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101.
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103.
Dufour G Valentin A Henry A Hurtmans D Camy-Peyret C 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(14):10045-3352
Simultaneous ultraviolet (UV) and infrared (IR) measurements of ozone concentration in air in the 1200-300 ppbv range have been performed using the ultraviolet absorption in the Hartley band at 0.2537 microm and the infrared absorption of a doublet at 9.507 microm in the nu(3) vibration-rotation band. Infrared concentration measurements were achieved using the tunable diode laser spectrometer of LPMA in Paris with interferometric control of the emitted wavelength while the UV concentration measurements were performed with the 49PS Megatec ozone generator of the Bureau National de Metrologie (BNM). The simultaneous recording of spectra of a reference cell filled with pure distilled ozone and of a low concentration mixture inside a long absorbing path Herriott cell allows to carry out infrared concentration measurements with an accuracy of the same order as the ultraviolet ones and provides the instrumental parameters of the spectrometer corresponding to each concentration measurement, which reduces systematic errors. Within the respective absolute uncertainties proper to the two techniques, no systematic discrepancy was evidenced between the IR and the UV measurements. The ozone ultraviolet absorption coefficient value determined by Hearn (308.3 +/- 4 cm(-1)atm(-1)) and used by the BNM and the National Institute of Standards and Technology (NIST) is confirmed by the present work. 相似文献
104.
Lynne A. McCullough Bruno Dufour Krzysztof Matyjaszewski 《Journal of polymer science. Part A, Polymer chemistry》2009,47(20):5386-5396
2‐Acrylamido‐2‐methyl‐N‐propanesulfonic acid (AMPSA) was successfully polymerized via atom transfer radical polymerization (ATRP) using a copper chloride/2,2′‐bipyridine (bpy) catalyst complex after in situ neutralization of the acidic proton in AMPSA with tri(n‐butyl)amine (TBA). A 5 mol % excess of TBA was required to completely neutralize the acid and prevent protonation of the bpy ligand, as well as to avoid side reactions caused by large excess of TBA. The use of activators generated by electron transfer (AGET) ATRP with ascorbic acid as reducing agent resulted in both increased conversion of the AMPSA monomer during polymerization (up to 50% with a 0.8 [ascorbic acid]/[Cu(II)] ratio) and much shorter polymerization times (<30 min). Block copolymers and molecular brushes containing AMPSA side chains were prepared using this method, and the solution and surface behavior of these materials were investigated. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5386–5396, 2009 相似文献
105.
A. Mougin C. Dufour N. Maloufi K. Dumesnil Ph. Mangin 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(2):289-296
Single crystal RFe2(110) films were grown by molecular beam epitaxy to a total thickness of 1000 ? at different substrate temperatures ranging
from 450
°
C to 660
°
C. The first stages of growth and the surface morphology of the deposited layers have been studied using Reflection High Energy
Electron Diffraction (RHEED) and Atomic Force Microscopy (AFM). The growth is first strained but further deposit induces the
formation of three-dimensional fully relaxed islands. Subsequently, the morphology of the RFe2(110) nanosystems evolves from anisotropic dots to a smooth surface, as a function of the preparation parameters, i.e. nominal thickness and substrate temperature. It also depends on the rare earth involved in the compound.
Received 29 June 2000 相似文献
106.
Corinne Lacaze‐Dufour Tzonka Mineva Nino Russo 《International journal of quantum chemistry》2001,85(3):162-170
Model core potential computations were performed for Rh2, Rh3, and Rh4 clusters and their respective cations and anions using the linear combination of Gaussian‐type orbital, nonlocal spin density method. The optimized geometries, electronic and magnetic structures, binding and fragmentation energies, adiabatic ionization potentials, and electron affinities were determined. Results show that the ionization potentials, electron affinities, binding energies, and magnetic moments decrease with the cluster size. For Rh2 and Rh3 the most stable structures exhibit ferromagnetic properties, while Rh4 in its ground state is found to be paramagnetic. The structures of minimum energy for the charged species often differs from the corresponding neutral one. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001 相似文献
107.
Xaviera Pennanec Alain Dufour Dominique Haras Karine Réhel 《Rapid communications in mass spectrometry : RCM》2010,24(3):384-392
Concerns with water quality have increased in recent years, in part due to the more frequent contamination of water by pathogens like E. coli and L. pneumophila. Current methods for the typing of bacteria in water samples are based on culture of samples on specific media. These techniques are time‐consuming, subject to the impact of interferents and do not totally meet all the requirements of prevention. There is a need for accurate and rapid identification of these microorganisms. This report deals with the detection of bacteria, more precisely of Legionella spp., and the development of an analytical strategy for a rapid and unambiguous identification of these pathogens in water from diverse origins. Therefore, a protein mass mapping using matrix‐assisted laser desorption/ionisation mass spectrometry (MALDI MS) of whole bacteria combined with a home‐made database of bacteria spectra is applied. A large variety of different bacteria and microorganisms is used to approach the actual composition of samples with numerous interferents. The objective is to propose a universal method for sampling preparation before MALDI MS analysis and optimised spectrometric conditions for reproducible intense peaks. Several experimental factors known to influence signal quality such as time and media of culture have been studied. The proposed method gives promising results for a sure differentiation of Legionella species and subspecies and a rapid identification of bacteria which are the most dangerous or difficult to eradicate. This method is easy to perform with an excellent reproducibility. The analytical protocol and the corresponding database were validated on samples from different origins (cooling tower, plumbing hot water). Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
108.
Coldham I Dufour S Haxell TF Patel JJ Sanchez-Jimenez G 《Journal of the American Chemical Society》2006,128(33):10943-10951
Dynamic resolution has been studied as a method for the asymmetric synthesis of 2-substituted pyrrolidines. Highly enantioselective electrophilic substitutions of racemic 2-lithiopyrrolidines in the presence of a chiral ligand have been achieved. The organolithium compounds were prepared by tin-lithium exchange from the corresponding tributylstannanes and n-butyllithium or by deprotonation of N-(tert-butyloxycarbonyl)pyrrolidine with sec-butyllithium. A range of N-substituents and chiral ligands were investigated for the dynamic resolution. Electrophilic quench of the resolved diastereomeric 2-lithiopyrrolidine-chiral ligand complexes provided the enantiomerically enriched 2-substituted pyrrolidines. With N-alkyl derivatives, the resolution occurs conveniently at (or just below) room temperature and either enantiomer of the product can be formed by appropriate choice of the chiral ligand. The asymmetric induction occurs as a result of a thermodynamic preference for one of the diastereomeric complexes. The minor complex was found to have a faster rate of reaction with the electrophile. The use of N-allylic derivatives provides a means to prepare the N-unsubstituted pyrrolidine products. Best results were obtained with the N-2,3-dimethylbut-2-enyl derivative, and this N-substituent could be cleaved using 1-chloroethyl chloroformate. With N-Boc-2-lithiopyrrolidine, the enantioselectivity arises by a kinetic resolution and high levels of asymmetric induction in the presence of excess n-butyllithium can be obtained. Dynamic kinetic resolution of the N-Boc derivative is limited in the scope of electrophile that can be used. 相似文献
109.
Katherine Nott Samuel Dufour Sylvie Heilporn Patrick Rollin Georges Lognay Michel Paquot 《Tetrahedron letters》2005,46(43):7377-7380
An efficient chemoselective ligation approach using an oxime bond was developed for the synthesis of amino acid derivatives of virginiamycin M1, a highly sensitive streptogramin antibiotic. 相似文献
110.
A procedure to prepare nonionic reactive surfactants with different polymerizable groups is described. The synthesis involves the initiation of living anionic ring-opening polymerization of ethylene oxide and propylene oxide (for the hydrophilic part and the hydrophobic part, respectively) by a potassium salt prepared from the stoichiometric reaction of potassium hydride and diethylene glycol monomethyl ether. The resulting anion is reacted with chloride compounds (methacryloyl, allyl, vinylacetoyl) and maleic anhydride, as well as with isobutanoyl chloride, leading to a nonpolymerizable compound having a similar structure. Then, it was possible to produce a range of reactive surfactants more or less reactive with the monomers. These surfactants are expected to be used further in emulsion polymerization processes (styrene and butyl acrylate). This procedure gives good control of both hydrophobic and hydrophilic parts, and the end reaction for the different functionality of surfmers is quite quantitative. All the surfactants were characterized by size-exclusion chromatography and 1H NMR. Physicochemical properties, such as the critical micellar concentration and the specific area, were also measured. 相似文献