全文获取类型
收费全文 | 318篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
化学 | 127篇 |
力学 | 11篇 |
数学 | 84篇 |
物理学 | 98篇 |
出版年
2024年 | 2篇 |
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 8篇 |
2019年 | 8篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 18篇 |
2015年 | 12篇 |
2014年 | 7篇 |
2013年 | 43篇 |
2012年 | 11篇 |
2011年 | 18篇 |
2010年 | 7篇 |
2009年 | 7篇 |
2008年 | 9篇 |
2007年 | 12篇 |
2006年 | 14篇 |
2005年 | 9篇 |
2004年 | 9篇 |
2003年 | 4篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 6篇 |
1998年 | 2篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1985年 | 3篇 |
1984年 | 8篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1972年 | 3篇 |
1965年 | 2篇 |
1943年 | 2篇 |
1940年 | 2篇 |
1933年 | 2篇 |
1918年 | 2篇 |
1898年 | 1篇 |
1893年 | 1篇 |
排序方式: 共有320条查询结果,搜索用时 0 毫秒
51.
Using techniques of localization for Grothendieck categories with a family of projective generators, we show that for a graded
ring R = ⊕
σ∈G
R
σ
with finite support if R
e
has Gabriel dimension then has Gabriel dimension. Moreover, adding some lattice results, we prove that if has Gabriel dimension then also has Gabriel dimension.
This research has been supported by grant MTM2005-3227 from MEC. 相似文献
52.
Favero LB Velino B Caminati W Arnason I Kvaran A 《The journal of physical chemistry. A》2006,110(33):9995-9999
The rotational spectra of the main isotopomer, of the (29)Si and of all (13)C isotopologues of axial and equatorial forms of 1-fluoro-silacyclohexane have been measured by conventional (only main species) and molecular beam Fourier transform microwave spectroscopy. r(0) and partial r(s) structures are given separately for the two forms. The main structural differences are discussed. From dipole moments and relative intensity measurements, a slight preference (E(Eq) - E(Ax) = 42 +/- 24 cm(-1)) for the axial conformer was found. The rotational spectra of some, the most intense, vibrational satellites have also been measured. They belong to the ring-puckering motions. 相似文献
53.
The radiosterilization potential and dosimetric feature of allantoin were investigated through the molecular degradations produced after ultraviolet and gamma irradiation using electron spin resonance, infrared, and ultraviolet spectroscopies and thermal measurement techniques (differential thermal analysis and the glass transition temperature). Although ultraviolet-irradiated allantoin presents no electron spin resonance signal, gamma irradiation exhibited an electron spin resonance signal of triplet appearance. Room temperature and high-temperature line intensity and spectrum area data and their variations with applied microwave power, storage time, annealing time, annealing temperature, and applied radiation dose were analyzed by assuming the production of two different types of radicals having different spectroscopic and decay characteristics. Based on its relatively stable nature toward gamma and ultraviolet radiations, it was concluded that allantoin itself and the products containing it can be sterilized by gamma and/or ultraviolet radiations without creating a great loss in its beneficial effects in the allowed radiosterilization dose limits. 相似文献
54.
M. Arends A. Hebecker K. Heimpel S. Kraus D. Lüst C. Mayrhofer C. Schick T. Weigand 《Fortschritte der Physik》2014,62(8):647-702
55.
We compute the axial anomaly of a Lifshitz fermion theory with anisotropic scaling z = 3 which is minimally coupled to geometry in 3+1 space‐time dimensions. We find that the result is identical to the relativistic case using path integral methods. An independent verification is provided by showing with spectral methods that the η‐invariant of the Dirac and Lifshitz fermion operators in three dimensions are equal. Thus, by the integrated form of the anomaly, the index of the Dirac operator still accounts for the possible breakdown of chiral symmetry in non‐relativistic theories of gravity. We apply this framework to the recently constructed gravitational instanton backgrounds of Hořava–Lifshitz theory and find that the index is non‐zero provided that the space‐time foliation admits leaves with harmonic spinors. Using Hitchin's construction of harmonic spinors on Berger spheres, we obtain explicit results for the index of the fermion operator on all such gravitational instanton backgrounds with SU(2) × U(1) isometry. In contrast to the instantons of Einstein gravity, chiral symmetry breaking becomes possible in the unimodular phase of Hořava–Lifshitz theory arising at λ = 1/3 provided that the volume of space is bounded from below by the ratio of the Ricci to Cotton tensor couplings raised to the third power. Some other aspects of the anomalies in non‐relativistic quantum field theories are also discussed. 相似文献
56.
FMR formulas for (001) cubic films with an applied uniaxial or isotropic in-plane stress σ are derived for various film orientations toward the external magnetic field H. The resonance field shift δH caused by σ is explicitly evaluated including quadratic terms (∼ σ2) and the magnetocrystalline anisotropy effect. Measurements of δH performed on LPE garnet thin films (composition Y3Fe4.87Mn0.13O12) are well described by the theory. 相似文献
57.
We review the worldsheet analysis for intersecting branes with focus on small and large angles. For small angles, we review the Yang‐Mills fluctuation analysis in [1] and find an additional family of massless modes. They are the components of a Goldstone scalar corresponding to the spontaneously broken U(2)‐gauge symmetry. For branes at large angles, we derive an effective tachyon field theory from BSFT results. We show how the gauge symmetry of this system implies a mass spectrum which is consistent with the worldsheet analysis. 相似文献
58.
59.
Sufficient conditions for the invertibility of adapted perturbations of identity on the Wiener space
Let (W, H, μ) be the classical Wiener space. Assume that U = I W + u is an adapted perturbation of identity, i.e., u : W → H is adapted to the canonical filtration of W. We give some sufficient analytic conditions on u which imply the invertibility of the map U. In particular it is shown that if ${u\in {\rm ID}_{p,1}(H)}$ is adapted and if ${\exp(\frac{1}{2}\|\nabla u\|_2^2-\delta u)\in L^q(\mu)}$ , where p ?1 + q ?1 = 1, then I W + u is almost surely invertible. With the help of this result it is shown that if ${\nabla u\in L^\infty(\mu,H\otimes H)}$ , then the Girsanov exponential of u times the Wiener measure satisfies the logarithmic Sobolev inequality and this implies the invertibility of U = I W + u . As a consequence, if, there exists an integer k ≥ 1 such that ${\|\nabla^k u\|_{H^{\otimes(k+1)}}\in L^\infty(\mu)}$ , then I W + u is again almost surely invertible under the almost sure continuity hypothesis of ${t\to\nabla^i \dot{u}_t}$ for i ≤ k ? 1. 相似文献
60.