全文获取类型
收费全文 | 355篇 |
免费 | 9篇 |
国内免费 | 5篇 |
专业分类
化学 | 177篇 |
晶体学 | 1篇 |
力学 | 4篇 |
数学 | 68篇 |
物理学 | 119篇 |
出版年
2023年 | 3篇 |
2022年 | 8篇 |
2021年 | 18篇 |
2020年 | 7篇 |
2019年 | 13篇 |
2018年 | 13篇 |
2017年 | 14篇 |
2016年 | 6篇 |
2015年 | 13篇 |
2014年 | 13篇 |
2013年 | 18篇 |
2012年 | 11篇 |
2011年 | 25篇 |
2010年 | 15篇 |
2009年 | 21篇 |
2008年 | 19篇 |
2007年 | 16篇 |
2006年 | 11篇 |
2005年 | 18篇 |
2004年 | 12篇 |
2003年 | 5篇 |
2002年 | 6篇 |
2001年 | 6篇 |
2000年 | 5篇 |
1998年 | 2篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1990年 | 6篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1976年 | 5篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 1篇 |
排序方式: 共有369条查询结果,搜索用时 15 毫秒
71.
Mössbauer studies of57Fe in RBa2?y K y (Cu1?x Fe x )3Oz, with R=Y and Pr;y=0 and 0.5;x=0.01, 0.05 and 0.1 andz between 5.9 and 7.1, have been performed. A minority of the iron ions enter the Cu(2) site and reveal its magnetic order. In nonsuperconducting YBa1.5K0.5(Cu0.95Fe0.05)3O6.1 two distinctly inequivalent magnetic iron sites are observed, probably corresponding to iron in the Cu(2) site with different Ba?K neighbours. In superconducting (T c =60 K) YBa1.5K0.5(Cu0.95Fe0.05)3O6.5 one Cu(2) subsite remains magnetic (T N=440 K). The implications of these findings on the valencies of the Cu ions are discussed. 相似文献
72.
A rich variety of magnetic phenomena is observed in Mössbauer studies of ferritin. Depending on the amount of iron in the horse spleen ferritin core, a paramagnetic relaxation spectrum, or quadrupole split doublet or a magnetically split sextet showing superpara-magnetism, are obtained a 4.1 K. Mössbauer studies of the recently prepared iron loaded concanavalin A yield hyperfine parameters identical to those found previously in mammalian ferritin, yet show the existence of larger iron aggregates. Due to the larger particle size it is possible to follow the magnetic hyperfine field and to obtain the magnetic ordering temperature as 240 K. This is exactly the Neél temperature of ferrihydrite, thus establishing that this is indeed the iron compound in the ferritin core. 相似文献
73.
Egorin Andrei Sokolnitskaya Tatiana Azarova Yuliya Portnyagin Arseniy Balanov Mikhail Misko Darya Shelestyuk Evgeny Kalashnikova Anastasia Tokar Eduard Tananaev Ivan Avramenko Valentin 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(1):243-251
Sorption of micro- and microamounts of Sr from seawater has been studied using granulated Na-birnessite. Distribution coefficients of 90Sr in the natural seawater are 0.8–1.2?×?103 ml g?1, in the model seawater they are 1.6–1.8?×?103 ml g?1. Application of Na-birnessite was shown to be prospective in sorption–desorption–regeneration regime. In dynamic sorption conditions, over 150 bed volumes of seawater can be purified till 5% breakthrough occurs at feed rate 10 BV h?1. Na-birnessite can be used for 90Sr radionuclide removal from liquid radioactive wastes containing seawater.
相似文献74.
Periodica Mathematica Hungarica - We examine the ideals of nowhere dense sets in three topologies on the set of positive integers, namely Furstenberg’s, Rizza’s and the common division... 相似文献
75.
Gabriel M. VeithRongji Chen Guerman PopovMark Croft Yuliya ShokhIsrael Nowik Martha Greenblatt 《Journal of solid state chemistry》2002,166(2):292-304
A series of oxygen-deficient n=2 Ruddlesden-Popper phases, Sr3Fe2−xCoxO7−δ (0.25≤x≤1.75), were prepared by solid-state reactions. Temperature-dependent susceptibility and field-dependent magnetization data indicate that for x≥0.25 the dominant magnetic interactions are ferromagnetic. The onset of strong ferromagnetic interactions is evident at ∼200 K, and a transition to a cluster-glass state is observed for all compositions below ∼45 K. The temperature variation of resistivity for all the compounds shows variable-range hopping behavior with two different localization energy scales: one for T<40 K and another for T>80 K. Large negative magnetoresistance (the largest MR ∼−65% for x=0.25) is observed for all phases. The magnetic susceptibility, Mössbauer and X-ray absorption near-edge spectroscopy data indicate that the formal oxidation state of Fe is close to 4+. The key role of d delocalization in the Sr3Fe2−xCoxO7−δ system is compared to the Sr3Fe2−xMnxO7−δ series, where d localization dominates the properties. 相似文献
76.
Yuliya Prokopenko Valdas Jakštas Vaidotas Žvikas Victoriya Georgiyants Liudas Ivanauskas 《Natural product research》2019,33(13):1961-1963
The aim of research was to study the content of amino acids using in extracts of Fumaria schleicheri L., Ocimum basilicum L., and Corylus avellana L. by HILIC MS/MS method. Separation of amino acids in the samples was carried out with Acquity H-class UPLC system (Waters, Milford, USA) equipped with SeQuant ZIC-Hilic collumn (2.1 × 150 mm, 3.5 μm) (Merck Millipore, Darmstadt, Germany). The MS/MS fragment ion chromatograms of the test solutions established the presence of 19 amino acids. The obtained results have shown that O. basilicum L. characterized the highest concentrations of different neurogenic amino acids (128.1 mg/kg), comparing with F. schleicheri L. and C. avellana L. (57.72 and 52.91 mg/kg, respectively). 相似文献
77.
78.
79.