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92.
93.
In the geometric optics approximation, we predict the effect of additional twisting of spinning particle trajectories in an absorbing medium. The effect is determined by the particle polarization (chirality) and the curvature of the particle trajectory. Using our results, we quantitatively estimate the deviation from the mirror reflection law for ultracold neutrons. 相似文献
94.
讨论了圆形面偶极层静电势问题的正确解法,阐明了对于延拓法的正确理解,给出了有限间距时圆形平行板(分别带有异性面电荷)的静电势问题。 相似文献
95.
Salt-mediated electrostatics interactions play an essential role in biomolecular structures and dynamics. Because macromolecular systems modeled at atomic resolution contain thousands of solute atoms, the electrostatic computations constitute an expensive part of the force and energy calculations. Implicit solvent models are one way to simplify the model and associated calculations, but they are generally used in combination with standard atomic models for the solute. To approximate electrostatics interactions in models on the polymer level (e.g., supercoiled DNA) that are simulated over long times (e.g., milliseconds) using Brownian dynamics, Beard and Schlick have developed the DiSCO (Discrete Surface Charge Optimization) algorithm. DiSCO represents a macromolecular complex by a few hundred discrete charges on a surface enclosing the system modeled by the Debye-Hückel (screened Coulombic) approximation to the Poisson-Boltzmann equation, and treats the salt solution as continuum solvation. DiSCO can represent the nucleosome core particle (>12,000 atoms), for example, by 353 discrete surface charges distributed on the surfaces of a large disk for the nucleosome core particle and a slender cylinder for the histone tail; the charges are optimized with respect to the Poisson-Boltzmann solution for the electric field, yielding a approximately 5.5% residual. Because regular surfaces enclosing macromolecules are not sufficiently general and may be suboptimal for certain systems, we develop a general method to construct irregular models tailored to the geometry of macromolecules. We also compare charge optimization based on both the electric field and electrostatic potential refinement. Results indicate that irregular surfaces can lead to a more accurate approximation (lower residuals), and the refinement in terms of the electric field is more robust. We also show that surface smoothing for irregular models is important, that the charge optimization (by the TNPACK minimizer) is efficient and does not depend on the initial assigned values, and that the residual is acceptable when the distance to the model surface is close to, or larger than, the Debye length. We illustrate applications of DiSCO's model-building procedure to chromatin folding and supercoiled DNA bound to Hin and Fis proteins. DiSCO is generally applicable to other interesting macromolecular systems for which mesoscale models are appropriate, to yield a resolution between the all-atom representative and the polymer level. 相似文献
96.
97.
Complex tree-like nanostructures with controlled morphology are becoming increasingly important for the development of nanoscale
devices. The position of branches on III–V semiconductor nanotrees is determined by the distribution of Au seed particles.
Here we report the dependence of the distribution of Au aerosol nanoparticles on nanowires on parameters including distance
between wires, particle size, wire length, wire diameter, III–V material and particle charge. It was observed that different
wire lengths and separation distances as well as different particle polarities have a significant effect on the resulting
particle distribution while different wire diameters, particle diameters, materials and deposition voltages do not. 相似文献
98.
提出了一种新型栅耦合型静电泄放(ESD)保护器件——压焊块电容栅耦合型保护管.该结构不仅解决了原有栅耦合型结构对特定ESD冲击不能及时响应的问题,而且节省了版图面积,提高了ESD失效电压.0.5 μm标准互补型金属氧化物半导体工艺流片测试结果表明,该结构人体模型ESD失效电压超过8 kV.给出了栅耦合型ESD保护结构中ESD检测结构的设计方法,能够精确计算检测结构中电容和电阻的取值.
关键词:
静电泄放
栅耦合
金属氧化物半导体场效应管
压焊块电容 相似文献
99.
Hsin‐Yi Liao 《International journal of quantum chemistry》2008,108(1):84-89
The Lewis acid‐base H3?nFnN–BFmH3?m (n = 0–3; m = 0–3) system was examined using the density functional theory calculations. The N? B bond strength can be adjusted stepwise by increasing the number of substituted fluorine atoms. The main finding of this work is the bond distances of the complexes do not correlate directly with the bond strengths. Some rationalization of this interesting observation was provided by the fluorine substitution effect on the HOMO‐LUMO gap, hybridization of bonding orbitals and electrostatic interaction. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 相似文献
100.
Boris V. Lvov 《Spectrochimica Acta Part B: Atomic Spectroscopy》1999,54(14):2063-2065
The significance of Walsh’s idea of the absolute method of analysis for the development of electrothermal atomic absorption spectrometry and, in particular, the absolute analysis project is discussed. 相似文献