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981.
Strength and barrier properties of MFC films 总被引:1,自引:0,他引:1
The preparation of microfibrillar cellulose (MFC) films by filtration on a polyamide filter cloth, in a dynamic sheet former
and as a surface layer on base paper is described. Experimental evidence of the high tensile strength, density and elongation
of films formed by MFC is given. Typically, a MFC film with basis weight 35 g/m2 had tensile index 146 ± 18 Nm/g and elongation 8.6 ± 1.6%. The E modulus (17.5 ± 1.0 GPa) of a film composed of randomly oriented fibrils was comparable to values for cellulose fibres with
a fibril angle of 50°. The strength of the films formed in the dynamic sheet former was comparable to the strength of the
MFC films prepared by filtration. The use of MFC as surface layer (0–8% of total basis weight) on base paper increased the
strength of the paper sheets significantly and reduced their air permeability dramatically. FEG-SEM images indicated that
the MFC layer reduced sheet porosity, i.e. the dense structure formed by the fibrils resulted in superior barrier properties.
Oxygen transmission rates (OTR) as low as 17 ml m−2 day−1 were obtained for films prepared from pure MFC. This result fulfils the requirements for oxygen transmission rate in modified
atmosphere packaging. 相似文献
982.
AL Saari H Hyvönen M Lahtinen M Ylisirniö P Turhanen E Kolehmainen S Peräniemi J Vepsäläinen 《Molecules (Basel, Switzerland)》2012,17(9):10928-10945
Aminobisphosphonates, e.g., alendronate and neridronate, are a well known class of molecules used as drugs for various bone diseases. Although these molecules have been available for decades, a detailed understanding of their most important physicochemical properties under comparable conditions is lacking. In this study, ten aminobisphosphonates, H2N(CH2)nC(OH)[P(O)(OH)2]2, in which n = 2-5, 7-11 and 15 have been synthesized. Their aqueous solubility as a function of temperature and pH, pKa-values, thermal stability, IR absorptions, and NMR spectral data for bothliquid (1H, 13C, 31P-NMR) and solid state (13C, 15N and 31P-CPMAS NMR) were determined. 相似文献
983.
The electrical conductivity of Cr2O3 nominally doped with 2 mol% MgO has been studied by the four point a.c. technique as a function of the oxygen activity (O2 + Ar, CO + CO2 and H2 + H2O) in the temperature range 400–1200 °C. It is concluded that Cr2O3 doped with MgO is an extrinsic conductor and that the dissolved Mg-dopant is compensated by the formation of electron holes at near atmospheric oxygen pressures and by oxygen vacancies (or possibly interstitial chromium ions) at highly reduced oxygen activities (in CO + CO2 and H2 + H2O gas mixtures). In H2 + H2O mixtures Mg-doped chromia also dissolves hydrogen as protons and significantly affects the defect structure and electrical conductivity. The defect structure of the oxide under various conditions is discussed. 相似文献
984.
Pulsed digital holographic interferometry has been used to investigate the plume and the shock wave generated in the ablation process of a Q-switched Nd-YAG (λ=1064 nm and pulse duration=12 ns) laser pulse on a polycrystalline boron nitride (PCBN) target under atmospheric air pressure. A special setup based on two synchronised wavelengths from the same laser for simultaneous processing and measurement has been used. Digital holograms were recorded for different time delays using collimated laser light (λ=532 nm) passed through the volume along the target. Numerical data of the integrated refractive index field were calculated and presented as phase maps showing the propagation of the shock wave and the plume generated by the process. Radon inversion has been used to estimate the 3D refractive index fields measured from the projections assuming rotational symmetry. The shock wave density has been calculated using the point explosion model and the shock wave condition equation and its behaviour with time at different power densities ranging from 1.4 to 9.1 GW/cm2 is presented. Shock front densities have been calculated from the reconstructed refractive index fields using the Gladstone–Dale equation. A comparison of the shock front density calculated from the reconstructed data and that calculated using the point explosion model at different time delays has been done. The comparison shows quite good agreement between the model and the experimental data. Finally the reconstructed refractive index field has been used to estimate the electron number density distribution within the laser-induced plasma. The electron number density behaviour with distance from the target at different power densities and its behaviour with time are shown. The electron number densities are found to be in the order of 1018 cm?3 and decay at a rate of 3×1015 electrons/cm3 ns. 相似文献
985.
Per Christian Hansen James G. Nagy Konstantinos Tigkos 《BIT Numerical Mathematics》2014,54(3):649-671
We describe iterative deblurring algorithms that can handle blur caused by a rotation along an arbitrary axis (including the common case of pure rotation). Our algorithms use a sparse-matrix representation of the blurring operation, which allows us to easily handle several different boundary conditions. We also include robust stopping rules for the iterations. The performance of our algorithms is illustrated with examples. 相似文献
986.
Regularization Tools version 4.0 for Matlab 7.3 总被引:2,自引:0,他引:2
Per Christian Hansen 《Numerical Algorithms》2007,46(2):189-194
This communication describes version 4.0 of Regularization Tools, a Matlab package for analysis and solution of discrete ill-posed
problems. The new version allows for under-determined problems, and it is expanded with several new iterative methods, as
well as new test problems and new parameter-choice methods.
相似文献
987.
Keld Alstrup Jensen Ismo Kalevi Koponen Per Axel Clausen Thomas Schneider 《Journal of nanoparticle research》2009,11(1):133-146
Single-drop and rotating drum dustiness testing was used to investigate the dustiness of loose and compacted montmorillonite (Bentonite) and an organoclay (Nanofil®5), which had been modified from montmorillonite-rich Bentonite. The dustiness was analysed based on filter measurements as well as particle size distributions, the particle generation rate, and the total number of generated particles. Particle monitoring was completed using a TSI Fast Mobility Particle Sizer (FMPS) and a TSI Aerosol Particle Sizer (APS) at 1 s resolution. Low-pressure uniaxial powder compaction of the starting materials showed a logarithmic compaction curve and samples subjected to 3.5 kg/cm2 were used for dustiness testing to evaluate the role of powder compaction, which could occur in powders from large shipments or high-volume storage facilities. The dustiness tests showed intermediate dustiness indices (1,077–2,077 mg/kg powder) in tests of Nanofil®5, Bentonite, and compacted Bentonite, while a high-level dustiness index was found for compacted Nanofil®5 (3,487 mg/kg powder). All powders produced multimodal particle size-distributions in the dust cloud with one mode around 300 nm (Bentonite) or 400 nm (Nanofil®5) as well as one (Nanofil®5) or two modes (Bentonite) with peaks between 1 and 2.5 μm. The dust release was found to occur either as a burst (loose Bentonite and Nanofil®5), constant rate (compacted Nanofil®5), or slowly increasing rate (compacted Bentonite). In rotating drum experiments, the number of particles generated in the FMPS and APS size-ranges were in general agreement with the mass-based dustiness index, but the same order was not observed in the single-drop tests. Compaction of Bentonite reduced the number of generated particles with app. 70 and 40% during single-drop and rotating drum dustiness tests, respectively. Compaction of Nanofil®5 reduced the dustiness in the single-drop test, but it was more than doubled in the rotating drum test. Physically relevant low-pressure compaction may reduce the risk of particle exposure if powders are handled in operations with few agitations such as pouring or tapping. Repeated agitation, e.g., mixing, of these compacted powders, would result in reduced (app. 20% for Bentonite) or highly increased (app. 225% for Nanofil®5) dustiness and thereby alter the exposure risk significantly. 相似文献
988.
Tsuneo Hirano Rei Okuda Yoshihiro Nakashima Per Jensen 《Journal of Molecular Spectroscopy》2007,243(2):202-218
We have calculated the three-dimensional potential energy surfaces for the 1 2A′ and 1 2A″ states of BrCN+ at the MR-SDCI_DK+Q/[QZP-ANO-RCC (Br, C, N)] level of theory, where MR-SDCI_DK means ‘multi-reference single and double excitation configuration interaction calculation with Douglas-Kroll Hamiltonian.’ These ab initio potential energy surfaces have a common minimum (corresponding to the state) at a linear equilibrium structure with re(Br-C) = 1.735 Å and re(C-N) = 1.199 Å. Variational RENNER calculations yield a zero-point averaged structure (with the structural parameters calculated as expectation values over rovibrational wavefunctions) with 〈r(Br-C)〉0 = 1.739 Å, 〈r(C-N)〉0 = 1.204 Å, and 〈∠(Br-C-N)〉0 = 172(4)°. A severe Fermi resonance between 2ν2 and ν3 has been found theoretically for the 2A″ potential energy surface. Comparing the ab initio zero-point averaged structure with a recent, experimentally derived r0 structure, it is concluded that the effects of large-amplitude bending motion should be taken into account explicitly in the process of deriving the r0 structure from the experimental values of the rotational constants. The electronic structure of BrCN+ has also been discussed. 相似文献
989.
MC SCF and contracted CI calculations have been performed for the three ligand-field states of CuF2 and also for two charge-transfer states. With the most extensive basis set the calculated d-d transition energies, including a Davidson correctior for cluster effects, are 4150 cm?1 (211g) and 10560 cm?1 (2Δg). These calculations were made with 98 basis functions, including of orbitals on Cu and d orbitals on F. To check the charge distribution in the molecule, calculations of the ESR g factors were also made at the SCF and CI levels of approximation. Resulting CI values are g| = 1.93 (1.91) and g1 = 2.76 (2.60). with corresponding experimental numbers in parentheses. 相似文献
990.
The structure of engleromycin isolated from Hennings has been established as by spectral techniques. 相似文献