全文获取类型
收费全文 | 126篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
化学 | 78篇 |
晶体学 | 2篇 |
力学 | 2篇 |
数学 | 28篇 |
物理学 | 17篇 |
出版年
2021年 | 2篇 |
2020年 | 2篇 |
2016年 | 3篇 |
2013年 | 1篇 |
2012年 | 7篇 |
2011年 | 6篇 |
2010年 | 1篇 |
2009年 | 4篇 |
2008年 | 8篇 |
2007年 | 3篇 |
2006年 | 7篇 |
2005年 | 3篇 |
2004年 | 7篇 |
2003年 | 4篇 |
2002年 | 5篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有127条查询结果,搜索用时 15 毫秒
1.
2.
V. P. Borovik I. Yu. Bagryanskaya Yu. V. Gatilov O. P. Shkurko 《Journal of Structural Chemistry》2003,44(4):650-654
The crystal structures of 2-amino-4-phenyl-9H-pyrimido[4,5-b]indole and its nitrate were determined by XRD analysis. 13C NMR, XRD, and quantum-chemical data indicate that the acid proton is predominantly localized at the N(3) atom of the pyrimidine ring in both isolated nitrate molecules and in molecules in crystal and solution. 相似文献
3.
Aryl-substituted six-membered azaaromatic heterocycles have a range of properties that make it possible to use them in scientific investigations and in modern regions of technology. The possibilities of using arylazines in chemical analysis, in catalytic processes, and as optical and photochromic materials in polymer chemistry are surveyed.Novosibirsk Institute of Organic Chemistry. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1011–1029, August, 1997. 相似文献
4.
Thompson [1] showed that if p is an odd prime number, A is a p-group of operators of the finite group P in which the Frattini subgroup (P) is elementary and central, and P/(P) is a free ZpA-module, then Cp(A) covers CP/(P)(A). Then he proposed the question of whether it is possible in this theorem to weaken the hypothesis that (P) be elementary and central. In the work it is shown that this hypothesis may be replaced by a much weaker one; it is sufficient that P be met-Abelian and have nilpotence class 相似文献
5.
V. P. Borovik Yu. V. Gatilov M. M. Shakirov O. P. Shkurko 《Russian Chemical Bulletin》2012,61(2):326-331
Three 12-aryl-5H,7H-pyrido[2,3-b:6,5-b??]diindoles (Ar = Ph, 4-BrC6H4, and 4-MeOC6H4) were obtained from appropriate 3-arylidene-2-ethoxyindolenines and hydrazine hydrate. 相似文献
6.
7.
The purpose of this paper is to introduce, for a finite Coxeter groupW, the mod 2 boundary operator on the space of all Coxeter matroids (also known asWP-matroids) forWandP, wherePvaries through all the proper standard parabolic subgroups ofW(Theorem 3 of the paper). A remarkably simple interpretation of Coxeter matroids as certain sets of faces of the generalized permutahedron associated with the Coxeter groupW(Theorem 1) yields a natural definition of the boundary of a Coxeter matroid. The latter happens to be a union of Coxeter matroids for maximal standard parabolic subgroupsQiofP(Theorem 2). These results have very natural interpretations in the case of ordinary matroids and flag-matroids (Section 3). 相似文献
8.
Dey A Hocking RK Larsen P Borovik AS Hodgson KO Hedman B Solomon EI 《Journal of the American Chemical Society》2006,128(30):9825-9833
Iron L-edge, iron K-edge, and sulfur K-edge X-ray absorption spectroscopy was performed on a series of compounds [Fe(III)H(3)buea(X)](n-) (X = S(2-), O(2-), OH(-)). The experimentally determined electronic structures were used to correlate to density functional theory calculations. Calculations supported by the data were then used to compare the metal-ligand bonding and to evaluate the effects of H-bonding in Fe(III)(-)O vs Fe(III)(-)S complexes. It was found that the Fe(III)(-)O bond, while less covalent, is stronger than the Fe(III)(-)S bond. This dominantly reflects the larger ionic contribution to the Fe(III)(-)O bond. The H-bonding energy (for three H-bonds) was estimated to be -25 kcal/mol for the oxo as compared to -12 kcal/mol for the sulfide ligand. This difference is attributed to the larger charge density on the oxo ligand resulting from the lower covalency of the Fe-O bond. These results were extended to consider an Fe(IV)(-)O complex with the same ligand environment. It was found that hydrogen bonding to Fe(IV)(-)O is less energetically favorable than that to Fe(III)(-)O, which reflects the highly covalent nature of the Fe(IV)(-)O bond. 相似文献
9.
A method was developed for the synthesis of 2-oxo-4-phenyl-2,3-dihydro-9H-pyrimido[4,5-b]indole as well as of 2-chloro- and 2-nitramino-4-phenylpyrimido[4,5-b]indoles. The replacement of the chlorine atom in 2-chloropyrimidoindole gave rise to a number of its functional derivatives (morpholino, azido, and cyano). The reaction of 2-chloro-substituted pyrimidoindole with hydrazine hydrate and catalytic hydrogenation of 2-nitraminopyrimidoindole were studied. 相似文献
10.
Paula Borovik Dr. Víctor Oestreicher Prof. Cristián Huck-Iriart Prof. Matías Jobbágy 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(39):10077-10086
Calcium phosphates stand among the most promising nanobiomaterials in key biomedical applications, such as bone repairment, signalling or drug/gene delivery. Their intrinsic properties as crystalline structure, composition, particle shape and size define their successful use. Among these compounds, metastable amorphous calcium phosphate (ACP) is currently gaining particular attention due to its inherently high reactivity in solution, which is crucial in bone development mechanisms. However, the preparation of this highly desired (bio)material with control over its shape, size and phase purity remains as a synthetic challenge. In this work, the epoxide route was adapted for the synthesis of pure and stable ACP colloids. By using biocompatible solvents, such as ethylene glycol and/or glycerine, it was possible to avoid the natural tendency of ACP to maturate into more stable and crystalline apatites. Moreover, this procedure offers size control, ranging from small nanoparticles (60 nm) to micrometric spheroids (>500 nm). The eventual fractalization of the internal mesostructured can be tuned, by simply adjusting the composition of the ethylene glycol:glycerine solvent mixture. These findings introduce the use of green solvents as a new tool to control crystallinity and/or particle size in the synthesis of nanomaterials, avoiding the use of capping agents and preserving the natural chemical reactivity of the pristine surface. 相似文献