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   494913篇
  免费   6229篇
  国内免费   1424篇
化学   233983篇
晶体学   6491篇
力学   18806篇
综合类   13篇
数学   50017篇
物理学   133237篇
无线电   60019篇
  2021年   4145篇
  2020年   4721篇
  2019年   5039篇
  2018年   6477篇
  2017年   6258篇
  2016年   9622篇
  2015年   5938篇
  2014年   9386篇
  2013年   21610篇
  2012年   16533篇
  2011年   20331篇
  2010年   14646篇
  2009年   15215篇
  2008年   19973篇
  2007年   20309篇
  2006年   18994篇
  2005年   17298篇
  2004年   16084篇
  2003年   14385篇
  2002年   14050篇
  2001年   15778篇
  2000年   12392篇
  1999年   10032篇
  1998年   8613篇
  1997年   8280篇
  1996年   7962篇
  1995年   7211篇
  1994年   7100篇
  1993年   6741篇
  1992年   7379篇
  1991年   7475篇
  1990年   7112篇
  1989年   6787篇
  1988年   6615篇
  1987年   6002篇
  1986年   5648篇
  1985年   7187篇
  1984年   7264篇
  1983年   5812篇
  1982年   5809篇
  1981年   5795篇
  1980年   5340篇
  1979年   5659篇
  1978年   5786篇
  1977年   5678篇
  1976年   5568篇
  1975年   5141篇
  1974年   5108篇
  1973年   5116篇
  1972年   3626篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
201.
Russian Journal of Applied Chemistry - A spectral-kinetic investigation was carried out to study the fluorescent properties of complexes of molecules of photochromic nitro-substituted spiropyran...  相似文献   
202.
Journal of Thermal Analysis and Calorimetry - The operating temperature of Li-ion batteries used in modern electric vehicles should be maintained within an allowable range to avoid thermal runaway...  相似文献   
203.
Journal of Analytical Chemistry - A new liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method has been developed and validated for alfuzosin quantification in...  相似文献   
204.
Russian Chemical Bulletin - Gradient polymer composites were prepared by melt-mixing of carbon black and polypropylene in a compounder and subsequent hot pressing of pellets. The thermally treated...  相似文献   
205.
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   
206.
207.
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   
208.
209.
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   
210.
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   
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