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991.
采用分散控制方案能有效解决大尺度土木结构在地震作用下的结构振动控制问题。本文将静态输出反馈、重叠分散控制方法、线性矩阵不等式方法和H∞范数控制算法相结合,提出了多重叠分散静态输出反馈H∞控制方法。通过对状态矩阵添加一个微小的扰动,解决了在求解相应的线性矩阵不等式(LMI)时所遇到的计算困难问题。文中对20层Benchmark建筑结构模型进行数值模拟与计算。结果表明,部分输出反馈控制、重叠静态输出反馈控制和多重叠静态输出反馈控制均获得了与全状态集中控制相近的控制效果,减少了计算成本和控制器设计的复杂性。 相似文献
992.
The scaling laws are given for the entropies in the information theory, including the Shannon's entropy, its power, the Fisher's information and the Fisher–Shannon product, using the exponential-cosine screened Coulomb potential. The scaling laws are specified, in the r-space, as a function of |μ ? μc, n?|, where μ is the screening parameter and μc, n? its critical value for the specific quantum numbers n and ?. Scaling laws for other physical quantities, such as energy eigenvalues, the moments, static polarisability, transition probabilities, etc. are also given. Some of these are reported for the first time. The outcome is compared with the available literatures’ results. 相似文献
993.
两厂商情形下二度价格歧视的需求分段数研究 总被引:1,自引:0,他引:1
在线性需求函数条件下,对两寡头厂商实行二度价格歧视进行了静态博弈分析,以确定对需求量区间的合理分段数.研究结果表明:对需求量区间的划分原则和评价标准以及分段数目类似于垄断情形,仍以二至三段为宜. 相似文献
994.
995.
The total cross sections for positron impact on hydrocarbons have been calculated using the additivity rule in which the total
cross section for a molecule is the sum of the total cross section for the constituent atoms. The energy range considered
is from a few eV to several thousand eV. The total cross sections for positron impact on an atom are calculated by employing
a complex spherical potential which comprises of a static, polarization and an absorption potential. We have good agreement
with the experimental results for hydrocarbons for positron energy ⩾100 eV. Our results also agree with the available calculations
for CH4 and C2H2 which employed full molecular wavefunctions beyond 100 eV. Our absorption cross sections also agree with molecular wave-function
calculations for C2H2 and CH4 beyond 100 eV. We have shown the Bethe plots fore
+−C ande
+−H scattering systems and Bethe parameters have been extracted. We have fitted the cross section for positron impact on hydrocarbons
in the formσ
t(C
n
H
m
)=naE
−
b+mcE
−
d in the energy range 300–5000 eV wherea=195.0543,b=0.7986,c=371.1757 andd=1.1379 withE in eV andσ
t in 10−16 cm2. 相似文献
996.
L.F. Lemmens F. Brosens J.T. Devreese 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,31(2):195-202
A full analysis of domain structure using a micromagnetic model is developed in order to get a clear insight into the behaviour
of transverse initial susceptibility as a function of dc applied field for thin films and bilayers exhibiting both in-plane
and perpendicular anisotropy. The numerical simulations are in good agreement with available experimental results in case
of single layers with the so-called stripe domain pattern while some predictions are done for bilayers. As the main result,
it is shown that in low field, the transverse initial susceptible cannot be interpreted without the knowledge of the static
domain pattern while, above saturation, it is only affected by the in-plane anisotropy.
Received 10 October 2002 Published online 4 February 2003
RID="a"
ID="a"e-mail: ml@lpmtm.univ-paris13.fr
RID="b"
ID="b"UMR CNRS 8634 相似文献
997.
B. Schmidt V. Yushankhai L. Siurakshina P. Thalmeier 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,32(1):43-47
A pronounced Curie-like upturn of the magnetic susceptibility χ(
T
) of the quasi one-dimensional spin chain compound Ba2V3O9 has been found recently [#!kaul:02!#]. Frequently this is taken as a signature for a staggered field mechanism due to the
presence of g-factor anisotropy and Dzyaloshinskii-Moriya interaction. We calculate this contribution within a realistic structure of vanadium
3
d- and oxygen 2
p-orbitals and conclude that this mechanism is far too small to explain experimental results. We propose that the Curie term
is rather due to a segmentation of spin chains caused by broken magnetic bonds which leads to uncompensated S
= ? spins of segments with odd numbers of spins. Using the finite-temperature Lanczos method we calculate their effective moment
and show that ∼ 1% of broken magnetic bonds is sufficient to reproduce the anomalous low-T behavior of χ(
T
) in Ba2V3O9.
Received 19 December 2002 / Received in final form 29 January 2003 Published online 14 March 2003 相似文献
998.
999.
We study the poor decay of correlations for equilibrium states of inhomogeneous fluids and solids, in the regimes of both classical and quantum statistical mechanics. Our main observation is the usefulness of the statistical mechanical expression of thestress tensor and its long-range correlations with the particle density. From this we are able to infer a very slow decay of correlations for the various molecular distribution functions under discussion. The derived results are of relevance both for completely inhomogeneous systems such as quasicrystals or granular structures and for the slightly more regular cases of, e.g., phase separating layers in fluids and solids, ideal crystals, etc. As one of the byproducts we prove the nonexistence of planequantum interfaces in two dimensions (thus extending earlier results of Requardt to the quantum regime). The results hold for arbitrary potentials of not too long range. 相似文献
1000.
In this paper we propose a variational model for the irreversible quasi static growth in brittle fractures for a linearly
elastic homogeneous isotropic plate, subject to a time dependent vertical displacement on a part of its lateral surface. The
model is based on the Griffith’s criterion for crack growth and is inspired to the model proposed in [11] by Francfort and
Marigo in the case of 3-D elasticity. We give a precise mathematical formulation of the model and in this framework we prove
an existence result.
Mathematics Subject Classification (2000) 74K20, 35J35, 74G65, 35R35, 35A35, 74R10 相似文献