全文获取类型
收费全文 | 241篇 |
免费 | 5篇 |
专业分类
化学 | 200篇 |
晶体学 | 1篇 |
力学 | 3篇 |
数学 | 9篇 |
物理学 | 33篇 |
出版年
2021年 | 1篇 |
2018年 | 1篇 |
2016年 | 4篇 |
2014年 | 1篇 |
2013年 | 6篇 |
2012年 | 2篇 |
2011年 | 6篇 |
2010年 | 4篇 |
2008年 | 9篇 |
2007年 | 6篇 |
2006年 | 7篇 |
2005年 | 6篇 |
2004年 | 9篇 |
2003年 | 5篇 |
2002年 | 7篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 7篇 |
1998年 | 6篇 |
1997年 | 7篇 |
1996年 | 4篇 |
1995年 | 8篇 |
1994年 | 6篇 |
1993年 | 9篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 1篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1976年 | 3篇 |
1975年 | 7篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1972年 | 2篇 |
1971年 | 5篇 |
1970年 | 3篇 |
1969年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有246条查询结果,搜索用时 389 毫秒
21.
22.
Vernaleken A Weitenberg J Sartorius T Russbueldt P Schneider W Stebbings SL Kling MF Hommelhoff P Hoffmann HD Poprawe R Krausz F Hänsch TW Udem T 《Optics letters》2011,36(17):3428-3430
We report on single-pass high-harmonic generation (HHG) with amplified driving laser pulses at a repetition rate of 20.8?MHz. An Yb:YAG Innoslab amplifier system provides 35?fs pulses with 20?W average power at 1030?nm after external pulse compression. Following tight focusing into a xenon gas jet, we observe the generation of high-harmonic radiation of up to the seventeenth order. Our results show that state-of-the-art amplifier systems have become a promising alternative to cavity-assisted HHG for applications that require high repetition rates, such as frequency comb spectroscopy in the extreme UV. 相似文献
23.
Xuan Pang Jun Wu Cynthia Reinhart‐King Chih‐Chang Chu 《Journal of polymer science. Part A, Polymer chemistry》2010,48(17):3758-3766
A new family of positively charged, water soluble and functional amino acid‐based poly(ester amide)s ( Arg‐AG PEA ) consisting of four building blocks (L ‐Arginine, DL ‐2‐Allylglycine, oligoethylene glycol, and aliphatic diacid) were synthesized by the solution copolycondensation. Functional pendant carbon–carbon double bonds located in the DL ‐2‐allylglycine unit were incorporated into these Arg‐AG PEAs, and the double bond contents could be adjusted by tuning the feed ratio of L ‐arginine to DL ‐2‐allylglycine monomers. Chemical structures of this new functional Arg‐AG PEA family were confirmed by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) spectra. The thermal property of these polymers was investigated; increasing the methylene chain in both the amino acid and diacid segments resulted in a reduction in the polymer glass‐transition temperature. All these cationic Arg‐AG PEAs had good solubility in water and polar organic solvents. The cytotoxity of Arg‐AG PEAs was evaluated by 3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay. These preliminary MTT results indicated that Arg‐AG PEAs were nontoxic to bovine aortic endothelial cells (BAECs). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3758–3766, 2010 相似文献
24.
A. Alatas A.H. Said H. Sinn C.N. Kodituwakku B. Reinhart M.-L. Saboungi 《Journal of Physics and Chemistry of Solids》2005,66(12):2230-2234
The dynamical structure factors of supercooled-liquid and hot-solid silicon are measured by inelastic X-ray scattering at the same temperature, 1620 K. Two significant changes in the averaged longitudinal sound velocities and in the longitudinal modulus are observed. First, we observe a different longitudinal modulus in the polycrystalline hot-solid silicon compared to the extrapolated value obtained from the single-crystal measurement. This reduction of the modulus may be a precursor of the semiconductor-to-metal transition. Second, the increase in the longitudinal modulus in the liquid upon supercooling is consistent with an increase in the degree of the directional bonding. 相似文献
25.
26.
F. K. Reinhart G. Badertscher 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1977,28(6):1172-1172
Ohne Zusammenfassung 相似文献
27.
28.
Reinhart Schultz 《Numerische Mathematik》1978,31(1):77-95
Summary A numerical method for constrained approximation problems in normed linear spaces is presented. The method uses extremal subgradients of the norms or sublinear functionals involved in the approximation problem considered. Under certain weak assumptions the convergence of the method is proved. For various normed spaces hints for practical realization are given and several numerical examples are described.
Ein Abstiegsverfahren für Approximationsaufgaben in normierten Räumen相似文献
29.
30.
Jin Wang Eric Landahl Timothy Graber Reinhart Pahl Reinhart Pahl Linda Young 《Synchrotron Radiation News》2013,26(4):24-31
Scientific research in the time domain using the pulsed structure of the X-ray beams from a third-generation synchrotron source, such as the Advanced Photon Source (APS), has become a major interest among synchrotron users. The traditional material science, chemistry, and biology communities are getting an early glimpse of the potential impact of fast time-resolved X-ray studies. The scientific disciplines that have benefited from these studies include atomic and molecular physics, biology, chemical science, condensed matter physics, engineering science, environmental science, material science, and nuclear science. Technically, the turn-key-type femtosecond (fs) optical lasers with high peak power, used as pumps in many X-ray pump-probe experiments, have only recently become available. 相似文献