全文获取类型
收费全文 | 315篇 |
免费 | 7篇 |
专业分类
化学 | 202篇 |
晶体学 | 3篇 |
力学 | 7篇 |
数学 | 58篇 |
物理学 | 52篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 8篇 |
2020年 | 10篇 |
2019年 | 5篇 |
2018年 | 11篇 |
2017年 | 6篇 |
2016年 | 19篇 |
2015年 | 11篇 |
2014年 | 11篇 |
2013年 | 23篇 |
2012年 | 12篇 |
2011年 | 13篇 |
2010年 | 15篇 |
2009年 | 13篇 |
2008年 | 22篇 |
2007年 | 22篇 |
2006年 | 24篇 |
2005年 | 22篇 |
2004年 | 13篇 |
2003年 | 11篇 |
2002年 | 8篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 6篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有322条查询结果,搜索用时 0 毫秒
1.
Mira Bozzini Licia Lenarduzzi Robert Schaback 《Advances in Computational Mathematics》2002,16(4):375-387
We present an adaptive method to extract shape-preserving information from a univariate data sample. The behavior of the signal is obtained by interpolating at adaptively selected few data points by a linear combination of multiquadrics with variable scaling parameters. On the theoretical side, we give a sufficient condition for existence of the scaled multiquadric interpolant. On the practical side, we give various examples to show the applicability of the method. 相似文献
2.
Bernd A Simon S Ramirez Bosca A Kippenberger S Diaz Alperi J Miquel J Villalba Garcia JF Pamies Mira D Kaufmann R 《Photochemistry and photobiology》1999,69(2):218-221
Extracts of Hypericum perforatum (St. John's wort) are used in the treatment of depression. They contain the plant pigment hypericin and hypericin derivates. These compounds have light-dependent activities. In order to estimate the potential risk of phototoxic skin damage during antidepressive therapy, we investigated the phototoxic activity of hypericin extract using cultures of human keratinocytes and compared it with the effect of the well-known phototoxic agent psoralen. The absorbance spectrum of our Hypericum extract revealed maxima in the whole UV range and in parts of the visible range. We cultivated human keratinocytes in the presence of different Hypericum concentrations and irradiated the cells with 150 mJ/cm2 UVB, 1 J/cm2 UVA or 3 h with a white light of photon flux density 2.6 mumol m-2 s-1. The determination of the bromodeoxyuridine incorporation rate showed a concentration- and light-dependent decrease in DNA synthesis with high hypericin concentrations (> or = 50 micrograms/mL) combined with UVA or visible light radiation. In the case of UVB irradiation a clear phototoxic cell reaction was not detected. We found phototoxic effects even with 10 ng/mL psoralen using UVA with the same study design as in the case of the Hypericum extract. These results confirm the phototoxic activity of Hypericum extract on human keratinocytes. However, the blood levels that are to be expected during antidepressive therapy are presumably too low to induce phototoxic skin reactions. 相似文献
3.
4.
Mira Zorkot Ramin Golestanian Douwe Jan Bonthuis 《The European physical journal. Special topics》2016,225(8-9):1583-1594
Using nonequilibrium Langevin dynamics simulations of an electrolyte with explicit solvent particles, we investigate the effect of hydrodynamic interactions on the power spectrum of ionic nanopore currents. At low frequency, we find a power-law dependence of the power spectral density on the frequency, with an exponent depending on the ion density. Surprisingly, however, the exponent is not affected by the presence of the neutral solvent particles. We conclude that hydrodynamic interactions do not affect the shape of the power spectrum in the frequency range studied. 相似文献
5.
CM Silva MF Duarte ML Mira MH Florêncio K Versluis AJ Heck 《Rapid communications in mass spectrometry : RCM》1999,13(12):1098-1103
Fast atom bombardment, combined with high-energy collision-induced tandem mass spectrometry, has been used to investigate gas-phase metal-ion interactions with captopril, enalaprilat and lisinopril, all angiotensin-converting enzyme inhibitors.Suggestions for the location of metal-binding sites are presented. For captopril, metal binding occurs most likely at both the sulphur and the nitrogen atom. For enalaprilat and lisinopril, binding preferably occurs at the amine nitrogen. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
6.
Monika Sinha Manjari Bagchi Jishnu Dey Mira Dey Subharthi Ray Siddhartha Bhowmick 《Physics letters. [Part B]》2004,590(3-4):120-125
Strange stars (ReSS) calculated from a realistic equation of state (EOS), that incorporate chiral symmetry restoration as well as deconfinement at high density [Phys. Lett. B 438 (1998) 123; Phys. Lett. B 447 (1999) 352, Addendum; Phys. Lett. B 467 (1999) 303, Erratum; Indian J. Phys. B 73 (1999) 377] show compact objects in the mass radius curve. We compare our calculations of incompressibility for this EOS with that of nuclear matter. One of the nuclear matter EOS has a continuous transition to ud-matter at about five times normal density. Another nuclear matter EOS incorporates density dependent coupling constants. From a look at the consequent velocity of sound, it is found that the transition to ud-matter seems necessary. 相似文献
7.
Selective addition to iridium of aryl C-H bonds ortho to coordinating groups. Not chelation-assisted
Zhang X Kanzelberger M Emge TJ Goldman AS 《Journal of the American Chemical Society》2004,126(41):13192-13193
Precursors of the pincer-ligated iridium species, (PCP)Ir, react with nitrobenzene or acetophenone at ambient temperature to give O,C-chelated complexes resulting from addition of an aryl C-H bond and coordination of a nitro or acetyl oxygen. The C-H additions appear to be completely regioselective for the position ortho to the functional group; however, structural characterization and low-temperature NMR studies demonstrate that the reaction does not proceed via coordination of the functional group followed by C-H addition. In the case of nitrobenzene, kinetic preference for the para and meta positions is demonstrated at low temperature. Addition occurs more slowly at the ortho position, without assistance by the functional group; the ortho-C-H addition product is then trapped by chelation. 相似文献
8.
9.
Assuming confinement and chiral symmetry breaking, we have calculated constituent quark masses from phenomenological q potentials by using a BCS-like gap equation. 相似文献
10.
We construct a large family of complete maximal surfaces in the static Robertson–Walker 3-spaces with negative base curvature.
These examples provide a wide variety of non-standard foliations of such spaces by entire maximal graphs. 相似文献