全文获取类型
收费全文 | 698812篇 |
免费 | 3221篇 |
国内免费 | 1500篇 |
专业分类
化学 | 345585篇 |
晶体学 | 14165篇 |
力学 | 31829篇 |
综合类 | 19篇 |
数学 | 82051篇 |
物理学 | 229884篇 |
出版年
2021年 | 6429篇 |
2020年 | 7262篇 |
2019年 | 7983篇 |
2018年 | 9502篇 |
2017年 | 9635篇 |
2016年 | 13957篇 |
2015年 | 8810篇 |
2014年 | 13655篇 |
2013年 | 31588篇 |
2012年 | 24387篇 |
2011年 | 29694篇 |
2010年 | 21432篇 |
2009年 | 21288篇 |
2008年 | 27081篇 |
2007年 | 26811篇 |
2006年 | 24787篇 |
2005年 | 21868篇 |
2004年 | 20662篇 |
2003年 | 18304篇 |
2002年 | 18652篇 |
2001年 | 20879篇 |
2000年 | 15884篇 |
1999年 | 12754篇 |
1998年 | 10694篇 |
1997年 | 10267篇 |
1996年 | 9768篇 |
1995年 | 8656篇 |
1994年 | 8616篇 |
1993年 | 8277篇 |
1992年 | 9149篇 |
1991年 | 9409篇 |
1990年 | 9059篇 |
1989年 | 8916篇 |
1988年 | 8692篇 |
1987年 | 8583篇 |
1986年 | 8213篇 |
1985年 | 10411篇 |
1984年 | 10652篇 |
1983年 | 8709篇 |
1982年 | 8896篇 |
1981年 | 8676篇 |
1980年 | 8264篇 |
1979年 | 8868篇 |
1978年 | 8974篇 |
1977年 | 8860篇 |
1976年 | 8758篇 |
1975年 | 8255篇 |
1974年 | 8167篇 |
1973年 | 8111篇 |
1972年 | 5866篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
171.
172.
The supersymetric path integrals in solving the problem of relativistic spinning particle interacting with pseudoscalar potentials
is examined. The relative propagator is presented by means of path integral, where the spin degrees of freedom are described
by odd Grassmannian variables and the gauge invariant part of the effective action has a form similar to the standard pseudoclassical
action given by Berezin and Marinov. After integrating over fermionic variables (Grassmannian variables), the problem is reduced
to a nonrelativistic one with an effective supersymetric potential. Some explicit examples are considered, where we have extracted
the energy spectrum of the electron and the wave functions.
PACS numbers: 03.65. Ca-Formalism, 03.65. Db-Functional analytical methods, 03.65. Pm-Relativistic wave equations. 相似文献
173.
L. S. Pul’kina 《Journal of Mathematical Sciences》2007,144(1):3832-3840
The author proves the existence and uniqueness of a generalized solution of a nonlocal problem with an integral condition
for a hyperbolic equation with n spatial variables.
This work is a continuation of the studies started in [3–5], where the solvability problem of nonlocal problems with an integral
condition was studied for hyperbolic equations on the plane.
__________
Translated from Sovremennaya Matematika i Ee Prilozheniya (Contemporary Mathematics and Its Applications), Vol. 33, Suzdal
Conference-2004, Part 1, 2005. 相似文献
174.
V. M. Budanov 《Journal of Mathematical Sciences》2007,146(3):5931-5937
This paper investigates algorithms of motion planning for a six-legged walking machine over complex terrain. Application of
the Rodrigues-Hamilton parameters for describing the orientation of the body enables one to develop algorithms of motion planning
for the body and legs in an absolute coordinate frame with automatic adaptation to the surface. Experiments with a laboratory
scale walking machine have demonstrated the efficiency of proposed algorithms.
__________
Translated from Fundamentalnaya i Prikladnaya Matematika, Vol. 11, No. 7, pp. 197–206, 2005. 相似文献
175.
176.
Audrey A S G Lonni Ieda S Scarminio Lucas M C Silva Dalva T Ferreira 《Analytical sciences》2003,19(7):1013-1017
Phytochemical investigation of the aerial parts of three Baccharis species (Asteraceae family) was performed using HPLC and chemometric methods, with the objective of distinguishing between three morphologically very similar species: Baccharis genistelloides Persoon var. trimera (Less.) DC, B. milleflora (Less.) DC and B. articulata (Lam.) Persoon. With the help of Principal Component Analysis (PCA) and variance weights, it was possible to characterize the chromatographic profiles of the alcoholic extracts of the three species. Application of Soft Independent Modeling of Class Analogy (SIMCA) and K-Nearest Neighbor (KNN) methods on a training set of 74 extracts resulted in models that correctly classified all eight samples in an independent test set. 相似文献
177.
178.
For the NO molecule, modelled as a Morse oscillator, time-dependent (TD) nuclear Schr?dinger equation has been numerically
solved for the multiphoton vibrational dynamics of the molecule under a far-infrared laser of wavelength 10503 nm, and four
different intensities,I = 1 × 108, 1 × 1013, 5 × 1016, and 5 × 1018 W cm−2 respectively. Starting from the vibrational ground state at zero time, various TD quantities such as the norm, dissociation
probability, potential energy curve and dipole moment are examined. Rich high-harmonics generation (HHG) spectra and above-threshold
dissociation (ATD) spectra, due to the multiphoton interaction of vibrational motions with the laser field, and consequent
elevation to the vibrational continuum, have been obtained and analysed.
Dedicated to Professor C N R Rao on his 70th birthday
An erratum to this article is available at . 相似文献
179.
M. H. Eggar 《Linear and Multilinear Algebra》1995,38(4):333-341
This paper records two results about graded Hopf algebras that do not appear to be stated explicitly in the literature. Let B be a graded set, graded by the positive integers. Let V be the graded vector space with basis B over a field K of characteristic zero and V'=K⊕V, where K is in grading zero. Let L ne the free graded Lie algebra on B over K and let T be the free graded tensor algebra on B. The first result is the "graded Witt formula" giving the dimension of the subspace of L in each grading. The second result is the observation that any graded coassociative, co-commutative comultiplication Δ:V'→V'⊗V', with co-unit the projection V1→K. extends to a graded Hopf algebra structure on T that is in fact isomorphic to the natural graded Hopf algebra structure on T. In the ungraded case the statement analogous to the second result is false. 相似文献
180.
A. M. Gurin 《Journal of Mathematical Sciences》2007,146(1):5505-5508
The number of combinatorially nonequivalent Dirichlet-Voronoi diagrams constructed for the centers of balls in the packing
obtained from the densest lattice packing of equal spheres by a small displacement of the spheres is estimated.
__________
Translated from Fundamentalnaya i Prikladnaya Matematika, Vol. 11, No. 5, pp. 79–84, 2005. 相似文献