全文获取类型
收费全文 | 1340篇 |
免费 | 11篇 |
国内免费 | 6篇 |
专业分类
化学 | 616篇 |
晶体学 | 13篇 |
力学 | 90篇 |
数学 | 195篇 |
物理学 | 443篇 |
出版年
2022年 | 16篇 |
2021年 | 16篇 |
2020年 | 29篇 |
2019年 | 24篇 |
2018年 | 28篇 |
2017年 | 36篇 |
2016年 | 46篇 |
2015年 | 13篇 |
2014年 | 36篇 |
2013年 | 38篇 |
2012年 | 51篇 |
2011年 | 67篇 |
2010年 | 56篇 |
2009年 | 41篇 |
2008年 | 53篇 |
2007年 | 51篇 |
2006年 | 45篇 |
2005年 | 35篇 |
2004年 | 45篇 |
2003年 | 30篇 |
2002年 | 20篇 |
2001年 | 39篇 |
2000年 | 26篇 |
1999年 | 12篇 |
1998年 | 13篇 |
1997年 | 24篇 |
1996年 | 16篇 |
1994年 | 19篇 |
1993年 | 12篇 |
1992年 | 12篇 |
1991年 | 19篇 |
1990年 | 15篇 |
1989年 | 25篇 |
1988年 | 15篇 |
1987年 | 21篇 |
1986年 | 14篇 |
1985年 | 26篇 |
1984年 | 13篇 |
1983年 | 11篇 |
1982年 | 15篇 |
1981年 | 15篇 |
1979年 | 12篇 |
1978年 | 16篇 |
1976年 | 21篇 |
1975年 | 16篇 |
1974年 | 11篇 |
1973年 | 11篇 |
1972年 | 11篇 |
1969年 | 14篇 |
1968年 | 17篇 |
排序方式: 共有1357条查询结果,搜索用时 15 毫秒
71.
Theoretical analysis of the spatial, noise, and energy characteristics of an amplifier has been performed in the mode of spectral and time selection using subnanosecond stimulated Raman Scattering gain of weak echo signals in crystalline active media that are known for high (up to 10–1 cm/MW) gain coefficients. The possibility to reach high gain values has been demonstrated for weak signals from objects at acceptable angular sizes of the field of vision of an amplifier. To provide a signal-to-noise ratio that exceeds unity over the entire field of vision, the number of photons at the input to an amplifier that is required has to exceed the number of its resolution elements. Accurate determination of the possibilities of recording of weak echo signals and quality of images of targets that are obtained using amplifiers under stimulated Raman Scattering requires additional special experiments. 相似文献
72.
A theory of the reradiation of ultrashort electromagnetic pulses by arbitrary polyatomic systems of isolated complex atoms has been developed. The technique used allows the spatial inhomogeneity of the field of an ultrashort pulse and photon momenta in reradiation processes to be accurately taken into account. The angular distributions of the reradiation spectra have been obtained for an arbitrary number of atoms in the system. The processes of interference between the photon emission amplitudes are shown to give rise to characteristic “diffraction” maxima. We consider one-dimensional, two-dimensional, and three-dimensional rectangular lattices as examples as well as planar and cylindrical structures as models of planar nanosystems and nanotubes. 相似文献
73.
Riik I. I. Makarov A. L. Mnatsakanov S. S. 《Russian Journal of Applied Chemistry》2010,83(10):1892-1894
The rheological and spectrophotometric characteristics of polymer compositions containing optical bleaching agent were examined.
The mechanism of interaction between the components of the polymer composition was studied. 相似文献
74.
Under the conditions of the Plato technique, the problem of convection in a droplet immersed in a nonuniformly heated liquid is solved analytically. The influence of gravitational convection on the thermocapillary flow is studied. In the linear approximation with respect to the Marangoni and Grashof numbers and their product, the shape of the droplet and the displacement of its center of the mass are obtained.Perm. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 4, pp. 43–51, July–August, 1996. 相似文献
75.
Using two-frequency technique for the multiple photon dissociation of OsO4 molecule by IR laser radiation, the following new results have been obtained: 1. the narrow resonances of multiple photon absorption on few low lying vibrational transitions have been found in the dissociation yield as a function of exciting frequency ν1; 2. the structure of the dissociation yield as a function of dissociating frequency ν2 connected with high lying vibrational transition has been studied; 3. the kinetic of the vibration relaxation of high vibrationally excited molecules was investigated; 4. the unimolecular character of the multiple photon dissociation of OsO4 has been proved. 相似文献
76.
77.
78.
79.
80.