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   1798篇
  免费   147篇
  国内免费   241篇
化学   52篇
晶体学   4篇
力学   210篇
综合类   24篇
数学   1611篇
物理学   285篇
  2024年   3篇
  2023年   27篇
  2022年   10篇
  2021年   21篇
  2020年   37篇
  2019年   34篇
  2018年   43篇
  2017年   44篇
  2016年   37篇
  2015年   41篇
  2014年   67篇
  2013年   125篇
  2012年   61篇
  2011年   80篇
  2010年   73篇
  2009年   103篇
  2008年   129篇
  2007年   127篇
  2006年   127篇
  2005年   126篇
  2004年   88篇
  2003年   112篇
  2002年   86篇
  2001年   75篇
  2000年   93篇
  1999年   69篇
  1998年   50篇
  1997年   61篇
  1996年   47篇
  1995年   19篇
  1994年   22篇
  1993年   11篇
  1992年   8篇
  1991年   11篇
  1990年   6篇
  1989年   11篇
  1988年   9篇
  1987年   10篇
  1986年   5篇
  1985年   9篇
  1984年   17篇
  1983年   8篇
  1982年   9篇
  1981年   6篇
  1980年   11篇
  1979年   7篇
  1978年   2篇
  1977年   2篇
  1976年   5篇
  1974年   1篇
排序方式: 共有2186条查询结果,搜索用时 375 毫秒
1.
设 $\varphi$ 是单位园盘 $D$ 到自身的解析映射, $X$ 是 $D$ 上解析函数的 Banach 空间, 对 $f\in X$, 定义复合算子$C_\varphi $ : $C_\varphi (f)=f\circ \varphi$. 我们利用从 ${\cal B}^0$到 $E(p,q)$ 和 $E_0(p,q)$ 空间的复合算子研究了空间 $E(p,q)$ 和 $E_0(p,q)$, 给出了一个新的特征.  相似文献   
2.
本文应用上、下解方法和 Leray-Schauder不动点定理 ,证明了一类拟线性椭圆方程边值问题弱解的存在性 ,并且给出了一个应用实例  相似文献   
3.
The ultraviolet band systemsA 1Π-X 1Σ+ of P14N and P15N were excited in an electrodeless tube containing traces of phosphorus specpure nitrogen and neon using a microwave discharge (2450 MHz). Bands of the isotopic species, P15N, were obtained using15N2 enriched to 95.5%. Rotational analyses of eleven bands of P14N and sixteen bands of P15N were carried out. Three perturbing statese 3Σ,d 3Δ andb 3Π, arising from the lower valence configurations were identified from the observed perturbations in thev′=0–4 levels of theA 1Π state. Deperturbation studies led to the determination of molecular constants of the perturbing states. Vibrational assignments of the perturbing states were made from isotope shift studies.  相似文献   
4.
A method for computing low Mach number flows using high‐resolution interpolation and difference formulas, within the framework of the Marker and Cell (MAC) scheme, is presented. This increases the range of wavenumbers that are properly resolved on a given grid so that a sufficiently accurate solution can be obtained without extensive grid refinement. Results using this scheme are presented for three problems. The first is the two‐dimensional Taylor–Green flow which has a closed form solution. The second is the evolution of perturbations to constant‐density, plane channel flow for which linear stability solutions are known. The third is the oscillatory instability of a variable density plane jet. In this case, unless the sharp density gradients are resolved, the calculations would breakdown. Under‐resolved calculations gave solutions containing vortices which grew in place rather than being convected out. With the present scheme, regular oscillations of this instability were obtained and vortices were convected out regularly. Stable computations were possible over a wider range of sensitive parameters such as density ratio and co‐flow velocity ratio. Copyright © 2004 John Wiley Sons, Ltd.  相似文献   
5.
6.
By applying geometric techniques to real analytic singularly perturbed vector fields on the plane, we develop a way to give a bound on the Gevrey type of the Taylor development of canard manifolds at degenerate planar turning points. By blowing up the phase space at the turning point, we find asymptotic estimates even when such expansions w.r.t. traditional phase space variables do not exist. The asymptotic estimates are then used to give a sufficient and necessary condition on the existence of (local) canard solutions.  相似文献   
7.
We introduce a random perturbed version of the classical fidelity and we show that it converges with the same rate of decay of correlations, but not uniformly in the noise. This makes the classical fidelity unstable in the zero-noise limit.  相似文献   
8.
We extract some properties of Mahlo’s operation and show that some other very natural operations share these properties. The weakly compact sets form a similar hierarchy as the stationary sets. The height of this hierarchy is a large cardinal property connected to saturation properties of the weakly compact ideal.  相似文献   
9.
A natural criterion for dimensional full-valuedness of locally compact spaces with finitely generated local homology is given.  相似文献   
10.
A functional equation of nonlinear iterates is discussed on the circle S1 for its continuous solutions and differentiable solutions. By lifting to R, the existence, uniqueness and stability of those solutions are obtained. Techniques of continuation are used to guarantee the preservation of continuity and differentiability in lifting.  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