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排序方式: 共有116条查询结果,搜索用时 312 毫秒
21.
Barbara Di Credico Dipl.‐Chem. Fabrizia Fabrizi de Biani Dr. Luca Gonsalvi Dr. Annalisa Guerri Dr. Andrea Ienco Dr. Franco Laschi Prof. Dr. Maurizio Peruzzini Dr. Gianna Reginato Dr. Andrea Rossin Dr. Piero Zanello Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(44):11985-11998
The reaction of [CpRuCl(PPh3)2] (Cp=cyclopentadienyl) and [CpRuCl(dppe)] (dppe=Ph2PCH2CH2PPh2) with bis‐ and tris‐phosphine ligands 1,4‐(Ph2PC≡C)2C6H4 ( 1 ) and 1,3,5‐(Ph2PC≡C)3C6H3 ( 2 ), prepared by Ni‐catalysed cross‐coupling reactions between terminal alkynes and diphenylchlorophosphine, has been investigated. Using metal‐directed self‐assembly methodologies, two linear bimetallic complexes, [{CpRuCl(PPh3)}2(μ‐dppab)] ( 3 ) and [{CpRu(dppe)}2(μ‐dppab)](PF6)2 ( 4 ), and the mononuclear complex [CpRuCl(PPh3)(η1‐dppab)] ( 6 ), which contains a “dangling arm” ligand, were prepared (dppab=1,4‐bis[(diphenylphosphino)ethynyl]benzene). Moreover, by using the triphosphine 1,3,5‐tris[(diphenylphosphino)ethynyl]benzene (tppab), the trimetallic [{CpRuCl(PPh3)}3(μ3‐tppab)] ( 5 ) species was synthesised, which is the first example of a chiral‐at‐ruthenium complex containing three different stereogenic centres. Besides these open‐chain complexes, the neutral cyclic species [{CpRuCl(μ‐dppab)}2] ( 7 ) was also obtained under different experimental conditions. The coordination chemistry of such systems towards supramolecular assemblies was tested by reaction of the bimetallic precursor 3 with additional equivalents of ligand 2 . Two rigid macrocycles based on cis coordination of dppab to [CpRu(PPh3)] were obtained, that is, the dinuclear complex [{CpRu(PPh3)(μ‐dppab)}2](PF6)2 ( 8 ) and the tetranuclear square [{CpRu(PPh3)(μ‐dppab)}4](PF6)4 ( 9 ). The solid‐state structures of 7 and 8 have been determined by X‐ray diffraction analysis and show a different arrangement of the two parallel dppab ligands. All compounds were characterised by various methods including ESIMS, electrochemistry and by X‐band ESR spectroscopy in the case of the electrogenerated paramagnetic species. 相似文献
22.
23.
Martina Bottoni Giovanna Baron Francesca Gado Fabrizia Milani Laura Santagostini Lorenzo Colombo Paola Sira Colombo Elisabetta Caporali Alberto Spada Marco Biagi Claudia Giuliani Piero Bruschi Giancarlo Aldini Gelsomina Fico 《Molecules (Basel, Switzerland)》2022,27(23)
A multidisciplinary investigation on Achillea moschata Wulfen (Asteraceae) is outlined herein. This work, part of the European Interreg Italy–Switzerland B-ICE project, originated from an ethnobotanical survey performed in Chiesa in Valmalenco (Sondrio, Lombardy, Northern Italy) in 2019–2021 which highlighted this species’ relevance of use in folk medicine to treat gastrointestinal diseases. In addition, this contribution included analyses of the: (a) phytochemical profile of the aqueous and methanolic extracts of the dried flower heads using LC-MS/MS; (b) morpho-anatomy and histochemistry of the vegetative and reproductive organs through Light, Fluorescence, and Scanning Electron Microscopy; (c) biological activity of the aqueous extract concerning the antioxidant and anti-inflammatory potential through cell-based in vitro models. A total of 31 compounds (5 phenolic acids, 13 flavonols, and 13 flavones) were detected, 28 of which included in both extracts. Covering and secreting trichomes were observed: the biseriate 10-celled glandular trichomes prevailing on the inflorescences represented the main sites of synthesis of the polyphenols and flavonoids detected in the extracts, along with volatile terpenoids. Finally, significant antioxidant and anti-inflammatory activities of the aqueous extract were documented, even at very low concentrations; for the first time, the in vitro tests allowed us to formulate hypotheses about the mechanism of action. This work brings an element of novelty due to the faithful reproduction of the traditional aqueous preparation and the combination of phytochemical and micromorphological research approaches. 相似文献
24.
Andrs Strawczynski Renzo Ros Raymond Roulet Fabrizia Grepioni Dario Braga 《Helvetica chimica acta》1988,71(8):1885-1894
The two complexes [Ir4(CO)10(diarsine)] (1) and [Ir4(CO)10(1,5-cyclooctadiene)] (2) bear a bidentate ligand chelating one metal atom of the basal face of the Ir4 tetrahedron. However, they differ in fluxional behaviour as observed by 2D-exchange and variable-temperature 13C-NMR. The CO-site exchange with lowest activation energy proceeds via an unbridged intermediate in 2 , whereas that in 1 occurs via a concerted edge-bridging of CO's to an alternative face of the metal core. This difference is apparently related to different ground-state geometries: the basal CO's are symmetrically bridging in 2 , whereas two CO's are semi-bridging in 1 . The molecular structure of 2 was determined by single crystal X-ray diffractometry. The crystals are orthorhombic, space group Pbca, a = 11.651(4), b = 13.118(3), c = 28.64(1)Å. The idealized molecular symmetry is Cs. The diolefin chelates a basal Ir-atom replacing an axial and a radial CO group on the tetrahedral metal-atom framework. 相似文献
25.
Reactions that occur within or between molecular crystals, in particular those reactions that are activated by mechanical methods, are reviewed. The focus is on processes (whether intrasolid or intersolid) that are controlled primarily by supramolecular bonding, such as template cycloadditions, formation of inclusion compounds, reactions between molecular crystals by the reassembling of noncovalent bonds, and the formation of complexes and coordination compounds. It is proposed that solvent-free mechanochemical methods, for example, cogrinding, milling, and kneading, represent viable "green" routes for the preparation of novel molecular and supramolecular solids. 相似文献
26.
Michele R. Chierotti Dr. Luca Ferrero Dr. Nadia Garino Dr. Roberto Gobetto Prof. Luca Pellegrino Dr. Dario Braga Prof. Fabrizia Grepioni Prof. Lucia Maini Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(14):4347-4358
Five new polymorphs and one hydrated form of 2‐thiobarbituric acid have been isolated and characterised by solid‐state methods. In both the crystalline form II and in the hydrate form, the 2‐thiobarbituric molecules are present in the enol form, whereas only the keto isomer is present in crystalline forms I (reported in 1967 by Calas and Martinex), III , V and VI . In form IV , on the other hand, a 50:50 ordered mixture of enol/keto molecules is present. All new forms have been characterised by single‐crystal X‐ray diffraction, 1D and 2D (1H, 13C, and 15N) solid‐state NMR spectroscopy, Raman spectroscopy and X‐ray powder diffraction at variable temperature. It has been possible to induce keto–enol conversion between the forms by mechanical methods. The role of hydrogen‐bond interactions in determining the relative stability of the polymorphs and as a driving force in the conversions has been ascertained. To the best of the authors’ knowledge, the 2‐thiobarbituric family of crystal forms represents the richest collection of examples of tautomeric polymorphism so far reported in the literature. 相似文献
27.
Fulvio Rossi Fabrizia Fabrizi de Biani Piero Zanello Piotr Buchalski 《Journal of Solid State Electrochemistry》2009,13(10):1505-1510
A collection of nickelocene and cobaltocene analogs with one or two nickelafluorenyl rings has been recently synthesized starting
from 9-nickelafluorenyllithium complex. The redox ability of the whole series of derivates has been investigated by electrochemical
techniques, and the nature of the frontier orbitals responsible for the electron transfer activity of this class of compounds
has been supported by extended Hückel calculations.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
28.
Kuritka I Negri F Brancolini G Suess C Salaneck WR Friedlein R 《The journal of physical chemistry. B》2006,110(38):19023-19030
Structural and electronic properties of pristine and lithium-intercalated, phenyl-capped aniline dimers as a model for the lithium-polyaniline system have been studied by photoelectron spectroscopy and quantum chemical calculations. It was found that the electronic structure of reduced and oxidized forms of oligoanilines is only weakly affected by isomerism. Upon intercalation, charge transfer from the Li-atoms is remarkable and highly localized at N-atomic sites, where configurations are energetically favored in which both N atoms of the dimers are bound to Li atoms. Conversion of nitrogen sites is different for the two forms of aniline dimers and incomplete up to high intercalation levels, indicating a pronounced role of solid-state effects in the formation of such compounds. 相似文献
29.
D. Braga S. L. Giaffreda M. Curzi Lucia Maini M. Polito Fabrizia Grepioni 《Journal of Thermal Analysis and Calorimetry》2007,90(1):115-123
Supramolecular reactions between crystalline materials can be exploited to prepare both hydrogen bonded co-crystals and coordination
networks. Mechanical mixing of molecular crystals as well as kneading provide an alternative, solvent-free, route to novel
materials hence these methods represent a green route to supramolecular solid-state chemistry. 相似文献
30.