全文获取类型
收费全文 | 4245篇 |
免费 | 175篇 |
国内免费 | 196篇 |
专业分类
化学 | 832篇 |
晶体学 | 9篇 |
力学 | 74篇 |
综合类 | 24篇 |
数学 | 2054篇 |
物理学 | 1623篇 |
出版年
2024年 | 3篇 |
2023年 | 16篇 |
2022年 | 80篇 |
2021年 | 59篇 |
2020年 | 44篇 |
2019年 | 41篇 |
2018年 | 52篇 |
2017年 | 53篇 |
2016年 | 52篇 |
2015年 | 41篇 |
2014年 | 88篇 |
2013年 | 255篇 |
2012年 | 153篇 |
2011年 | 339篇 |
2010年 | 250篇 |
2009年 | 469篇 |
2008年 | 441篇 |
2007年 | 363篇 |
2006年 | 385篇 |
2005年 | 241篇 |
2004年 | 127篇 |
2003年 | 91篇 |
2002年 | 202篇 |
2001年 | 150篇 |
2000年 | 121篇 |
1999年 | 76篇 |
1998年 | 89篇 |
1997年 | 50篇 |
1996年 | 72篇 |
1995年 | 36篇 |
1994年 | 42篇 |
1993年 | 9篇 |
1992年 | 16篇 |
1991年 | 13篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 9篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1973年 | 6篇 |
排序方式: 共有4616条查询结果,搜索用时 15 毫秒
21.
LIU Zhongkui 《数学年刊B辑(英文版)》2004,25(1):129-138
Let (S,≤) be an ordered set. Recall that (S,≤) is artinian if every strictly decreasingsequence of elements of S is ?nite, and that (S,≤) is narrow if every subset of pairwiseorder-incomparable elements of S is ?nite. Let S be a commutative monoid. Unl… 相似文献
22.
Deák L. Bottyán L. Major M. Nagy D. L. Spiering H. Szilágyi E. Tanczikó F. 《Hyperfine Interactions》2002,144(1-4):45-52
Hyperfine Interactions - Synchrotron Mössbauer Reflectometry (SMR), the grazing incidence nuclear resonant scattering of synchrotron radiation, can be applied to perform depth-selective phase... 相似文献
23.
Keka Chakraborty S K Paranjpe V Siruguri O D Jayakumar S K Kulshreshtha 《Pramana》1997,48(6):1115-1122
Neutron diffraction and M?ssbauer measurements have been carried out on the cubic Laves phase intermetallic TbMnFe. The magnetic
moment on the transition metal atom is found to be low, 0.2μ
B, at room temperature. This moment is temperature independent down to 10 K. Magnetic moment on the rare earth atom varies
from 2.5μ
B at 296 K to 7.27μ
B at 10 K. M?ssbauer spectra recorded at 298 K and 78 K have magnetic character but there is a large distribution of hyperfine
field values. Both these features arise due to magnetic frustration created in the sample due to the competing ferro and antiferromagnetic
interactions between the transition metal atoms. 相似文献
24.
Jesús de la Cal Javier Cárcamo 《Journal of Mathematical Analysis and Applications》2007,334(2):1106-1115
As a consequence of Jensen's inequality, centered operators of probabilistic type (also called Bernstein-type operators) approximate convex functions from above. Starting from this fact, we consider several pairs of classical operators and determine, in each case, which one is better to approximate convex functions. In almost all the discussed examples, the conclusion follows from a simple argument concerning composition of operators. However, when comparing Szász-Mirakyan operators with Bernstein operators over the positive semi-axis, the result is derived from the convex ordering of the involved probability distributions. Analogous results for non-centered operators are also considered. 相似文献
25.
An energy-dependent partitioning scheme is explored for extracting a small number of eigenvalues of a real symmetric matrix with the help of genetic algorithm. The proposed method is tested with matrices of different sizes (30 × 30 to 1000 × 1000). Comparison is made with Löwdin’s strategy for solving the problem. The relative advantages and disadvantages of the GA-based method are analyzed 相似文献
26.
G. K. Shenoy 《Hyperfine Interactions》2006,170(1-3):5-13
Stanley L. Ruby (1924–2004) made major contributions to Mössbauer spectroscopy and was the first to suggest the feasibility of observing the Mössbauer effect using synchrotron radiation. In this article we recall his scientific legacy that have inspired his scientific colleagues. 相似文献
27.
Fe–Al alloys around the concentration of 30 at. % Al present re-entrant spin-glass behaviour at low temperatures. This behaviour is not completely understood and Mössbauer spectroscopy, combined with other experimental techniques, is useful to describe and explain this behaviour. Results show that the Mössbauer spectra coincide with the magnetic behaviour showed in literature and they can be explained as a magnetic cluster system whose magnetic clusters are getting smaller when the temperature is decreasing. When the temperature is reaching to the spin-glass transition at 92 K the spins in the paramagnetic matrix are moving slower and below this transition the spins are completely frozen. 相似文献
28.
29.
A. Veiga N. Martínez P. Mendoza Zélis G. A. Pasquevich F. H. Sánchez 《Hyperfine Interactions》2006,167(1-3):905-909
A prototype of a programmable constant-velocity scaler is presented. This instrument allows the acquisition of partial Mössbauer spectra in selected energy regions using standard drivers and transducers. It can be fully operated by a remote application, thus data acquisition can be automated. The instrument consists of a programmable counter and a constant-velocity reference. The reference waveform generator is amplitude modulated with 13-bit resolution, and is programmable in a wide range of frequencies and waveforms in order to optimize the performance of the transducer. The counter is compatible with most standard SCA, and is configured as a rate-meter that provides counts per selectable time slice at the programmed velocity. As a demonstration of the instrument applications, a partial Mössbauer spectrum of a natural iron foil was taken. Only positive energies were studied in 512 channels, accumulating 20 s per channel. A line width of 0.20 mm/s was achieved, performing with an efficiency of 80%. 相似文献
30.
E. K. Sadykov V. V. Arinin G. I. Petrov A. V. Pyataev F. G. Vagizov O. A. Kocharovskaya 《Hyperfine Interactions》2006,167(1-3):893-896
The role of quantum interference (QI) in spectra of the resonant Mössbauer scattering is investigated. As a mechanism ensuring the QI conditions, the radio-frequency (RF) mixing of the spin sublevels of the excited nuclear state is considered. It is shown that QI leads to a significant intensity redistribution of the elastic and Raman scattering. 相似文献