全文获取类型
收费全文 | 433篇 |
免费 | 5篇 |
国内免费 | 2篇 |
专业分类
化学 | 223篇 |
晶体学 | 7篇 |
力学 | 1篇 |
数学 | 38篇 |
物理学 | 171篇 |
出版年
2022年 | 2篇 |
2021年 | 12篇 |
2020年 | 7篇 |
2019年 | 4篇 |
2018年 | 9篇 |
2017年 | 8篇 |
2016年 | 11篇 |
2015年 | 8篇 |
2014年 | 8篇 |
2013年 | 19篇 |
2012年 | 21篇 |
2011年 | 37篇 |
2010年 | 21篇 |
2009年 | 22篇 |
2008年 | 31篇 |
2007年 | 23篇 |
2006年 | 14篇 |
2005年 | 19篇 |
2004年 | 15篇 |
2003年 | 14篇 |
2002年 | 10篇 |
2001年 | 9篇 |
2000年 | 18篇 |
1999年 | 6篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 4篇 |
排序方式: 共有440条查询结果,搜索用时 46 毫秒
91.
92.
93.
Leite JF Dougherty DA Lester HA Shahgholi M 《Rapid communications in mass spectrometry : RCM》2003,17(15):1677-1684
In a previous study utilizing benzophenone-based topological probes to study conformationally dependent changes in mouse muscle nicotinic acetylcholine receptor (nAChR) topology, electrospray ionization tandem mass spectrometric (ESI-MS/MS) analysis led to a consistent -2.0 Da mass deviation from expected values. In the present study a synthetic peptide, corresponding to nAChR alpha1 subunit residues 130-139, was photolabeled. MS/MS analysis of this peptide using an ion trap confirmed the previously observed mass deviation, associated only with fragment ions that contain the incorporated benzophenone moiety. Analysis of peak profiles for the photolabeled ions does not indicate the typical 'peak fronting' that produces a mass shift when labile ions are prematurely ejected from the ion trap. Rather, hydrogen/deuterium (H/D) exchange experiments support the hypothesis that a chemical rearrangement involving phenyl migration and ketone formation has formed an unexpected oxidized peptide, with molecular mass 2 Da less than that expected, that is isolated for collision-induced dissociation in the ion trap together with the predicted precursor due to the broad ion isolation window specified. 相似文献
94.
95.
Luiz Claudio de Santa Maria Marcia C.A.M. Leite José M.S. Ribeiro Manoel R. Silva 《European Polymer Journal》2003,39(4):843-846
Iron composite materials based on styrene/divinylbenzene network hosts were produced using aqueous suspension polymerization. The effects of different kinds of porogen agent, toluene, toluene/n-heptane mixture or a toluene solution of polyphenyleneoxide on the bulk density, swelling in toluene and ferromagnetic properties of these materials were evaluated. The specific area and average porous diameter of network resins were characterized by BET and BJH methods, while the iron content was determined by atomic absorption spectrometry. The morphology of the composites was studied by both optical microscopy and scanning electron microscopy with energy dispersive X-ray analysis. All the spherical beads, irrespective of their sizes, have agglomerated iron particles located only on their surface. The particles have exhibited ferromagnetic behavior, with a coercivity of 328.69 Oe. The porogen agents used affect the iron particle distribution on the bead surfaces. 相似文献
96.
Synthesis and non-isothermal kinetic study of the thermal decomposition of gadolinium(III) complexes
W. S. Lopes C. R. da S. Morais A. G. de Souza V. D. Leite 《Journal of Thermal Analysis and Calorimetry》2005,79(2):343-347
Summary Pyrrolidinedithiocarbamate (Pyr), piperidinedithiocarbamate (Pip), morpholinedithiocarbamate (Mor) and diethanolaminedithiocarbamate (DEDC) ammonium salts; pyrrolidinedithiocarbamic acid-pyrrolidineammonium salt (HPyrPyr), piperidinedithiocarbamic acid-piperidineammonium salt (HPipPip), morpholinedithiocarbamic acid-morpholineammonium salt (HMorMor), hexamethylenedithiocarbamic acid-hexamethyleneammonium salt (HHexHex), diethanolaminedithiocarbamic acid-diethanolamineammonium salt (HDEADEDC) were synthesized, characterized by IR and elemental analysis and their thermal behaviours were investigated using thermogravimetry (TG) and differential scanning calorimetry (DSC). 相似文献
97.
N Duran M C Marcucci M S Gatti L C Leite 《Journal of photochemistry and photobiology. B, Biology》1990,4(4):371-378
Strains of Escherichia coli which lack 4-thiouridine (S4U) exhibit a higher survival rate than their wild-type parents which contain S4U after treatment with enzyme-generated triplet indole-3-aldehyde. In a similar manner to results obtained with monochromatic 334 nm UV light, the survival is related to single-strand breakage of DNA in E. coli containing the pBR 322 plasmid. The effects of the excited states generated by an enzymatic system suggest that S4U is an important chromophore in the lethal effects observed. The results also suggest that the energy transferred from triplet indole-3-aldehyde to S4U may also be passed from S4U of t-RNA to DNA, possibly through a singlet oxygen intermediate generated by excited S4U, resulting in a decrease in the survival rate of E. coli containing S4U. These results emphasize the importance of excited states in biological systems. 相似文献
98.
99.
We analyze the role played by the Brazilian physicist Cesar Lattes (1924–2005) in the historical development of the nuclear emulsion technique and in the co-discovery of the pion. His works influenced and gave impetus to the development of experimental physics in Brazil, the foundation of a national center dedicated to physics research, the beginnings of Brazilian “Big Science,” and the inauguration of a long-lasting collaboration between Brazil and Japan in the field of comic ray physics. 相似文献