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   1574篇
  免费   7篇
  国内免费   10篇
化学   495篇
晶体学   5篇
力学   20篇
数学   858篇
物理学   213篇
  2023年   3篇
  2022年   5篇
  2021年   3篇
  2020年   7篇
  2019年   3篇
  2018年   4篇
  2017年   5篇
  2016年   7篇
  2015年   4篇
  2014年   30篇
  2013年   138篇
  2012年   23篇
  2011年   214篇
  2010年   134篇
  2009年   14篇
  2008年   26篇
  2007年   39篇
  2006年   77篇
  2005年   58篇
  2004年   53篇
  2003年   50篇
  2002年   48篇
  2001年   25篇
  2000年   25篇
  1999年   34篇
  1998年   31篇
  1997年   24篇
  1996年   30篇
  1995年   44篇
  1994年   35篇
  1993年   40篇
  1992年   121篇
  1991年   136篇
  1990年   34篇
  1989年   43篇
  1988年   4篇
  1987年   5篇
  1986年   7篇
  1985年   4篇
  1984年   2篇
  1982年   2篇
排序方式: 共有1591条查询结果,搜索用时 0 毫秒
1.
We give the estimate for the growth of the group Fourier transforms of the Hardy spaces and establish and Hp-multipleir theorem satisfying Michlin condition on the Heisenberg group.  相似文献   
2.
In this paper, we consider a class of functional equations and prove three theorems which give the approximation properties and error estimates of the optimal polynomial approximation of slution of those functional equations.  相似文献   
3.
Note on Bernstein polynomials and Kantorovich polynomials   总被引:2,自引:0,他引:2  
We obtain two asymptotic representations of remainder of approximation of derivable functions by Bernstein polynomials and Kantorovich polynomials separately.  相似文献   
4.
To further evaluate the causality between endogenous pyrogen (EP)-induced fever and cyclic adenosine-3',5'-monophosphate (cyclic AMP) level, the effects of sodium salicylate (SS) on the febrile response and increased levels of cyclic AMP in both cerebrospinal fluid (c.s.f.) and plasma during EP-induced fever in rabbits were observed. The results suggest that cyclic AMP is probably involved in the central mediation of EP-induced fever and that increased concentration of cyclic AMP in c.s.f. associated with EP-induced fever is not the result of temperature elevation but appears to be caused by the increased synthesis in the central nervous system. In addition it is confirmed that blood is impossibly a contributory source of increased cyclic AMP in c.s.f. during EP fever, and that SS may act subsequent to the increase in cyclic AMP.  相似文献   
5.
The purpose of this paper is to investigate the problem of approximating fixed points of non-Lipschitizian asymptotically pseudocontractive mappings in an arbitrary real Banach space by the modified Ishikawa iterative sequences with errors.  相似文献   
6.
The effect of hormones on progesterone secretion by 6-8 week human trophoblast tissue cultured in serum-free medium has been investigated. GnRH at low concentration (10(-10)-10(-8) mol/L) stimulated progesterone secretion, while high dose (10(-6)-10(-5) mol/L) produced inhibitory effect. The progesterone secretion could be significantly decreased by addition of anti-hCG antiserum or monoclonal anti-hCG IgG in a dose- and time-dependent manner. Various concentrations of TRH, PGE2, PGF2 alpha, testosterone and estradiol were found to be ineffective. These data indicate clearly that progesterone production by human trophoblast tissue at early gestation stage is under the modulation of GnRH and hCG.  相似文献   
7.
In this paper, we propose and analyze an SQP-type method for solving linearly constrained convex minimization problems where the objective functions are too complex to be evaluated exactly. Some basic results for global convergence and local superlinear convergence are obtained according to the properties of the approximation sequence. We illustrate the applicability of our approach by proposing a new method for solving two-stage stochastic programs with fixed recourse.  相似文献   
8.
Natural convections in conjugated single and double enclosures   总被引:7,自引:0,他引:7  
The natural convection in single and double conjugated enclosures are numerically investigated. The single and double enclosures are formed by low conductance walls with finite thickness. The outside vertical surfaces of the conducting walls are of the third kind of boundary condition while the top and bottom outside surfaces are adiabatic. The problem studied is characterized by a dominant horizontal temperature gradient and the thermal boundary conditions at the cavity surfaces can not be specified in priori. Numerical results reveal the characteristics in such kind of enclosures and show the importance of the thermal boundary conditions on the natural convection in enclosures. It is also found that the natural convections in the conjugated double enclosures are basically the same, with a major difference in their fluid temperature levels.  相似文献   
9.
Let ∑, Г be two n-by-n diagonal matrices with σi,γi as their diagonals. For the inverse eigenvalue problem: look for y∈Rn such that Г + yyT is similar to ∑, we prove thatu also the sufficient condition for the solvability of this inverse problem. Its solution (set) is given explicitly. In some case, the problem is unstable. But we prove that the sums of the square of some contigious components keep stable, i.e., small sum keeps small, large sum has a small relative perturbation, see Theorem 3.  相似文献   
10.
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