全文获取类型
收费全文 | 743篇 |
免费 | 12篇 |
国内免费 | 1篇 |
专业分类
化学 | 481篇 |
晶体学 | 11篇 |
力学 | 10篇 |
数学 | 93篇 |
物理学 | 161篇 |
出版年
2023年 | 5篇 |
2022年 | 15篇 |
2021年 | 11篇 |
2020年 | 14篇 |
2019年 | 8篇 |
2018年 | 15篇 |
2017年 | 9篇 |
2016年 | 16篇 |
2015年 | 13篇 |
2014年 | 12篇 |
2013年 | 63篇 |
2012年 | 37篇 |
2011年 | 40篇 |
2010年 | 45篇 |
2009年 | 37篇 |
2008年 | 53篇 |
2007年 | 41篇 |
2006年 | 54篇 |
2005年 | 28篇 |
2004年 | 24篇 |
2003年 | 34篇 |
2002年 | 25篇 |
2001年 | 11篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 8篇 |
1995年 | 12篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 2篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 4篇 |
1987年 | 8篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 9篇 |
1981年 | 7篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1974年 | 3篇 |
1955年 | 3篇 |
1954年 | 4篇 |
1935年 | 2篇 |
排序方式: 共有756条查询结果,搜索用时 15 毫秒
101.
The local-field correction near the surface of a dipolar crystal has been studied by explicitly computing the non-retarded electric field produced by a finite array of classical point dipoles induced by a time-varying electric field. Crystals of simple cubic, f.c.c. and b.c.c. structures are considered, and results presented for the self-consitent dipole moment and the local electric field at a lattice point. The utility of the method and its possible applications are discussed. 相似文献
102.
To lowest order of perturbation theory we show that an equivalence can be established between a
-symmetric generalized quartic anharmonic oscillator model and a Hermitian position-dependent mass Hamiltonian h. An important feature of h is that it reveals a domain of couplings where the quartic potential could be attractive, vanishing or repulsive. We also
determine the associated physical quantities. 相似文献
103.
Bandyopadhyay S Chakraborty S Bagchi B 《The journal of physical chemistry. B》2006,110(41):20629-20634
Recent experiments have shown that the time dependence of fluorescence Stokes shift of a chromophore is substantially different when the chromophore is located in a molten globule (MG) state and in the native state of the same protein. To understand the origin of this difference, particularly the role of water in the differential solvation of the protein in the native and the MG states, we have carried out fully atomistic molecular dynamics simulations with explicit water of a partially unfolded MG state of the protein HP-36 and compared the results with the solvation dynamics of the protein in the folded native state. It is observed that the polar solvation dynamics of the three helical segments of the protein is influenced in a nonuniform heterogeneous manner in the MG state. While the equilibrium solvation time correlation function for helix-3 has been found to relax faster in the MG state as compared to that in the native state, the decay of the corresponding function for the other two helices slows down in the MG state. A careful analysis shows that the origin of such heterogeneous relative solvation behavior lies in the differential location of the polar probe residues and their exposure to bulk solvent. We find a significant negative cross-correlation between the contribution (to the solvation energy of a tagged amino acid residue) of water and the other groups of the protein, indicating a competing role in solvation. The sensitivity of solvation dynamics to the secondary structure and the immediate environment can be used to discriminate the partially unfolded and folded states. These results therefore should be useful in explaining recent solvation dynamics experiments on native and MG states of proteins. 相似文献
104.
We used variationally improved perturbation theory (VIPT) in calculating the slope and curvature of Isgur-Wise (I-W) function
with the Cornell potential −$
\frac{{4\alpha _s }}
{{3r}}
$
\frac{{4\alpha _s }}
{{3r}}
+br + c instead of the usual stationary state perturbation theory as done earlier. We used −(4α
s
/3r), i.e. the Coulombic potential, as the parent and the linear one, i.e. br+c as the perturbed potential in the theory and calculated the slope and curvature of Isgur-Wise function including three states
in the summation involved in the first-order correction to wave function in the method. 相似文献
105.
Sharmistha Bagchi Snehal Jani N. Lakshmi 《Journal of magnetism and magnetic materials》2010,322(24):3851-3856
The present study reports the effect of swift heavy ion irradiation on structural and magnetic properties of sputtered W/Fe multilayer structure (MLS) having bilayer compositions of [W(10 Å)/Fe(20 Å)]10BL. The MLS is irradiated by 120 MeV Au9+ ions of fluences 1×1013 and 4×1013 ions/cm2. Techniques like X-ray reflectivity (XRR), cross-sectional transmission electron microscopy (X-TEM) and DC magnetization with a vibrating sample magnetometer (VSM) are used for structural and magnetic characterization of pristine and irradiated MLS. Analysis of XRR data using Parratt’s formalism shows a significant increase in W/Fe layer roughness. X-TEM studies reveal that intra-layer microstructure of Fe layers in MLS becomes nano-crystalline on irradiation. DC magnetization study shows that with spacer layer thickness interlayer coupling changes between ferromagnetic to antiferromagnetic. 相似文献
106.
The generalized Stokes parameters, which are two-point extensions of conventional Stokes parameters, are determined for a pair of points in the cross-section of a partially coherent broadband light beam. For this purpose, using a two-mirror and two-beam-splitter assembly, unpolarized, linearly polarized and partially polarized electromagnetic beams are generated. This simple experimental method for determining generalized Stokes parameters establishes an analogy with the experimental scheme of determining conventional Stokes parameters, which in succession contributes to appreciable reduction in uncertainty in the measurements. 相似文献
107.
108.
109.
110.
We report an experimental method to determine the elements of the electric cross-spectral density matrix for laser light. For this purpose an additional setup consisting of mirrors and reflecting prisms is utilized with the conventional Young's interferometer to overcome existing experimental limitations. The generalized Stokes parameters, which are the characteristics of two spatial points of the electromagnetic field, are also obtained for a pair of points. The knowledge of these two quantities might be useful in determining the change in polarization properties of light in propagation and their effects in optical measurements. 相似文献