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   276568篇
  免费   4153篇
  国内免费   790篇
化学   157530篇
晶体学   3595篇
力学   10113篇
综合类   10篇
数学   33887篇
物理学   76376篇
  2021年   2593篇
  2020年   2882篇
  2019年   3208篇
  2018年   4417篇
  2017年   4160篇
  2016年   6261篇
  2015年   4139篇
  2014年   5678篇
  2013年   12958篇
  2012年   11030篇
  2011年   12780篇
  2010年   8751篇
  2009年   8244篇
  2008年   11914篇
  2007年   11912篇
  2006年   10980篇
  2005年   10135篇
  2004年   8845篇
  2003年   7832篇
  2002年   7414篇
  2001年   7018篇
  2000年   5628篇
  1999年   4165篇
  1998年   3572篇
  1997年   3580篇
  1996年   3509篇
  1995年   2779篇
  1994年   2925篇
  1993年   2956篇
  1992年   3106篇
  1991年   3085篇
  1990年   2942篇
  1989年   2894篇
  1988年   2783篇
  1987年   2763篇
  1986年   2648篇
  1985年   3488篇
  1984年   3628篇
  1983年   2849篇
  1982年   3216篇
  1981年   3058篇
  1980年   2837篇
  1979年   3008篇
  1978年   3106篇
  1977年   3089篇
  1976年   3106篇
  1975年   2933篇
  1974年   2907篇
  1973年   3070篇
  1972年   1985篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
Journal of Applied Spectroscopy - Aqueous solutions of human hemoglobin have been studied by the multi-angle static light scattering method. The tendency of sickle-shaped erythrocytes to aggregate...  相似文献   
92.
Russian Journal of Organic Chemistry - A procedure has been proposed for the synthesis of a series of substituted N-(1,3-thiazol-2-yl)-pyrimidin-2-amines and N-(pyrimidin-2-yl)thioureas by...  相似文献   
93.
Optical and Quantum Electronics - In the past few decades, the academic research and industrial synergy is dramatically accelerating to conceptualize high data rate services. The congestion in the...  相似文献   
94.
Russian Journal of Organic Chemistry - Selenopheno[2,3-d]pyrimidine- and selenopheno[2,3-d][1,2,3]triazine-containing compounds were synthesized starting from...  相似文献   
95.
It is known that under resonance conditions, a group of strongly interacting bosonic atoms, trapped in a double-well potential, mimics a single particle, performing Rabi oscillations between the wells. By implication, all atoms need to tunnel at roughly the same time, even though the Bose–Hubbard Hamiltonian accounts only for one-atom-at-a-time transfers. The mechanism of this collective behavior is analyzed, the Rabi frequencies in the process are evaluated, and the limitation of this simple picture is discussed. In particular, it is shown that the small rapid oscillations superimposed on the slow Rabi cycle result from splitting the transferred cluster at the sudden onset of tunnelling, and disappear if tunnelling is turned on gradually.  相似文献   
96.
Partially fluorinated poly(arylene ether sulfone) multiblock copolymers bearing perfluorosulfonic functions (ps‐PES‐FPES), with ionic exchange capacity (IEC) ranging between 0.9 and 1.5 meq H+/g, are synthesized by regioselective bromination of partially fluorinated poly(arylene ether sulfone) multiblock copolymers (PES‐FPES), followed by Ullman coupling reaction with lithium 1,1,2,2‐tetrafluoro‐2‐(1,1,2,2‐tetrafluoro‐2‐iodoethoxy)ethanesulfonate. The PES‐FPES are prepared by aromatic nucleophilic substitution reaction by an original approach, that is, “one pot two reactions synthesis.” The chemical structures of polymers are analyzed by 1H and 19F NMR spectroscopy. The resulted ionomers present two distinct glass transitions and α relaxations revealing phase separation between the hydrophilic and the hydrophobic domains. The phase separation is observed at much lower block lengths of ps‐PES‐FPES as compared with the literature. AFM and SANS observations supported the phase separation, the hydrophilic domains are well dispersed but the connectivity to each other depends on the ps‐PES block lengths. The thermomechanical behavior, the water up‐take, and the conductivity of the ps‐PES‐FPES membranes are compared with those of Nafion 117® and randomly functionalized polysulfone (ps‐PES). Conductivities close or higher to those of Nafion 117® are obtained. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1941–1956  相似文献   
97.
Saleh  Z. M.  Nasser  H.  Özkol  E.  Günöven  M.  Abak  K.  Canli  S.  Bek  A.  Turan  R. 《Journal of nanoparticle research》2015,17(10):1-12
Journal of Nanoparticle Research - Plasmonic interfaces consisting of silver nanoparticles of different sizes (50–100&;nbsp;nm) have been processed by the self-assembled dewetting...  相似文献   
98.
The biomimetic sol—gel synthesis of silicon—chitosan-containing glycerohydrogels was carried out using silicon tetraglycerolate as a precursor. It was found that chitosan accelerates gel formation in weakly acidic media. In more acidic media, the kinetics of the process changes according to the curve with a maximum, which can be attributed to different mechanisms of silanol condensation before and after the isoelectric point. The investigated silicon—chitosan-containing glycerohydrogels exhibit antibacterial, anti-inflammatory, and wound healing activity. The synthesized hybrid glycerohydrogels are promising materials for biomedical applications.  相似文献   
99.
100.
A fully quantitative theory of the relationship between protein conformation and optical spectroscopy would facilitate deeper insights into biophysical and simulation studies of protein dynamics and folding. In contrast to intense bands in the far-ultraviolet, near-UV bands are much weaker and have been challenging to compute theoretically. We report some advances in the accuracy of calculations in the near-UV, which were realised through the consideration of the vibrational structure of the electronic transitions of aromatic side chains.  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