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941.
The electron work function, contact potential difference, and surface stress of the elastically deformed faces of the metal covered by a dielectric are calculated by using the Kohn–Sham method and stabilized jellium model. Our calculations demonstrate the opposite deformation dependencies of the work function and contact potential difference. Dielectric coating leads to a negative change in the work function and a positive change in the contact potential difference. It is shown that the measurements of the contact potential difference of a deformed face by the Kelvin method give only the change in the value of the one-electron effective potential in the plane of a virtual image behind the surface, rather than the value of the electron work function. The obtained values of the electron work function and surface stress for Al, Au, Cu, and Zn are in agreement with the results of experiments for polycrystals. 相似文献
942.
By chemically modifying the FeO(1 1 1) thin film on Pt(1 1 1), we show that it is possible to unambiguously correlate its STM morphology with its underlying structure without recourse to STM simulations. Partial reduction of the oxide surface leads to the formation of triangularly-shaped oxygen vacancy dislocation loops at specific sites in the moiré structure of the film. Their presence allows unambiguous identification of the high-symmetry domains of the moiré structure, whose differing chemical properties govern the templating effect on adsorbed metal atoms, clusters and molecules. 相似文献
943.
We have measured W 4f7/2 core-level photoemission spectra from W(1 1 0) in the presence of Pd overlayers for coverages up to ∼1 pseudomorphic monolayer (ML). At coverages close to 0.05 ML a striking change in the W core-level spectrum is observed, which we interpret as indicating a long-range lateral effect of 2D Pd islands upon the W electronic structure in both the first and second W layers. As the coverage increases the long-range effect weakens and finally vanishes near 0.85 ML. Above this coverage the W spectra are typical for a W-based bimetallic interface, with the first-layer W atoms exhibiting a small interfacial core-level shift (−95 ± 5 meV) compared to the bulk atoms. 相似文献
944.
Photon stimulated ion desorption (PSID) studies have been performed in condensed formic acid using oxygen 1s-edge synchrotron radiation from the Brazilian synchrotron light source (LNLS), operating in a single-bunch mode. Ion formation was discussed in terms of the Auger stimulated ion desorption (ASID) and X-ray induced electron stimulated desorption (XESD) mechanisms. It is found that O 1s(C-OH) → π*(CO) and O 1s(CO) → 3s/σ*(HCO) transitions favored the production of C+, CH+, O+, O− and H− ions. The hydroxyl anion has not been observed while the hydroxyl cation showed low intensity or was absent. Some anion formation routes from dissociative reactions are suggested taking into account the positive ion yields. 相似文献
945.
We have measured W and Pt 4f7/2 core-level photoemission spectra from interfaces formed by ultrathin Pt layers on W(1 1 0), completing our core-level measurements of W(1 1 0)-based bimetallic interfaces involving the group-10 metals Ni, Pd, and Pt. With increasing Pt coverage the sequence of W spectra can be described using three interfacial core-level peaks with binding-energy (BE) shifts (compared to the bulk) of −0.220 ± 0.015, −0.060 ± 0.015, and +0.110 ± 0.010 eV. We assign these features to 1D, 2D pseudomorphic (ps), and 2D closed-packed (cp) Pt phases, respectively. For ∼1 ps ML the Pt 4f7/2 BE is 71.40 ± 0.02 eV, a shift of +0.46 ± 0.09 eV with respect to the BE of bulk Pt metal. The W 4f7/2 core-level shifts induced by all three adsorbates are semiquantitatively described by the Born-Haber-cycle based partial-shift model of Nilsson et al. [39]. As with Ni/W(1 1 0), the difference in W 4f7/2 binding energies between ps and cp Pt phases has a large structural contribution. The Pt 4f lineshape is consistent with a small density of states at the Fermi level, reflective of the Pt monolayer having noble-metal-like electronic structure. 相似文献
946.
提出了一种结构模型来分析由工艺引起的波导侧壁起伏对于聚合物波导光学梳状滤波器的滤波特性的影响。含氟聚酰亚胺高分子聚合物制备多级马赫一曾德尔串联型光学梳状滤波器件的工作参量为中心波长1550nm,波长间隔为0.8nm,40通道的波长交错分离。模拟计算:表明,对由高分子聚合物材料制备的多级马赫-曾德尔串联型光学梳状滤波器件,其主要影响是增大了信道之间的串扰,中心波长1550nm处的信道串扰由理想情况下的-40dB降为-12dB,极大地影响了器件的性能。在此基础上,提出一种改善光学梳状滤波器串扰性能的新结构,该结构由多级马赫-曾德尔耦合器和微环共振滤波器串接构成,40个通道的串扰改善为-0dB以下。 相似文献
947.
948.
针对测频器件的缺陷,提出了利用声光器件对电磁波进行实时测频的设计方案。根据现代光学理论设计了声光频谱分析系统,研制出软硬件设备。通过试验和仿真,达到了对电磁频谱进行实时检测分析的目的。与其他测频器件相比,所设计的系统体积小、耗能少、稳定性好,传递速度快,且易于计算机控制。采用声光器件制成的Bragg声光接收机能够在复杂的电磁环境中同时快速检测出多束射频电磁波,在电子战中有很高的应用价值。 相似文献
949.
串扰对密集波分复用网络扩展性的影响 总被引:1,自引:0,他引:1
串扰是限制密集波分复用网络扩展的一个重要因素。理论分析了三种典型光交叉连接中的串扰。结果表明基于扩展贝奈斯光交换结构的光交叉连接可以完全消除低于二阶的各类串扰,同时,若将可调谐的窄带滤波器引入到结构2中可以消除低于三阶的各类串扰。用数值模拟的方法分析了带内串扰对强度调制直接检测网络扩展性的影响。结果表明,基于扩展贝奈斯光交换结构的光交叉连接对器件串扰系数的要求得到了很大的放宽,用它来组建的密集波分复用网络具有很好的扩展性。串扰多是由构成光交换节点中各种器件的非理想性造成的,通过分析得出器件中产生的串扰可以从系统中得到很好的解决。 相似文献
950.
用电子分析天平测量静电力及真空介电常量 总被引:2,自引:1,他引:1
介绍了用电子分析天平测量平行板电容器两极板间的静电力和真空介电常量的原理和方法. 相似文献