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   1483404篇
  免费   44964篇
  国内免费   19986篇
化学   763999篇
晶体学   21562篇
力学   81343篇
综合类   823篇
数学   257560篇
物理学   423067篇
  2021年   16825篇
  2020年   19181篇
  2019年   19547篇
  2018年   17910篇
  2017年   16353篇
  2016年   32989篇
  2015年   25212篇
  2014年   35797篇
  2013年   81452篇
  2012年   49486篇
  2011年   49223篇
  2010年   45178篇
  2009年   46956篇
  2008年   44995篇
  2007年   40935篇
  2006年   44120篇
  2005年   36871篇
  2004年   36043篇
  2003年   32893篇
  2002年   33325篇
  2001年   33055篇
  2000年   28037篇
  1999年   25049篇
  1998年   22886篇
  1997年   22665篇
  1996年   22681篇
  1995年   20536篇
  1994年   19889篇
  1993年   19208篇
  1992年   19404篇
  1991年   19533篇
  1990年   18561篇
  1989年   18453篇
  1988年   17896篇
  1987年   17833篇
  1986年   16868篇
  1985年   23153篇
  1984年   24216篇
  1983年   20312篇
  1982年   21893篇
  1981年   21051篇
  1980年   20407篇
  1979年   20692篇
  1978年   21877篇
  1977年   21492篇
  1976年   21270篇
  1975年   19925篇
  1974年   19590篇
  1973年   20039篇
  1972年   14521篇
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
91.
Li  Mingjun  Zhu  Li 《应用数学和力学(英文版)》2021,42(8):1171-1182
This study is to numerically test the interfacial instability of ferrofluid flow under the presence of a vacuum magnetic field. The ferrofluid parabolized stability equations(PSEs) are derived from the ferrofluid stability equations and the Rosensweig equations, and the characteristic values of the ferrofluid PSEs are given to describe the ellipticity of ferrofluid flow. Three numerical models representing specific cases considering with/without a vacuum magnetic field or viscosity are created to mathematically examine the interfacial instability by the computation of characteristic values. Numerical investigation shows strong dependence of the basic characteristic of ferrofluid Rayleigh-Taylor instability(RTI) on viscosity of ferrofluid and independence of the vacuum magnetic field.For the shock wave striking helium bubble, the magnetic field is not able to trigger the symmetry breaking of bubble but change the speed of the bubble movement. In the process of droplet formation from a submerged orifice, the collision between the droplet and the liquid surface causes symmetry breaking. Both the viscosity and the magnetic field exacerbate symmetry breaking. The computational results agree with the published experimental results.  相似文献   
92.
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   
93.
Crystallography Reports - The crystal and molecular structures of Cl–C6H4–O–C16H33 (I) have been studied, and its differential scanning calorimetry (DSC) study is performed....  相似文献   
94.
Gawad  Dina A.  Elnaggar  Mai M.  Belal  Tarek S. 《Chromatographia》2022,85(7):617-628
Chromatographia - The present work deals with the optimization, validation and application of a versatile HPLC–DAD method for concurrent estimation of nine antimicrobials and proton pump...  相似文献   
95.
David Hull     
Journal of Optimization Theory and Applications -  相似文献   
96.
Algebra and Logic - Unary functions definable in o-stable ordered groups of nonvaluational type are studied. Such functions are proved to be piecewise monotone and continuous.  相似文献   
97.
Journal of Applied Mechanics and Technical Physics - A refined model of viscoelastic-plastic deformation of flexible plates with spatial reinforcement structures has been developed. Strains of the...  相似文献   
98.
Crystallography Reports - The recombinant С-terminal fragment of myomesin-2 was purified to a homogeneous state. The crystallization conditions for the С-terminal fragment of myomesin-2...  相似文献   
99.
Faul  Peter F. 《Semigroup Forum》2021,102(3):655-673
Semigroup Forum - It is well known that the set of isomorphism classes of extensions of groups with abelian kernel is characterized by the second cohomology group. In this paper we generalise this...  相似文献   
100.
Kumar  Sanjay  Jiwari  Ram  Mittal  R. C.  Awrejcewicz  Jan 《Nonlinear dynamics》2021,104(1):661-682
Nonlinear Dynamics - In this article, the authors simulate and study dark and bright soliton solutions of 1D and 2D regularized long wave (RLW) models. The RLW model occurred in various fields such...  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