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871.
Rahmani Parisa Haj Seyyed Javadi Hamid Bakhshi Hamidreza Hosseinzadeh Mehdi 《Wireless Personal Communications》2018,103(3):2285-2316
Wireless Personal Communications - Spectrum allocation is a major challenge in wireless ad hoc networks due to restrictions on the number of available communication channels and also passive... 相似文献
872.
Zoltan Szabo Rainer M. Vallant Anikó Takátsy Rania Bakry Muhammad Najam‐ul‐Haq Matthias Rainer Christian W. Huck Günther K. Bonn 《Journal of mass spectrometry : JMS》2010,45(5):545-552
In spite of the growing acceptance of matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry for the analysis of a wide variety of compounds, including polymers and proteins, its use in analyzing low‐molecular‐weight molecules (<1000m/z) is still limited. This is mainly due to the interference of matrix molecules in the low‐mass range. Here the derivatized fullerenes covalently bound to silica particles with different pore sizes are applied as thin layer for laser desorption/ionization (LDI) mass spectrometric analysis. Thus, an interference of intrinsic matrix ions can be eliminated or minimized in comparison with the state‐of‐the‐art weak organic acid matrices. The desorption/ionization ability of the developed fullerene–silica materials depends on the applied laser power, sample preparation and pore size of the silica particles. Thus, fullerene–silica serves as an LDI support for mass spectrometric analysis of molecules (<1500 Da). The performance of the fullerene–silica is demonstrated by the mass analysis of variety of small molecules such as carbohydrates, amino acids, peptides, phospholipids and drugs. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
873.
Collins Appaw Richard D. Gilbert Saad A. Khan John F. Kadla 《Cellulose (London, England)》2010,17(3):533-538
The addition of cellulose acetate (CA) to a mixed solvent of N,N dimethylacetamide (DMA) and water is examined at different CA concentrations and water contents. Unlike the addition of water
to a CA/DMA solution, the addition of CA to a DMA/water solution leads to a transition from a homogeneous solution at low
water content to a two-phase system at higher water contents. The two-phase system has an upper liquid layer with an almost
clear “solution-like” appearance and a lower gel-like layer. Treating the two-phase system at 100 °C for 30 min results in
the formation of a uniform gel structure, similar to that produced by directly adding water to a CA/DMA solution. Although
the phase behavior of these systems is similar, their viscoelastic properties are not. The moduli of the heat treated gels
do not significantly vary from that of the bottom gel-like portion of the original two-phase samples. This may indicate that
thermal treatment at 100 °C is not able to disrupt the pre-established CA intra- and intermolecular interactions and form
the stronger CA-DMA interactions. 相似文献
874.
Sung In Jeong Melissa D. Krebs Christopher A. Bonino Saad A. Khan Eben Alsberg 《Macromolecular bioscience》2010,10(8):934-943
Alginate, a natural polysaccharide that has shown great potential as a cell scaffold for the regeneration of many tissues, has only been nominally explored as an electrospun biomaterial due to cytotoxic chemicals that have typically been used during nanofiber formation and crosslinking. Alginate cannot be electrospun by itself and is often co‐spun with poly(ethylene oxide) (PEO). In this work, a cell adhesive peptide (GRGDSP) modified alginate (RA) and unmodified alginate (UA) were blended with PEO at different concentrations and blending ratios, and then electrospun to prepare uniform nanofibers. The ability of electrospun RA scaffolds to support human dermal fibroblast cell attachment, spreading, and subsequent proliferation was greatly enhanced on the adhesion ligand‐modified nanofibers, demonstrating the promise of this electrospun polysaccharide material with defined nanoscale architecture and cell adhesive properties for tissue regeneration applications.
875.
The microwave-assisted synthesis, characterization and photophysical properties of hexadeca-substituted phthalocyanine (Pc) complexes with bulky phenoxy substituents are reported. NMR and UV-Vis analyses confirm the ability of bulky groups to induce steric isolation of Pc cores even in the solid state. The Z-scan measurement indicates that the Zn-containing derivative has promising nonlinear optical properties (NLOs). 相似文献
876.
The existence of group divisible designs with two associate classes has been studied for over 50 years. Probably the most
difficult cases to solve are those in which the number of groups is less than the size of the blocks. Recently, such an existence
problem was solved in the case where the groups have the same size and the blocks have size 3. In this paper, we continue
to focus on blocks of size 3, solving the existence problem when the required designs are gregarious (each block intersects
each group). These designs are tight to construct in the sense that they satisfy equality in one of the bounds required for
GDDs to exist. 相似文献
877.
878.
<正>In this paper we study the computational performance of variants of an algebraic additive Schwarz preconditioner for the Schur complement for the solution of large sparse linear systems.In earlier works,the local Schur complements were computed exactly using a sparse direct solver.The robustness of the preconditioner comes at the price of this memory and time intensive computation that is the main bottleneck of the approach for tackling huge problems.In this work we investigate the use of sparse approximation of the dense local Schur complements.These approximations are computed using a partial incomplete LU factorization.Such a numerical calculation is the core of the multi-level incomplete factorization such as the one implemented in pARMS. The numerical and computing performance of the new numerical scheme is illustrated on a set of large 3D convection-diffusion problems;preliminary experiments on linear systems arising from structural mechanics are also reported. 相似文献
879.
880.