全文获取类型
收费全文 | 63篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
化学 | 13篇 |
晶体学 | 1篇 |
力学 | 2篇 |
数学 | 22篇 |
物理学 | 26篇 |
出版年
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2012年 | 3篇 |
2011年 | 2篇 |
2010年 | 1篇 |
2009年 | 1篇 |
2008年 | 3篇 |
2007年 | 4篇 |
2006年 | 6篇 |
2005年 | 1篇 |
2003年 | 1篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1998年 | 1篇 |
1996年 | 3篇 |
1993年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有64条查询结果,搜索用时 319 毫秒
41.
Motoko -Kwete D. Segers M. Dorikens L. Dorikens-Vanpraet P. Clauws I. Lemahieu 《Applied Physics A: Materials Science & Processing》1989,49(6):659-664
Positron-annihilation lifetime and Doppler-broadening measurements are used to investigate defects in silicon irradiated at 373 K with 6 MeV electrons to a dose of 1×l019e/cm2. In the unirradiated silicon sample (p type) a temperature-independent behaviour of the bulk-lifetime is observed in the temperature interval 110–500 K with a constant value of 220±1 ps. The slight effect observed on the S-parameter evolution is explained taking into account the thermal expansion of the lattice. The lifetime results obtained at 80 K and at 300 K after isochronal annealing as well as the behaviour of the intensity of the second lifetime componentI
2 during lifetime measurements below the irradiation temperature in the irradiated silicon sample (n type), clearly indicate the temperature dependent characteristics of the positron trapping cross section t(T) T
n
withn= –1.905±0.016. From isochronal annealing results, an annealing stage is observed in which di-vacancies agglomerate into quadri-vacancies. The mean positron lifetime in those quadri-vacancies is 350 ps.A.B.O.S., on leave from University of Kinshasa, Zaïre 相似文献
42.
The replacement of indicator functions by integrated beta kernels in the definition of the empirical tail dependence function is shown to produce a smoothed version of the latter estimator with the same asymptotic distribution but superior finite-sample performance. The link of the new estimator with the empirical beta copula enables a simple but effective resampling scheme. 相似文献
43.
Dr. Erik Andris Koen Segers Jaya Mehara Dr. Lubomír Rulíšek Prof. Jana Roithová 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(51):23337-23344
Iron(IV)-oxo intermediates in nature contain two unpaired electrons in the Fe–O antibonding orbitals, which are thought to contribute to their high reactivity. To challenge this hypothesis, we designed and synthesized closed-shell singlet iron(IV) oxo complex [(quinisox)Fe(O)]+ ( 1+ ; quinisox-H =(N-(2-(2-isoxazoline-3-yl)phenyl)quinoline-8-carboxamide). We identified the quinisox ligand by DFT computational screening out of over 450 candidates. After the ligand synthesis, we detected 1+ in the gas phase and confirmed its spin state by visible and infrared photodissociation spectroscopy (IRPD). The Fe–O stretching frequency in 1+ is 960.5 cm−1, consistent with an Fe–O triple bond, which was also confirmed by multireference calculations. The unprecedented bond strength is accompanied by high gas-phase reactivity of 1+ in oxygen atom transfer (OAT) and in proton-coupled electron transfer reactions. This challenges the current view of the spin-state driven reactivity of the Fe–O complexes. 相似文献
44.
S. Van Petegem D. Segers V. Pelosin J. Kuriplach 《Applied Physics A: Materials Science & Processing》2005,81(5):1039-1044
A water-quenched martensitic CuAlNi shape-memory alloy was investigated by a combination of coincidence Doppler broadening and positron-lifetime spectroscopy, supported by positron-lifetime calculations. We find a high defect concentration in the as-quenched samples. The positron-lifetime calculations suggest that the defects are not only single vacancies but also vacancies associated with dislocations and stacking faults. Annealing in the martensitic phase has no significant influence on the vacancy concentration but results in a different chemical environment around the vacancies. After aging in the austenitic phase the vacancy concentration decreases significantly. PACS 61.72.Ji; 78.70.Bj 相似文献
45.
Dirk Segers 《Mathematische Zeitschrift》2006,252(2):429-455
Let K be a p-adic field. We explore Igusa's p-adic zeta function, which is associated to a K-analytic function on an open and compact subset of Kn. First we deduce a formula for an important coefficient in the Laurent series of this meromorphic function at a candidate
pole. Afterwards we use this formula to determine all values less than −1/2 for n=2 and less than −1 for n=3 which occur as the real part of a pole. 相似文献
46.
N. Van Caenegem L. Duprez K. Verbeken Y. Houbaert D. Segers J. Van Humbeeck 《The European physical journal. Special topics》2008,158(1):27-32
Ferrous shape memory alloys (SMAs) do not possess a
complete shape recovery. Several attempts to improve the shape recovery
still fail to achieve 100% recovery. For some applications, however, the
recovery stress under constraint might be more important. In this work, a
procedure was designed to measure these stresses under constraint in a
Fe29MnSiCr SMA.
The net recovery stress was defined as the maximal difference between the
stresses developed in deformed and an undeformed sample. The calculation of
σthermal(T) = E(T)α(T)(T-T0) can replace the measurement of the stress
developed in the undeformed sample. The effect of partially free recovery
before recovery under constraint is also investigated. It was remarkable
that after annealing at 200°C, the net stress did not decrease although
about 50% of the shape recovery has already taken place. This allows to
use this alloy as a pipe joint, where the diameter of the joint can be
larger than the one of the pipes, since the free recovery will hardly lower
the recovery stresses under constraint. 相似文献
47.
D. Segers C. Dauwe H. Schut A. Van Veen L. Palffy T. Van Hoecke B. Van Waeyenberge 《Journal of Radioanalytical and Nuclear Chemistry》1996,211(1):39-45
Porous anodic layers were grown on aluminium alloys under different anodizing conditions. Positron annihilation energy spectra were measured as a function of the positron energy. Ortho-positronium formation in the porous layer was detected. The positron characteristics could be correlated to known parameters of the layers. This demonstrates that the positron annihilation method is a particularly useful technique to characterise the anodic layers. 相似文献
48.
Smit RH Untiedt C Rubio-Bollinger G Segers RC van Ruitenbeek JM 《Physical review letters》2003,91(7):076805
Using a scanning tunnel microscope or mechanically controllable break junctions atomic contacts for Au, Pt, and Ir are pulled to form chains of atoms. We have recorded traces of conductance during the pulling process and averaged these for a large number of contacts. An oscillatory evolution of conductance is observed during the formation of the monoatomic chain suggesting a dependence on the numbers of atoms forming the chain being even or odd. This behavior is not only observed for the monovalent metal Au, as was predicted, but is also found for the other chain-forming metals, suggesting it to be a universal feature of atomic wires. 相似文献
49.
L. Dorikens-Vanpraet D. Segers M. Dorikens F. Van Brabander 《Applied physics. B, Lasers and optics》1981,24(1):29-31
A detailed study of the prompt resolution curve of a positron annihilation lifetime spectrometer shows that the isotope used
as source has great influence on its shape. 相似文献
50.
D. Segers L. De Schepper M. Dorikens L. Dorikens-Vanpraet G. Knuyt L. Stals P. Moser 《Physics letters. A》1982,89(7):347-350
The 511 keV positron annihilation lineshape was measured as a function of temperature in pure iron and in carbon doped (50 appm C) iron. After annealing at 900°C, trapping and detrapping from dislocation-like defects in the pre-vacancy region in iron was seen around 650°C. A positron-dislocation binding energy of (0.63±0.03) eV was derived for iron. 相似文献