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1.
The conductances of aqueous CaCl2, Ca(CH3COO)2, and Ca(CH3COO)2.nCH3COOH were measured from 348 to 523 K at pressures near 10 MPa using a flow conductometric technique. The first association constant for calcium chloride and the first and second association constants for calcium acetate in water, were derived from a least-squares fit of the measurements to a conductance model in which activity coefficients were calculated using the mean spherical approximation (MSA) and the conductance was modeled by the Turq, Blum, Bernard, and Kunz (TBBK) equation, plus a mixture model.  相似文献   
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Metalloporphyrin molecules have a wide range of potential applications in diverse technological areas ranging from electronics to optoelectronics, electrochemistry, photophysics, chemical sensors, and catalysis. In particular, self-assembled monolayers of porphyrin molecules have recently attracted considerable interest. In this work we have studied for the first time the self-assembly of a novel Cu deutero porphyrin functionalized with disulfide moieties using electrochemical techniques, UV-vis absorption spectroscopy, polarization modulation infrared reflection absorption spectroscopy, and photoelectron spectroscopies (XPS and UPS). Experimental results indicate that the molecule adsorbs retaining its molecular integrity without forming molecular aggregates via the formation of Au-S covalent bonds. Furthermore, the monolayer consists of a packed array of molecules adsorbed with the plane of the porphyrin molecule at an angle of around 30° with respect to the surface normal. Interestingly, adsorption induces reduction of the Cu center and its consequent removal from the center of the porphyrin ring resulting in porphyrin demetalation. Our results are important in the design of self-assembled monolayers of metallo porphyrins where not only blocking of the metal center by the functional groups that drive the self-assembly should be considered but also possible adsorption induced demetalation with the consequent loss in the properties imparted by the metal center.  相似文献   
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Osmium pyridine-bipyridine redox centers have been tethered to Au electrodes by chemical modification through Au-S and Au-C bonds respectively. 4-Mercapto benzoic acid and the reduction product of the aryl diazonium salt of 4-amino benzoic acid were reacted on Au surfaces, with further post-functionalization by chemical reaction of the osmium complex amino-pyridine derivative with the surface carboxylates. The resulting modified Au surfaces were characterized by polarization modulated infrared reflection absorption spectroscopy (PM-IRRAS), scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), resonant raman spectroscopy and cyclic voltammetry.  相似文献   
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We propose an innovative strategy to obtain crack-free gels by using a surfactant as a template for the silica pores. We use a neutral surfactant – n-octylamine – which weakly interacts by hydrogen bonding with the silica precursor. This allows it to be removed by simple drying in ambient air. We investigate the effect of the surfactant in simple inorganic silica obtained from tetraethoxysilane (TEOS) and an organic–inorganic hybrid xerogel, containing TEOS and polydimethylsiloxane (PDMS), as precursors. Although both the syntheses promote the formation of a crack-free uniform mesoporous silica gel, the hybrid gel network exhibits a larger pore size than the gel containing exclusively the silica from TEOS.  相似文献   
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The synthesis of the rhenacycles [Re(CO)3(PR3){Ph2P(Se)NP(Se)Ph22Se}], PR3 = PPh3 (1), PMePh2 (2), and PMe2Ph (3) by a straightforward high yield procedure is described. Attempts at the preparation of the spiro [Re(CO)2(Ph2PCH2CH2PPh22P){Ph2P(Se)NP(Se)Ph22Se}] resulted in the formation of complexes [Re2(CO)6{Ph2P(Se)NP(Se)Ph22Se}2(μ-Ph2PCH2CH2PPh2)] (4) and [Re(CO)3(Ph2PCH2CH2PPh22P){Ph2P(Se)NP(Se)Ph2Se}] (5). All new inorganic rhenacycles 1-5 were characterized in solution and in solid state. The X-ray diffraction analysis of [Re(CO)3PPh3{Ph2P(Se)NP(Se)Ph22Se}] showed that its MnSePNPSe ring conformation is sensitive to temperature.  相似文献   
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Analytical and Bioanalytical Chemistry - A new electrochemical interface based on polyacrylic acid (PAAcid) immobilized in a Nafion® polymeric matrix on graphite screen-printed electrodes for...  相似文献   
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Reaction of ReBr(CO)5 with Li[Ph2P(O)NP(O)Ph2] afforded the cryptate Li[Re2(CO)6{μ-Ph2P(O)NP(O)Ph22O,O’}3]; whereas K[Ph2P(O)NP(O)Ph2] reacted with ReBr(CO)5 to give K[Re2(CO)6{μ-Ph2P(O)NP(O)Ph22O,O′}{Ph2P(O)NP(O)Ph22O,O′}2]. Other chalcogen ligands’ salts M[Ph2P(E)NP(E)Ph2], E = Se and S, M = K and Li gave dirhenium carbonyls with bromido and Ph2P(E)NP(E)Ph2, E = Se or S bridges upon reaction with ReBr(CO)5.  相似文献   
9.
New nanomaterials for consolidating stone   总被引:1,自引:0,他引:1  
A novel sol-gel synthesis, in which a surfactant acts to make the pore size of the gel network more coarse and uniform, is shown to provide an effective alternative for the consolidation of stone. The new mesoporous silica avoids the main inconvenience of current commercial consolidants, which is their tendency to crack inside the pores of the stone. Since the cracking of xerogels is a well-known drawback of the sol-gel process, the synthesis presented here can be extended to other applications. Finally, preliminary studies of the effectiveness of the novel surfactant-templated sol in consolidating a typical biocalcareous stone are also discussed.  相似文献   
10.
A novel and environmentally friendly method based on mixing of colloidal polymer particles and graphene sheets has been developed. It is found that colloidal polymers can be employed to stabilize graphene oxide (GO) sheets during reduction to graphene. Adsorption of polymer particles at the surface of graphene layers seems to be underlying mechanism of stabilization of graphene sheets. Surface polarity of the polymer particles is crucial for the successful stabilization of graphene layers. Presence of colloidal particles at the surface of graphene prohibits restacking and agglomeration of nanolayers, resulting in fine dispersion of graphene throughout the polymeric matrix. Formation of strong bond between polar segments of the polymer chain and oxygen groups of graphene sheets generates a strong interface improving final properties of the composites. Inclusion of merely 2 wt% of graphene into an acrylic resin resulted in an increase of 522% and 242% in modulus and hardness, respectively.  相似文献   
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