全文获取类型
收费全文 | 2902篇 |
免费 | 234篇 |
国内免费 | 192篇 |
专业分类
化学 | 77篇 |
晶体学 | 1篇 |
力学 | 93篇 |
综合类 | 35篇 |
数学 | 2865篇 |
物理学 | 257篇 |
出版年
2024年 | 4篇 |
2023年 | 45篇 |
2022年 | 37篇 |
2021年 | 86篇 |
2020年 | 111篇 |
2019年 | 105篇 |
2018年 | 83篇 |
2017年 | 93篇 |
2016年 | 116篇 |
2015年 | 96篇 |
2014年 | 150篇 |
2013年 | 386篇 |
2012年 | 102篇 |
2011年 | 152篇 |
2010年 | 141篇 |
2009年 | 187篇 |
2008年 | 187篇 |
2007年 | 155篇 |
2006年 | 149篇 |
2005年 | 124篇 |
2004年 | 68篇 |
2003年 | 109篇 |
2002年 | 97篇 |
2001年 | 71篇 |
2000年 | 57篇 |
1999年 | 55篇 |
1998年 | 62篇 |
1997年 | 47篇 |
1996年 | 33篇 |
1995年 | 22篇 |
1994年 | 18篇 |
1993年 | 13篇 |
1992年 | 19篇 |
1991年 | 23篇 |
1990年 | 12篇 |
1989年 | 11篇 |
1988年 | 10篇 |
1987年 | 15篇 |
1986年 | 6篇 |
1985年 | 9篇 |
1984年 | 13篇 |
1983年 | 6篇 |
1982年 | 12篇 |
1981年 | 3篇 |
1980年 | 9篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1974年 | 1篇 |
1973年 | 6篇 |
排序方式: 共有3328条查询结果,搜索用时 78 毫秒
11.
12.
Franziska Kühn 《Mathematische Nachrichten》2019,292(2):358-376
We present an existence result for Lévy‐type processes which requires only weak regularity assumptions on the symbol with respect to the space variable x. Applications range from existence and uniqueness results for Lévy‐driven SDEs with Hölder continuous coefficients to existence results for stable‐like processes and Lévy‐type processes with symbols of variable order. Moreover, we obtain heat kernel estimates for a class of Lévy and Lévy‐type processes. The paper includes an extensive list of Lévy(‐type) processes satisfying the assumptions of our results. 相似文献
13.
14.
The Bayesian model are established for the VaR and related risk measurements. The relationship between VaR and other risk measurements including expect shortfall, tail condition expectation and conditional value at risk are discussed. Furthermore, the Bayesian estimates and Bayesian predictors of these risk measurement are derived. Thirdly, the consistency and asymptotic normality in the exponential risk model are proved. Finally, the numerical simulation method is used to verify the convergence rate under different sample sizes. 相似文献
15.
We study “large” nonnegative solutions for a class of quasilinear equations model of which is We give a sufficient condition on the exponents and for the removability of isolated singularities. 相似文献
16.
Explicit and partly sharp estimates are given of integrals over the square of Bessel functions with an integrable weight which can be singular at the origin. They are uniform with respect to the order of the Bessel functions and provide explicit bounds for some smoothing estimates as well as for the L2 restrictions of Fourier transforms onto spheres in which are independent of the radius of the sphere. For more special weights these restrictions are shown to be Hölder continuous with a Hölder constant having this independence as well. To illustrate the use of these results a uniform resolvent estimate of the free Dirac operator with mass in dimensions is derived. 相似文献
17.
《Stochastic Processes and their Applications》2019,129(6):2086-2129
Many properties of Brownian motion on spaces with varying dimension (BMVD in abbreviation) have been explored in Chen and Lou (2018). In this paper, we study Brownian motion with drift on spaces with varying dimension (BMVD with drift in abbreviation). Such a process can be conveniently defined by a regular Dirichlet form that is not necessarily symmetric. Through the method of Duhamel’s principle, it is established in this paper that the transition density of BMVD with drift has the same type of two-sided Gaussian bounds as that for BMVD (without drift). As a corollary, we derive Green function estimate for BMVD with drift. 相似文献
18.
19.
《Operations Research Letters》2020,48(2):176-179
When buyer valuations are drawn IID from a known regular distribution, a second price auction with a symmetric reserve price is the revenue-optimal single-item auction. When this distribution is irregular, we provide the first separation result showing that a second price auction with reserves earns at most 0.778 times the revenue of Myerson’s optimal auction, even when the reserves can be asymmetric. Since the lower bound is 0.745 for i.i.d. buyers, our result is nearly tight. 相似文献
20.
《Operations Research Letters》2020,48(6):827-834
We consider a sequence of age-replacement problems with a general lifetime distribution parametrized by an a-priori unknown parameter. There is a trade-off: Preventive replacements are censored but cheap, whereas corrective replacements are uncensored but costly observations of the lifetime distribution. We first analyze the optimal policy for a finite sequence and establish some properties. We then propose a myopic Bayesian policy that almost surely learns the unknown parameter and converges to the optimal policy with full knowledge of the parameter. 相似文献