全文获取类型
收费全文 | 1155篇 |
免费 | 57篇 |
国内免费 | 87篇 |
专业分类
化学 | 182篇 |
力学 | 83篇 |
综合类 | 9篇 |
数学 | 820篇 |
物理学 | 205篇 |
出版年
2023年 | 13篇 |
2022年 | 5篇 |
2021年 | 12篇 |
2020年 | 21篇 |
2019年 | 31篇 |
2018年 | 32篇 |
2017年 | 39篇 |
2016年 | 32篇 |
2015年 | 25篇 |
2014年 | 41篇 |
2013年 | 92篇 |
2012年 | 33篇 |
2011年 | 47篇 |
2010年 | 52篇 |
2009年 | 54篇 |
2008年 | 77篇 |
2007年 | 76篇 |
2006年 | 65篇 |
2005年 | 67篇 |
2004年 | 54篇 |
2003年 | 53篇 |
2002年 | 60篇 |
2001年 | 46篇 |
2000年 | 39篇 |
1999年 | 34篇 |
1998年 | 21篇 |
1997年 | 28篇 |
1996年 | 10篇 |
1995年 | 11篇 |
1994年 | 17篇 |
1993年 | 10篇 |
1992年 | 14篇 |
1991年 | 10篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 9篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1969年 | 3篇 |
排序方式: 共有1299条查询结果,搜索用时 15 毫秒
91.
Let (ℋ
t
)
t≥0 be the Ornstein-Uhlenbeck semigroup on ℝ
d
with covariance matrix I and drift matrix −λ(I+R), where λ>0 and R is a skew-adjoint matrix and denote by γ
∞ the invariant measure for (ℋ
t
)
t≥0. Semigroups of this form are the basic building blocks of Ornstein-Uhlenbeck semigroups which are normal on L
2(γ
∞). We investigate the weak type 1 estimate of the Riesz transforms for (ℋ
t
)
t≥0. We prove that if the matrix R generates a one-parameter group of periodic rotations then the first order Riesz transforms are of weak type 1 with respect
to the invariant measure γ
∞. We also prove that the Riesz transforms of any order associated to a general Ornstein-Uhlenbeck semigroup are bounded on
L
p
(γ
∞) if 1<p<∞.
The authors have received support by the Italian MIUR-PRIN 2005 project “Harmonic Analysis” and by the EU IHP 2002-2006 project
“HARP”. 相似文献
92.
With the newly developed octonion analytic function theory, we confirm the octonionic analogue of the Calderón's conjecture. As application, we obtain the Plemelj formula in octonionic space. 相似文献
93.
94.
Based on the vectorial Rayleigh–Sommerfeld integrals, the analytical propagation expression of a vectorial Laguerre–Gaussian beam beyond paraxial approximation is presented. The far field expression and the scalar paraxial result are obtained as special cases of the general formulae. According to the analytical representation, the light intensity distribution of the vectorial Laguerre–Gaussian beam is depicted in the reference plane. The light intensity distribution of a vectorial Laguerre–Gaussian beam with cos m is also compared with that of a vectorial Laguerre–Gaussian beam with sin m. 相似文献
95.
J. Fritz 《Journal of statistical physics》1986,44(1-2):25-47
We consider certain small stochastic perturbations of ad-dimensional infinite system of coupled anharmonic oscillators. The evolution law is reversible in the Yaglom sense, thus Gibbs states with the given interaction and temperature are stationary measures. If d<3 then some stability properties of the interaction imply the converse statement; if d>2 then the same is proven for translation invariant measures only. The methods and results of Ref. 4, 6–8 are extended to second-order systems of stochastic differential equations. 相似文献
96.
J. L. López 《Constructive Approximation》2001,17(4):535-559
Symmetric standard elliptic integrals are considered when two or more parameters are larger than the others. The distributional
approach is used to derive seven expansions of these integrals in inverse powers of the asymptotic parameters. Some of these
expansions also involve logarithmic terms in the asymptotic variables. These expansions are uniformly convergent when the
asymptotic parameters are greater than the remaining ones. The coefficients of six of these expansions involve hypergeometric
functions with less parameters than the original integrals. The coefficients of the seventh expansion again involve elliptic
integrals, but with less parameters than the original integrals. The convergence speed of any of these expansions increases
for an increasing difference between the asymptotic variables and the remaining ones. All the expansions are accompanied by
an error bound at any order of the approximation.
January 31, 2000. Date revised: May 18, 2000. Date accepted: August 4, 2000. 相似文献
97.
对积分学第一中值定理的中间点当区间长度趋于零时的渐近性研究.新得到的结果不仅包含了过去若干已有结果,而且对涉及函数f(x),g(x)要求的条件几乎就是中值定理的,一个为连续,一个为可积不变号. 相似文献
98.
99.
G. Mastroeni 《Journal of Optimization Theory and Applications》2001,109(3):539-555
We consider the variational inequality that represents the first-order optimality condition for the class of variational problems with the property that the integrand in the objective functional does not depend on the derivative of the unknown function. This allows the development of an iterative method for solving the statistical decision problem of testing simple hypotheses. 相似文献
100.
李艳红 《数学的实践与认识》2008,38(5):158-162
针对模糊测度空间上已建立的模糊值Choquet积分,将这种积分整体看成可测空间上取值于模糊数的集函数,当模糊测度满足一般S性和PGP性时,研究了这种模糊值集函数所保持的遗传性质. 相似文献