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41.
Francine Blanger‐Garipy Michle Dartiguenave Frdrique Loiseau Andr L. Beauchamp 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):e338-e339
Pairs of individual molecules of the title compound, C19H17O2P, (I), containing tetrahedrally coordinated P atoms are connected across crystallographic inversion centres via complementary O—H?O=P hydrogen bonds. 相似文献
42.
Franois Brisse Mohamed Atfani Jean‐Yves Bergeron Francine Blanger‐Garipy Michel Armand 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(2):190-192
The title compounds of sulfur, C10H6N2O4S2, (I), and selenium, C10H6N2O4Se2, (II), are isomorphous. The crystallographically centrosymmetric molecules are planar. The bond distances and angles, except for those involving the S and Se atoms, are comparable. The molecules are disposed in layers parallel to the bc plane. The molecular axes differ by 75° for (I) and by 80° for (II) from one layer to the next. 相似文献
43.
Stephane Fontanay Francine Kedzierewicz Raphael Emmanuel Duval Igor Clarot 《Journal of inclusion phenomena and macrocyclic chemistry》2012,73(1-4):341-347
Hydroxy pentacyclic triterpenoic acids (HPTAs) have been described to exhibit numerous pharmacological properties. They also exhibit poor hydrosolubility, thus affecting their potential clinical interest. The association of these active substances with cyclodextrins could be employed to improve some properties such as bioavailability and activity. 1:1 Inclusion complexes of ursolic, oleanolic and betulinic acids with γ-cyclodextrin were evaluated by DSC and 1H NMR spectroscopy. The apparent formation constants (Kf) of the formed complexes were determined using RP-HPLC. Thermodynamic parameters ΔGo, ΔHo and ΔSo were calculated with temperatures ranging from 25 to 45?°C to evaluate the complexation process. Finally the influence of γ-CD on the HPTA water solubility was investigated by phase-solubility studies. 相似文献
44.
Romain Sallio Stéphane Lebrun Francine Agbossou-Niedercorn Christophe Michon Eric Deniau 《Tetrahedron: Asymmetry》2012,23(13):998-1004
Two alternative synthetic approaches to a variety of enantioenriched 6-arylated piperidin-2-ones have been developed. The first one is based on the hydrogenation of suitably arylated chiral cyclic enehydrazides. The second approach relies on the asymmetric catalytic hydrogenation of the corresponding N-alkylated precursors. 相似文献
45.
Paul Ionut Dron Francine Cazier David Landy Gheorghe Surpateanu 《Supramolecular chemistry》2013,25(5):473-477
The first results of the complexing ability of cyclobis-(paraquat-p-phenylene) as supramolecular host with different aromatic volatile organic compounds are presented. The formation constants of cyclobis(paraquat-p-phenylene) with toluene and halogenobenzenes were determined in aqueous solution by static headspace associated with gas chromatography and compared with the ones obtained by cyclodextrins. The data indicated the formation of 1:1 inclusion compounds in both cases. The results underlined a greater complexation ability for cyclobis(paraquat-p-phenylene) which was confirmed by a theoretical study. 相似文献
46.
In order to implement a simpler, less expensive and more safe sample dissolution procedure, we have substituted the HF-HClO4 mixture by NH4F. By testing three certified reference materials, lichen 336, basalt BE-N, soil 7, it was found that the three-reagents digestion without HF and HClO4 (HNO3 + H2O2 + NH4F was used) was very effective for the pretreatment of ICP-MS measurement. The comparison was based on the measurement results and their uncertainties. All are reference material for amount contents of different trace elements. The accuracy and precision of the developed method were tested by replicate analyses of reference samples of established element contents. The accuracy of the data as well as detection limits (LODs) vary among elements but are usually very good (accuracy better than 8%, LODs usually below 1 μg/g in solids). ICP-MS capabilities enable us to determine routinely 13 and 16 minor and trace elements in basalt and soil. 相似文献
47.
Kivlehan F Lanyon YH Arrigan DW 《Langmuir : the ACS journal of surfaces and colloids》2008,24(17):9876-9882
This paper reports on the electrochemical behavior of bovine insulin at the interface between two immiscible electrolyte solutions (ITIES). The voltammetric ion-transfer response obtained in the presence of insulin was dependent on the aqueous phase pH conditions and on the nature of the organic phase electrolyte employed in experiments. Optimal detection was obtained at acidic pH below the isoelectric point of insulin where it was positively charged. A shift in transfer potentials to lower potential values was observed with decreasing hydrophobicity of the anion of the organic phase electrolyte. No ion-transfer response was observed at pH values of the aqueous phase above the isoelectric point, where insulin was negatively charged. These results suggest that the voltammetric response is due to ion-pairing interactions at the ITIES between positively charged insulin and the hydrophobic anion of the organic phase electrolyte, together with adsorption of the ion-pair at the interface. The voltammetric response was obtained for insulin at concentrations down to 1 muM. These results show that electrochemistry is useful in studying the behavior of this important protein molecule at the polarized water-1,2-DCE interface and provides an alternative detection mode for bioanalytical applications. 相似文献
48.
Leclercq L Suisse I Agbossou-Niedercorn F 《Chemical communications (Cambridge, England)》2008,(3):311-313
Biphasic hydroformylation of dec-1-ene and styrene, at commercially competitive rates, can be successfully performed in imidazolium triflate ionic liquids; the ionic liquid network forms 'inclusion complexes' with the phosphane ligands used to modify the rhodium catalyst. 相似文献
49.
Mouhamad Jida Guillaume Laconde Olivier-Mohamad Soueidan Nicolas Lebegue Germain Revelant Lydie Pelinski Francine Agbossou-Niedercorn Benoit Deprez Rebecca Deprez-Poulain 《Tetrahedron letters》2012,53(39):5215-5218
An efficient method for a stereoselective synthesis of optically pure N-Boc-3-arylpiperazines has been developed. After optimization of the protecting group strategy and experimental conditions, compounds were obtained via a highly stereoselective synthesis in up to 45% overall yield. This is a practical route to optically pure piperazines for medicinal chemistry. 相似文献
50.
Calcium silicate hydrate (C-S-H) is the main constituent of hydrated cement paste and determines its cohesive properties. Because of the environmental impact of cement industry, it is more and more common to replace a part of the clinker in cement by secondary cementitious materials (SCMs). These SCMs are generally alumina-rich and as a consequence some aluminum is incorporated into the C-S-H. This may have consequences on the cohesion and durability of the material, and it is thus of importance to know the amount and the location of Al in C-S-H and what the parameters are that control these features. The present paper reports the (29)Si and (27)Al MAS NMR analyses of well-characterized C-A-S-H samples (C-S-H containing Al). These samples were synthesized using an original procedure that successfully leads to pure C-A-S-H of controlled compositions in equilibrium with well-characterized solutions. The (27)Al MAS NMR spectra were quantitatively interpreted assuming a tobermorite-like structure for C-A-S-H to determine the aluminum location in this structure. For this purpose, an in-house written software was used which allows decomposing several spectra simultaneously using the same constrained spectral parameters for each resonance but with variable intensities. The hypothesis on the aluminum location in the C-A-S-H structure determines the proportion of each silicon site. Therefore, from the (27)Al NMR quantitative results and the chemical composition of each sample, the intensity of each resonance line in the (29)Si spectra was set. The agreement between the experimental and calculated (29)Si MAS NMR spectra corroborates the assumed C-A-S-H structure and the proposed Al incorporation mechanism. The consistency between the results obtained for all compositions provides another means to assess the assumptions on the C-A-S-H structure. It is found that Al substitutes Si mainly in bridging positions and moderately in pairing positions in some conditions. Al in pairing site is observed only for Ca/(Si+Al) ratios greater than 0.95 (equivalent to 4 mmol.L(-1) of calcium hydroxide). Finally, the results suggest that penta and hexa-coordinated aluminum are adsorbed on the sides of the C-A-S-H particles. 相似文献