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581.
582.
Muhammet U. Kahveci M. Atilla Tasdelen Yusuf Yagci 《Macromolecular rapid communications》2008,29(3):202-206
This study describes the use of diphenyliodonium salts with highly nucleophilic counter anions to photoinitiate the cationic cross‐linking of divinyl ethers. Both direct and indirect initiating modes are used. In the direct acting system, only a diphenyliodonium salt with a highly nucleophilic counter anion and a zinc halide are employed as initiator and activator, respectively. In the indirect systems, in addition to direct system components, photosensitive additives such as anthrecene, perylene, 2,2‐dimethoxy‐2‐phenyl acetophenone, benzophenone, and thioxanthone, which absorb the energy of the incident light and activate the iodonium salt, are used to initiate polymerization. All systems employed in this study initiated quite vigorous polymerizations.
583.
U?ur?Tamer Yusuf?Gündo?du ?smail?Hakk??Boyac? Kadir?Pekmez 《Journal of nanoparticle research》2010,12(4):1187-1196
The production of monodispersed magnetic nanoparticles with appropriate surface modification has attracted increasing attention
in biomedical applications including drug delivery, separation, and purification of biomolecules from the matrices. In the
present study, we report rapid and room temperature reaction synthesis of gold-coated iron nanoparticles in aqueous solution
using the borohydride reduction of HAuCl4 under sonication for the first time. The resulting nanoparticles were characterized with transmission electron microscopy
(TEM), electron spectroscopy for chemical analysis (ESCA), ultraviolet visible spectroscopy (UV–Vis), and X-ray diffraction
(XRD). Surface charges and magnetic properties of the nanoparticles were also examined. The pattern of Fe3O4 nanoparticles is face centered cubic with an average diameter of 9.5 nm and the initial reduction of gold on the surface
of Fe3O4 particles exhibits uniform Fe3O4–Au nanoparticles with an average diameter of 12.5 nm. The saturation magnetization values for the uncoated and gold-coated
Fe3O4 nanoparticles were found to be 30 and 4.5 emu/g, respectively, at 300 K. The progression of binding events between boronic
acid terminated ligand shell and fructose based on the covalent bonding interaction was measured by absorbance spectral changes.
Immunomagnetic separation was also performed at different E. coli concentration to evaluate capturing efficiency of resulting nanoparticles. Immunomagnetic separation percentages were varied
in a range of 52.1 and 21.9% depend on the initial bacteria counts. 相似文献
584.
A spin-1 transverse Ising model with longitudinal crystal field in a longitudinal magnetic field is examined by introducing an effective field approximation (IEFT) which includes the correlations between different spins that emerge when expanding the identities. The effects of the crystal field as well as the transverse and longitudinal magnetic fields on the thermal and magnetic properties of the spin system are discussed in detail. The order parameters, Helmholtz free energy, entropy and specific heat curves are calculated numerically as functions of the temperature and Hamiltonian parameters. A number of interesting phenomena such as reentrant phenomena originating from the temperature, crystal field, transverse and longitudinal magnetic fields have been found. 相似文献
585.
This paper addresses the ring-cavity fiber laser system. A class of gray and black soliton solutions of the model are reported by adopting an appropriate envelope ansatz. Further more, the modulation instability (MI) of the equation is studied using the linear-stability analysis (LSA) technique and the MI gain spectrum is derived. Some physical interpretations and analysis of the results obtained are also presented. 相似文献
586.
587.
The photoinitiated cationic polymerization of cyclohexene oxide with N‐phenacyl‐N,N‐dimethylanilinium hexafluoroantimonate (PDA+SbF6–) and a polynuclear aromatic compound, such as perylene, anthracene or phenothiazine, or an aromatic carbonyl compound, such as benzophenone or thioxanthone, was studied at λinc > 340 nm. All the aromatic sensitizers except benzophenone and thioxanthone are effective in initiating the polymerization at wavelengths where PDA+SbF6– is transparent. An initiation mechanism is proposed that involves electron transfer from the excited sensitizer to PDA+SbF6–. 相似文献
588.
Arca Anil Omer Faruk Sadak Bartu Karakurt Dr. Yusuf Kocak Dr. Igor Lyubinetsky Prof. Dr. Emrah Ozensoy 《Chemphyschem》2023,24(13):e202200787
Understanding the activation of CO2 on the surface of the heterogeneous catalysts comprised of metal/metal oxide interfaces is of critical importance since it is not only a prerequisite for converting CO2 to value-added chemicals but also often, a rate-limiting step. In this context, our current work focuses on the interaction of CO2 with heterogeneous bi-component model catalysts consisting of small MnOx clusters supported on the Pd(111) single crystal surface. These metal oxide-on-metal ‘reverse’ model catalyst architectures were investigated via temperature programmed desorption (TPD) and x-ray photoelectron spectroscopy (XPS) techniques under ultra-high vacuum (UHV) conditions. Enhancement of CO2 activation was observed upon decreasing the size of MnOx nanoclusters by lowering the preparation temperature of the catalyst down to 85 K. Neither pristine Pd(111) single crystal surface nor thick (multilayer) MnOx overlayers on Pd(111) were not capable of activating CO2, while CO2 activation was detected at sub-monolayer (∼0.7 ML) MnOx coverages on Pd(111), in correlation with the interfacial character of the active sites, involving both MnOx and adjacent Pd atoms. 相似文献
589.
Yusuf Yagci 《Macromolecular Symposia》2000,161(1):19-36
This paper on recent developments in the use of photoinitiating systems in polymer synthesis concentrates on: (i) the possiblity of controlled//living polymerization by photopolymerization, (ii) major photoinitiating systems for both cationic and radical polymerization and (iii) preparation of block copolymers and functional polymers by photoinduced processes. Much progress has been made in the past ten years in preparation of block copolymers by photoinduced reactions of either chromophoric groups incorporated into polymers or low‐molecular‐weight compounds with suitable functional groups present in polymer chains. 相似文献
590.
The compounds 2‐thioxanthone‐thioacetic acid and 2‐(carboxymethoxy)thioxanthone, bimolecular photoinitiators for free radical polymerization, are synthesized and characterized. Their capability to act as initiators for the polymerization of methyl methacrylate was examined. The postulated mechanism is based on the intermolecular electron‐transfer reaction of the excited photoinitiator with the sulfur or oxygen atom of the ground state of the respective photoinitiator followed by decarboxylation. The resulting alkyl radicals initiate the polymerization.