Mendez M. Sanchez Tuchin E. S. Khodan A. N. Traore M. Azouani R. Kanaev A. Tuchin V. V. 《Optics and Spectroscopy》2021,129(8):846-850
Optics and Spectroscopy - We study the photocatalytic activity of nanocomposites based on θ-phase alumina (Al2O3) with different TiO2 concentrations for heterogeneous photocatalysis and... 相似文献
94.
The health monitoring has been studied to ensure integrity of design of engine structure by detection, quantification, and prediction of damages. Early detection of faults may allow the downtime of maintenance to be rescheduled, thus preventing sudden shutdown of machines. In cylinder pressure developed, vibrations and noise emissions data provide a rich source of information about condition of engines. Monitoring of vibrations and noise emissions are novel non-intrusive methodologies for which positioning of various transducers are important issue. The presented work shows applicability of these diagnosis methodologies adopted in case of diesel engines. The effects of changing various fuel injection parameters was analyzed. Scope of using non-intrusive technique has been analyzed by changing locations of microphone. Novelty of this worklies in exploring signal processing methods for various locations around the engine test set up. Various frequency ranges of contributing noise and vibration sources were identified. Time-Frequency analysis showed the onset of various cyclic. Based on the identification of various frequency bands, it is possible to device suitable filters in order to extract more information. 相似文献
95.
Mathematical Notes - Subspaces of the space of analytic functions on a convex domain in the complex plane that are invariant with respect to the differentiation operator are studied. The problem of... 相似文献
96.
Ukrainian Mathematical Journal - Among all two-dimensional algebras of the second rank with unit e over the field of complex numbers ?, we find a semisimple algebra ??0 := {c1e... 相似文献
97.
Physics of Atomic Nuclei - Emission of short electron bunches with high charge in RF guns is considered. The emission mechanism in the case of picosecond laser pulses and the presence of a strong... 相似文献
98.
Russian Physics Journal - The temperature dependences of the linear dielectric permittivity ε′ and the third harmonic coefficient γ3ω for nanocomposites obtained by embedding a... 相似文献
99.
McElroy Tucker S. Politis Dimitris N. 《Statistical Inference for Stochastic Processes》2022,25(3):471-483
Statistical Inference for Stochastic Processes - The problem of linear interpolation in the context of a multivariate time series having multiple (possibly non-consecutive) missing values is... 相似文献
100.
Knyazev Yu. V. Kazak N. V. Gavrichkov V. A. Polukeev S. I. Ovchinnikov S. G. 《JETP Letters》2022,116(8):567-573
JETP Letters - Changes in the magnetic properties of FeBO3 single crystals in the course of spin crossover occurring with increasing pressure up to 63 GPa are studied both experimentally and... 相似文献