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   1197篇
  免费   56篇
  国内免费   103篇
化学   87篇
力学   16篇
综合类   24篇
数学   1092篇
物理学   137篇
  2024年   1篇
  2023年   11篇
  2022年   21篇
  2021年   14篇
  2020年   30篇
  2019年   22篇
  2018年   21篇
  2017年   25篇
  2016年   32篇
  2015年   13篇
  2014年   49篇
  2013年   121篇
  2012年   30篇
  2011年   60篇
  2010年   42篇
  2009年   77篇
  2008年   89篇
  2007年   94篇
  2006年   74篇
  2005年   56篇
  2004年   57篇
  2003年   45篇
  2002年   54篇
  2001年   41篇
  2000年   38篇
  1999年   38篇
  1998年   41篇
  1997年   25篇
  1996年   20篇
  1995年   13篇
  1994年   15篇
  1993年   12篇
  1992年   10篇
  1991年   6篇
  1990年   9篇
  1989年   3篇
  1988年   3篇
  1987年   2篇
  1985年   3篇
  1984年   9篇
  1983年   5篇
  1982年   3篇
  1981年   2篇
  1980年   2篇
  1979年   6篇
  1978年   4篇
  1977年   4篇
  1971年   1篇
  1970年   2篇
  1959年   1篇
排序方式: 共有1356条查询结果,搜索用时 15 毫秒
71.

We characterize the compactness of a subset of compact operators between Banach spaces when the domain space does not have a copy of

  相似文献   

72.
In this paper, we give necessary and sufficient conditions for infinite matrices mapping from the Nakano vector-valued sequence space (X, p) into any BK-space, and by using this result, we obtain the matrix characterizations from (X, p) into the sequence spaces (Y), c0(Y, q), c(Y), s(Y), Er(Y), and Fr(Y), where p = (pk) and q = (qk) are bounded sequences of positive real numbers such that pk 1 for all k N, r 0, and s 1.AMS Subject Classification (2000): 46A45  相似文献   
73.
The method of quasilinearization is a procedure for obtaining approximate solutions of differential equations. In this paper, this technique is applied to a differential-algebraic problem. Under some natural assumptions, monotone sequences converge quadratically to a unique solution of our problem.  相似文献   
74.
We study rate of convergence in the strong law of large numbers for finite and infinite variance time series in both contexts of weak and strong dependence.  相似文献   
75.
In this paper, we are concerned with the global behavior ofthe solutions of the difference equation
where
and . Necessary and sufficient conditions for boundedness, persistence,and periodicity of all solutions will be established. The oscillatorybehavior will be investigated.  相似文献   
76.
The finite-difference time-domain method based on recursive convoltion method (RC-FDTD) for the electric anisotropic dispersive medium is discussed in detail. To exemplify the availability of the three-dimensional RC-FDTD algorithm, the backscattering Radar-Cross-Section(RCS) of a non-magnetized plasma sphere is computed, and the numerical results are the same as the one of the Shift Operater-FDTD method, and show that the RC-FDTD method is correct and efficient. In addition, the co-polarized and cross-polarized backscattering time-domain of a magnetized plasma sphere are obtained by the RC-FDTD algorithm. The results show that when the external magnetic field is implemented, the cross-polarized component appear, evidently.  相似文献   
77.
Chameleon sequences are amino acid sequences found in several distinct configurations in experiment. They challenge our understanding of the link between sequence and structure, and provide insight into structural competition in proteins. Here, we study the energy landscapes for three such sequences, and interrogate how pulling and twisting forces impact the available structural ensembles. Chameleon sequences do not necessarily exhibit multiple structural ensembles on a multifunnel energy landscape when we consider them in isolation. The application of even small forces leads to drastic changes in the energy landscapes. For pulling forces, we observe transitions from helical to extended structures in a very small span of forces. For twisting forces, the picture is much more complex, and highly dependent on the magnitude and handedness of the applied force as well as the reference angle for the twist. Depending on these parameters, more complex and more simplistic energy landscapes are observed alongside more and less diverse structural ensembles. The impact of even small forces is significant, confirming their likely role in folding events. In addition, small forces exerted by the remaining scaffold of a protein may be sufficient to lead to the adoption of a specific structural ensemble by a chameleon sequence.  相似文献   
78.
It is shown that the multiplier norm of a shifted Jacobi multiplier sequence can be estimated by the (same) multiplier norm of the original sequence uniformly with respect to the shift. Muckenhoupt’s transplantation theorem for Jacobi series is used essentially, for which also a functional analytic understanding is given in terms of the minimality of the Jacobi system in weighted L p -spaces.   相似文献   
79.
Recently, the space bvp of real or complex numbers consisting of all sequences whose differences are in the space lp has been studied by Basar, Altay [Ukrainian Math. J. 55(1)(2003), 136-147], where 1 ≤ p ≤ ∞. The main purpose of the present paper is to introduce the space bvp(F) of sequences of p-bounded variation of fuzzy numbers. Moreover, it is proved that the space bvp(F) includes the space lp(F) and also shown that the spaces bvp(F) and lp(F) axe isomorphic for 1 ≤ p ≤∞. Furthermore, some inclusion relations have been given.  相似文献   
80.
In this paper, a new type of bivariate basis on a triangle is presented, which is constructed by extending the univariate NTP basis proposed by Delgado and Peña. Some algebraic properties and its recursive formulae are given. Then a new type of surfaces that is called triangular DP surface is defined, and its recursive evaluation algorithm is obtained. Also, in the case of low degree, its subdivision algorithm and degree elevation algorithm are derived. It is shown that this type of surfaces is obviously more advantageous than triangular Bézier surface, and hence extremely useful for geometric design, especially for the situation in which the surface needs to be evaluated quickly.  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