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101.
We construct invariant polynomials on truncated multicurrent algebras, which are Lie algebras of the form , where is a finite-dimensional Lie algebra over a field of characteristic zero, and I is a finite-codimensional ideal of generated by monomials. In particular, when is semisimple and is algebraically closed, we construct a set of algebraically independent generators for the algebra of invariant polynomials. In addition, we describe a transversal slice to the space of regular orbits in . As an application of our main result, we show that the center of the universal enveloping algebra of acts trivially on all irreducible finite-dimensional representations provided I has codimension at least two. 相似文献
102.
A. Carel N. Kwamen Gilles S. de Macedo Constanze Wiederhold Prof. Dr. Iris M. Oppel Prof. Dr. Markus Albrecht 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(17):3829-3833
The thioester moiety is introduced as a lithium binding unit for the hierarchical formation of titanium(IV) catecholate-based lithium-bridged helicates. In solution, the coordination compounds show a monomer–dimer equilibrium which —in comparison to the oxo esters— is significantly shifted towards the monomers. In addition, the influence of the thioester side chain on the dimerization behavior is investigated and an expansible/compressible molecular switch is synthesized. In the latter case expansion and compression are performed reversibly in methanol, whereas in DMSO spontaneous expansion occurs. 相似文献
103.
Iron bulk self-diffusion coefficients were measured in Fe2O3 single crystals using original methodology based on the utilization of 57Fe stable isotope as iron tracer and depth profiling by secondary ion-mass spectrometry (SIMS). The iron self-diffusion coefficients were measured along and perpendicular to the c-axis, between 900 and 1100°C, in an oxygen atmosphere. Along the c-axis, the coefficients can be described by D ∥ c (cm2/s)?=?5.2?×?106?exp[?510 (kJ/mol)/RT], and are close to reliable data, available in the literature, obtained by means of radioactive techniques. Perpendicular to the c-axis, D ⊥c (cm2/s)?= 83?exp[?430 (kJ/mol)/RT], and the coefficients are smaller than coefficients along the c-axis. The data are compared with previously results of cation bulk self-diffusion in Cr2O3 and Al2O3 single crystals. 相似文献
104.
Fernando Macedo Jr. César C. AndreiDanilo Campiom Noemia K. Ishikawa 《Tetrahedron letters》2011,52(14):1612-1614
The origin of the highly regioselective acylation of methylhydroquinone dimethyl ether was investigated using geometry minimization (ab initio and DFT) and NOE spectroscopic measurements. The theoretical and experimental results were consistent with the indirect participation of the aromatic methyl group in blocking the electrophile attack at position 3 of the aromatic ring. 相似文献
105.
J. F. Fangueiro A. S. Macedo S. Jose M. L. Garcia S. B. Souto E. B. Souto 《Journal of Thermal Analysis and Calorimetry》2012,108(1):275-282
This article reports the thermodynamic changes of lipid nanoparticles (LN) upon delivery of lipophilic vitamin E derivatives
to the skin. Skin penetration of α-tocopherol (α-T) and α-tocopherol acetate (α-Ta) into and across porcine ear skin was investigated
in vitro using tape-stripping test in modified Franz diffusion cells. Wide angle X-ray scattering (WAXS) and differential
scanning calorimetry (DSC) have been used to characterize the polymorphism of the solid matrix of LN before and after in vitro
skin penetration assay. Cetyl palmitate LN with a loading capacity of 20% of vitamin E derivatives (with regard to the lipid
matrix) have shown the typical β’ modification of waxes, with a crystallinity index (%CI) between 30 and 40%. Mean particle
size and shelf life stability was assessed by static (laser diffractometry, LD) and dynamic (photon correlation spectroscopy,
PCS) light scattering techniques. Submicron-sized LN were produced, i.e., 99% of LN showed a size below 600 nm immediately
after production. A mean size between 180 and 350 nm (polydispersity index < 0.25) was obtained for LN stored at both 8 and
22 °C, and this size range was kept constant for at least 20 days of shelf life. Quantification of α-T and α-Ta in the skin
using tape-stripping provided a 3.4-fold increase in the level of actives within the stratum corneum (SC) and 1.3-fold increase
in the viable epidermis (VE). LN increased skin penetration of both actives, following a cumulative release during 8 h in
modified Franz diffusion cells. The differences in the distribution levels observed between α-T and α-Ta when delivered via
LN was due to the different thermodynamic activity of both actives, i.e., following increased partition coefficient of α-Ta
into SC and VE, in comparison to α-T. 相似文献
106.
107.
108.
Rodrigues TH Rocha MV de Macedo GR Gonçalves LR 《Applied biochemistry and biotechnology》2011,164(6):929-943
In this work, the potential of microwave-assisted alkali pretreatment in order to improve the rupture of the recalcitrant
structures of the cashew able bagasse (CAB), lignocellulosic by-product in Brazil with no commercial value, is obtained from
cashew apple process to juice production, was studied. First, biomass composition of CAB was determined, and the percentage
of glucan and lignin was 20.54 ± 0.70% and 33.80 ± 1.30%, respectively. CAB content in terms of cellulose, hemicelluloses,
and lignin, 19.21 ± 0.35%, 12.05 ± 0.37%, and 38.11 ± 0.08%, respectively, was also determined. Results showed that, after
enzymatic hydrolysis, alkali concentration exerted influence on glucose formation, after pretreatment with 0.2 and 1.0 mo L−1 of NaOH (372 ± 12 and 355 ± 37 mg gglucan−1) when 2% (w/v) of cashew apple bagasse pretreated by microwave-assisted alkali pretreatment (CAB-M) was used. On the other hand, pretreatment
time (15–30 min) and microwave power (600–900 W) exerted no significant effect on hydrolysis. On enzymatic hydrolysis step,
improvement on solid percentage (16% w/v) and enzyme load (30 FPU gCAB-M−1) increased glucose concentration to 15 g L−1. The fermentation of the hydrolyzate by Saccharomyces cerevesiae resulted in ethanol concentration and productivity of 5.6 g L−1 and 1.41 g L−1 h−1, respectively. 相似文献
109.
Rodríguez O Cristóvão RO Tavares AP Macedo EA 《Applied biochemistry and biotechnology》2011,164(4):524-533
The activity and stability of laccase and their kinetic mechanisms in water soluble ionic liquids (ILs): 1-butyl-3-methyl
imidazolium chloride [C4mim][Cl], 1-octyl-3-methyl imidazolium chloride [C8mim][Cl], and 1-decyl-3-methyl imidazolium chloride [C10mim][Cl] were investigated. The results show that an IL concentration up to 10% is satisfactory for initial laccase activity
at pH 9.0. The laccase stability was well maintained in [C4mim][Cl] IL when compared to the control. The inactivation of laccase increases with the length of the alkyl chain in the
IL: [C10mim][Cl] > [C8mim][Cl] > [C4mim][Cl]. The kinetic studies in the presence of ABTS as substrate allowed calculating the Michaelis–Menten parameters. Among
the ILs, [C4mim][Cl] was the suitable choice attending to laccase activity and stability. Alkyl chains in the ions of ILs have a deactivating
effect on laccase, which increases strongly with the length of the alkyl chain. 相似文献
110.
Noelia Calvar Elena Gómez Ángeles Domínguez Eugénia A. Macedo 《The Journal of chemical thermodynamics》2011,43(8):1256-1262
The osmotic and activity coefficients and vapour pressures of binary mixtures containing 1-propanol, or 2-propanol and imidazolium-based ionic liquids with bis(trifluoromethylsulfonyl)imide as anion (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, C2MimNTf2, 1-methyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide, C3MimNTf2, and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, C4MimNTf2) were determined at T = 323.15 K using the vapour pressure osmometry technique. The experimental osmotic coefficients were correlated using the extended Pitzer model modified by Archer and the MNRTL model, obtaining standard deviations lower than 0.033 and 0.064, respectively. The mean molal activity coefficients and the excess Gibbs free energy for the mixtures studied were calculated from the parameters of the extended Pitzer model modified by Archer. Besides the effect of the alkyl-chain of the cation, the effect of the anion can be assessed comparing the experimental results with those previously obtained for imidazolium ionic liquids with sulphate anions. 相似文献