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951.
    
Silicene, a new 2D material has attracted intense research because of the ubiquitous use of silicon in modern technology. However, producing free-standing silicene has proved to be a huge challenge. Until now, silicene could be synthesized only on metal surfaces where it naturally forms strong interactions with the metal substrate that modify its electronic properties. Here, the authors report the first experimental evidence of silicene nanoribbons on an insulating NaCl thin film. This work represents a major breakthrough, for the study of the intrinsic properties of silicene, and by extension to other 2D materials that have so far only been grown on metal surfaces.  相似文献   
952.
    
Fullerenes are candidates for theranostic applications because of their high photodynamic activity and intrinsic multimodal imaging contrast. However, fullerenes suffer from low solubility in aqueous media, poor biocompatibility, cell toxicity, and a tendency to aggregate. C70@lysozyme is introduced herein as a novel bioconjugate that is harmless to a cellular environment, yet is also photoactive and has excellent optical and optoacoustic contrast for tracking cellular uptake and intracellular localization. The formation, water-solubility, photoactivity, and unperturbed structure of C70@lysozyme are confirmed using UV-visible and 2D 1H, 15N NMR spectroscopy. The excellent imaging contrast of C70@lysozyme in optoacoustic and third harmonic generation microscopy is exploited to monitor its uptake in HeLa cells and lysosomal trafficking. Last, the photoactivity of C70@lysozyme and its ability to initiate cell death by means of singlet oxygen (1O2) production upon exposure to low levels of white light irradiation is demonstrated. This study introduces C70@lysozyme and other fullerene-protein conjugates as potential candidates for theranostic applications.  相似文献   
953.
    
Here, a fluoride-assisted route for the controlled in-situ synthesis of metal nanoparticles (NPs) (i.e., AgNPs, AuNPs) on polydimethylsiloxane (PDMS) is reported. The size and coverage of the NPs on the PDMS surface are modulated with time and over space during the synthetic process, leveraging the improved yield (10×) and faster kinetics (100×) of NP formation in the presence of F ions, compared to fluoride-free approaches. This enables the maskless preparation of both linear and step gradients and patterns of NPs in 1D and 2D on the PDMS surface. As an application in flexible plasmonics/photonics, continuous and step-wise spatial modulations of the plasmonic features of PDMS slabs with 1D and 2D AgNP gradients on the surface are demonstrated. An excellent spatially resolved tuning of key optical parameters, namely, optical density from zero to 5 and extinction ratio up to 100 dB, is achieved with AgNP gradients prepared in AgF solution for 12 minutes; the performance are comparable to those of commercial dielectric/interference filters. When used as a rejection filter in optical fluorescence microscopy, the AgNP-PDMS slabs are able to reject the excitation laser at 405 nm and retain the green fluorescence of microbeads (100 µm) used as test cases.  相似文献   
954.
    
Controlling the electromechanical response of piezoelectric biological structures including tissues, peptides, and amino acids provides new applications for biocompatible, sustainable materials in electronics and medicine. Here, the piezoelectric effect is revealed in another class of biological materials, with robust longitudinal and shear piezoelectricity measured in single crystals of the transmembrane protein ba3 cytochrome c oxidase from Thermus thermophilus. The experimental findings from piezoresponse force microscopy are substantiated using a range of control measurements and molecular models. The observed longitudinal and shear piezoelectric responses of ≈ 2 and 8 pm V−1, respectively, are comparable to or exceed the performance of commonly used inorganic piezoelectric materials including quartz, aluminum nitride, and zinc oxide. This suggests that transmembrane proteins may provide, in addition to physiological energy transduction, technologically useful piezoelectric material derived entirely from nature. Membrane proteins could extend the range of rationally designed biopiezoelectric materials far beyond the minimalistic peptide motifs currently used in miniaturized energy harvesters, and the finding of robust piezoelectric response in a transmembrane protein also raises fundamental questions regarding the molecular evolution, activation, and role of regulatory proteins in the cellular nanomachinery, indicating that piezoelectricity might be important for fundamental physiological processes.  相似文献   
955.
Cu(In,Ga)Se2 thin-film solar cells have attracted significant research interest in recent decades due to their high efficiency in converting solar energy into electricity for enabling a sustainable future. Although the Cu(In,Ga)Se2 absorber can be grown as a single crystal, its polycrystalline form is dominating the market not only due to its lower costs, but also due to its unexpectedly higher cell efficiency. However, this absorber contains a high fraction of grain boundaries. These are structural defects where deep-trap states can be localized leading to an increase in recombination activity. This controversy is mirrored in the existing literature studies where two main contradictory believes exist: 1) to be crucial grain boundaries in Cu(In,Ga)Se2 absorber are anomalous, being benign in terms of cell performance, and 2) grain boundaries are regions characterized by an increased recombination activity leading to deteriorated cell performance. Therefore, the present review tackles this issue from a novel perspective unraveling correlations between chemical composition of grain boundaries and their corresponding electronic properties. It is shown that features such as Cu depletion/In enrichment, segregation of 1-2at.% of alkali dopants, and passivation by a wide-bandgap or type inversion at grain boundaries are crucial ingredients for low open-circuit voltage loss and, hence, for superior cell performance.  相似文献   
956.
    
Alloy anodes composed of microsized particles receive increasing attention recently, which outperform the nanostructured counterparts in both the manufacturing cost and volumetric energy density. However, the pulverization of particles and fracture of solid electrolyte interphase (SEI) during cycling brings about fast capacity degradation. Herein, it is shown how normally considered fragile SEI can become highly elastic through electrolyte chemistry regulation. Compared to the SEI constructed in classic carbonate electrolyte, the atomic force microscopy tests reveal that the one built in ether-based electrolyte doubles the maximum elastic strain to accommodate the repeated swelling-contracting. Such an SEI effectively encapsulates the microsized Sb anodes to prevent the capacity loss from particle isolation. Coupled with an intercalation-assisted alloying reaction mechanism, a sustained capacity of ≈573 mAh g−1 after 180 cycles at 0.1 A g−1 with outstanding initial Coulombic efficiency is obtained, which is among the highest values achieved in K-ion batteries. This study emphasizes the significance of building robust SEI, which offers the opportunity to enable stable microsized alloy anodes.  相似文献   
957.
    
Ionically mediated phenomena underpin the functioning of various devices, including batteries, solid oxide fuel cells, memristors, and neuromorphic devices. The ionic behavior corresponding to ionically mediated phenomena causes not only variations in the electrical properties but also mechanical deformation, which is crucial for device reliability. However, the interrelation between ionically mediated electrical properties and mechanical deformation has not been elucidated yet. This study investigates ionically mediated mechanical deformation accompanied by memristive switching in a TiO2 single crystal through simultaneous conductive atomic force microscopy and electrochemical strain microscopy. A comprehensive analysis indicates the existence of a relationship between mechanical deformation and memristive switching based on the ionic behavior. Furthermore, an ionic state variable is used to simplify the interrelation between the electrochemical strain hysteresis and memristive switching associated with applied voltage. This study provides insights on the ionic behavior and can be extended to other systems for the general analysis of the relationship between mechanical deformation and electrical properties.  相似文献   
958.
    
The practical applications of high-energy-density lithium (Li) metal batteries (LMB) have been hindered by the formation and growth of Li dendrites. Homogenizing the Li-ion flux to suppress Li dendrites by regulating the solid electrolyte interphase (SEI) originating from electrolyte degradation is necessary but still challenging. Herein, ion-affiliative cellulose acetate (CA) with functional Li salts is prepared to generate the SEI with fast Li+ diffusion kinetics. First, the correlations between the functional ester group and LiN(CF3SO2)2 (LiTFSI) are theoretically and experimentally identified, where CO strongly adsorbed N(CF3SO2)2 through electrostatic interaction to enhance the charge-transfer-promoted decomposition of LiTFSI. Furthermore, the CA with ex situ doped LiTFSI amplifies this fluorinated degradation effect, and the LiF-enriched SEI nanostructure is consequently established in situ, as confirmed by cryogenic transmission electron microscopy. As a result, the dendritic Li growth during cycling is efficiently suppressed, and the lifespan is prolonged by more than six times at a high current density of 3 mA cm−2. This study provides insights into the interphase design for realizing ultrastable LMB.  相似文献   
959.
    
In this study, in situ transmission electron microscopy is performed to study the interaction between single (monomer) and paired (dimer) Sn atoms at graphene edges. The results reveal that a single Sn atom can catalyze both the growth and etching of graphene by the addition and removal of C atoms respectively. Additionally, the frequencies of the energetically favorable configurations of an Sn atom at a graphene edge, calculated using density functional theory calculations, are compared with experimental observations and are found to be in good agreement. The remarkable dynamic processes of binary atoms (dimers) are also investigated and is the first such study to the best of the knowledge. Dimer diffusion along the graphene edges depends on the graphene edge termination. Atom pairs (dimers) involving an armchair configuration tend to diffuse with a synchronized shuffling (step-wise shift) action, while dimer diffusion at zigzag edge terminations show a strong propensity to collapse the dimer with each atom diffusing in opposite directions (monomer formation). Moreover, the data reveals the role of C feedstock availability on the choice a single Sn atom makes in terms of graphene growth or etching. This study advances the understanding single atom catalytic activity at graphene edges.  相似文献   
960.
    
Amorphous solids are potential candidates for room temperature applications, such as structural materials, due to their outstanding mechanical properties. For the first time, the local atomic dynamics of amorphous metallic nanorods are spatially resolved at room temperature using electron microscopy. Methodologically, quasi-equilibrium conditions are verified by two-time correlation functions. FeNiP is chosen as a suitable model system since a bamboo structure forms upon electrodeposition into nanotubular confinement, consisting of thin Fe-rich and Ni-rich amorphous layers. Therefore, the present nano-glassy structure allows studying the glass dynamics of two glassy phases at once, at the same time avoiding any preparation-related structural artifacts of the intrinsically electron-transparent samples. By comparing the local atomic mobility with the local composition and the local structural information of the glassy phases, correlations between medium-range order and time scales of heterogeneous glassy dynamics are consistently obtained.  相似文献   
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