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61.
C. Jun L. Lin T. Lu L. Yong 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,9(4):593-598
The embedded-cluster numerical variational method has been developed to calculate the electronic structure of perfect MgO,
F and F+-centers in MgO. The energy band, bulk density of states has been calculated by cluster Mg14O13, Mg14O12F+ and Mg14O12F. The calculated absorption energy for F+ and F centers is in good agreement with experimental data. In our calculated defect energy levels, that the first excited
state of F+-center is at CB-3.46 eV, indicates the necessity of a large photoelectron yielding energy. We also calculate the radius of
color center electron, and plot the map of charge-density distribution of valence electrons in which the structure of the
color center is shown directly.
Received 22 May 1998 相似文献
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Superconducting wire-networks are paradigms to study Cooper pairing issues, vortex dynamics and arrangements. Recently, emergent low-dimensional crystalline superconductors were reported in the minimal-disorder limit, providing novel platforms to reveal vortices-related physics. Study on superconducting loops with high-crystallinity is thus currently demanded. Here, we report fabrication and transport measurement of finite square-network based on two-dimensional crystalline superconductor Mo2C. We observe oscillations in the resistance as a function of the magnetic flux through the loops. Resistance dips at both matching field and fractional fillings are revealed. Temperature and current evolutions are carried out in magnetoresistance to study vortex dynamics. The amplitude of oscillation is enhanced due to the interaction between thermally activated vortices and the currents induced in the loops. The driving current reduces the effective activation energy for vortex, giving rise to stronger vortex interaction. Moreover, by the thermally activated vortex creep model, we derive the effective potential barrier for vortex dissipation, which shows well-defined correspondence with structures in magnetoresistance. Our work shows that low-dimensional crystalline superconducting network based on Mo2C possesses pronounced potential in studying the modulation of vortex arrangements and dynamics, paving the way for further investigations on crystalline superconducting network with various configurations. 相似文献
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The principal purpose of Ad-Hoc wireless networks is to increase service efficiency in terms of transmission scheduling and packet transfer rate. The approaches that assume frame unicity to satisfy a given set of packets minimize the end-to-end delay. However, they do not guarantee a maximum packet delivery rate due to the difficulty of establishing robust paths for packet transfer across nodes deployed in the network, especially in a three-dimensional (3D) environment. The objective is to minimize the end-to-end delay by ensuring the maximum delivery of packets to their destinations. Furthermore, the signal-to-interference-and-noise-ratio (SINR) model is considered to optimize transmission scheduling. In this paper, an optimal node coordinates optimization approach is proposed to extend two recently investigated schemes in the literature (S-RDSP and I-RDSP). The developed algorithms, named S-MPDR and I-MPDR, seek to reduce the end-to-end delay by delivering a collection of inserted packets over a 3D environment while also maximizing the delivery rate of these packets. Desirability functions are used to evaluate the network’s performance in various scenarios involving two different environments, Level 0 and Level 1. Numerical results demonstrate that the developed algorithms outperform both schemes in terms of end-to-end delay and packet delivery rate. In the Level 0 environment, the overall minimum delay and packet delivery rate scores provided by S-MPDR are increased by 28% and 88% compared to S-RDSP, respectively. In comparison, those provided by I-MPDR are increased by 24% and 16% compared to I-RDSP. Similarly, in the Level 1 environment, the scores provided by S-MPDR are increased by 25% and 100% compared to S-RDSP, respectively, while those provided by I-MPDR are increased by 23% and 25% compared to I-RDSP. 相似文献
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Investigation of fill factor losses on 20.2% efficient n‐type mono‐like silicon solar cells with laser contact opening 下载免费PDF全文
Alexander Frey Josh Engelhardt Gabriel Micard Giso Hahn Barbara Terheiden 《固体物理学:研究快报》2016,10(2):143-147
Large area (243.36 cm2) back‐junction passivated emitter, rear totally diffused (PERT) solar cells with laser contact opening (LCO) on n‐type mono‐like crystalline Si with efficiencies of 20.2% are presented. Boron emitters with high electrical quality (implied open circuit voltage iVOC up to 700 mV) are formed during a co‐diffusion step using SiOx:B layers. Increasing the rear metal contact coverage, we observed a decrease in fill factor (FF) instead of the expected increase due to the decrease of the back side series resistance. We show that it can be attributed to recombination centers (RCs) in the space charge region underneath the contact spots inducing an increasing second diode contribution. The presented empirical model for the RCs implemented in Synopsys Sentaurus TCAD allows for a successful reproduction of the FF, pseudo FF and VOC behaviour with contact coverage. According to this model, the RCs induced by laser ablation and subsequently evaporation of Al have a shallow exponential distribution with a characteristic length of LT = 0.2 µm and an effective surface density of N *T0 = 25 cm–1. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
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