全文获取类型
收费全文 | 787篇 |
免费 | 40篇 |
专业分类
化学 | 559篇 |
晶体学 | 3篇 |
力学 | 27篇 |
数学 | 85篇 |
物理学 | 153篇 |
出版年
2023年 | 5篇 |
2022年 | 15篇 |
2021年 | 18篇 |
2020年 | 29篇 |
2019年 | 11篇 |
2018年 | 21篇 |
2017年 | 11篇 |
2016年 | 26篇 |
2015年 | 33篇 |
2014年 | 40篇 |
2013年 | 42篇 |
2012年 | 68篇 |
2011年 | 67篇 |
2010年 | 37篇 |
2009年 | 33篇 |
2008年 | 49篇 |
2007年 | 47篇 |
2006年 | 43篇 |
2005年 | 36篇 |
2004年 | 26篇 |
2003年 | 25篇 |
2002年 | 27篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1997年 | 5篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1992年 | 3篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1979年 | 5篇 |
1977年 | 3篇 |
1911年 | 2篇 |
1906年 | 2篇 |
1905年 | 2篇 |
1904年 | 3篇 |
1902年 | 3篇 |
1901年 | 5篇 |
1897年 | 2篇 |
1892年 | 2篇 |
1884年 | 4篇 |
1883年 | 2篇 |
1882年 | 3篇 |
1880年 | 4篇 |
1878年 | 3篇 |
排序方式: 共有827条查询结果,搜索用时 15 毫秒
51.
52.
53.
Aneta Slodczyk Philippe Colomban Daniel Lamago Marie-Helene Limage François Romain Stephanie Willemin Beatrice Sala 《Ionics》2008,14(3):215-222
H+-containing lanthanide-doped perovskites A(Ba, Sr etc.)B(Zr, Ce, Ti etc.)O3 are potential ceramic membranes for fuel cell and medium temperature water electrolysis (300–800 °C). The comparison studies
of the hydrated and non-hydrated Yb-doped BaZrO3 and SrZrO3 were performed by thermal expansion, medium–high temperature neutron and room-temperature high-pressure Raman scattering.
Neutron diffraction and elastic/quasi-elastic studies carried out for BaZrO3 ceramic show the presence of the protons, their successive diffusion above ∼600 °C, and then their departure above 750 °C
(under vacuum). Phase transitions and their modification by proton insertion are discussed. A high-pressure Raman study of
SrZrO3 performed at room temperature in the diamond anvil cell reveals the presence of two pressure-induced phase transitions at
about 5 and 22 GPa and confirms that proton insertion modifies the phase transition sequences.
Paper presented at the 11th EuroConference on the Science and Technology of Ionics, Batz-sur-Mer, Sept. 9–15, 2007. 相似文献
54.
Optimization conditions for the separation of rare earth elements,americium, curium and cesium with HPLC technique 总被引:1,自引:0,他引:1
F. Goutelard C. Caussignac R. Brennetot G. Stadelmann C. Gautier 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(2):669-675
In order to validate the neutronic code calculations used in the nuclear field, it is necessary to quantify the isotopic composition
of the nuclear irradiated fuels with high precision and accuracy. A separation step whose objective is to isolate the elements
of interest in a fraction as pure as possible, is performed before mass spectrometry detection (MC-ICP-MS, TIMS), in order
to eliminate isobaric interferences. In a first step, uranium and plutonium are separated from the fission products by ion
exchange chromatography. Then, fission products are separated by high performance liquid chromatography (HPLC). A gradient
separation with a silica sulphonated support as stationary phase and hydroxy-methyl butyric acid (HMB) as eluent solution
provides a good degree of separation of the rare earth elements, Am, Cm and Cs. But, for a same manufacturer, the rate of
sulphonated groups is variable from one column to another for a given production batch. For every replacement of column, it
is necessary to adjust the separation conditions. Furthermore, the high radioactivity of the samples injected damages the
stationary phase, dragging a regular renewal of the columns. The goal of this study is to determine the optimal separation
conditions with a minimum of tests in order to limit the time assigned to this operation. A first Doehlert experimental design
with pH and HMB concentration as variables has been implemented to optimize Gd, Eu separation, in isocratic initial conditions.
A second one has been tested in order to separate the higher lanthanides and to fix the final conditions of the gradient separation.
A last set of tests has been performed to characterize the cesium behaviour. Finally, the gradient conditions have been adjusted
in order to perform the full separation of lanthanides, Cs, Am and Cm with nuclear facilities. 相似文献
55.
C.P. Hauri J. Gautier A. Trisorio E. Papalazarou P. Zeitoun 《Applied physics. B, Lasers and optics》2008,90(3-4):391-394
We present an adaptive technique for the formation of multiple co-propagating and stationary filaments in a gaseous medium.
Wavefront shaping of the initial beam is performed using a deformable mirror to achieve a complete two-dimensional control
of the multi-spot intensity pattern in the laser focus. The spatial organization of these intensity spots yields reliable
formation of up to five stable and stationary filaments providing a test bed for fundamental studies on multiple filamentation.
PACS 42.65.Jx; 52.38.Hb; 42.65.Sf 相似文献
56.
P. Gautier R. Gruber et F. Troyon 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1979,30(5):867
Sans résumé 相似文献
57.
58.
Acoustic Emission (AE) was investigated in order to monitor in real time the Mullins effect. Cyclic uniaxial tensile tests were carried out on two different natural rubbers. Different behaviour is revealed depending on whether or not the material undergoes the Mullins effect. The acoustic emission activity is very important during the first cycle, but decreases gradually with increasing number of cycles, when the Mullins effect is observed. On the contrary, when there is no Mullins effect no significant AE activity is recorded. 相似文献
59.
Najahi E Sudor J Chabchoub F Nepveu F Zribi F Duval R 《Molecules (Basel, Switzerland)》2010,15(12):8841-8855
In this paper we present the room temperature synthesis of a novel serie of 1,4-disubstituted-1,2,3-triazoles 4a-l by employing the (3+2) cycloaddition reaction of pyrimidinones containing alkyne functions with different model azides in the presence of copper sulphate and sodium ascorbate. To obtain the final triazoles, we also synthesized the major precursors 6-amino-5-cyano-1,4-disubstituted-2(1H)-pyrimidinones 3a-r from ethyl 2,2-dicyanovinylcarbamate derivatives 2a-c and various primary aromatic amines containing an alkyne group. The triazoles were prepared in good to very good yields. 相似文献
60.
Cyrielle Roquelet Jean‐Sébastien Lauret Dr. Valérie Alain‐Rizzo Dr. Christophe Voisin Dr. Romain Fleurier Dr. Morgan Delarue Damien Garrot Dr. Annick Loiseau Prof. Philippe Roussignol Prof. Jacques A. Delaire Prof. Emmanuelle Deleporte Prof. 《Chemphyschem》2010,11(8):1667-1672
We report on a new, original and efficient method for π‐stacking functionalization of single‐wall carbon nanotubes. This method is applied to the synthesis of a high‐yield light‐harvesting system combining single‐wall carbon nanotubes and porphyrin molecules. We developed a micelle‐swelling technique that leads to controlled and stable complexes presenting an efficient energy transfer. We demonstrate the key role of the organic solvent in the functionalization mechanism. By swelling the micelles, the solvent helps the non‐water‐soluble porphyrins to reach the micelle core and allows a strong enhancement of the interaction between porphyrins and nanotubes. This technique opens new avenues for the functionalization of carbon nanostructures. 相似文献