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   633317篇
  免费   7730篇
  国内免费   1748篇
化学   338989篇
晶体学   9357篇
力学   28325篇
综合类   20篇
数学   77441篇
物理学   188663篇
  2021年   4975篇
  2020年   5734篇
  2019年   6239篇
  2018年   8176篇
  2017年   7974篇
  2016年   12347篇
  2015年   7783篇
  2014年   11770篇
  2013年   28541篇
  2012年   21829篇
  2011年   26535篇
  2010年   18693篇
  2009年   18338篇
  2008年   24524篇
  2007年   24546篇
  2006年   22719篇
  2005年   20439篇
  2004年   18887篇
  2003年   16802篇
  2002年   16558篇
  2001年   18140篇
  2000年   14004篇
  1999年   10997篇
  1998年   9276篇
  1997年   9058篇
  1996年   8761篇
  1995年   7920篇
  1994年   7946篇
  1993年   7567篇
  1992年   8555篇
  1991年   8549篇
  1990年   8244篇
  1989年   7909篇
  1988年   8085篇
  1987年   7858篇
  1986年   7464篇
  1985年   9715篇
  1984年   10034篇
  1983年   8204篇
  1982年   8345篇
  1981年   8259篇
  1980年   7915篇
  1979年   8225篇
  1978年   8602篇
  1977年   8431篇
  1976年   8446篇
  1975年   7746篇
  1974年   7849篇
  1973年   8002篇
  1972年   5647篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
Central European Journal of Operations Research - Sustainability practice within supply chains remains in an early development phase. Enterprises still need tools that support the integration of...  相似文献   
32.
Nikazad  T.  Karimpour  M. 《Numerical Algorithms》2021,86(3):1265-1284
Numerical Algorithms - This paper considers different versions of block-column iterative (BCI) methods for solving nonnegative constrained linear least squares problems. We present the convergence...  相似文献   
33.
Journal of Applied Mechanics and Technical Physics - Implicit finite-volume predictor-corrector algorithms based on the splitting method are proposed for the numerical solution of the...  相似文献   
34.
Nonlinear Dynamics - Given a data-set of Ribonucleic acid (RNA) sequences we can infer the phylogenetics of the samples and tackle the information for scientific purposes. Based on current data and...  相似文献   
35.
Optics and Spectroscopy - The current–voltage characteristics and photocurrent of “monolithic” diode optical pairs optically coupled by a substrate made of InAs common for them...  相似文献   
36.
Set-Valued and Variational Analysis - In a Hilbert framework ℌ, we study the convergence properties of a Newton-like inertial dynamical system governed by a general maximally monotone...  相似文献   
37.
We prove a well-posedness result for two pseudo-parabolic problems, which can be seen as two models for the same electrical conduction phenomenon in heterogeneous media, neglecting the magnetic field. One of the problems is the concentration limit of the other one, when the thickness of the dielectric inclusions goes to zero. The concentrated problem involves a transmission condition through interfaces, which is mediated by a suitable Laplace-Beltrami type equation.  相似文献   
38.
Kobayashi  M.  Zhang  Y.  Ishikawa  H.  Sun  J.  Oddershede  J.  Juul Jensen  D.  Miura  H. 《Experimental Mechanics》2021,61(5):817-828
Experimental Mechanics - The internal strain distribution developing during plastic deformation is important for understanding the mechanical properties of polycrystalline materials. Such...  相似文献   
39.
Russian Physics Journal - The specific features of the sorption activity of silver nanoparticles (AgNPs) on biodegradable polymers of natural (collagen) and artificial (polyamide 6.6) origin have...  相似文献   
40.
A formal computation proving a new operator identity from known ones is, in principle, restricted by domains and codomains of linear operators involved, since not any two operators can be added or composed. Algebraically, identities can be modelled by noncommutative polynomials and such a formal computation proves that the polynomial corresponding to the new identity lies in the ideal generated by the polynomials corresponding to the known identities. In order to prove an operator identity, however, just proving membership of the polynomial in the ideal is not enough, since the ring of noncommutative polynomials ignores domains and codomains. We show that it suffices to additionally verify compatibility of this polynomial and of the generators of the ideal with the labelled quiver that encodes which polynomials can be realized as linear operators. Then, for every consistent representation of such a quiver in a linear category, there exists a computation in the category that proves the corresponding instance of the identity. Moreover, by assigning the same label to several edges of the quiver, the algebraic framework developed allows to model different versions of an operator by the same indeterminate in the noncommutative polynomials.  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