全文获取类型
收费全文 | 147398篇 |
免费 | 2097篇 |
国内免费 | 594篇 |
专业分类
化学 | 60991篇 |
晶体学 | 1431篇 |
力学 | 8462篇 |
综合类 | 12篇 |
数学 | 41379篇 |
物理学 | 37814篇 |
出版年
2020年 | 760篇 |
2019年 | 596篇 |
2018年 | 10988篇 |
2017年 | 10835篇 |
2016年 | 7519篇 |
2015年 | 2089篇 |
2014年 | 1763篇 |
2013年 | 3618篇 |
2012年 | 6529篇 |
2011年 | 13353篇 |
2010年 | 7485篇 |
2009年 | 7614篇 |
2008年 | 9320篇 |
2007年 | 11395篇 |
2006年 | 2956篇 |
2005年 | 3702篇 |
2004年 | 3572篇 |
2003年 | 3733篇 |
2002年 | 2632篇 |
2001年 | 2007篇 |
2000年 | 1668篇 |
1999年 | 1223篇 |
1998年 | 1110篇 |
1997年 | 1036篇 |
1996年 | 1167篇 |
1995年 | 1100篇 |
1994年 | 1043篇 |
1993年 | 1102篇 |
1992年 | 1109篇 |
1991年 | 961篇 |
1990年 | 901篇 |
1989年 | 875篇 |
1988年 | 807篇 |
1987年 | 823篇 |
1986年 | 797篇 |
1985年 | 1062篇 |
1984年 | 1088篇 |
1983年 | 879篇 |
1982年 | 931篇 |
1981年 | 950篇 |
1980年 | 922篇 |
1979年 | 901篇 |
1978年 | 905篇 |
1977年 | 847篇 |
1976年 | 847篇 |
1975年 | 769篇 |
1974年 | 720篇 |
1973年 | 710篇 |
1967年 | 644篇 |
1966年 | 533篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
G. Münzenberg S. Hofmann H. Folger F. P. Heßberger J. Keller K. Poppensieker B. Quint W. Reisdorf K. H. Schmidt H. J. Schött P. Armbruster M. E. Leino R. Hingmann 《Zeitschrift für Physik A Hadrons and Nuclei》1985,322(2):227-235
In irradiations of207Pb and208Pb, respectively, with54Cr theα-decay of the isotopes259106,260106, and261106 could be observed for the first time. For260106 a spontaneous fission branch of (50 ?20 +30 )% was observed. The isotopes were identified by genetic relationships of α-decay after separation in-flight with the velocity filter SHIP and implantation into a position-sensitive silicon surface-barrier detector. The measured partial fission halflife of the doubly even isotope260106 of (7.2 ?2.7 +4.8 )ms exceeds the predicted values by at least a factor of 40. This result could be explained by the high shell corrections of the ground state mass, derived from the measured α-decay energies. The experimental results show evidence for an island of purely shell stabilized nuclei in the region of deformed isotopes beyond the actinides. 相似文献
993.
A. Bähring E. Meyer I. V. Hertel H. Schmidt 《Zeitschrift für Physik A Hadrons and Nuclei》1985,320(1):141-149
Pronounced polarization effects have been observed in inelastic collisions of laser state-prepared Na*(3p,M L) with Na+ leading to Na*(3d) for the energy rangeE CM=20–45 eV. Using linearly polarized light the dependence of the inelastic process on the alignment of the electronic charge cloud of the Na*(3p) prior to the collision has been measured. In studies with left and right hand circularly polarized light the angular momentum transferred in the collision process has been determined. The results are compared with similar data for the 3p→3s deexitation process studied previously [6]. The density matrix of the Na*(3p) state has been evaluated with respect to the collisional excitation to Na*(3d). Semiclassical calculations based on the coupled channel impact parameter approximation using pseudopotentials [7] and nonadiabatic rotational coupling elements for the Na 2 * system [12] have been performed. The agreement with the experimental results is good, in particular for the higher collision energies. 相似文献
994.
995.
U. Hardebusch W. Gerhardt J. S. Schilling 《Zeitschrift für Physik B Condensed Matter》1985,60(2-4):463-470
Previous studies of the magnetic susceptibility of a Ag-3 at.% Mn spin-glass under high pressure are extended to include the systems Au-3at.% Mn, Cu-3at.% Mn and Au-3at.% Fe. In all four alloys the spin-glass freezing temperatureT
0 increases with pressure, yielding the volume dependences lnT
0/ lnV=–3.6±0.4, –4.1±0.6, –2.1±0.4 and –1.64±0.25, respectively. These results give information about the nature of the interaction mechanisms responsible for the spin-glass freezing phenomena. The pressure dependence of the Curie temperature of ferromagnetic Au-20at.% Fe was also studied.Dedicated to B. Mühlschlegel on the occasion of his 60th birthday 相似文献
996.
C. P. Grünfeld 《Letters in Mathematical Physics》1985,10(4):289-295
We obtain a certain transformation relating the solutions of the space-uniform Boltzmann equation with the Lorentz force term to those of the Boltzmann equation without external force. This enables us, in the case of angular cut-off intermolecular potentials, to prove the global existence, uniqueness and positivity of strict solutions for the former equation by means of known results on the latter one. 相似文献
997.
H. E. Hansen R. Talja H. Rajainmäki H. K. Nielsen B. Nielsen R. M. Nieminen 《Applied Physics A: Materials Science & Processing》1985,36(2):81-92
Molybdenum single crystals are irradiated at 20 K with 6 MeV protons. The radiation damage and lattice defect annealing is studied by positron lifetime spectroscopy in the temperature range from 15 to 720 K. Loss of vacancies due to recombination with mobile interstitials is observed at 40 K (Stage I) in agreement with resistivity measurements. This is the first time Stage I is observed by positrons below 77 K. The implanted hydrogen decorates the vacancies around 100 K, which is consistent with a hydrogen migration energy in molybdenum:E
M
H
= 0.3–0.4 eV. Clustering of spatially correlated vacancies takes place in a wide temperature region below the usual vacancy clustering stage (Stage III). Stage III is observed at rather low temperatures (400–480 K) due to the very high vacancy concentration. Hydrogen bound to vacancies and vacancy clusters is released above 540 K, which puts an upper limit to the hydrogen binding energy:E
B
H
1.4 eV. The present work emphasizes the advantage of employing a vacancy sensitive technique to study hydrogen in metals, where its intrinsic solubility is low. In such metals (as molybdenum) both the effective solubility and the effective mobility of hydrogen are strongly influenced by the presence of vacancies. 相似文献
998.
Triphenylphosphane Nickel(0) Complexes with Isocyanide Ligands — [(RNC)nNi(PPh3)4–n] (n = 1–3) Synthesis and properties of the isocyanide triphenylphosphane nickel(0) complexes [(RNC)Ni(PPh3)3], [(RNC)2Ni(PPh3)2] and [(RNC)3Ni(PPh3)] (R = tBu, Cy, PhCH2, p-TosCH2) are described. I.r. and 31P n.m.r. spectra were recorded and the X-ray crystal structure of [(PhCH2NC)2Ni(PPh3)2] was determined. 相似文献
999.
1000.
B. Schuh C. Neureiter H. Jäger L. Windholz 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1996,37(2):149-153
Laserspectroscopic investigations were performed on a collimated atomic beam of barium (natural isotope abundance). The metastable ground levels (3D1,2,3 and 1D2) of the investigated lines were populated by a discharge burning in barium vapour directly in front of the oven hole. We could investigate 14 spectral lines between 580 and 690 nm. The tensor polarizabilities of the upper and the lower level as well as the differences in the scalar polarizabilities could be determined. Spectra in magnetic fields up to 0.03 Tesla showed no deviation from the pattern resulting from a simple Russell-Sounders coupling. 相似文献