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281.
Salvatore Magazù Federica Migliardo Antonio Benedetto Miguel Angel Gonzalez 《Journal of Non》2011,357(2):664-670
The main aim of the present work is to investigate the dynamical effects of the addition of disaccharides to hydrated lysozyme. The Self-Distribution-Function procedure is at first applied on Elastic Incoherent Neutron Scattering data obtained by the IN13 spectrometer on trehalose/H2O and sucrose/H2O where it highlights a different Q-dependence for the two disaccharides. Then a quantitative analysis of the Mean Square Displacement of lysozyme/trehalose/H2O and of lysozyme/sucrose/H2O from Elastic Incoherent Neutron Scattering data obtained by the IN10 spectrometer is presented. It is shown how the resolution function gives rise to a time integration of a given time-dependent Mean Square Displacement function. Furthermore the analysis shows that the protein dynamical transition, registered at a temperature value of about T = 200-220 K in the H2O hydrated lysozyme sample, is inhibited by the addition of the disaccharides. 相似文献
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284.
Quarks are proposed to be grouped together to make quark-clusters due to the strong interaction in cold quark matter at a few nuclear densities, because a weakly coupling treatment of the interaction between quarks there would be inadequate. Cold quark matter is then conjectured to be in solid state (i.e., forming a crystal structure) if the inter-cluster potential is deep enough to localize clusters in lattice. Such a solid state of cold quark matter would be very necessary for us to understand different manifestations of pulsar-like compact stars, and could not be ruled by first principles. 相似文献
285.
Pitois A de las Heras LA Zampolli A Menichetti L Carlos R Lazzerini G Cionini L Salvatori PA Betti M 《Analytical and bioanalytical chemistry》2006,384(3):751-760
Boron neutron capture therapy (BNCT) is a bimodal radiotherapeutic treatment based on the irradiation of neoplastic tissues
with neutrons after the tissues have selectively accumulated molecules loaded with nuclides with large neutron capture cross-sections
(such boron-10). Boron-10 carriers have been tested to a limited extent, and clinical trials have been conducted on sulfhydryl
borane (10B-BSH) and boronophenylalanine (10B-BPA). However, precise and accurate measurements of boron-10 concentrations (0.1–100 μg/g) in specimens and samples of limited
size (μg scale) are needed in order to be able to biologically characterise new compounds in predictive tissue dosimetry,
toxicology and pharmacology studies as well as in clinical investigations. A new approach based on fast separation and detection
of 10B-BPA performed by coupling capillary electrophoresis to electrospray mass spectrometry is reported. This method allows the
quantitative analysis and characterisation of 10B-BPA in a short time with a high separation efficiency. Detection limits of 3 μM for 10B-BPA and 30 ng/mL for 10B were obtained with CE–ESI–MS. A quantification limit of 10 μM for 10B-BPA (100 ng/mL for 10B) was attained. The total boron-10 concentration was determined by high-resolution inductively coupled mass spectrometry
in order to validate the method. Boron-10 isotope measurements were carried out by HR–ICP–MS at medium resolution (R=4000)
due to the presence of an isobaric interference at mass 10. Good agreement was obtained between the values from CE–ESI–MS
and those from HR–ICP–MS. The method has been successfully used to determine the 10B-BPA in two lines of cultured cells. 相似文献
286.
287.
The cross sections of the fragments produced in the projectile fragmentation reactions of the even calcium isotopes from A=36 to A=52 are calculated using the statistical abrasion ablation model.The neutron skin thickness are studied by investigating the fragments isotopic cross section distributions.The neutron-skin thicknesses of the calcium isotopes have a good linear correlation to the peak positions of their fragment isotopic cross section distributions.The correlation between the neutron skin thickness and the neutron density distributions of 48 Ca is investigated by introducing a parameter to adjust the diffuseness parameter in the fermi-type density distribution. 相似文献
288.
I. V. Golosovsky O. P. Smirnov R. G. Delaplane A. Wannberg Y. A. Kibalin A. A. Naberezhnov S. B. Vakhrushev 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,54(2):211-216
By neutron diffraction it was shown that nanostructured Se confined within a porous glass matrix exists in a
crystalline as well as in an amorphous state. The spontaneous crystallization of crystalline Se from confined amorphous
phase was observed. The root-mean-square amplitudes of the atomic motions in the bulk as well as in confinement are found
to be essentially different in a basal plane and in the perpendicular direction along the hexagonal axis. The atomic
motions in the confined Se differ from the atomic motions in the bulk at low temperatures. The results shows an unusual
“freezing" of the atomic motion along the chains, while the atomic motions in the perpendicular plane still keep. This
“freezing" is accompanied by the deformation of nanoparticles and the appearance of inner stresses. This effect is
attributed to the interaction of confined nanoparticle with the cavity walls. 相似文献
289.
Seok Il Yun Lan Cao Tae-Beom Kang Mongyoung Huh Mario Gauthier 《Journal of Macromolecular Science: Physics》2013,52(12):2318-2333
Arborescent (dendrigraft) copolymers with a branched polystyrene (PS) core grafted at the chain termini with deuterated poly(ethylene oxide) segments (PS-dPEO) were characterized in benzene and acetone by small-angle neutron scattering measurements using the contrast matching technique. While copolymers incorporating a G1 (twice-grafted) PS core aggregated to some extent, the portion of the scattering curve corresponding to non-aggregated copolymer molecules could still be analyzed to determine the shape and segment radial density profile for core and shell. These were derived from the pair distance distribution function P(r) and the scattering length density contrast profile Δρ(r) = ρ(r) ? ρ(solvent), obtained by the indirect Fourier transformation and deconvolution methods. The profiles obtained for the G1 copolymer are consistent with a well-defined PS core–dPEO shell morphology, only observed previously for upper generation (G4) polymers with deuterated PS (dPS) chains grafted randomly on arborescent PS substrates. Detailed morphological analysis could not be carried out for an analogous G3 arborescent PS copolymer terminally grafted with dPEO segments due to extensive aggregation in both solvents. 相似文献
290.
A. Cunsolo 《Molecular physics》2013,111(3):455-463
This paper reports on a high resolution/high contrast measurement of the spectrum of heavy water achieved by two complementary techniques, Inelastic Neutron and X-Ray Scattering. The mutual consistency between the spectral shapes measured by the two methods is subjected to thorough scrutiny and the results of their combined best fit are discussed. In particular, the presence of a low frequency mode related to shear propagation is studied in connection with the structural relaxation active in water at lower frequencies. The best fit analysis leads to the conclusion that the onset of a shear mode can only be observed at timescales approaching the solid-like regime, i.e. before internal rearrangements of the structure are fully accomplished. Finally, it is shown that the lifetime of the low frequency mode is fully consistent with the one predicted for a shear wave approaching the macroscopic limit. 相似文献