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1.
The combined effects of micellar and chemical catalysis were studied with a view to improving the features of catalytic kinetic determinations. For this purpose we chose the reaction between N,N-dimethyl-p-phenylenediamine (DPD) and N,N-dimethylaniline (DA) to form Bindschedler's Green leuco base, which is oxidized by hydrogen peroxide in a reaction catalysed by Cu(II). This reaction was found to be accelerated by anionic sodium dodecylsulphate (SDS) and cationic dodecyltrimethylammonium bromide (DTAB) micelles. Several advantages were gained in relation to the analytical features of the kinetic photometric determination of Cu(II) when the reaction was developed in the presence of micelles compared to that occurring in an aqueous medium. Such advantages include a lower detection limit, higher sensitivity, precision and solubility of DPD and DA, and substantially increased selectivity in some cases. A detailed study of the parameters which influence both reactions is reported. Some observations on the effect of SDS and DTAB on the reaction are also commented on. 相似文献
2.
Tecla Gasperi M.Antonietta Loreto Paolo A. TardellaElisabetta Veri 《Tetrahedron letters》2003,44(27):4953-4956
The reactions of exocyclic α,β-unsaturated γ-lactones with NsONHCO2Et and CaO produce N-(ethoxycarbonyl) spiroaziridino γ-lactones. By reaction with acetic acid these products give ring opening reaction and acetylated N-protected α-amino γ-butyrolactones are obtained. The ring opening reaction is quantitative and highly regioselective. 相似文献
3.
Lunar L Rubio S Pérez-Bendito D Jiménez C 《Rapid communications in mass spectrometry : RCM》2002,16(17):1622-1630
N-Hydroxyethyl-N-ethyl-3-methyl-p-phenylenediamine (CD(4)) is commonly used as a developing agent in color photographic processes. The main by-products formed in developer baths used in the process were separated and identified by liquid chromatography/electron ionization mass spectrometry (LC/EI-MS) and liquid chromatography/atmospheric pressure ionization mass spectrometry (LC/API-MS). A number of side reactions, in addition to the main reactions involved in the developing process, were found to occur. Such side reactions involved in the formation of CD(4) by-products included oxidation, hydroxylation, sulfonation and the formation of coupling products. A reaction pathway for the degradation of CD(4) based on the nature of the by-products identified is proposed and discussed. 相似文献
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M.Antonietta Loreto Lucio Pellacani Paolo A Tardella Elena Toniato 《Tetrahedron letters》1984,25(38):4271-4274
Ethoxycarbonylnitrene (EtOCON) generated by α-elimination adds cleanly to allylic ethers giving substituted aziridines. Similar addition via nitrenium ion (EtOCONH+) gives derivatives of β-amino alcohols. 相似文献
7.
The reaction of (α-trimethylsilanylmethyl)cyclohexylidene esters with NsONHCO2Et and CaO produces the N-(ethoxycarbonyl)spiroaziridines which, after ring-opening, gives the corresponding β,β-disubstituted β-amino ester derivatives. The stereochemical outcome of the reaction is influenced by substituents on the cyclohexyl group. 相似文献
8.
Loreto Salazar Modesta Espada Carmen Avendao Jos Elguero 《Journal of heterocyclic chemistry》1990,27(4):1109-1110
N-Amination of the 3(5)-amino-1,2,4-triazolide anion with hydroxylamine-O-sulfonic acid is studied. This method provided an access to the previously unknown 1,5-diamino-1,2,4-triazole. 相似文献
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C. Castellano F. Cecconi V. Loreto D. Parisi F. Radicchi 《The European Physical Journal B - Condensed Matter and Complex Systems》2004,38(2):311-319
The investigation of community structures in networks is an important issue in many domains and disciplines. In this paper we present a new class of local and fast algorithms which incorporate a quantitative definition of community. In this way the algorithms for the identification of the community structure become fully self-contained and one does not need additional non-topological information in order to evaluate the accuracy of the results. The new algorithms are tested on artificial and real-world graphs. In particular we show how the new algorithms apply to a network of scientific collaborations both in the unweighted and in the weighted version. Moreover we discuss the applicability of these algorithms to other non-social networks and we present preliminary results about the detection of community structures in networks of interacting proteins.Received: 7 November 2003, Published online: 14 May 2004PACS:
89.75.Hc Networks and genealogical trees - 87.23.Ge Dynamics of social systems - 87.90. + y Other topics in biological and medical physics 相似文献