全文获取类型
收费全文 | 508篇 |
免费 | 5篇 |
国内免费 | 3篇 |
专业分类
化学 | 288篇 |
晶体学 | 2篇 |
力学 | 26篇 |
数学 | 72篇 |
物理学 | 128篇 |
出版年
2022年 | 4篇 |
2019年 | 8篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 6篇 |
2015年 | 5篇 |
2014年 | 9篇 |
2013年 | 20篇 |
2012年 | 28篇 |
2011年 | 30篇 |
2010年 | 11篇 |
2009年 | 11篇 |
2008年 | 13篇 |
2007年 | 26篇 |
2006年 | 22篇 |
2005年 | 23篇 |
2004年 | 22篇 |
2003年 | 13篇 |
2002年 | 17篇 |
2001年 | 7篇 |
2000年 | 13篇 |
1999年 | 11篇 |
1998年 | 5篇 |
1997年 | 7篇 |
1996年 | 5篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 9篇 |
1984年 | 15篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1981年 | 13篇 |
1980年 | 3篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 12篇 |
1975年 | 6篇 |
1974年 | 9篇 |
1973年 | 8篇 |
1967年 | 4篇 |
1966年 | 3篇 |
1883年 | 2篇 |
排序方式: 共有516条查询结果,搜索用时 15 毫秒
91.
92.
Geoffrey C. Allen Philip M. Tucker Brian E. Hayden Derek F. Klemperer 《Surface science》1981,102(1):207-226
The initial stages in the oxidation of magnesium, aluminium and magnesium/aluminium alloys have been studied using a photoelectron spectrometer (XPS and exoelectron energy spectra) and the diode technique (surface potentials and volumetric adsorption of oxygen). This paper describes and characterises the exoelectron emission and the visible wavelength photoemission which occurs during oxidation. At low oxygen exposures (< 10 L), exoelectrons with a 4 eV energy spread are emitted in the dark from magnesium and magnesium/aluminium alloy. Aluminium shows no such emission. Another, dark pressure-dependent emission of exoelectrons occurs only on magnesium/aluminium alloy and aluminium at high oxygen exposures. The onset of this emission lies 3 eV higher and it again has a 4 eV spread. When the surface is illuminated, it is possible to distinguish photo/exoelectron emission, which occurs during oxygen uptake, and true photoemission which occurs in vacuo. Both these types of emission, which were only recorded on magnesium, show a resolved triplet. Photoelectric work functions as low as 0.3 eV were observed. A patchy surface evidently develops during oxidation. This process, which may correspond to the nucleation of oxide islands, is slower than the chemisorption of of oxygen. The nature of the low work function patches, which we associate with the electron emissions, is therefore very dependent on the oxygen ambient pressure. A tentative energy scheme is given for such “exopatches” which are neither metal nor oxide and contain a curious energy level that must be situated above the vacuum level of the patch, as well as above the metal Fermi level. The energy with which exoelectrons are emitted derives from the heat of adsorption. 相似文献
93.
Polyene antibiotics. 3. The structure of tetrin B 总被引:3,自引:0,他引:3
94.
J. A. Gelbwachs M. Birnbaum A. W. Tucker C. L. Fincher 《Optical and Quantum Electronics》1972,4(2):155-160
The concentrations of nitrogen dioxide (NO2) in the atmosphere have been determined in real time and with a sensitivity of one part per billion. Laser excitation of NO2 was at 4416 and 4880 Å and fluorescence was monitored at 0.7 to 0.8 m. Results obtained on typical smoggy days in Los Angeles are presented. 相似文献
95.
A Lagrangian giving the constraints and boundary conditions of the Neveu Schwarz-Ramond model is presented. 相似文献
96.
97.
Motivated by the theory of relativistic strings, the theory of a two-dimensional relativistic membrane whose action is proportional to the three-dimensional area it traces out in space-time is investigated both in Lagrangian and Hamiltonian formalisms. The quantum theory is developed using Dirac's method for constrained systems and the question of gauge choices is considered in some detail. 相似文献
98.
Total neutron scattering data from a powdered sample of MnO collected at 10 K have been analyzed using the reverse Monte Carlo method to refine the nuclear and magnetic structure. The results give the first unambiguous assignment of the average magnetic structure. The magnetic moments are aligned ferromagnetically within (111) sheets with the magnetization vectors of alternate sheets along axes parallel and antiparallel to the <112> directions, albeit with a small modulated out-of-plane component. Small displacements of Mn and O (modulated with the same periodicity) accompany the magnetic ordering and both atomic and magnetic structures may be described in the monoclinic space group C2. 相似文献
99.
Joly KM Wilson C Blake AJ Tucker JH Moody CJ 《Chemical communications (Cambridge, England)》2008,(41):5191-5193
Planar chirality associated with the ferrocene in ferrocenyl oximes and hydrazones bearing chiral auxiliaries effectively competes with or overrides the normally excellent stereocontrol afforded by the auxiliary in determining the diastereoselectivity of addition to the C=N bond. 相似文献
100.
Tucker DJ Southwell IA Lowe RF Russell MF Brereton IM 《Magnetic resonance in chemistry : MRC》2007,45(12):1081-1083
Lepidozenal and isobicyclogermacrenal were isolated from the leaves of Eucalyptus dawsonii and a complete assignment of their 1H and 13C NMR spectra was carried out using 2D NMR methods. 相似文献