全文获取类型
收费全文 | 1034篇 |
免费 | 38篇 |
国内免费 | 2篇 |
专业分类
化学 | 783篇 |
晶体学 | 2篇 |
力学 | 8篇 |
数学 | 86篇 |
物理学 | 195篇 |
出版年
2022年 | 7篇 |
2021年 | 10篇 |
2020年 | 13篇 |
2019年 | 19篇 |
2018年 | 7篇 |
2017年 | 9篇 |
2016年 | 29篇 |
2015年 | 30篇 |
2014年 | 27篇 |
2013年 | 53篇 |
2012年 | 54篇 |
2011年 | 62篇 |
2010年 | 39篇 |
2009年 | 41篇 |
2008年 | 45篇 |
2007年 | 48篇 |
2006年 | 32篇 |
2005年 | 50篇 |
2004年 | 46篇 |
2003年 | 40篇 |
2002年 | 24篇 |
2001年 | 14篇 |
2000年 | 16篇 |
1999年 | 15篇 |
1998年 | 16篇 |
1997年 | 11篇 |
1996年 | 9篇 |
1995年 | 11篇 |
1994年 | 10篇 |
1993年 | 15篇 |
1992年 | 9篇 |
1991年 | 11篇 |
1990年 | 17篇 |
1989年 | 7篇 |
1988年 | 13篇 |
1987年 | 14篇 |
1986年 | 17篇 |
1985年 | 16篇 |
1984年 | 13篇 |
1983年 | 11篇 |
1982年 | 20篇 |
1981年 | 12篇 |
1980年 | 18篇 |
1979年 | 17篇 |
1978年 | 10篇 |
1977年 | 9篇 |
1976年 | 12篇 |
1973年 | 6篇 |
1971年 | 8篇 |
1967年 | 5篇 |
排序方式: 共有1074条查询结果,搜索用时 0 毫秒
131.
The optimum conditions for the photometric determination of tantalum with pyrogallol in sulphuric acid solution at 405 nm have been elaborated. The method has been checked statistically. 相似文献
132.
A recent global optimization algorithm using decomposition (GOP), due to Floudas and Visweswaran, when specialized to the case of polynomial functions is shown to be equivalent to an interval arithmetic global optimization algorithm which applies natural extension to the cord-slope form of Taylor's expansion. Several more efficient variants using other forms of interval arithmetic are explored. Extensions to rational functions are presented. Comparative computational experiences are reported. 相似文献
133.
Phuoc KT Corde S Shah R Albert F Fitour R Rousseau JP Burgy F Mercier B Rousse A 《Physical review letters》2006,97(22):225002
We demonstrate that betatron x-ray radiation accurately provides direct imaging of electrons trajectories accelerated in laser wakefields. Experimental far field x-ray beam profiles reveal that electrons can follow similar transverse trajectories with typical excursions of 1.5 microm+/-0.5 microm in the plane of laser polarization and 0.7 microm+/-0.2 microm in the plane perpendicular. 相似文献
134.
Wex B Kaafarani BR Danilov EO Neckers DC 《The journal of physical chemistry. A》2006,110(51):13754-13758
Six aromatic compounds with embedded thiophenes differing in the number of rings (2-5) and thiophene orientation along the long axis of the molecule (syn, anti) were investigated. Photophysical properties, steady-state absorption, fluorescence, phosphorescence, lifetimes, quantum yields, and a comprehensive time-resolved spectroscopic analysis (femtosecond and nanosecond transient absorption spectroscopy) have been studied as a function of molecular structure. 相似文献
135.
Henni Khadidja Louis Pierre-Yves Vannier Brigitte Moussa Ahmed 《Advances in Data Analysis and Classification》2020,14(3):543-570
Advances in Data Analysis and Classification - Clustering via marked point processes and influence space, Is-ClusterMPP, is a new unsupervised clustering algorithm through adaptive MCMC sampling of... 相似文献
136.
Competitiveness in global markets requires the ongoing identification and full utilization of improvement potential. To cut costs by means of process optimization, logistics service providers need to focus on efficient planning — not only for external but also for internal transports. This contribution will demonstrate that significant reductions in internal transports at one of the Deutsche Post World Net’s main parcel sorting centers can be achieved by applying the robust solution of a modified three-dimensional linear assignment model. 相似文献
137.
Evidence for temperature-dependent electron band dispersion in a pentacene thin film polymorph on graphite is provided by angle- and energy-dependent ultraviolet photoelectron spectroscopy. The bands derived from the highest occupied molecular orbital exhibit dispersion of approximately 190 meV at room temperature, and approximately 240 meV at 120 K. Intermolecular electronic coupling in pentacene thin films is thus confirmed to be dependent on temperature and possibly crystal structure, as suggested by additional infrared absorption measurements. 相似文献
138.
A. R. Vieira Brigitte Hiller M. C. Nemes Marcos Sampaio 《International Journal of Theoretical Physics》2013,52(10):3494-3503
Arbitrary regularization dependent parameters in Quantum Field Theory are usually fixed on symmetry or phenomenology grounds. We verify that the quadratically divergent behavior responsible for the lack of naturalness in the Standard Model (SM) is intrinsically arbitrary and regularization dependent. While quadratic divergences are welcome for instance in effective models of low energy QCD, they pose a problem in the SM treated as an effective theory in the Higgs sector. Being the very existence of quadratic divergences a matter of debate, a plausible scenario is to search for a symmetry requirement that could fix the arbitrary coefficient of the leading quadratic behavior to the Higgs boson mass to zero. We show that this is possible employing consistency of scale symmetry breaking by quantum corrections. Besides eliminating a fine-tuning problem and restoring validity of perturbation theory, this requirement allows to construct bounds for the Higgs boson mass in terms of $\delta m^{2}/m^{2}_{H}$ (where m H is the renormalized Higgs mass and δm 2 is the 1-loop Higgs mass correction). Whereas $\delta m^{2}/m^{2}_{H}<1$ (perturbative regime) in this scenario allows the Higgs boson mass around the current accepted value, the inclusion of the quadratic divergence demands $\delta m^{2}/m^{2}_{H}$ arbitrarily large to reach that experimental value. 相似文献
139.
Marco Sangermano Sven Pegel Petra Ptschke Brigitte Voit 《Macromolecular rapid communications》2008,29(5):396-400
Antistatic epoxy coatings are obtained, for the first time, by cationic UV curing of an epoxy resin in the presence of a very low content of carbon nanotubes (CNTs). It is shown that the addition of only 0.025 wt.‐% of CNTs into the resin is sufficient to obtain a composite suitable for applications that require electrostatic discharge. An extended percolative structure that forms a conductive CNT network is clearly evidenced within the polymeric matrix, notwithstanding the very small CNT content. The use of such UV‐cured epoxy material systems for antistatic coatings is quite realistic and promising.
140.
High refractive index hyperbranched polyvinylsulfides for planar one‐dimensional all‐polymer photonic crystals 下载免费PDF全文
Serena Gazzo Giovanni Manfredi Robert Pötzsch Qiang Wei Marina Alloisio Brigitte Voit Davide Comoretto 《Journal of Polymer Science.Polymer Physics》2016,54(1):73-80
We report on the growth and characterization of one‐dimensional (1D) planar all‐polymer photonic crystals (PhC) with high dielectric contrast (Δn = 0.3) prepared by spin coating using hyperbranched polyvinylsulfide polymers (HB‐PVS) as high refractive index material and cellulose acetate as low refractive index material. Solution processable HB‐PVS show a near ultraviolet absorption inducing an increased refractive index in the visible‐near infrared (n = 1.68, λ = 1000 nm). HBPVS:Cellulose Acetate Distributed Bragg Reflectors show a very clear fingerprint of the photonic band gap possessing the expected polarized dispersion properties as a function of the incidence angle. Moreover, engineered microcavities tuned on the weak fluorescence spectrum of the HB‐PVS show directional fluorescence enhancement effects due to spectral redistribution of the emission oscillator strength. The combination of all these properties testifies the high optical quality of the obtained photonic structures thus indicating HB‐PVS as an interesting material for the preparation of such PhC. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 73–80 相似文献