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991.
Bernhard Beckermann Valery Kalyagin Ana C. Matos Franck Wielonsky 《Constructive Approximation》2013,37(1):101-134
We prove existence and uniqueness of a solution to the problem of minimizing the logarithmic energy of vector potentials associated to a d-tuple of positive measures supported on closed subsets of the complex plane. The assumptions we make on the interaction matrix are weaker than the usual ones, and we also let the masses of the measures vary in a compact subset of $\mathbb{R}_{+}^{d}$ . The solution is characterized in terms of variational inequalities. Finally, we review a few examples taken from the recent literature that are related to our results. 相似文献
992.
Ana Danelia 《Acta Mathematica Hungarica》2013,138(3):281-293
The estimates of the partial moduli of continuity of k-th order (k≧3) of the conjugate functions of several variables are obtained in the space ?(T n ). The exactness of these estimates is established by proper examples. 相似文献
993.
Leitão JM Esteves da Silva JC Girón AJ Muñoz de la Peña A 《Journal of fluorescence》2008,18(6):1065-1076
Excitation emission fluorescence matrices (EEMs) of Verapamil drug were obtained by direct and by derivatization fluorescence
spectroscopy. The fluorescence excitation and emission wavelengths were displaced to longer wavelengths and the fluorescence
intensity was enhanced upon derivation with respect to the native fluorescence of the drug. The complete EEM of the native
fluorescence of the drug and of the derivatization product were rapidly acquired by using a charged-coupled device detector
(CCD), which is advantageous in terms of speed in the analysis, with respect to the use of a conventional photomultiplier
detector. The EEMs were analyzed by several second-order multivariate calibration methods exploiting the second order advantage.
The three-dimensional decomposition methods used, based in different assumptions about the trilinearity of the three way data
structure under analysis, were parallel factor analysis (PARAFAC), bilinear least squares (BLLS), parallel factor analysis
2 (PARAFAC2) and multivariate curve resolution—alternating least squares (MCR-ALS). The determination was performed by using
the standard addition approach. The figures of merit of the PARAFAC and BLLS methods were calculated, obtaining a lower limit
of detection with the derivatization procedure, when compared with the direct measurement of the fluorescence of the drug.
In Verapamil drug the best estimations were found with the BLLS and the MCR-ALS models. In the quantification of Verapamil
in a pharmaceutical formulation the best estimation, when compared with the result obtained by the US Pharmacopeia high performance
liquid chromatography approach, was obtained by direct fluorescence spectroscopy with MCR-ALS and by derivatization fluorescence
spectroscopy with the PARAFAC2 model. 相似文献
994.
Structural characterization of MnNi and MnPt antiferromagnetic materials for spintronic applications
J.M. Teixeira J. Ventura J.P. Araujo J.B. Sousa V.S. Amaral B. Negulescu M. Rickart P.P. Freitas 《Journal of Non》2008,354(47-51):5275-5278
MnNi and MnPt become antiferromagnetic (AFM) when annealed at high enough temperatures, for which a face-centered cubic (fcc) to face-centered tetragonal (fct) structural transition occurs. Thus, structural information is essential when optimizing exchange bias in these materials. We performed structural (X-ray diffraction), magnetic (Magneto-Optical Kerr effect) and magneto-transport (magnetoresistance) measurements on MnNi based spin valves subjected to different annealing procedures and MnPt/CoFe bilayers with different MnPt thicknesses. We show that high annealing temperatures can in fact lead to the fct antiferromagnetic phase in both materials, but the annealing procedure is also an important factor on the obtained exchange field values. Also, MnPt/CoFe bilayers allowed us to probe the influence of average AFM-grain size on exchange bias. 相似文献
995.
Miljevic N Golobocanin D Ogrinc N Bondzic A 《Isotopes in environmental and health studies》2008,44(2):137-148
Stable hydrogen and oxygen isotopes were analysed in water samples from the River Danube and its tributaries during a longitudinal survey performed in August 2005 on Serbian territory. Danube river water data ranged from-80 per thousand to-66 per thousand for delta2H, and from-11.2 per thousand to-9.3 per thousand for delta18O with delta values increasing downstream. The isotopic signatures of the adjacent tributaries (the Tisza, the Sava and the Velika Morava) sampled at the locations close to their confluence with the Danube (Titel, Ostruznica and Ljubicevski most, respectively) just about the time of the campaign were enriched (-67 per thousand and-63 per thousand for delta2H, and-9.3 per thousand and-8.9 per thousand for delta18O) with respect to the Danube water because of their catchment effects. Hydrogen and oxygen stable isotope values were used in combination with measured physico-chemical and biological parameters to trace hydrological and transport processes in these river systems. The mixing relationships between the Danube main stream and its tributaries were estimated using the mass balance for isotopic composition and electrical conductivity as conservative parameters. Evidence of an incomplete mixing process at the Centa location, 8 km below the confluence of the Tisza river, with its participation of 88% was shown by its oxygen-18 content. The correlations between river water isotope composition and physico-chemical and biological parameters are discussed. 相似文献
996.
Marely E. Tejeda‐Ferrari Chelsea L. Brown Gabriela C. C. C. Coutinho Ghabriel A. Gomes de S Julio L. Palma Manuel J. Llansola‐Portoles Gerdenis Kodis Vladimiro Mujica Junming Ho Devens Gust Thomas A. Moore Ana L. Moore 《Photochemistry and photobiology》2019,95(1):211-219
Three Pd(II) phthalocyanine–carotenoid dyads featuring chromophores linked by amide bonds were prepared in order to investigate the rate of triplet–triplet (T‐T) energy transfer from the tetrapyrrole to the covalently attached carotenoid as a function of the number of conjugated double bonds in the carotenoid. Carotenoids having 9, 10 and 11 conjugated double bonds were studied. Transient absorption measurements show that intersystem crossing in the Pd(II) phthalocyanine takes place in 10 ps in each case and that T‐T energy transfer occurs in 126, 81 and 132 ps in the dyads bearing 9, 10 and 11 double bond carotenoids, respectively. To identify the origin of this variation in T‐T energy transfer rates, density functional theory (DFT) was used to calculate the T‐T electronic coupling in the three dyads. According to the calculations, the primary reason for the observed T‐T energy transfer trend is larger T‐T electronic coupling between the tetrapyrrole and the 10‐double bond carotenoid. A methyl group adjacent to the amide linker that connects the Pd(II) phthalocyanine and the carotenoid in the 9 and 11‐double bond carotenoids is absent in the 10‐double bond carotenoid, and this difference alters its electronic structure to increase the coupling. 相似文献
997.
Ana Maria Montagut Albert Granados Anna Ballesteros Roser Pleixats Montserrat Llagostera Pilar Cortés Rosa María Sebastián Adelina Vallribera 《Tetrahedron》2019,75(1):102-108
Surface coating of metal nanoparticles is one of the major aspects to be optimized in the design of antimicrobial nanoparticles. The novelty of this work is that antimicrobial derivatives have been used as stabilizers to protect silver nanoparticles (Ag NPs). Microbicidal activity studies of fabricated cotton textiles coated with these Ag@Antibio were performed. Protective ligand layers of Ag NPs resulted to be a deterministic factor in their antimicrobial activity. The best bactericidal activity was obtained for Fabric TAM (coated with Ag NPs with triarylmethane derivates in surface, Ag@TAMSH), with a bacterial decrease of 3 log units for the S. aureus strain. Intrinsic antibiotic activity and partial positive charge of the TAMSH probably enhanced their antimicrobial effects. Fabric Eu (coated with Ag NPs with eugenol derivates in surface, Ag@EugenolSH) and Fabric FQPEG (coated with Ag NPs embedded in PEG-fluoroquinolone derivatives in surface, Ag@FQPEG) displayed antibacterial activity for both Staphylococcus aureus and Pseudomonas aeruginosa strains. These coated antimicrobial cotton fabrics can be applied in different medical textiles. 相似文献
998.
Mélanie Fonte Natália Fagundes Ana Gomes Ricardo Ferraz Cristina Prudêncio Maria João Araújo Paula Gomes Cátia Teixeira 《Tetrahedron letters》2019,60(17):1166-1169
A multi-step synthetic route towards N4,N9-disubstituted 4,9-diaminoacridines that, to the best of our knowledge, has no precedence in the literature, has been developed. The target structures are likely to reveal interesting biological activities in the near future, not only due to their mepacrine-like core, but also because they embed simultaneously the pharmacophores of chloroquine and primaquine, antimalarial drugs that act at different stages of malaria infection. 相似文献
999.
Robert Stepi Christian R. Wick Vinzent Strobel Daniel Berger Nataa Vu
emilovi‐Alagi Marco Haumann Peter Wasserscheid Ana‐Sun
ana Smith David M. Smith 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(3):751-755
Supported ionic liquid phase (SILP) catalysis enables a highly efficient, Ru‐based, homogeneously catalyzed water‐gas shift reaction (WGSR) between 100 °C and 150 °C. The active Ru‐complexes have been found to exist in imidazolium chloride melts under operating conditions in a dynamic equilibrium, which is dominated by the [Ru(CO)3Cl3]? complex. Herein we present state‐of‐the‐art theoretical calculations to elucidate the reaction mechanism in more detail. We show that the mechanism includes the intermediate formation and degradation of hydrogen chloride, which effectively reduces the high barrier for the formation of the requisite dihydrogen complex. The hypothesis that the rate‐limiting step involves water is supported by using D2O in continuous catalytic WGSR experiments. The resulting mechanism constitutes a highly competitive alternative to earlier reported generic routes involving nucleophilic addition of hydroxide in the gas phase and in solution. 相似文献
1000.
Melanie Miller William E. Robinson Ana Rita Oliveira Nina Heidary Nikolay Kornienko Julien Warnan Inês A. C. Pereira Erwin Reisner 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(14):4649-4653
The integration of enzymes with synthetic materials allows efficient electrocatalysis and production of solar fuels. Here, we couple formate dehydrogenase ( FDH ) from Desulfovibrio vulgaris Hildenborough (DvH) to metal oxides for catalytic CO2 reduction and report an in‐depth study of the resulting enzyme–material interface. Protein film voltammetry (PFV) demonstrates the stable binding of FDH on metal‐oxide electrodes and reveals the reversible and selective reduction of CO2 to formate. Quartz crystal microbalance (QCM) and attenuated total reflection infrared (ATR‐IR) spectroscopy confirm a high binding affinity for FDH to the TiO2 surface. Adsorption of FDH on dye‐sensitized TiO2 allows for visible‐light‐driven CO2 reduction to formate in the absence of a soluble redox mediator with a turnover frequency (TOF) of 11±1 s?1. The strong coupling of the enzyme to the semiconductor gives rise to a new benchmark in the selective photoreduction of aqueous CO2 to formate. 相似文献