全文获取类型
收费全文 | 688篇 |
免费 | 26篇 |
国内免费 | 2篇 |
专业分类
化学 | 442篇 |
晶体学 | 7篇 |
力学 | 25篇 |
数学 | 102篇 |
物理学 | 140篇 |
出版年
2023年 | 2篇 |
2022年 | 27篇 |
2021年 | 23篇 |
2020年 | 15篇 |
2019年 | 20篇 |
2018年 | 13篇 |
2017年 | 18篇 |
2016年 | 31篇 |
2015年 | 23篇 |
2014年 | 24篇 |
2013年 | 52篇 |
2012年 | 47篇 |
2011年 | 59篇 |
2010年 | 27篇 |
2009年 | 41篇 |
2008年 | 45篇 |
2007年 | 35篇 |
2006年 | 29篇 |
2005年 | 22篇 |
2004年 | 27篇 |
2003年 | 11篇 |
2002年 | 20篇 |
2001年 | 12篇 |
2000年 | 10篇 |
1999年 | 6篇 |
1998年 | 7篇 |
1996年 | 7篇 |
1995年 | 9篇 |
1994年 | 7篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1979年 | 3篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1966年 | 1篇 |
1932年 | 1篇 |
1914年 | 1篇 |
1913年 | 1篇 |
1905年 | 1篇 |
1904年 | 1篇 |
1890年 | 1篇 |
排序方式: 共有716条查询结果,搜索用时 15 毫秒
81.
A static, plane-symmetric scalar field of long range is considered in general relativity, and a one-parameter class of exact solutions with cosmical time is studied in harmonic coordinates. The geodetic equations are solved. A velocity-dependent acceleration field is found, acting attractively on the component of the velocity normal to the plane of symmetry, and repulsively on the component parallel to that plane. The manifold is complete. Test particles at rest are insensitive to it. 相似文献
82.
Denilson S.S. dos Santos Alete P. Teixeira José T.P. Barbosa Sérgio L.C. Ferreira Maria das Graças A. Korn Leonardo S.G. Teixeira 《Spectrochimica Acta Part B: Atomic Spectroscopy》2007
In this work, the use of cetyltrimethylammonium bromide as surfactant for the preparation of oil-in-water emulsions for the determination of Cu and Cr in gasoline by electrothermal atomic absorption spectrometry (ET AAS) was evaluated. The surfactant amount was tested in the range of 25 to 300 mg, added to 2 ml of gasoline, and completed to 10 mL with 0.1% (v/v) nitric acid solution. 150 mg of surfactant was found optimum, and a sonication time of 10 min sufficient to form an oil-in-water emulsion that was stable for several hours. The ET AAS temperature program was established based on pyrolysis and atomization curves. The pyrolysis temperatures were set at 700 and 1300 °C for Cu and Cr, respectively and the selected atomization temperatures were 2400 and 2500 °C. The time and temperature of the drying stage and the atomization time were experimentally tested to provide optimum conditions. The limits of detection were found to be 5 μg L− 1 and 1.5 μg L− 1 for Cu and Cr, respectively in the original gasoline samples. The relative standard deviation (RSD) ranged from 4 to 9% in oil-in-water emulsions spiked with 5 μg L− 1 and 15 μg L− 1 of each metal, respectively. Recoveries varied from 90 to 98%. The accuracy of the proposed method was tested by an alternate procedure using complete evaporation of the gasoline sample. The method was adequate for the determination of Cu and Cr in gasoline samples collected from different gas stations in Salvador, BA, Brazil. 相似文献
83.
84.
F. Gomes Teixeira 《Monatshefte für Mathematik》1913,24(1):347-354
Sans résumé 相似文献
85.
Rendiconti del Circolo Matematico di Palermo Series 1 - 相似文献
86.
J. Teixeira 《Il Nuovo Cimento D》1994,16(9):1433-1437
Summary The dynamics of water molecules occupying very small volumes can be probed by incoherent quasi-elastic neutron scattering.
We summarise some results obtained with wet samples of porous silica and hydrated proteins. The movements of the molecules
in the vicinity of the substrate are extremely reduced as compared to those of bulk water at the same temperature. Almost
only rotational movements subsist and the local diffusion is of the order of that observed in deeply supercooled water.
Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994. 相似文献
87.
Teixeira P.I.C. Graner F. Fortes M.A. 《The European physical journal. E, Soft matter》2002,9(1):447-452
The European Physical Journal E - Amongst the two-dimensional cellular patterns that fill a plane, dry foams at stable equilibrium typify a particular subset for which the total perimeter P of cell... 相似文献
88.
J. L. Alexandre M. A. Z. Vasconcellos S. R. Teixeira I. J. R. Baumvol 《Applied Physics A: Materials Science & Processing》1993,56(2):113-118
Thin film multilayers of Fe and Al with thicknesses ranging from 10 nm/2 nm to 10 nm/420 nm Fe/Al are used as starting structures to produce intermetallic phases by solid-phase reaction during high-vacuum thermal annealings. By measuring the relative concentrations of the reacting Fe and Al species nearby the growing interfaces and using the recently introduced concept of effective heat of mixing of binary thin-film metallic systems, a method is suggested to predict the phases to be obtained from different combinations of initial multilayer thickness and annealing temperature. 相似文献
89.
M. F. Teixeira 《Mathematische Nachrichten》1982,107(1):131-137
90.
Paul Baret Eliezer Barreiro Andrew E. Greene Jean-Louis Luch Marco-Antonio Teixeira Pierre Crabbe 《Tetrahedron》1979,35(24):2931-2938
New allenic prostanoids 5c, d, 7,9c, and 15b have been prepared by total synthesis. In each case a cuprate-propargylic acetate reaction was used as the key step. 相似文献