全文获取类型
收费全文 | 8565篇 |
免费 | 315篇 |
国内免费 | 4篇 |
专业分类
化学 | 5200篇 |
晶体学 | 171篇 |
力学 | 183篇 |
数学 | 1665篇 |
物理学 | 1665篇 |
出版年
2023年 | 42篇 |
2022年 | 68篇 |
2021年 | 84篇 |
2020年 | 138篇 |
2019年 | 188篇 |
2018年 | 204篇 |
2017年 | 234篇 |
2016年 | 442篇 |
2015年 | 338篇 |
2014年 | 415篇 |
2013年 | 738篇 |
2012年 | 476篇 |
2011年 | 505篇 |
2010年 | 370篇 |
2009年 | 296篇 |
2008年 | 532篇 |
2007年 | 476篇 |
2006年 | 411篇 |
2005年 | 334篇 |
2004年 | 266篇 |
2003年 | 201篇 |
2002年 | 174篇 |
2001年 | 123篇 |
2000年 | 121篇 |
1999年 | 80篇 |
1998年 | 82篇 |
1997年 | 57篇 |
1996年 | 69篇 |
1995年 | 61篇 |
1994年 | 52篇 |
1993年 | 35篇 |
1992年 | 44篇 |
1991年 | 61篇 |
1990年 | 46篇 |
1989年 | 58篇 |
1988年 | 63篇 |
1987年 | 51篇 |
1986年 | 52篇 |
1985年 | 111篇 |
1984年 | 108篇 |
1983年 | 73篇 |
1982年 | 65篇 |
1981年 | 80篇 |
1980年 | 67篇 |
1979年 | 54篇 |
1978年 | 42篇 |
1977年 | 33篇 |
1976年 | 47篇 |
1975年 | 42篇 |
1974年 | 34篇 |
排序方式: 共有8884条查询结果,搜索用时 46 毫秒
21.
Sajewicz Mieczysław Hauck Heinz-E. Drabik Gabriela Namysło Ewa Głód Bronisław Kowalska Teresa 《平面色谱法杂志一现代薄层色谱法》2006,19(4):278-281
JPC – Journal of Planar Chromatography – Modern TLC - We have previously described unexpected two-dimensionality in the thin-layer chromatographic separation of pairs of enantiomers of... 相似文献
22.
23.
24.
A. Odrzywołek 《The European Physical Journal C - Particles and Fields》2007,52(2):425-434
The spectrum of the neutrinos produced in the massive photon and longitudinal plasmon decay process has been computed with
four levels of approximation for the dispersion relations. Some analytical formulae in the limit cases are derived. Interesting
conclusions related to previous calculations of the energy loss in stars are presented. The high energy tail of the neutrino
spectrum is shown to be proportional to exp(-E/kT), where E is the neutrino energy and kT is the temperature of the plasma.
PACS 97.90.+j; 97.60.-s; 95.55.Vj; 52.27.Ep 相似文献
25.
We study the Friedmann-Robertson-Walker model with dynamical dark energy modelled in terms of the equation of state p
X
= w
X
(a(z)) ρ
X
in which the coefficient w
X
is parameterized by the scale factor a or redshift z. We use methods of qualitative analysis of differential equations to investigate the space of all admissible solutions for
all initial conditions on the two-dimensional phase plane. We show advantages of representing this dynamics as a motion of
a particle in the one-dimensional potential V(a). One of the features of this reduction is the possibility of investigating how typical big rip singularities are in the
future evolution of the model. The properties of potential function V can serve as a tool for qualitative classification of all evolution paths. Some important features like resolution of the
acceleration problem can be simply visualized as domains on the phase plane. Then one is able to see how large is the class
of solutions (labelled by the inset of the initial conditions) leading to the desired property. 相似文献
26.
Bart De Bruyn 《Journal of Algebraic Combinatorics》2006,24(1):23-29
Brouwer and Wilbrink [3] showed the nonexistence of regular near octagons whose parameters s, t2, t3 and t satisfy s ≥ 2, t2 ≥ 2 and t3 ≠ t2(t2+1). Later an arithmetical error was discovered in the proof. Because of this error, the existence problem was still open
for the near octagons corresponding with certain values of s, t2 and t3. In the present paper, we will also show the nonexistence of these remaining regular near octagons.
MSC2000 05B25, 05E30, 51E12
Postdoctoral Fellow of the Research Foundation - Flanders 相似文献
27.
28.
A mistake concerning the ultra LI-ideal of a lattice implication algebra is pointed out, and some new sufficient and necessary conditions for an LI-ideal to be an ultra LI-ideal are given. Moreover, the notion of an LI-ideal is extended to MTL-algebras, the notions of a (prime, ultra, obstinate, Boolean) LI-ideal and an ILI-ideal of an MTL-algebra are introduced, some important examples are given, and the following notions are proved to be equivalent in MTL-algebra: (1) prime proper LI-ideal and Boolean LI-ideal, (2) prime proper LI-ideal and ILI-ideal, (3) proper obstinate LI-ideal, (4) ultra LI-ideal.
This work was supported by the Zhejiang Provincial Natural Science Foundation of China (Grant No. Y605389) and K. C. Wong
Magna Fund in Ningbo University. 相似文献
29.
Orotic acid (vitamin B13) is a key intermediate in biosynthesis of the pyrimidine nucleotides in living organisms, moreover, it may serve as the biological carrier for some metal ions. cis-Diammine(orotato)platinum(II), cis-[Pt(C5H2N2O4)(NH3)2] can be considered as a new potential cisplatin analogue. The FT-Raman and FT-IR spectra of the title complex are reported, for the first time. The molecular structure, vibrational frequencies, and the theoretical infrared and Raman intensities have been calculated by the density functional mPW1PW91 method. The detailed vibrational assignment has been made on the basis of the calculated potential energy distribution. The theoretically predicted IR and Raman spectra show very good agreement with experiment. Natural bond orbital (NBO) analyses were performed for cisplatin, carboplatin and the title complex. The results provided new data on the nature of platinum–ligand bonding in these compounds. Strong intramolecular hydrogen bond between the orotate ligand and the coordinated ammonia group stabilizes the structure of the platinum(II) complex. Thus, it is suggested that the orotate ligand in the title complex is more inert to the substitution reactions than the chloride ligands in cisplatin. 相似文献
30.
J. Sładkowski 《International Journal of Theoretical Physics》1991,30(4):517-520
A generalization of theG-theory defined by A. Heilet al. is presented. 相似文献