全文获取类型
收费全文 | 455篇 |
免费 | 14篇 |
国内免费 | 2篇 |
专业分类
化学 | 323篇 |
晶体学 | 4篇 |
力学 | 7篇 |
数学 | 56篇 |
物理学 | 81篇 |
出版年
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 4篇 |
2019年 | 7篇 |
2018年 | 6篇 |
2017年 | 8篇 |
2016年 | 19篇 |
2015年 | 10篇 |
2014年 | 12篇 |
2013年 | 21篇 |
2012年 | 31篇 |
2011年 | 35篇 |
2010年 | 9篇 |
2009年 | 19篇 |
2008年 | 29篇 |
2007年 | 26篇 |
2006年 | 24篇 |
2005年 | 20篇 |
2004年 | 26篇 |
2003年 | 24篇 |
2002年 | 28篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 11篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1994年 | 2篇 |
1992年 | 4篇 |
1990年 | 3篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 5篇 |
1984年 | 7篇 |
1983年 | 1篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1967年 | 3篇 |
1964年 | 1篇 |
排序方式: 共有471条查询结果,搜索用时 28 毫秒
461.
Kinoshita K Minami H Tarutani Y Tajima K Okubo M Yanagimoto H 《Langmuir : the ACS journal of surfaces and colloids》2011,27(8):4474-4480
Polystyrene (PS)/aluminum hydroxide (Al(OH)(3)) composite particles were successfully prepared by the sol-gel process of aluminum isopropoxide (Al(OPr(i))(3)) in a hydrophilic ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF(4)]) using ammonium hydroxide (NH(4)OH) as a catalyst in the presence of PS seed. Transmission electron microscopy observation of ultrathin cross-sections of the composite particles revealed that the composite particles had a core-shell morphology consisting of a PS core and a Al(OH)(3) shell having high crystallinity. The amount of secondary nucleated Al(OH)(3) could be reduced by dropwise addition of NH(4)OH. Moreover, PS/η-Al(2)O(3) composite particles were successfully prepared by heat treatment of PS/Al(OH)(3) at 300 °C in N(2) atmosphere, which is below the decomposition temperature of PS. 相似文献
462.
Alvaro Gonzalez Yoshinori Uzawa Yasunori Fujii Keiko Kaneko 《Infrared Physics & Technology》2011,54(6):488-496
The ALMA Band 10 (787–950 GHz) receiver is a dual-polarization heterodyne system based on NbTiN superconducting technology. The coupling of energy from the secondary mirror of the ALMA Cassegrain antenna to the Superconductor–Insulator–Superconductor (SIS) mixers used for down-conversion is achieved by a frequency-independent optical system composed of two elliptical mirrors to focus and redirect the incoming radiation, a wire-grid to separate orthogonal linear polarizations and two corrugated horns, one for each polarization and SIS mixer. In this paper, we present the ALMA Band 10 tertiary optics design and evaluate its performance by quasi-optical techniques, Physical Optics simulations and measurements. Detailed results of secondary aperture efficiency and beam-squint are provided. The characterization procedure described in this paper can be used for any optical system at around 1 THz. 相似文献
463.
Yasunori Watanabe Ayumi Saruwatari David M. Ingram 《Journal of computational physics》2008,227(4):2344-2365
A numerical method which fulfils the free-surface boundary conditions and extrapolates the fluid velocity into empty grid cells outside the fluid region on a fixed Cartesian grid system is presented. The complex, three-dimensional, vortex structures formed via surface/vortex interaction and induction between vortices have been computed using the proposed technique implemented within a level-set method for both vertical and oblique droplet impacts in incompressible fluids. The present results have been validated through numerical tests which confirm zero tangential shear at the free-surface and comparisons with experimental observations of cavity and vortex ring formation underneath the impact location. In some cases, transitions from a concentric vortex ring to a fully three-dimensional vortex structure has been confirmed. Whilst the primary vortex ring is initiated at the highly curved contact surface between the droplet and receiving surface, azimuthal instabilities are manifested in the shear layer around the cavity crater developing after the vertical impact, resulting in axial counter-rotating vorticity between the cavity and descending vortex ring. Underlying mechanisms which induce local deformation of the free-surface, creating a so-called scar, due to the sub-surface vortices at the oblique impacts are also discussed. 相似文献
464.
Tanaka Y Takeuchi T Lovesey SW Knight KS Chainani A Takata Y Oura M Senba Y Ohashi H Shin S 《Physical review letters》2008,100(14):145502
Enantiomers, or stereoisomers, have crystal structures that are mirror images of each other and are thus handed, like our right and left hands. The physical properties of enantiomers are identical except for optical activity, which rotates linearly polarized light by equal amounts but in opposite directions. While conventional x-ray Bragg diffraction can determine crystal structures, it does not distinguish between right- and left-handed crystals. We show resonant Bragg diffraction using circularly polarized x rays reveals the handedness of crystals by coupling x-ray helicity to a crystal screw axis. The intensity of resonantly allowed reflection of alpha-quartz is well described by an admixture of a parity-even and a parity-odd process. Our results are of general importance and demonstrate a new method to directly study chiral motifs in structures that include biomaterials, liquid crystals, magnets, multiferroics, etc. 相似文献
465.
Ishida Y Eguchi R Matsunami M Horiba K Taguchi M Chainani A Senba Y Ohashi H Ohta H Shin S 《Physical review letters》2008,100(5):056401
Resonant photoemission at the Ti 2p and O 1s edges on a Nb-doped SrTiO(3) thin film revealed that the coherent state (CS) at the Fermi level (E(F)) had a mainly Ti 3d character whereas the incoherent in-gap state (IGS) positioned approximately 1.5 eV below E(F) had a mixed character of Ti 3d and O 2p states. This indicates that the IGS is formed by a spectral-weight transfer from the CS and subsequent spectral-weight redistribution through d-p hybridization. We discuss the evolution of the excitation spectrum with 3d band filling and rationalize the IGS through a mechanism similar to that proposed by Haldane and Anderson. 相似文献
466.
T Suzuki H Inagaki H Hamajima H Uesaka K Hori T Ikami 《Chemical & pharmaceutical bulletin》1999,47(6):880-883
Three metabolites of N-[2-(1-azabicyclo[3.3.0]octan-5-yl)ethyl]-2-nitroaniline fumarate (SK-946), a novel central muscarinic cholinergic receptor agonist, were prepared to confirm their proposed structures, and tested for muscarinic receptor affinity in vitro. 相似文献
467.
468.
469.
470.