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   351篇
  免费   17篇
  国内免费   47篇
化学   40篇
力学   6篇
综合类   8篇
数学   298篇
物理学   63篇
  2023年   2篇
  2022年   5篇
  2021年   7篇
  2020年   4篇
  2019年   10篇
  2018年   8篇
  2017年   15篇
  2016年   11篇
  2015年   14篇
  2014年   20篇
  2013年   37篇
  2012年   25篇
  2011年   17篇
  2010年   16篇
  2009年   24篇
  2008年   23篇
  2007年   17篇
  2006年   22篇
  2005年   15篇
  2004年   9篇
  2003年   15篇
  2002年   9篇
  2001年   12篇
  2000年   10篇
  1999年   5篇
  1998年   17篇
  1997年   10篇
  1996年   6篇
  1994年   2篇
  1993年   1篇
  1992年   3篇
  1991年   2篇
  1990年   3篇
  1989年   1篇
  1988年   3篇
  1987年   1篇
  1986年   1篇
  1984年   2篇
  1983年   1篇
  1982年   3篇
  1981年   2篇
  1978年   3篇
  1977年   1篇
  1975年   1篇
排序方式: 共有415条查询结果,搜索用时 15 毫秒
31.
由于几何秩在线性等距映射下是不变的,因此几何秩是研究算子代数线性等距映射的一个强有力的工具.证明了在一定条件下,套代数弱闭模中的n秩算子的几何秩的上、下界分别为n2和n(n+1)2,这表明套代数弱闭模中有限秩算子的充要条件是算子的几何秩有限.  相似文献   
32.
We present three different derivations of the transition probabilities to the continuum. It is shown that calculations, performed as a direct application of the postulates of orthodox quantum mechanics (OQM), do not yield results consistent with experiments. Traditional treatments are summarized and criticized. The relation of the transitions to the continuum with the traditional quantum measurement problem is pointed out; we sum up and comment some contributions concerning this issue. It is shown that an approach based on the notion of spontaneous projections yields expressions of the transition probabilities similar to those obtained in the traditional way and new predictions which could be submitted to experimental tests.  相似文献   
33.
The plane stress boundary value problem of quasi-static linear orthotropic thermoelasticity is discussed. The thermoelastic system on a bounded simply-connected domain is decoupled. The decoupled temperature equation is investigated by using accurate estimation and the contraction mapping principle. Representations of solutions of the field equation are obtained, and some solvability results are proved. The results are of both theoretical and numerical interest.  相似文献   
34.
FRACTAL PROPERTIES OF STATISTICALLY SELF-SIMILAR SETS I   总被引:1,自引:1,他引:0  
In this paper,authors compute the Packing dimension of statistically selfsimilar sets and obtaine the dimension and dimension distribution of statistically selfsimilar measure.  相似文献   
35.
We study the multiple-sets split feasibility problem that requires to find a point closest to a family of closed convex sets in one space such that its image under a linear transformation will be closest to another family of closed convex sets in the image space. By casting the problem into an equivalent problem in a suitable product space we are able to present a simultaneous subgradients projections algorithm that generates convergent sequences of iterates in the feasible case. We further derive and analyze a perturbed projection method for the multiple-sets split feasibility problem and, additionally, furnish alternative proofs to two known results.  相似文献   
36.
We single out the Besov spaces that embed into the class of continuous functions and enjoy the Fredholm theory of linear singular integral equations with Cauchy kernel. We give basic results of this theory in the class of continuous (rather than Holder continuous) functions in terms of Besov spaces. Alongside elliptic operators we consider violations of ellipticity: the degeneration of the symbol of an operator at finitely many points.  相似文献   
37.
序压缩映射的不动点定理   总被引:22,自引:0,他引:22  
张宪 《数学学报》2005,48(5):973-978
本文在序Banach空间中引入了几种按序压缩的压缩型映射,证明了相应的不动点定理.  相似文献   
38.
The successive projections algorithm (SPA) is widely used to select variables for multiple linear regression (MLR) modeling. However, SPA used only once may not obtain all the useful information of the full spectra, because the number of selected variables cannot exceed the number of calibration samples in the SPA algorithm. Therefore, the SPA-MLR method risks the loss of useful information. To make a full use of the useful information in the spectra, a new method named “consensus SPA-MLR” (C-SPA-MLR) is proposed herein. This method is the combination of consensus strategy and SPA-MLR method. In the C-SPA-MLR method, SPA-MLR is used to construct member models with different subsets of variables, which are selected from the remaining variables iteratively. A consensus prediction is obtained by combining the predictions of the member models. The proposed method is evaluated by analyzing the near infrared (NIR) spectra of corn and diesel. The results of C-SPA-MLR method showed a better prediction performance compared with the SPA-MLR and full-spectra PLS methods. Moreover, these results could serve as a reference for combination the consensus strategy and other variable selection methods when analyzing NIR spectra and other spectroscopic techniques.  相似文献   
39.
In this paper, we introduce a new definition of Lipschitz-type continuity of a bifunction. Using this definition, we prove the contraction of the proximal mapping and apply it to the equilibrium problem over the fixed-point set of a nonexpansive mapping. We present a new algorithm for this problem. Under classical conditions, the convergence of the algorithm is proved. Finally, we present some numerical results for the proposed algorithm.  相似文献   
40.
畅含笑  屈彪 《数学杂志》2017,37(6):1234-1244
本文主要研究带1-范数约束的分裂可行问题的求解算法.用一种交替投影算法,求得了问题的解,提出松弛交替投影算法,改进了直接往闭凸集上投影这一不足,并证明了该算法的收敛性.  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