全文获取类型
收费全文 | 77篇 |
免费 | 0篇 |
专业分类
化学 | 42篇 |
物理学 | 35篇 |
出版年
2013年 | 1篇 |
2012年 | 6篇 |
2011年 | 3篇 |
2010年 | 2篇 |
2009年 | 3篇 |
2008年 | 2篇 |
2007年 | 4篇 |
2006年 | 2篇 |
2005年 | 5篇 |
2004年 | 7篇 |
2003年 | 1篇 |
2002年 | 3篇 |
2001年 | 5篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1993年 | 1篇 |
1991年 | 4篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1981年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1973年 | 3篇 |
1972年 | 1篇 |
排序方式: 共有77条查询结果,搜索用时 31 毫秒
1.
Accreditation and Quality Assurance - 相似文献
2.
3.
Stewart S. J. Mercader R. C. Punte G. Desimoni J. Cernicchiaro G. Scorzelli R. B. 《Hyperfine Interactions》2004,158(1-4):89-93
In this paper we analyze trend of EFG values measured at Cd impurity in a group of semiconducting delafossites with chemical
formula CuBO2 (B = Al, Fe, Cr, Nd). We conclude that this trend reveals one of the most subtle details in electronic spectrum of the compounds:
if impurity states are formed within or out of the band gap. In CuAlO2 and CuFeO2 the Cd EFG exhibits larger value than in CuCrO2 and CuNdO2, when Cd substitutes the Cu atom. This occurs because in the first two compounds the Cd forms shallow band within the gap,
and in the second two compounds does not. When Cd occupies the B position it exhibits almost the same EFG in all delafossites.
In this case, Cd does not form its states within the gap in none of the compounds. To arrive to these conclusions we analyzed
and calculated various systems (Cd-doped CuAlO2 and CuCrO2 compounds, fictitious molecules), using the FP-LAPW method. 相似文献
4.
A.Corsico Coda G. Desimoni A.Gamba Invernizzi P.P. Righetti G. Tacconi 《Tetrahedron letters》1985,26(26):3137-3140
The difference between thermal, AlCl3- and CF3 COOH-catalyzed reaction of (E)-4-benzal-1-phenyl-5-pyrazolone and 2,3-dimethylbutadiene is discussed in terms of Diels-Alder heterodiene reactivity. 相似文献
5.
The stereoisomers (1–4) of the tetrahydropyran[2′,3′:2,3] 2,3-dihydropyran[6,5-c] pyrazole system equilibrate in deuterated trifluoroacetic acid at 35°.The mechanism which causes incorporation of deuterium in the 4a-position is discussed.The isomers distribution is rationalized in terms of steric and electronic interactions, and the energy values for the interaction between the phenyl group in 5 and the substituent in position 6 on the pyrazole ring are given. 相似文献
6.
A nickel-catalysed chemically modified electrode is described which seems to represent a convenient compromise between ease of preparation, reproducibility, precision and detection limits for the determination of carbohydrates in biological matrices. 相似文献
7.
A. Corsico Coda G. Desimoni M. Pappalardo P.P. Righetti P.F. Seneci G. Tacconi R. Obberti 《Tetrahedron》1985,41(12):2545-2555
The copper(II) acetate complex of isatin-3-phenylhy-drazone (2a) reacted with dimethyl acetylenedicarboxylate (DMAD) by two competitive pathways: a Cu++ oxidation of the ligand and a [2+2] cycloaddition. The former reaction gave 3-car- benindolin-2-one (13) which reacted with DMAD in a l,3-dipolar cycloaddition, to give 3a. This was synthesized by an independent route. The phenyl radical, generated in the same process, was trapped by three DMAD and gave . The [2+2] cycloaddition gave a spiro adduct 10 which, by electrocyclic ring opening and intramolecular cyclization, allowed isolation of a pyridazino [3,4-b] indole (|5a). The reaction was performed on -chlorophe-nylhydrazone 1b and the structure of 5b was demonstrated by X-ray analysis. A rationalization of the reactivity was attempted in terms of MO interactions of the reactants. 相似文献
8.
9.
10.
Mössbauer studies of one representative hydromorphic soil of the coastal area of the Rio de La Plata
B. A. Guichon J. Desimoni R. C. Mercader P. A. Imbellone 《Hyperfine Interactions》2010,195(1-3):77-83
In the present work, we have applied Mössbauer spectroscopy as well as the traditional chemical analyses to assess the contents of different states of Fe in oxides and hydroxides in an Entisol soil from the Argentine coastal plain of the Rio de La Plata. Tentative assignments for the different Fe ion sites are proposed. Our findings show that the isomer shift and quadrupole splitting are sensitive to the changes detected in the Fe2?+? contents of the soluble phase while others remain constant within the experimental uncertainties. 相似文献