全文获取类型
收费全文 | 23590篇 |
免费 | 873篇 |
国内免费 | 11篇 |
专业分类
化学 | 15835篇 |
晶体学 | 171篇 |
力学 | 390篇 |
数学 | 3925篇 |
物理学 | 4153篇 |
出版年
2023年 | 157篇 |
2022年 | 158篇 |
2021年 | 299篇 |
2020年 | 380篇 |
2019年 | 371篇 |
2018年 | 492篇 |
2017年 | 434篇 |
2016年 | 902篇 |
2015年 | 702篇 |
2014年 | 739篇 |
2013年 | 1544篇 |
2012年 | 1555篇 |
2011年 | 1560篇 |
2010年 | 927篇 |
2009年 | 836篇 |
2008年 | 1363篇 |
2007年 | 1377篇 |
2006年 | 1212篇 |
2005年 | 1160篇 |
2004年 | 1005篇 |
2003年 | 783篇 |
2002年 | 685篇 |
2001年 | 503篇 |
2000年 | 452篇 |
1999年 | 343篇 |
1998年 | 246篇 |
1997年 | 223篇 |
1996年 | 295篇 |
1995年 | 211篇 |
1994年 | 231篇 |
1993年 | 198篇 |
1992年 | 196篇 |
1991年 | 176篇 |
1990年 | 173篇 |
1989年 | 154篇 |
1988年 | 142篇 |
1987年 | 133篇 |
1986年 | 133篇 |
1985年 | 195篇 |
1984年 | 202篇 |
1983年 | 125篇 |
1982年 | 131篇 |
1981年 | 145篇 |
1980年 | 137篇 |
1979年 | 95篇 |
1978年 | 96篇 |
1977年 | 104篇 |
1976年 | 82篇 |
1975年 | 87篇 |
1973年 | 71篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
51.
P. González D. Fernández J. Pou E. García J. Serra B. León M. Pérez-Amor T. Szörényi 《Applied Physics A: Materials Science & Processing》1993,57(2):181-185
A study of the gas-phase parameters involved in ArF laser induced chemical vapour deposition of silicon-oxide thin films is presented. A complete set of experiments has been performed showing the influence of the concentration of the precursor gases, N2O and SiH4, and their influence on total and partial pressures on film growth and properties. In this paper we demonstrate the ability of this LCVD method to deposit silicon oxide films of different compositions and densities by appropriate control of gas composition and total pressure. Moreover, a material specific calibration plot comprising data obtained using different preparation techniques is presented, allowing determination of the stoichiometry of SiO
x
films by using FTIR spectroscopy independently of the deposition method. For the range of processing conditions examined, the experimental results suggest that chemical processes governing deposition take place mainly in the gas phase. 相似文献
52.
V.I. Fernández A. Iucci C.M. Naón 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(1):53-56
We present an extension of the Tomonaga-Luttinger model in which left and right-moving particles have different Fermi velocities.
We derive expressions for one-particle Green's functions, momentum-distributions, density of states, charge compressibility
and conductivity as functions of both the velocity difference ε and the strength of the interaction β. This allows us to identify
a novel restricted region in the parameter space in which the system keeps the main features of a Luttinger liquid but with
an unusual behavior of the density of states and the static charge compressibility κ. In particular κ diverges on the boundary
of the restricted region, indicating the occurrence of a phase transition.
Received 20 May 2002 / Received in final form 23 August 2002 Published online 19 November 2002 相似文献
53.
Violeta D'Accurso Francisco A. Manzano Verónica B. Slezak 《Applied physics. B, Lasers and optics》1996,63(4):375-380
A detailed model for the optogalvanic effect in a neon hollow cathode discharge irradiated by a chopped CW dye laser is presented. A rate equation formalism is used to calculate the evolution of the first and second electronic configuration populations coupled by the laser and of the electric charges number density. Processes as ambipolar-like electrons loss, electronic collisional coupling of level populations and electron emission by the cathode due to VUV radiation from the 1s
2 resonant level are taken into account and further discussed.The transients and steady-state magnitude of the optogalvanic signal are calculated, compared with experimental data and related to population changes. We predict sign changes of the optogalvanic signal when the laser is tuned over transitions originating from the resonant level with respect to transitions involving the metastables states. The optogalvanic signal is shown to be basically determined by the laser-induced variations of the excited-state populations while changes in the electron temperature, due to laser energy transfer by collisions between electrons and excited atoms, play a negligible role. 相似文献
54.
We investigate the existence and stability of solutions for higher-order two-point boundary value problems in case the differential
operator is not necessarily positive definite, i.e. with superlinear nonlinearities. We write an abstract realization of the
Dirichlet problem and provide abstract existence and stability results which are further applied to concrete problems. 相似文献
55.
56.
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
57.
J. Łukasik G. Auger M. L. Begemann-Blaich N. Bellaize R. Bittiger F. Bocage B. Borderie R. Bougault B. Bouriquet J. L. Charvet A. Chbihi R. Dayras D. Durand J. D. Frankland E. Galichet D. Gourio D. Guinet S. Hudan P. Lautesse F. Lavaud A. Le Fèvre R. Legrain O. Lopez U. Lynen W. F. J. Müller L. Nalpas H. Orth E. Plagnol E. Rosato A. Saija C. Schwarz C. Sfienti B. Tamain W. Trautmann A. Trzciński K. Turzó E. Vient M. Vigilante C. Volant B. Zwiegliński 《Acta Physica Hungarica A》2006,25(2-4):229-239
Directed and elliptic flow for the 197Au+197Au system at incident energies between 40 and 150 MeV per nucleon has been measured using the INDRA 4π multi-detector. For semi-central collisions, the excitation function of elliptic flow shows a transition from in-plane to out-of-plane emission at around 100 MeV per nucleon. The directed flow changes sign at a bombarding energy between 50 and 60 MeV per nucleon and remains negative at lower energies. Molecular dynamics calculations (CHIMERA) indicate sensitivity of the global squeeze-out transition on the σ NN and demonstrate the importance of angular momentum conservation in transport codes at low energies. 相似文献
58.
The objective of this paper is to analyze under what well-known operations the class of quasipolyhedral convex functions,
which can be regarded as an extension of that of polyhedral convex functions, is closed. The operations that will be considered
are those that preserve polyhedral convexity, such that the image and the inverse image under linear transformations, right
scalar multiplication (including the case where λ=0+) and pointwise addition.
相似文献
59.
60.
Georg Pólya 《Mathematische Zeitschrift》1923,18(1):96-108
Ohne Zusammenfassung 相似文献