全文获取类型
收费全文 | 314篇 |
免费 | 10篇 |
国内免费 | 1篇 |
专业分类
化学 | 152篇 |
晶体学 | 1篇 |
力学 | 2篇 |
数学 | 47篇 |
物理学 | 103篇 |
无线电 | 20篇 |
出版年
2022年 | 5篇 |
2021年 | 12篇 |
2020年 | 4篇 |
2018年 | 2篇 |
2017年 | 6篇 |
2016年 | 2篇 |
2015年 | 6篇 |
2014年 | 4篇 |
2013年 | 20篇 |
2012年 | 14篇 |
2011年 | 23篇 |
2010年 | 11篇 |
2009年 | 14篇 |
2008年 | 14篇 |
2007年 | 12篇 |
2006年 | 18篇 |
2005年 | 18篇 |
2004年 | 7篇 |
2003年 | 17篇 |
2002年 | 20篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1989年 | 3篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1972年 | 3篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1966年 | 1篇 |
1961年 | 1篇 |
1956年 | 2篇 |
1955年 | 1篇 |
1940年 | 1篇 |
1937年 | 1篇 |
1928年 | 1篇 |
排序方式: 共有325条查询结果,搜索用时 15 毫秒
101.
G Marckmann E VerronL Gornet G ChagnonP Charrier P Fort 《Journal of the mechanics and physics of solids》2002,50(9):2011-2028
This paper reports on the development of a new network alteration theory to describe the Mullins effect. The stress-softening phenomenon that occurs in rubber-like materials during cyclic loading is analysed from a physical point of view. The Mullins effect is considered to be a consequence of the breakage of links inside the material. Both filler-matrix and chain interaction links are involved in the phenomenon. This new alteration theory is implemented by modifying the eight-chains constitutive equation of Arruda and Boyce (J. Mech. Phys. Solids 41 (2) (1993) 389). In the present method the parameters of the eight-chains model, denoted CR and N in the bibliography, become functions of the maximum chain stretch ratio. The accuracy of the resulting constitutive equation is demonstrated on cyclic uniaxial experiments for both natural rubbers and synthetic elastomers. 相似文献
102.
F. Jessen M. Knufinke S. C. Bell P. Vergien H. Hattermann P. Weiss M. Rudolph M. Reinschmidt K. Meyer T. Gaber D. Cano A. Günther S. Bernon D. Koelle R. Kleiner J. Fortágh 《Applied physics. B, Lasers and optics》2014,116(3):665-671
We describe the preparation of ultracold atomic clouds in a dilution refrigerator. The closed-cycle 3He/4He cryostat was custom made to provide optical access for laser cooling, optical manipulation and detection of atoms. We show that the cryostat meets the requirements for cold atom experiments, specifically in terms of operating a magneto-optical trap, magnetic traps and magnetic transport under ultrahigh vacuum conditions. The presented system is a step toward the creation of a quantum hybrid system combining ultracold atoms and solid-state quantum devices. 相似文献
103.
Maria Ada Malvindi Antonio Greco Francesco Conversano Albert Figuerola Maurizio Corti Marco Bonora Alessandro Lascialfari Houshang Amiri Doumari Marco Moscardini Roberto Cingolani Giuseppe Gigli Sergio Casciaro Teresa Pellegrino Andrea Ragusa 《Advanced functional materials》2011,21(13):2548-2555
A simple and efficient method for synthesizing a range of hybrid nanocomposites based on a core of silica nanospheres (160, 330, and 660 nm in diameter) covered by an outer shell of superparamagnetic nanoparticles, either iron oxide or heterodimeric FePt‐iron oxide nanocrystals, is presented. The magnetic and ultrasound characterization of the resulting nanocomposites shows that they have great potential as contrast agents for dual‐mode imaging purposes, combining magnetic resonance imaging (MRI) and ultrasonography (US). 相似文献
104.
John Natoli W.J. Benton C.A. Miller T. Fort Jr. 《Journal of Dispersion Science and Technology》2013,34(2):215-229
ABSTRACT Dilute aqueous “solutions” of anionic surfactants injected during enhanced oil recovery processes usually contain liquid crystalline material. Phase behavior has been studied in a model system containing sodium chloride brine with surfactant, alcohol, and salt contents maintained below 6, 10, and 3 weight percent respectively. Pseudoternary phase diagrams at constant salinities are used to represent the results. Some interpretation of the results is given in terms of micellar shape transformations produced by changes in the relative hydrophilic and hydrophobic properties of surfactant-alcohol mixtures. 相似文献
105.
106.
Hydrodynamic instabilities are usually investigated in confined geometries where the resulting spatiotemporal pattern is constrained by the boundary conditions. Here we study the Faraday instability in domains with flexible boundaries. This is implemented by triggering this instability in floating fluid drops. An interaction of Faraday waves with the shape of the drop is observed, the radiation pressure of the waves exerting a force on the surface tension held boundaries. Two regimes are observed. In the first one there is a coadaptation of the wave pattern with the shape of the domain so that a steady configuration is reached. In the second one the radiation pressure dominates and no steady regime is reached. The drop stretches and ultimately breaks into smaller domains that have a complex dynamics including spontaneous propagation. 相似文献
107.
The selective synthesis of ω-phtalimidoalkyl meth(acrylic) esters was obtained in 71 to 81% yields under phase transfer catalysis from corresponding bromoalkyl (meth)acrylates and potassium phtalimide. Chloro-derivatives gave the same products in the presence of catalytic amount of potassium iodide. 相似文献
108.
A. C. Fey-den Boer K. A. H. van Leeuwen H. C. W. Beijerinck C. Fort F. S. Pavone 《Applied physics. B, Lasers and optics》1996,63(2):117-120
Narrow linewidth, single spectral mode operation has been obtained in a high power, 810 nm broad-area diode laser in an extended cavity configuration with a grating as external reflector (grating feedback). For stable operation it was necessary to misalign the feedback slightly in the plane of the laser junction. Characteristics of the thus obtained laser system are a linewidth below 5 MHz, an output intensity of about 50% of the free running power, a large-scale tuning range of 15 nm and continuous scanning over 4 GHz. In the spatial domain, the laser remains multimode and astigmatic. To show the practical applicability of this system, saturated absorption of a krypton line is demonstrated. 相似文献
109.
In questa nota si affronta il problema della risoluzione di equazioni matriciali del tipoAX=B, doveA eB sono matrici a valori su un reticolo distributivo residuato rispetto a una moltiplicazione. In particolare, si individua
la più grande soluzione di una tale equazione e si danno condizioni relative alle soluzioni minimali. 相似文献
110.
Clean surfaces were produced on bulk aluminum samples by a new cutting procedure inside an ultra-high vacuum system. This cutting technique made it possible to stabilize the reference electrode of a vibrating capacitor by equilibration with the gas. Adsorption of water on the clean surfaces was studied by following changes in the work function of the surface at various temperatures and water vapor pressures. Water chemisorbed on the aluminum causing a work function change of − 1.4 V at one monolayer. The rate and amount of chemisorption were negatively dependent on temperature. The characteristics of the work function changes lead to the conclusion that the water chemisorbs by a precursor mechanism. 相似文献