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   526958篇
  免费   6679篇
  国内免费   1614篇
化学   285152篇
晶体学   8007篇
力学   22652篇
综合类   18篇
数学   60484篇
物理学   158938篇
  2021年   4094篇
  2020年   4641篇
  2019年   4958篇
  2018年   6286篇
  2017年   6172篇
  2016年   9733篇
  2015年   6261篇
  2014年   9470篇
  2013年   23809篇
  2012年   18014篇
  2011年   22272篇
  2010年   15438篇
  2009年   15067篇
  2008年   20294篇
  2007年   20301篇
  2006年   18990篇
  2005年   17224篇
  2004年   15924篇
  2003年   14059篇
  2002年   13872篇
  2001年   15678篇
  2000年   11830篇
  1999年   9429篇
  1998年   7875篇
  1997年   7624篇
  1996年   7409篇
  1995年   6715篇
  1994年   6467篇
  1993年   6304篇
  1992年   7099篇
  1991年   7157篇
  1990年   6834篇
  1989年   6739篇
  1988年   6704篇
  1987年   6617篇
  1986年   6281篇
  1985年   8193篇
  1984年   8403篇
  1983年   6761篇
  1982年   7084篇
  1981年   6930篇
  1980年   6582篇
  1979年   6984篇
  1978年   7253篇
  1977年   7052篇
  1976年   7006篇
  1975年   6544篇
  1974年   6432篇
  1973年   6600篇
  1972年   4545篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
211.
ABSTRACT

A new density functional for the study of associating inhomogeneous fluids based on Wertheim's first-order thermodynamic perturbation theory is presented and compared to the most currently used associating density functionals. This functional is developed using the weighted density approximation in the range of association of hard spheres. We implement this functional within the framework of classical density functional theory together with modified fundamental measure theory to account for volume exclusion of hard spheres. This approach is tested against molecular simulations from literature of pure associating hard spheres and mixtures of non-associationg and associating hard spheres with different number of bonding sites close to a hard uniform wall. Furthermore, we compare and review our results with the performance of associating functionals from literature, one based on fundamental measure theory and the inhomogeneous version of Wertheim's perturbation theory. Results obtained with classical DFT and the three functionals show excellent agreement with molecular simulations in systems with one hard wall. For the cases of small pores where only one or two layers of fluid are allowed discrepancies between results with classical DFT and molecular simulations were found.  相似文献   
212.
213.
Journal of Structural Chemistry - Thermodynamic characteristics are calculated for aqueous alkanolamine solutions that are obtained by substituting alkyl radicals for the protons in the amino group...  相似文献   
214.
Shi  D.  Feng  J.  Wang  J.  Zhao  W.  Li  X. 《Kinetics and Catalysis》2020,61(5):750-757
Kinetics and Catalysis - A series of Cu-SSZ-13@CeO2 catalysts with surface modification with CeO2 was prepared by the modified self-resemble method based on the one-pot synthesized Cu-SSZ-13...  相似文献   
215.
216.
The current work utilizes three separate techniques to study the physical aging process in amorphous poly(ethylene furanoate) (PEF), which is a recently introduced engineering thermoplastic with enhanced properties compared to petroleum‐sourced poly(ethylene terephthalate). Differential scanning calorimetry aging experiments were conducted at multiple aging temperatures and times, and the resultant enthalpic recovery values compared to the theoretical maximum enthalpy loss evaluated from calculations involving extrapolation of the equilibrium liquid line. Density measurements reveal densification of the matrix for the aged versus unaged samples, and provide an estimate for the reduction in free volume for the aged samples. Complementary oxygen permeation and pressure‐decay sorption experiments provide independent verification of the free volume reduction mechanism for physical aging in glassy polymers. The current work provides the first detailed aging study for PEF. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 389–399  相似文献   
217.
Radiophysics and Quantum Electronics - We propose and experimentally test a numerical method for correction of the influence of fluctuations in the distance to objects during noncontact probing in...  相似文献   
218.
Optics and Spectroscopy - The population kinetics of a two-level system has been theoretically investigated taking into account the transfer of spontaneous radiation under continuous optical...  相似文献   
219.
220.
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