全文获取类型
收费全文 | 6892篇 |
免费 | 195篇 |
国内免费 | 55篇 |
专业分类
化学 | 4297篇 |
晶体学 | 50篇 |
力学 | 108篇 |
数学 | 1315篇 |
物理学 | 1372篇 |
出版年
2024年 | 8篇 |
2023年 | 32篇 |
2022年 | 143篇 |
2021年 | 181篇 |
2020年 | 129篇 |
2019年 | 191篇 |
2018年 | 206篇 |
2017年 | 173篇 |
2016年 | 254篇 |
2015年 | 217篇 |
2014年 | 217篇 |
2013年 | 487篇 |
2012年 | 433篇 |
2011年 | 536篇 |
2010年 | 373篇 |
2009年 | 307篇 |
2008年 | 440篇 |
2007年 | 406篇 |
2006年 | 368篇 |
2005年 | 355篇 |
2004年 | 304篇 |
2003年 | 245篇 |
2002年 | 199篇 |
2001年 | 88篇 |
2000年 | 86篇 |
1999年 | 99篇 |
1998年 | 77篇 |
1997年 | 57篇 |
1996年 | 86篇 |
1995年 | 49篇 |
1994年 | 46篇 |
1993年 | 51篇 |
1992年 | 41篇 |
1991年 | 29篇 |
1990年 | 14篇 |
1989年 | 17篇 |
1988年 | 10篇 |
1987年 | 10篇 |
1986年 | 12篇 |
1985年 | 15篇 |
1984年 | 13篇 |
1983年 | 18篇 |
1982年 | 14篇 |
1981年 | 13篇 |
1979年 | 8篇 |
1978年 | 11篇 |
1977年 | 12篇 |
1976年 | 6篇 |
1975年 | 11篇 |
1973年 | 5篇 |
排序方式: 共有7142条查询结果,搜索用时 0 毫秒
91.
Ivan V. Dudinets Vladimir I. Man’ko 《International Journal of Theoretical Physics》2018,57(6):1631-1644
Tomographic probability representation of multimode electromagnetic field states in the scheme of center-of-mass tomography is reviewed. Both connection of the field state Wigner function and observable Weyl symbols with the center-of-mass tomograms as well as connection of the Grönewold kernel with the center-of-mass tomographic kernel determining the noncommutative product of the tomograms are obtained. The dual center-of-mass tomogram of the photon states are constructed and the dual tomographic kernel is obtained. The models of other generalized center-of-mass tomographies are discussed. Example of two-mode even and odd Schrödinger cat states is presented in details. 相似文献
92.
We present an approximate analytical theory and direct numerical computation of defect modes of a Bose-Einstein condensate loaded in an optical lattice and subject to an additional localized (defect) potential. Some of the modes are found to be remarkably stable and can be driven along the lattice by means of a defect moving following a steplike function defined by the period of Josephson oscillations and the macroscopic stability of the atoms. 相似文献
93.
94.
Jelena Đorović Zoran Marković Zorica D. Petrović Dušica Simijonović Vladimir P. Petrović 《Molecular physics》2017,115(19):2460-2468
The time-dependent density functional theory (TDDFT) was applied in conjunction with the natural bond orbital analysis to examine the UV-Vis properties of 10 phenolic Schiff bases. The calculations were performed with different functionals, but main discussion refers to results obtained at the B3LYP/6-311+G(d,p) level of theory. The approach based on the natural localised molecular orbital clusters indicates similar behaviour for majority of examined compounds. The HOMO (“highest occupied molecular orbital”) cluster is delocalised over the ring which is electron richer, the HOMO-1 cluster is spread over the other ring, whereas the LUMO (“lowest unoccupied molecular orbital”) cluster is situated on the imino group. The two bands at long wavelengths correspond to the HOMO → LUMO and HOMO-1 → LUMO transitions, i.e. from both A and B rings to the imino group. The next band originates from a transition from the imino group to the imino group. The band at the smallest wavelengths originates from a transition from the A ring to the A ring, or from the B ring to the B ring. Our findings are in very good agreement with the existing literature data. 相似文献
95.
Peter Adam Vladimir A. Andreev Margarita A. Man’ko Vladimir I. Man’ko 《Journal of Russian Laser Research》2017,38(6):491-506
We review the quantizer–dequantizer formalism of constructing symbols of the density operators and quantum observables, such as Wigner functions and tomographic-probability distributions. We present a tutorial consideration of the technique of obtaining minimal sets of dequantizers (quorum) related to the observable eigenvalues for one-qubit states. We discuss a generalization of the quantizer–dequantizer scheme on the example of spin-1/2 states. We consider the possibilities of extending the results to two-qubit systems using spin tomograms of the state density matrix. 相似文献
96.
97.
Radosevich AJ Mutyal NN Turzhitsky V Rogers JD Yi J Taflove A Backman V 《Optics letters》2011,36(24):4737-4739
In this Letter, we describe an easy to implement technique to measure the spatial backscattering impulse-response at length scales shorter than a transport mean free path with resolution of better than 10 μm using the enhanced backscattering phenomenon. This technique enables spectroscopic measurements throughout the visible range and sensitivity to all polarization channels. Through a combination of Monte Carlo simulations and experimental measurements of latex microspheres, we explore the various sensitivities of our technique to both intrinsic sample properties and extrinsic instrumental properties. We conclude by demonstrating the extraordinary sensitivity of our technique to the shape of the scattering phase function, including higher order shape parameters than the anisotropy factor (or first moment). 相似文献
98.
Huabing Liu Lizhi Xiao Huijun Yu Xin Li Baoxin Guo Zongfu Zhang Fangrong Zong Vladimir Anferov Sofia Anferova 《Applied magnetic resonance》2013,44(5):543-552
Combination of two-dimensional nuclear magnetic resonance (2-D NMR) correlation maps and a simple three-component model are proposed here to identify the structural composition of porous media. Homogeneous magnetic field and field with constant gradient of a novel Halbach sensor are employed for respective relaxation and diffusion measurements. NMR results are compared and confirmed with independent measurements on a scanning electron microscope and by energy dispersive spectrometer methods. 相似文献
99.
Aleksey Tyazhev Georgi Marchev Valeriy Badikov Adolfo Esteban‐Martin Dmitrii Badikov Vladimir Panyutin Galina Shevyrdyaeva Svetlana Sheina Anna Fintisova Valentin Petrov 《Laser \u0026amp; Photonics Reviews》2013,7(4):L21-L24
The defect chalcopyrite crystal HgGa2S4 has been employed in a 1064‐nm pumped optical parametric oscillator operating at 100 Hz, to generate ∼5 ns long idler pulses near 4 µm with energies as high as 6.1 mJ and average power of 610 mW. At crystal dimensions comparable to those available for the commercial AgGaS2 crystal, operation of the 1064‐nm pumped HgGa2S4 OPO is characterized by much lower pump threshold and higher conversion efficiency, with the most important consequence that such a device might become practical at pump levels sufficiently lower than the optical damage threshold. 相似文献
100.
This paper reports the feasibility of nano-oxide precipitate formation in Fe–Cr alloy by ion implantation synthesis. High contents of Al+ and O+ ions were implanted into thin films of high purity Fe–10%Cr alloy at room temperature and were studied by transmission electron microscopy (TEM) and atom probe tomography (APT). In contrast, to the common two-stage implantation/annealing scheme of precipitate ensemble synthesis by ion beams, cluster formation took place at the implantation stage in our study, requiring no subsequent high-temperature annealing. The post-implantation microstructural examination revealed in the as-implanted thin foil an array of precipitates with diameters in the range of 3–30?nm. The precipitate number density distribution was found to depend on the foil thickness. The precipitate enrichment with both Al and O was confirmed by the energy-filtered TEM analysis. Judging from the electron diffraction pattern and high-resolution TEM analysis, the crystal lattice of precipitates corresponds to some cubic modification of aluminium-rich oxide or pure aluminium oxide. The precipitate lattice alignment with the host matrix was revealed for at least a part of precipitates. The analysis of APT data using cluster detection algorithm indicates the presence of local zones enriched in Al and O, even in those areas of as-implanted samples where no clusters were visible by TEM. 相似文献