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   380246篇
  免费   4650篇
  国内免费   1219篇
化学   208912篇
晶体学   5750篇
力学   15391篇
综合类   5篇
数学   42534篇
物理学   113523篇
  2020年   3041篇
  2019年   3352篇
  2018年   4250篇
  2017年   4172篇
  2016年   6628篇
  2015年   4436篇
  2014年   6456篇
  2013年   17338篇
  2012年   13177篇
  2011年   15929篇
  2010年   10708篇
  2009年   10598篇
  2008年   14599篇
  2007年   14501篇
  2006年   13606篇
  2005年   12571篇
  2004年   11301篇
  2003年   10078篇
  2002年   9854篇
  2001年   11889篇
  2000年   8866篇
  1999年   7009篇
  1998年   5434篇
  1997年   5540篇
  1996年   5250篇
  1995年   4817篇
  1994年   4743篇
  1993年   4577篇
  1992年   5287篇
  1991年   5377篇
  1990年   5079篇
  1989年   4995篇
  1988年   4997篇
  1987年   4901篇
  1986年   4649篇
  1985年   6180篇
  1984年   6296篇
  1983年   5137篇
  1982年   5402篇
  1981年   5211篇
  1980年   5030篇
  1979年   5307篇
  1978年   5587篇
  1977年   5416篇
  1976年   5506篇
  1975年   5007篇
  1974年   5069篇
  1973年   5395篇
  1972年   3404篇
  1971年   2661篇
排序方式: 共有10000条查询结果,搜索用时 154 毫秒
11.
Journal of Structural Chemistry - Atomic and electronic structures of cyclic organosilicon compound 9,9,10,10-tetraethynyl-9,10-dihydrodisilaanthracene are studied by the density functional theory....  相似文献   
12.
Russian Journal of General Chemistry - The review article traces the main trends of the synthetic approach to the solution of the problem of overcoming the resistance of pathogenic bacterial...  相似文献   
13.
Low-flow chromatography has a rich history of innovation but has yet to reach widespread implementation in bioanalytical applications. Improvements in pump technology, microfluidic connections, and nano-electrospray sources for MS have laid the groundwork for broader application, and innovation in this space has accelerated in recent years. This article reviews the instrumentation used for nano-flow LC, the types of columns employed, and strategies for multidimensionality of separations, which are key to the future state of the technique to the high-throughput needs of modern bioanalysis. An update of the current applications where nano-LC is widely used, such as proteomics and metabolomics, is discussed. But the trend toward biopharmaceutical development of increasingly complex, targeted, and potent therapeutics for the safe treatment of disease drives the need for ultimate selectivity and sensitivity of our analytical platforms for targeted quantitation in a regulated space. The selectivity needs are best addressed by mass spectrometric detection, especially at high resolutions, and exquisite sensitivity is provided by nano-electrospray ionization as the technology continues to evolve into an accessible, robust, and easy-to-use platform.  相似文献   
14.

A kinetic study of the effect of thermoheliox (inhalation of a helium and oxygen mixture, 70 °C) on the functional hemodynamics of the human brain by functional magnetic resonance imaging was carried out. The dynamic responses of the BOLD signal were found to be biphasic. An empirical equation describing the first phase of the hemodynamic response to visual stimulus was proposed. It was shown that preliminary inhalation of thermoheliox stimulates the hemodynamic responses by slowing down the vasoconstriction.

  相似文献   
15.
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   
16.
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   
17.
Acta Mathematica Hungarica - Minkowski’s classical existence theorem provides necessary and sufficient conditions for a Borel measure on the unit sphere of Euclidean space to be the surface...  相似文献   
18.
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   
19.
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   
20.
Theoretical and Mathematical Physics - We consider three one-dimensional superconducting structures: 1) the one with $$p$$ -wave superconductivity; 2) the main experimental model of a nanowire with...  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