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331.
Andrea Cristofari Marianna De Santis Stefano Lucidi Francesco Rinaldi 《Journal of Optimization Theory and Applications》2017,172(2):369-401
In this paper, we describe a two-stage method for solving optimization problems with bound constraints. It combines the active-set estimate described in Facchinei and Lucidi (J Optim Theory Appl 85(2):265–289, 1995) with a modification of the non-monotone line search framework recently proposed in De Santis et al. (Comput Optim Appl 53(2):395–423, 2012). In the first stage, the algorithm exploits a property of the active-set estimate that ensures a significant reduction in the objective function when setting to the bounds all those variables estimated active. In the second stage, a truncated-Newton strategy is used in the subspace of the variables estimated non-active. In order to properly combine the two phases, a proximity check is included in the scheme. This new tool, together with the other theoretical features of the two stages, enables us to prove global convergence. Furthermore, under additional standard assumptions, we can show that the algorithm converges at a superlinear rate. Promising experimental results demonstrate the effectiveness of the proposed method. 相似文献
332.
Swarada Peerannawar William Horton Anne Kokel Fanni Török Marianna Török Béla Török 《Structural chemistry》2017,28(2):391-402
Structural and energetic features of a series of 15 diarylhydrazone derivatives were studied via density functional theory (DFT) in order to identify the key features that most likely contribute to their antioxidant effect. Theoretical calculations were carried out at the B3LYP/6-31G(d,p) level. The calculated physicochemical parameters included the ionization potential, N-H dissociation enthalpy, proton affinity, HOMO/LUMO energies, and the band gaps of the most stable conformation of the compounds. To assess the contribution of these factors to the in vitro activity, the compounds were synthesized and their antioxidant activity was also determined in three commonly used assays. The hydrazones were evaluated for their radical scavenging against the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS), and peroxyl (ORAC assay) radicals. The experimental radical scavenging data of the compounds have been then plotted against the physicochemical characteristics and based on the obtained fits conclusions have been drawn regarding the relative importance of the respective factors. 相似文献
333.
Divya Chopra Marianna Kontopoulou Dimitris Vlassopoulos Savvas G. Hatzikiriakos 《Rheologica Acta》2002,41(1-2):10-24
We investigated the thermo- rheological behavior of high glass transition, high molecular weight and small dynamic asymmetry
blends of poly(styrene-co-maleic anhydride) (SMA) and poly (methyl methacrylate) (PMMA) with varying amounts of maleic anhydride (MA) content, namely
8 wt%, 14 wt% and 32 wt%, in the SMA component. The phase separation (binodal) temperature of each blend was determined rheologically
using a combination of dynamic frequency and temperature sweeps in parallel plate geometry; it was marked by a change in slope
of the elastic modulus and the occurrence of a peak in tan δ in temperature sweeps. Failure of the time-temperature superposition
principle and observation of two peaks in the Cole-Cole plots corroborated these findings. The blends displayed lower critical
solution temperature (LCST) behavior with the critical temperatures exhibiting a non-monotonic dependence on the MA content.
From rheological and thermal measurements it was concluded that SMA/PMMA blends containing 14% MA were more miscible than
those containing 8% or 32% MA, a finding attributed to the compositional dependence of the interplay between SMA-SMA and SMA-PMMA
interactions in the different samples. MA also influenced the dynamic asymmetry and pretransitional concentration fluctuations.
The phase diagrams corresponding to each blend were modeled using a two-parameter temperature dependent interaction parameter,
based on the concept of generalized Gibbs free energy of mixing. The fitted values of interaction parameter were in good agreement
with values calculated explicitly using the Flory-Huggins theory.
Received: 16 February 2001 Accepted: 11 July 2001 相似文献
334.
Marianna Csörnyei Ville Suomala 《Journal of Mathematical Analysis and Applications》2012,393(2):680-691
For a large class of Cantor sets on the real-line, we find sufficient and necessary conditions implying that a set has positive (resp. null) measure for all doubling measures of the real-line. We also discuss same type of questions for atomic doubling measures defined on certain midpoint Cantor sets. 相似文献
335.
336.
Andrea Cappelli Marco Paolino Paolo Anzini Germano Giuliani Salvatore Valenti Marianna Aggravi Alessandro Donati Raniero Mendichi Lucia Zetta Antonella Caterina Boccia Fabio Bertini Filippo Samperi Salvatore Battiato Eugenio Paccagnini Salvatore Vomero 《Journal of polymer science. Part A, Polymer chemistry》2010,48(11):2446-2461
Three methyl end‐capped oligo(ethylene glycol) (MOEG) ethers ( 1b‐d ) and a methoxyderivative ( 1a ) of benzofulvene monomer BF3k were synthesized and induced to polymerize spontaneously by solvent removal to obtain soluble π‐stacked polymers bearing densely grafted MOEG side chains (poly‐ 1b – d ) and model polymer poly‐ 1a. The physicochemical features (e.g., solubility, NMR, MALDI‐TOF, and absorption/emission spectra, as well as MWD, conformation plot, and thermal properties) of the synthesized polymers were compared in a structure‐property relationship study. This approach afforded the following evidence. The structure of poly‐ 1a – d is very similar to that of BF3k , suggesting that the polymerization mechanism is not affected by the presence of the electron‐rich methoxy group or bulkier MOEG side chains. However, the latter appear to be capable of affecting the conformational behavior of the polymer backbone. The solubility of poly‐ 1a – d depends on the number of the oligo(ethylene glycol) monomeric units. In particular, poly‐ 1d , featuring a long MOEG side chain (n = 9), shows an amphiphilic character and is soluble in a number of organic solvents, whereas it interacts with water to give isolated macromolecules in equilibrium with nanosized water‐soluble aggregates. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2446–2461, 2010 相似文献
337.
Dr. Li‐Mei Yan Dr. Aleksandra Velkova Dipl.‐Chem. Marianna Tatarek‐Nossol Prof. Dr. Gerhard Rammes Dr. Andrei Sibaev Dr. Erika Andreetto Dipl.‐Ing. Michael Kracklauer Dipl.‐Biochem. Maria Bakou Dipl.‐Chem. Eleni Malideli Prof. Dr. Burkhard Göke Prof. Dr. Jörg Schirra Prof. Dr. Martin Storr Prof. Dr. Aphrodite Kapurniotu 《Angewandte Chemie (International ed. in English)》2013,52(39):10378-10383
338.
Victor A. Rozentsvet Nelly A. Korovina Valentina P. Ivanova Marianna G. Kuznetsova Sergei V. Kostjuk 《Journal of polymer science. Part A, Polymer chemistry》2013,51(15):3297-3307
The microstructure of poly(1,3‐pentadiene) synthesized by cationic polymerization of 1,3‐pentadiene with tBuCl/TiCl4 initiating system is analyzed using one‐dimensional‐ and two‐dimensional‐NMR spectroscopy. It is shown that unsaturated part of chain contains only homo and mixed dyads with trans?1,4‐, trans?1,2‐, and cis?1,2‐structures with regular and inverse (head‐to‐head or tail‐to‐tail) enchainment, whereas cis?1,4‐ and 3,4‐units are totally absent. The new quantitative method for the calculation of content of different structural units in poly(1,3‐pentadiene)s based on the comparison of methyl region of 13C NMR spectra of original and hydrogenated polymer is proposed. The signals of tert‐butyl head and chloromethyl end groups are identified in a structure of poly(1,3‐pentadiene) chain and the new approaches for the quantitative calculation of number‐average functionality at the α‐ and ω‐end are proposed. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3297–3307 相似文献
339.
Arianna Tocchetti Marianna Iorio Zeeshan Hamid Andrea Armirotti Angelo Reggiani Stefano Donadio 《Molecules (Basel, Switzerland)》2021,26(22)
NAI-112, a glycosylated, labionine-containing lanthipeptide with weak antibacterial activity, has demonstrated analgesic activity in relevant mouse models of nociceptive and neuropathic pain. However, the mechanism(s) through which NAI-112 exerts its analgesic and antibacterial activities is not known. In this study, we analyzed changes in the spinal cord lipidome resulting from treatment with NAI-112 of naive and in-pain mice. Notably, NAI-112 led to an increase in phosphatidic acid levels in both no-pain and pain models and to a decrease in lysophosphatidic acid levels in the pain model only. We also showed that NAI-112 can form complexes with dipalmitoyl-phosphatidic acid and that Staphylococcus aureus can become resistant to NAI-112 through serial passages at sub-inhibitory concentrations of the compound. The resulting resistant mutants were phenotypically and genotypically related to vancomycin-insensitive S. aureus strains, suggesting that NAI-112 binds to the peptidoglycan intermediate lipid II. Altogether, our results suggest that NAI-112 binds to phosphate-containing lipids and blocks pain sensation by decreasing levels of lysophosphatidic acid in the TRPV1 pathway. 相似文献
340.
Marianna Braza 《Flow, Turbulence and Combustion》2000,63(1-4):315-341
The three-dimensional transition to turbulence in flows around bodies of non-rectangular configuration has been analysed physically
by performing direct numerical simulation to solve the system of Navier-Stokes equations. The successive stages of 3D transition,
beyond the first bifurcation, have been detected first in the incompressible regime, for a circular cylinder configuration.
The generation of streamwise vorticity, organised according to spanwise periodic cells has been associated with the development
of large-scale coherent spanwise undulations of the originally rectilinear (nominally 2D) alternating vortex rows. The wavelengths
of these undulations have been determined as a function of Reynolds number. As this parameter increases, a further inherent
change of the flow transition is obtained and analysed, the natural vortex dislocations pattern. Beyond this change, the increase
of Reynolds number yields an abrupt shortening of the spanwise wavelength and the flow undergoes another transition step,
whose critical Reynolds number is evaluated by the present DNS approach in association with the Ginzburg-Landau model. Therefore,
the linear and non-linear parts of the flow transition have been quantified by means of the amplitude evolution versus time obtained by the present DNS, in conjunction with the mentioned global oscillator model.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献