全文获取类型
收费全文 | 130篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
化学 | 69篇 |
力学 | 9篇 |
数学 | 15篇 |
物理学 | 44篇 |
出版年
2022年 | 4篇 |
2021年 | 4篇 |
2020年 | 5篇 |
2019年 | 1篇 |
2018年 | 5篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 2篇 |
2013年 | 12篇 |
2012年 | 7篇 |
2011年 | 3篇 |
2010年 | 1篇 |
2009年 | 3篇 |
2008年 | 5篇 |
2007年 | 1篇 |
2006年 | 8篇 |
2005年 | 4篇 |
2004年 | 1篇 |
2003年 | 3篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1989年 | 2篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1955年 | 1篇 |
1906年 | 2篇 |
排序方式: 共有137条查询结果,搜索用时 31 毫秒
101.
J.P. Bourdin G. Tréglia M.C. Desjonquères J.P. Ganachaud D. Spanjaard 《Solid State Communications》1983,47(4):279-282
LEED and photoemission experiments have suggested that the (1 1 0) face of W may present a lateral reconstruction in which all atoms of the surface occupy three-fold coordinated sites. We present here a theoretical calculation in which the energy is minimized with respect to vertical and lateral displacements. The role played by electronic correlations is discussed. The unreconstructed and unrelaxed surface is found to be the most stable. 相似文献
102.
103.
104.
The adsorption of an active gas, like oxygen, on the surface of a metal or an alloy leads to an intensification of the positive ion emission produced by sputtering. In the present paper this phenomenon (called chemical ion emission) is observed by blowing the gas on the surface of the sample while it is sputtered. The general features of the chemical effect on M+ ion production are discussed in terms of coverage resulting from equilibrium between the rate of atoms sticking to the surface and the sputtering rate of adsorbed atoms, and in terms of ionization probability depending upon the coverage. Examples are given for pure metals (Al, W, Ni) and alloys (NiCr, CuBe, CuAl, …). Attention is drawn to the effects observed on nickel single crystals (100) and (110). At a critical coverage an incorporation process takes place, producing both changes in the work function and in the ionization probability. These results, largely consistent with those obtained by classical methods, show that secondary ion emission can be used for adsorption studies. Finally, investigations of metal-oxygen interaction by the dynamic method (present work) and the static method of secondary ion mass analysis will be discussed and compared. 相似文献
105.
A. Delapalme J. Mulak A. Blaise J.M. Fournier 《Journal of magnetism and magnetic materials》1982,30(1):117-121
A polarized neutron diffraction experiment at 4.2 K was carried out on two NpAs2 single crystals with different orientations of the crystallographic axes with respect to the magnetic field. Low temperature atomic positions are given together with the Fermi length of the Np atom: 1.015X10-12cm. The valence state of the Np ion is 4+, the ordered moment value is 1.46μB, a strong magnetocrystalline anisotropy and a field variation of the ordering temperature have been evidenced for the ferromagnetic state. 58 magnetic structure factors have been measured. A tentative crystal field model is presented. 相似文献
106.
W. Suski A. Wojakowski A. Blaise P. Salmon J.M. Fournier T. Mydlarz 《Journal of magnetism and magnetic materials》1976,3(3):195-200
Magnetic measurements on the orthorhombic uranium sesquichalcogenides and orthorhombic U3Te4 were performed in the temperature range 4.2–1000 K and in magnetic fields up to 140 kOe. The temperature dependence of the reciprocal susceptibility was found to be curvilinear for all the investigated compounds. At low temperatures U2Te3 and U3Te appeared to be antiferromagnetic below 106 K. U2Se3 and U2S3 seem to have a more considerable ferromagnetic contribution below 60 and 80 K, respectively. The magnetic properties are discussed in terms of crystal structure and related properties of the investigated compounds. 相似文献
107.
108.
The electrical resistivity of NpAs and NpAs2 has been measured over the temperature range 4.2–300 K. Both compounds are semi-metallic contrary to semi-conducting transition reported in NpAs. The present results agree qualitatively with previously observed complex magnetic behaviour. 相似文献
109.
The isotope shifts of unperturbed electron configurations have been determined from isotope shift measurements in the spectra of Th, U, Pu, and Am. The screening of the 7s electron charge density at the nucleus by 6d, 7s, and 7p electrons is discussed. It turns out that the same screening factors as for the 6s electron in lighter elements can be used. The screening of the 7s electron charge density at the nucleus by one 5f electron amounts to about 25%: [δT(f n s)?δT(f n )]/[δT(f n }s)?δ(f n} )]=0.75. The charge density at the nucleus due to the filleds (andp 1/2) shells is considerabely screened by anf electron. The isotope shiftδT(fn}-1 d m +2)?δT(f n d m ) produced by this effect is of the same order of magnitude as the isotope shiftδT(f n d m s)-δT(f n d m ) due to ans electron. The experimental isotope shift constants are found to be:Β C exp(Th230–Th232)=880±120;Β C exp(U233–U235)=1000±180;Β C exp(U234–U236)=1070±200;Β C exp(U236–U238)=1080±180;Β C exp(Pu238–Pu240)=1200±120;Β C exp(Pu239–Pu241)=1060±100;Β C exp(Pu240–Pu242)=900 ±90;Β C exp(Am241–Am243)=890±50 [10?3cm?1]. The ratiosΒ C exp/C th are discussed. 相似文献
110.
In the spirit of Y. Maréchal and A. Witkowski's [J. Chem. Phys. 48 (1968) 2697] work, one revisits, for weak H-bonds, the dependence of the angular frequency ω and of the equilibrium position qe of the υX–H high frequency mode q, on the position coordinate Q of the low frequency υX–HY mode. One considers: ω=ωo+bQ+cQ2 and qe=gQ+fQ2. That leads to the anharmonic potential U: U=k1q2+∑krQr+∑∑knmqnQm+k15qQ5. Here kr and kmn (r=2–5, n=1,2 and m=1–4) are interrelated through b, c, g and f. By aid of the Hamiltonian involving U, we find the direct damped auto correlation function of υX–H, which, by Fourier transform, gives the IR spectral density (SD). When only b≠0, the SD is nothing but that given in a previous paper [P. Blaise, O. Henri-Rousseau, Chem. Phys. 243 (1999) 229]. When the adiabatic approximation is performed, this SD becomes that of N. Rösch and M. Ratner [J. Chem. Phys. 61 (1974) 3444] which reduces in turn to that of Maréchal and Witkowski in the absence of damping. With respect to b≠0, c produces a narrowing of the SD if c>0 and a subtle broadening if c<0. Besides, g induces the same narrowing for g>0 and g<0, while f gives subtle changes very sensitive to the sign of f and to the values of b, c and g. The situation b<0 and f>0 which is physically the most probable, leads to SDs which are the most evoking experimental profiles. 相似文献