全文获取类型
收费全文 | 12163篇 |
免费 | 411篇 |
国内免费 | 4篇 |
专业分类
化学 | 7335篇 |
晶体学 | 84篇 |
力学 | 232篇 |
数学 | 2304篇 |
物理学 | 2623篇 |
出版年
2023年 | 96篇 |
2022年 | 87篇 |
2021年 | 143篇 |
2020年 | 188篇 |
2019年 | 191篇 |
2018年 | 241篇 |
2017年 | 232篇 |
2016年 | 499篇 |
2015年 | 459篇 |
2014年 | 476篇 |
2013年 | 833篇 |
2012年 | 724篇 |
2011年 | 839篇 |
2010年 | 495篇 |
2009年 | 405篇 |
2008年 | 574篇 |
2007年 | 543篇 |
2006年 | 438篇 |
2005年 | 301篇 |
2004年 | 282篇 |
2003年 | 304篇 |
2002年 | 253篇 |
2001年 | 158篇 |
2000年 | 162篇 |
1999年 | 141篇 |
1998年 | 124篇 |
1997年 | 127篇 |
1996年 | 129篇 |
1995年 | 96篇 |
1994年 | 98篇 |
1993年 | 95篇 |
1992年 | 102篇 |
1991年 | 82篇 |
1990年 | 91篇 |
1988年 | 84篇 |
1987年 | 78篇 |
1986年 | 77篇 |
1985年 | 110篇 |
1984年 | 124篇 |
1983年 | 78篇 |
1982年 | 91篇 |
1981年 | 99篇 |
1980年 | 90篇 |
1979年 | 98篇 |
1978年 | 91篇 |
1977年 | 82篇 |
1976年 | 105篇 |
1975年 | 96篇 |
1974年 | 96篇 |
1968年 | 77篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
E. Gečiauskas 《Lithuanian Mathematical Journal》1999,39(4):371-375
The distributions of the chord length and distance within oval domains are expressed in terms of the distributions of these
values in a circle and of some parameters of oval domains.
Institute of Mathematics and Informatics, Akademijos 4, 2600 Vilnius, Lithuania. Translated from Lietuvos Matematikos Rinkinys,
Vol. 39, No. 4, pp. 469–474, October–December, 1999.
Translated by E. Gečiauskas 相似文献
992.
Alfredas Račkauskas 《Acta Appl Math》1999,58(1-3):237-246
For a projection estimator fn of an unknown density f we investigate the behavior of large deviations probability P{Tn > rn} when rn , where Tn is appropriately centered and normed quadratic error fn-f)2. 相似文献
993.
We study limit distribution of partial sums SN,k(t) =
s = 1
[N t]
Ak(Xs) of Appell polynomials of the long-range dependent moving average process Xt> = i t bt - i i, where {i} is a strictly stationary and weakly dependent martingale difference sequence, and bi id - 1 (0 < d < 1/2). We show that if k(1-2 d)<1, then suitably normalized partial sums SN,k(t) converge in distribution to the kth order Hermite process. This result generalizes the corresponding results of Surgailis, and Avram and Taqqu obtained in the case of the i.i.d. sequence { i}. 相似文献
994.
Milan Kučera 《Czechoslovak Mathematical Journal》1999,49(3):449-474
Variational inequalities
are studied, where K is a closed convex cone in
, 3, B
is a × matrix, G is a small perturbation, a real parameter. The assumptions guaranteeing a Hopf bifurcation at some 0 for the corresponding equation are considered and it is proved that then, in some situations, also a bifurcation of periodic solutions to our inequality occurs at some I 0. Bifurcating solutions are obtained by the limiting process along branches of solutions to penalty problems starting at 0 constructed on the basis of the Alexander-Yorke theorem as global bifurcation branches of a certain enlarged system. 相似文献
995.
Vladimír Olejček 《International Journal of Theoretical Physics》1995,34(8):1643-1646
The q--algebra, i.e., the system of sets closed under complementation, countable disjoint unions, and containing the empty set, generated by the system of open balls coincides with the -field of Borel sets inR
sun forn=1,2, and 3. A first step to extend the proof forn=4, 5, 6, and 7 is indicated. 相似文献
996.
The presented one-capacitor pinch driver, designed as a compact coaxial structure (including spark-gap and discharge section) consistent with the capacitor output, generates a current of 200 kA with 700 ns quarter-period, suitable for studying the optimization of Z-pinch radiative characteristics. The driver is described, measurements of its parameters summarized, and relations to our previous and future activities briefly reviewed.This work was supported in part by the Grant Agency of the Czech Republic under contract No. 202/93/1023. 相似文献
997.
Faisal Zeeshan Joanna Hoszowska Jean-Claude Dousse Dimosthenis Sokaras Tsu-Chien Weng Roberto Alonso-Mori Matjaz Kavčič Mauro Guerra Jorge Miguel Sampaio Fernando Parente Paul Indelicato José Pires Marques José Paulo Santos 《X射线光谱测定》2019,48(5):351-359
We report on measurements of the Kβ diagram, valence-to-core (VtC), and hypersatellite X-ray spectra induced in metallic Cr by photon single and double K-shell ionization. The experiment was carried out at the Stanford Synchrotron Radiation Lightsource using the seven-crystal Johann-type hard X-ray spectrometer of the beamline 6-2. For the Kβ diagram and VtC transitions, the present study confirms the line shape features observed in previous works, whereas the Khβ hypersatellite transition was found to exhibit a complex spectral line shape and a characteristic low-energy shoulder. The energy shift of the hypersatellite relative to the parent diagram line was deduced from the measurements and compared with the result of extensive multiconfiguration Dirac–Fock (MCDF) calculations. A very good agreement between experiment and theory was found. The MCDF calculations were also used to compute the theoretical line shape of the hypersatellite. A satisfactory agreement was obtained between the overall shapes of the experimental and theoretical spectra, but deviations were observed on the low- and high-energy flanks of the hypersatellite line. The discrepancies were explained by chemical effects, which were not considered in the MCDF calculations performed for isolated atoms. 相似文献
998.
The fully frustrated spin-1/2 Heisenberg FM/AF square bilayer in a magnetic field with the ferromagnetic inter-dimer interaction and the antiferromagnetic intra-dimer interaction is explored by the use of localized many-magnon approach, which allows to connect the original purely quantum Heisenberg spin model on a square bilayer with the effective ferromagnetic Ising model on a simple square lattice. Magnetization and specific heat are investigated exactly at a field-driven phase transition from the singlet-dimer phase towards the fully saturated ferromagnetic phase, which changes from a discontinuous phase transition to a continuous one at a certain critical temperature. The mapping correspondence between the spin-1/2 Heisenberg FM/AF square bilayer and the ferromagnetic Ising square lattice suggests for this special critical point of the spin-1/2 Heisenberg FM/AF square bilayer critical exponents from the standard two-dimensional Ising universality class. 相似文献
999.
The fluorescence properties of selected benzo[c]phenanthridines (BPs) were examined. The effect of structure, pH and solvent on the fluorescence properties has been investigated. It was found out that the presence of charged iminium nitrogen significantly decreased the fluorescence of the compounds. The fluorescence (intensity as well as emission spectra shape) of the investigated compounds was significantly dependent on pH as well as used solvent. The utilization in epigenetic modification mechanisms studies as demethylase probe and as possible pH indicator was suggested. 相似文献
1000.
Vladimír Petrilla Vladimíra Tomečková Vladimír Komanický Lucia Lichardusová Martina Šutorová Monika Petrillová 《光谱学快报》2014,47(1):1-5
The aim of this paper was to characterize and compare spitting cobras of Africa. The autofluorescence of Naja ashei and Naja nigricollis venoms was investigated by atomic force microscopy and fluorescence analysis. The synchronous fluorescence analysis showed higher endogenous fluorescence of Naja ashei venom in comparison with Naja nigricollis venom. The atomic force microscopy revealed different surfaces of compared venoms as a result of different amounts of proteins. Our results confirmed different structures of Naja nigricollis and Naja ashei venom. The practical advantages of selected techniques are high sensitivity, minimal quantity of venom, and capability to measure the spitting cobra by autofluorescence. 相似文献