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53.
《Physics letters. A》2020,384(31):126794
An analytical approach for the electronic stopping force for non-relativistic energies that has no adjustable parameters has been developed. The approach combines the Bohr model for the close collisions and the Firsov model for the distant collisions. In order to combine the two models, a probabilistic model was introduced. We have applied our model to 16O in 12C, 16O in 27Al, 84 Kr in 27Al, 5Li in 12C, 12C in 12C, and 132Xe in 12C systems and compared with SRIM/MSTAR software, the original Bohr model, the Firsov model and available experimental data. We have found that the calculated electronic stopping force values are in agreement with the general qualitative behaviour of the electronic stopping force as a function of particle velocity reported in the literature. The proposed analytical formula is expected to be valid for other projectile-target combinations but more experimental data are needed to verify this assumption. 相似文献
54.
光子晶体光纤非线性系数与其结构参量及光波长的关系 总被引:24,自引:18,他引:6
推导计算了全内反射型光子晶体光纤的非线性系数与其两个几何结构参量:包层空气孔半径和空气孔间距之间的关系,给出了输入光波长为1550 nm处,非线性系数与这两个结构参量之间的关系曲线并对其进行了分析.给出了全内反射型光子晶体光纤的非线性系数随输入光波长变化的曲线,分析了短波处高非线性系数产生的原因并指出这一特性的应用潜力. 相似文献
55.
连续级联喇曼光纤激光器耦合波方程的修正 总被引:2,自引:1,他引:1
从最基本的耦合波方程出发,考虑光波正反向传输的情况下,推导出了一个全面的、准确的关于连续级联喇曼光纤激光器的理论模型,描述了各级Stokes光波功率沿光纤长度的变化.指出了相关一些文献中存在的不足,并且给出了多级斯托克斯光波相互作用的有效作用面积的表达式.此模型有助于喇曼光纤激光器的设计. 相似文献
56.
利用Monte Carlo模拟方法研究了加核自缩合乙烯基聚合反应体系中超支化高分子的二次回转半径随双键转化率的变化情况. 在模拟中, 重点考察了两类活性基团的反应活性差异、 引发核的配比及基团数等因素对超支化高分子均方回转半径的影响. 结果表明, 上述因素对于超支化高分子的尺度有着显著影响, 从而可为调控体系中高分子的空间尺度提供有效途径. 相似文献
57.
《Wave Motion》2017
Two methods for computing the complex-valued effective wavenumber of a rough beam in the context of linear time-harmonic theory are presented. The roughness of the beam is modelled as a continuous random process of known characteristic length and root-mean-square amplitude for either the beam mass or the beam rigidity. The first method is based on a random sampling method, with the effective wave field calculated as the mean of a large ensemble of wave fields for individual realisations of the roughness. The individual wave fields are calculated using a step approximation, which is validated for a deterministic problem via comparison to results produced by an integral equation approach. The second method assumes a splitting of the length scale of the fluctuations and an observation scale, employing a multiple-scale approximation to derive analytical expressions for the effective attenuation rate and phase change. Numerical comparisons show agreement of the results of the random sampling method and the multiple-scale approximation for a wide range of parameters. It is shown that the effective wavenumbers only differ by a real constant between the cases of varying beam mass and rigidity. 相似文献
58.
Vijay S. Raykar 《Physics letters. A》2010,374(45):4618-4621
A differential effective medium theory together with Brownian motion is used to predict Effective Thermal Conductivity (ETC) of CNT nanofluids. ETC was influenced significantly by Brownian motion and enhancement was higher in dilute nanofluids. A theoretical model employing an effective volume fraction with dispersibility factor agrees well with experimental data. 相似文献
59.
The binding energy of an off-center hydrogenic donor impurity in weakly oblate Ellipsoidal Quantum Dot (EQD), using the expansion method within the framework of effective mass approximation in strong confinement, is investigated. In this regard, the binding energies of different states of GaAs structures, as functions of the donor position and ellipticity parameter, are calculated. The results show that variations of binding energies are proportional to the ellipticity constant, the dot dimension and the location of impurity. 相似文献
60.
We study the effective conductivity
e
for a random wire problem on the d-dimensional cubic lattice
d
, d2 in the case when random conductivities on bonds are independent identically distributed random variables. We give exact expressions for the expansion of the effective conductivity in terms of the moments of the disorder parameter up to the 5th order. In the 2D case using the duality symmetry we also derive the 6th order expansion. We compare our results with the Bruggeman approximation and show that in the 2D case it coincides with the exact solution up to the terms of 4th order but deviates from it for the higher order terms. 相似文献