首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3041篇
  免费   198篇
  国内免费   293篇
化学   196篇
晶体学   3篇
力学   133篇
综合类   51篇
数学   2497篇
物理学   652篇
  2024年   4篇
  2023年   28篇
  2022年   41篇
  2021年   49篇
  2020年   66篇
  2019年   67篇
  2018年   77篇
  2017年   78篇
  2016年   100篇
  2015年   63篇
  2014年   149篇
  2013年   243篇
  2012年   125篇
  2011年   177篇
  2010年   159篇
  2009年   161篇
  2008年   237篇
  2007年   201篇
  2006年   190篇
  2005年   164篇
  2004年   142篇
  2003年   141篇
  2002年   146篇
  2001年   105篇
  2000年   92篇
  1999年   94篇
  1998年   99篇
  1997年   63篇
  1996年   54篇
  1995年   38篇
  1994年   29篇
  1993年   20篇
  1992年   15篇
  1991年   6篇
  1990年   19篇
  1989年   12篇
  1988年   8篇
  1987年   4篇
  1986年   10篇
  1985年   10篇
  1984年   9篇
  1982年   6篇
  1981年   6篇
  1980年   4篇
  1979年   4篇
  1978年   4篇
  1977年   2篇
  1976年   3篇
  1973年   3篇
  1936年   2篇
排序方式: 共有3532条查询结果,搜索用时 15 毫秒
51.
In this paper, we discuss the Cauchy-type integral formula of hypermonogenic functions on unbounded domains in real Clifford analysis, then we extend the Plemelj formula and Cauchy–Pompeiu formula of hypermonogenic functions on bounded domains to unbounded domains. We also deal with the Green-type formula on unbounded domains and get several important corollaries.  相似文献   
52.
53.
《Current Applied Physics》2015,15(10):1205-1215
Calculations of renormalized perpendicular conductivity within Kubo formula employing single particle temperature dependent Green's function formalism for bilayer graphene has been attempted. On the basis of numerical analysis, perpendicular conductivity as a function of temperature, interlayer coupling, onsite Coulomb interaction and carrier concentration per site has been analyzed for both AA- and AB-stacked bilayer graphene. It is found that perpendicular conductivity increases with interlayer coupling and also with temperature at low temperatures while at higher temperatures, there is saturation in perpendicular conductivity. Influences of onsite Coulomb interaction and carrier concentration per site on perpendicular conductivity is just opposite to each other while onsite Coulomb energy suppresses the rate of increase of σ/σ⊥0 with temperature, on the other hand increase in carrier density per site enhance this rate significantly. Finally, theoretically obtained results on temperature dependent perpendicular conductivity are viewed in terms of electronic transport data as well as recent theoretical works available in bilayer graphene.  相似文献   
54.
钟尔杰  黄廷祝 《大学数学》2006,22(5):163-166
利用梯形公式的余项,将被积函数的二阶导数做幂级数展开,证明了余项是关于求积区间长度的奇数次幂级数.推导出了复合梯形公式的一类渐近展开式,从另一方面印证了Euler-Maclaurin公式.  相似文献   
55.
1 引言 小波分析是结合泛函分析、应用数学、逼近论、调和分析、广义函数论等数学知识的结晶,具有深刻的理论意义和广泛的应用范围,被称为”数学显微镜”.基于其多分辨分析的特点以及在时、频两域都具有表征信号局部特征的功能,应用它可以解决许多Fourier变换不能解决的难题,为工程应用提供了一种新的、更有效的分析工具[1],由...  相似文献   
56.
We propose a conjecture on the relative twist formula of l-adic sheaves, which can be viewed as a generalization of Kato—Saito's conjecture. We verify this conjecture under some transversal assumptions. We also define a relative cohomological characteristic class and prove that its formation is compatible with proper push-forward. A conjectural relation is also given between the relative twist formula and the relative cohomological characteristic class.  相似文献   
57.
《Physics letters. A》2020,384(22):126428
We determine the classical diffusion of two dimensional Dirac-like quasiparticles, in the presence of conserving spin disorder (scattering off electric impurities) and non-conserving spin disorder (scattering off magnetic impurities). We use the Kubo formula for the conductivity tensor and employ diagrammatic perturbation theory to calculate the vertex correction and the renormalisation of the current operator for both electric and magnetic scattering. Scattering off electric impurities is isotropic and the current operator renormalised to two times the bare current operator irrespective of the direction of the dynamics, as usual for Dirac-like fermions. For magnetic scattering the renormalisation of the current operator depends on the direction of the dynamics and on the polarisation of the magnetic impurities, making the system anisotropic. We calculate the anisotropic magnetoresistance (AMR) and analyse it as a function of the ratio of the strength of the electric to the magnetic scattering potentials, for short range Gaussian correlation.  相似文献   
58.
《Current Applied Physics》2020,20(2):237-243
Three popular optical analysis methods (the transfer-matrix method, the Tinkham formula, and Beer's law) have been used for analyzing the optical spectra of thin films. While the transfer-matrix method is an accurate method, the Tinkham formula and Beer's law are approximate methods. Here we investigated the three methods using measured transmittance spectra of insulating transition-metal dichalcogenide (TMD) thin films on a quartz substrate. Three different semiconducting 2H-TMD systems (MoS2, MoSe2, and MoTe2) were measured and analyzed. The optical conductivities obtained from the measured transmittance spectra using the transfer-matrix method and Tinkham formula and the absorption coefficients obtained using the transfer-matrix method and Beer's law were compared. The comparisons show some discrepancies. The reasons for the discrepancies between the results obtained via the two different methods were examined and the application limitations of the Tinkham formula and Beer's law were discussed.  相似文献   
59.
Using an operator ordering method for some commutative superposition operators, we introduce two new multi-variable special polynomials and their generating functions, and present some new operator identities and integral formulas involving the two special polynomials. Instead of calculating complicated partial differential, we use the special polynomials and their generating functions to concisely address the normalization, photocount distributions and Wigner distributions of several quantum states that can be realized physically, the results of which provide real convenience for further investigating the properties and applications of these states.  相似文献   
60.
针对RC梁开裂荷载计算方法尚未统一的现状,首先,结合18根RC梁试验数据对比了已有的6种RC梁开裂弯矩计算公式,发现开裂弯矩理论计算值与试验值的偏差大小和混凝土强度有关;然后,通过提出塑性变形发展程度系数k,推导新的RC梁开裂弯矩计算公式,并进一步基于k值和塑性影响系数计算值γk进行改进;最后,选取12根RC试验梁验证改进公式的准确性,证明改进公式的计算值与试验值吻合更好且偏于安全。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号