全文获取类型
收费全文 | 1273篇 |
免费 | 26篇 |
国内免费 | 7篇 |
专业分类
化学 | 1024篇 |
晶体学 | 4篇 |
力学 | 20篇 |
数学 | 108篇 |
物理学 | 150篇 |
出版年
2023年 | 9篇 |
2022年 | 5篇 |
2021年 | 8篇 |
2020年 | 15篇 |
2019年 | 9篇 |
2018年 | 14篇 |
2017年 | 9篇 |
2016年 | 25篇 |
2015年 | 19篇 |
2014年 | 27篇 |
2013年 | 66篇 |
2012年 | 72篇 |
2011年 | 102篇 |
2010年 | 44篇 |
2009年 | 64篇 |
2008年 | 61篇 |
2007年 | 73篇 |
2006年 | 87篇 |
2005年 | 65篇 |
2004年 | 64篇 |
2003年 | 57篇 |
2002年 | 62篇 |
2001年 | 13篇 |
2000年 | 21篇 |
1999年 | 16篇 |
1998年 | 17篇 |
1997年 | 18篇 |
1996年 | 14篇 |
1995年 | 10篇 |
1994年 | 16篇 |
1993年 | 11篇 |
1992年 | 17篇 |
1991年 | 19篇 |
1990年 | 20篇 |
1989年 | 8篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 8篇 |
1985年 | 21篇 |
1984年 | 13篇 |
1983年 | 10篇 |
1982年 | 10篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 16篇 |
1975年 | 3篇 |
1974年 | 5篇 |
1973年 | 5篇 |
1971年 | 7篇 |
1968年 | 4篇 |
排序方式: 共有1306条查询结果,搜索用时 256 毫秒
101.
102.
Wall pressure fluctuations were measured in relation to the structure of coherent motions of a turbulent boundary layer. Their high and low frequency parts were found to be related with the large scale motions of the outer layer and the bursts in the wall region respectively. Based on the experimental results, a structure model of the coherent motions is presented.This paper was presented at the Ninth symposium on turbulence, University of Missouri-Rolla, October 1–3, 1984 相似文献
103.
Toshiyuki Arakane Takafumi Sato Takenori Fujii 《Journal of Physics and Chemistry of Solids》2011,72(5):552-555
We have investigated three-dimensional electronic structure for NaxCoO2 (x=0.77 and 0.65) by high-resolution angle-resolved photoemission spectroscopy to study the origin of antiferromagnetic (AF) transition of highly doped NaxCoO2(x>0.75). The a1g large hole-like Fermi surface (FS) in x=0.77 shows distinct three-dimensionality along the kz direction, and a three-dimensional small electron pocket appears around Γ point, indicating strong inter-layer electronic correlation. On the other hand, x=0.65 sample does not show three-dimensional behavior. This result indicates that transition of FS as a function of band filling is closely related to the occurrence of the magnetic transition in highly doped NaxCoO2. 相似文献
104.
We propose and demonstrate a scheme for boosting the efficiency of entanglement distribution based on a decoherence-free subspace over lossy quantum channels. By using backward propagation of a coherent light, our scheme achieves an entanglement-sharing rate that is proportional to the transmittance T of the quantum channel in spite of encoding qubits in multipartite systems for the decoherence-free subspace. We experimentally show that highly entangled states, which can violate the Clauser-Horne-Shimony-Holt inequality, are distributed at a rate proportional to T. 相似文献
105.
Masahiro Uchida Toshiyuki Suda Toshiro Fujimori Tadashi Fujii Tetsuhiko Inagaki 《Proceedings of the Combustion Institute》2011,33(2):2327-2333
Detonation experiments are conducted to investigate the detonation wave behavior in steam pipelines of boiling water reactors. Accumulated gases in BWRs are stoichiometric hydrogen/oxygen mixtures diluted with steam at 7 MPa. In the experiment, flammable gas mixture diluted with nitrogen at room temperature and up to 5 MPa is used to achieve equivalent detonation condition. Two test pieces are used, one is straight tube and the other is 90-degree bend. No initial pressure dependency in detonation wave behavior is observed in the experiments. However, in the straight tube tests, detonation velocities higher than theoretical values are measured when the initial pressures are greater than 2.3 MPa. This result is considered as attribution of real gas effect. In the 90-degree bend experiments, pressure time histories reveal pressure loads greater than the straight tube portion at two locations. One is a high pressure peak at the extrados of the bend and the other is a double pressure peak just downstream of the bend outlet. Second pressure peak just downstream of the bend outlet is due to transverse wave propagation. Additionally, the largest impulse is observed not at the extrados of the bend but at the intrados of bend outlet. These results show the importance of more investigations on transverse wave behaviors in failure potential evaluation. 相似文献
106.
In this study, we present a new method for placing markers for alignment of tomographic tilt-series of rod-shaped specimen before 3D reconstructions. By this method, markers (gold nanoparticles) were placed only on the carbon layer (referred to as the "marker area") deposited for protecting the specimen surface against ion beam irradiation; this placement was achieved by vacuum evaporation of gold with the help of a mask fabricated adjacent to the specimen. Experimental results showed that the use of the proposed method facilitates the identification of the markers in the alignment process, because the image of the marker area consists of simple high-contrast images of the gold nanoparticles on the carbon layer. The performance of the proposed method was successfully verified experimentally by applying it to a high-density Au/SiO? nanocomposite material as a test specimen. 相似文献
107.
Akira Zenidaka Toshiyuki Honda Mitsuhiro Terakawa 《Applied Physics A: Materials Science & Processing》2011,105(2):393-398
We describe the physics of the SERS based on the optical near-field intensity enhancement on the metallic (plasmonic) and
the nonmetallic (Mie scattering) nanostructured substrates with two-dimensional (2D) periodic nanohole arrays. The calculation
by the Finite-Difference Time-Domain (FDTD) method revealed that the optical intensity enhancement increases with the increase
of the thickness of a gold film coating on the nonmetallic (dielectric) nanostructured Si, GaAs, and SiC substrates. The resonance
spectrum shifts with the changes in the geometrical structure of the void diameter and inter-void distance. It was clarified
that the optical intensity enhancement obtained with the gold-coated substrate is equivalent to that with a gold substrate
at 70-nm thick gold coating on the dielectric substrates in this structure. The resonance spectral bandwidth for Mie scattering
and plasmonic near-fields is different. Therefore, if the Stokes line of the Raman scattering is located within the resonance
bandwidth, the SERS signal is enhanced proportionally to the fourth power of the electric near-field. However, if the Stokes
shift is located out of the resonance bandwidth, the SERS signal enhancement is only proportional to the square of the scattered
near-field. 相似文献
108.
Toshiyuki Kikuta Sho Takemori 《Abhandlungen aus dem Mathematischen Seminar der Universit?t Hamburg》2014,84(2):257-266
In the case of Siegel modular forms of degree \(n\) , we prove that, for almost all prime ideals \(\mathfrak {p}\) in any ring of algebraic integers, mod \(\mathfrak {p}^m\) cusp forms are congruent to true cusp forms of the same weight. As an application we give congruences for the Klingen-Eisenstein series and cusp forms, which can be regarded as a generalization of Ramanujan’s congruence. We will conclude by giving numerical examples. 相似文献
109.
We give a complete classification of intertwining operators (breaking symmetry operators ) between spherical principal series representations of O(n+1,1) and O(n,1) together with explicit formulae of the distribution kernels. Further we use this to determine the breaking symmetry operators between their irreducible composition factors. 相似文献
110.
Toshiyuki Moriuchi 《Tetrahedron letters》2010,51(34):4530-3213
Ferrocene-peptide-oligoaniline conjugates were designed by the introduction of two ferrocene-peptide conjugates into a π-conjugated phenylenediamine spacer to demonstrate the luminescent switching by changing the redox states of the π-conjugated phenylenediamine moiety, wherein the self-aggregation of the π-conjugated moiety was achieved in a higher concentration to induce the chirality organization with a red shift of the maximum emission wavelength. 相似文献