全文获取类型
收费全文 | 637篇 |
免费 | 19篇 |
专业分类
化学 | 364篇 |
晶体学 | 5篇 |
力学 | 23篇 |
数学 | 86篇 |
物理学 | 178篇 |
出版年
2023年 | 6篇 |
2021年 | 9篇 |
2020年 | 11篇 |
2019年 | 13篇 |
2018年 | 11篇 |
2017年 | 11篇 |
2016年 | 26篇 |
2015年 | 18篇 |
2014年 | 20篇 |
2013年 | 24篇 |
2012年 | 31篇 |
2011年 | 37篇 |
2010年 | 22篇 |
2009年 | 30篇 |
2008年 | 36篇 |
2007年 | 28篇 |
2006年 | 24篇 |
2005年 | 10篇 |
2004年 | 13篇 |
2003年 | 14篇 |
2002年 | 12篇 |
2001年 | 11篇 |
2000年 | 7篇 |
1999年 | 10篇 |
1997年 | 8篇 |
1996年 | 11篇 |
1995年 | 5篇 |
1994年 | 8篇 |
1993年 | 5篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1978年 | 10篇 |
1977年 | 15篇 |
1976年 | 6篇 |
1975年 | 3篇 |
1973年 | 3篇 |
1972年 | 5篇 |
1971年 | 4篇 |
1961年 | 5篇 |
1943年 | 3篇 |
1939年 | 4篇 |
1938年 | 3篇 |
1935年 | 4篇 |
排序方式: 共有656条查询结果,搜索用时 31 毫秒
1.
2.
Rolff Ferreira Spindola Hudson Zanin Cleidivan Silva Macena André Contin Rita de Cássia Silva Luz Flávio Santos Damos 《Journal of Solid State Electrochemistry》2017,21(4):1089-1099
A novel platform for electroanalysis of isoniazid based on graphene-functionalized multi-walled carbon nanotube as support for iron phthalocyanine (FePc/f-MWCNT) has been developed. The FePc/f-MWCNT composite has been dropped on glassy carbon forming FePc/f-MWCNT/GC electrode, which is sensible for isoniazid, decreasing substantially its oxidation potential to +200 mV vs Ag/AgCl. Electrochemical and electroanalytical properties of the FePc/f-MWCNT/GC-modified electrode were investigated by cyclic voltammetry, electrochemical impedance spectroscopy, scanning electrochemical microscopy, and amperometry. The sensor presents better performance in 0.1 mol L?1 phosphate buffer at pH 7.4. Under optimized conditions, a linear response range from 5 to 476 μmol L?1 was obtained with a limit of detection and sensitivity of 0.56 μmol L?1 and 0.023 μA L μmol?1, respectively. The relative standard deviation for 10 determinations of 100 μmol L?1 isoniazid was 2.5%. The sensor was successfully applied for isoniazid selective determination in simulated body fluids. 相似文献
3.
Antônio Gomes dos Santos Neto Franciele de Matos Morawski Ana Caroline Ferreira Santos Cláudia Quintino da Rocha Roberto Batista de Lima Marília Oliveira Fonseca Goulart Clenilton Costa dos Santos Flávio Colmati Antônio Euzébio Goulart Santana Marco Aurélio Suller Garcia Auro Atsushi Tanaka 《Electroanalysis》2023,35(5):e202200390
Here, we report multiwalled carbon nanotubes (MWCNTs) functionalized with γ-cyclodextrins (γCD) as a novel electrochemical strategy for Rutin determination, showing superior performance than β-cyclodextrins (βCD) modified MWCNTs, suggesting an adequate environment for host-guest interactions. Under optimized conditions, the sensor showed a linear range of 39–975 nmol L−1 and a limit of detection of 7 nmol L−1. When tested with quercetin, catechin, and caffeine, the platform presented high selectivity with an interference response <10 %. The method was employed to quantify Rutin in spiked pharmaceutical and herbal extracts, providing recovery of 93–98.4 %. Also, HPLC-PDA confirmed the method‘s accuracy. 相似文献
4.
Suellen Christtine da Costa Sanches Flávio de Vasconcelos Carlos Emmerson Ferreira da Costa Patrícia Santana Barbosa Marinho Marcos R. Guilherme Eraldo José Madureira Tavares José Antônio Picanço Diniz Júnior José Otávio Carréra Silva Júnior Roseane Maria Ribeiro-Costa 《Journal of Thermal Analysis and Calorimetry》2015,120(1):991-999
5.
Thierry Cazenave Flávio Dickstein Fred B. Weissler 《Journal of Dynamics and Differential Equations》2007,19(3):789-818
In this paper, we construct solutions u(t,x) of the heat equation on such that has nontrivial limit points in as t → ∞ for certain values of μ > 0 and β > 1/2. We also show the existence of solutions of this type for nonlinear heat equations.
相似文献
6.
The distinguished econometrician Ragnar Frisch (1895–1973) also played an important role in optimization theory. In fact, he was a pioneer of interior-point methods. This note reconsiders his contribution, relating it to history and modern developments. 相似文献
7.
8.
X. Fabian F. Mauger G. Quéméner Ph. Velten G. Ban C. Couratin P. Delahaye D. Durand B. Fabre P. Finlay X. Fléchard E. Liénard A. Méry O. Naviliat-Cuncic B. Pons T. Porobic N. Severijns J. C. Thomas 《Hyperfine Interactions》2015,232(1-3):87-95
We performed classical molecular dynamics (MD) simulations in order to search the conditions for efficient sympathetic cooling of highly charged ions (HCIs) in a linear Paul trap. Small two-component ion Coulomb crystals consisting of laser-cooled ions and HCIs were characterized by the results of the MD simulations. We found that the spatial distribution is determined by not only the charge-to-mass ratio but also the space charge effect. Moreover, the simulation results suggest that the temperature of HCIs do not necessarily decrease with increasing the number of laser-cooled ions in the cases of linear ion crystals. We also determined the cooling limit of sympathetically cooled 165Ho14+ ions in small linear ion Coulomb crystals. The present results show that sub-milli-Kelvin temperatures of at least 10 Ho14+ ions will be achieved by sympathetic cooling with a single laser-cooled Be+. 相似文献
9.
E. Liénard G. Ban C. Couratin P. Delahaye D. Durand X. Fabian B. Fabre X. Fléchard P. Finlay F. Mauger A. Méry O. Naviliat-Cuncic B. Pons T. Porobic G. Quéméner N. Severijns J. C. Thomas Ph. Velten 《Hyperfine Interactions》2015,234(1-3):1-7
The experimental achievements and the results obtained so far with the LPCTrap device installed at GANIL are presented. The apparatus is dedicated to the study of the weak interaction at low energy by means of precise measurements of the β ? ν angular correlation parameter in nuclear β decays. So far, the data collected with three isotopes have enabled to determine, for the first time, the charge state distributions of the recoiling ions, induced by shakeoff process. The analysis is presently refined to deduce the correlation parameters, with the potential of improving both the constraint deduced at low energy on exotic tensor currents (6He1+) and the precision on the V u d element of the quark-mixing matrix (35Ar1+ and 19Ne1+) deduced from the mirror transitions dataset. 相似文献
10.