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   271624篇
  免费   1913篇
  国内免费   626篇
化学   144490篇
晶体学   4296篇
力学   11998篇
综合类   9篇
数学   29911篇
物理学   83459篇
  2020年   2384篇
  2019年   2583篇
  2018年   3172篇
  2017年   3156篇
  2016年   4665篇
  2015年   2746篇
  2014年   4379篇
  2013年   10835篇
  2012年   8248篇
  2011年   10078篇
  2010年   7227篇
  2009年   6982篇
  2008年   9465篇
  2007年   9650篇
  2006年   9006篇
  2005年   8195篇
  2004年   7547篇
  2003年   6826篇
  2002年   6754篇
  2001年   7357篇
  2000年   5697篇
  1999年   4387篇
  1998年   3885篇
  1997年   3867篇
  1996年   3612篇
  1995年   3352篇
  1994年   3510篇
  1993年   3207篇
  1992年   3684篇
  1991年   3673篇
  1990年   3605篇
  1989年   3462篇
  1988年   3575篇
  1987年   3472篇
  1986年   3293篇
  1985年   4367篇
  1984年   4635篇
  1983年   3877篇
  1982年   4007篇
  1981年   3934篇
  1980年   3910篇
  1979年   3878篇
  1978年   4191篇
  1977年   4110篇
  1976年   4175篇
  1975年   3852篇
  1974年   3895篇
  1973年   4050篇
  1972年   2851篇
  1971年   2378篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Russian Journal of General Chemistry - Acylation of 5,7-di(tert-butyl)-2-{5,8-dimethyl-4-[(3,5-dimethylphenyl)amino]quinolin-2-yl}-3-[(3,5-dimethylphenyl)amino]tropone leads to...  相似文献   
62.
Russian Journal of General Chemistry - Azomethines were synthesized from 2,4,6-trimethylaniline, salicylaldehyde, and its 3(5)-halogen derivatives, as well as their complexes with zinc(II) (ZnL2)....  相似文献   
63.
Russian Chemical Bulletin - The method of one-stage catalytic polycyclocondensation according to the B4 + AB scheme was used to synthesize new tetraarm star-shaped oligoimides (SOIs) with terminal...  相似文献   
64.
Russian Chemical Bulletin - Two new D—π—A chromophores with the tricyanofuranyl acceptor (A), an amphi-divinyl quinoxaline π-electron conjugated bridge, and the carbazole or...  相似文献   
65.
Synchrotron radiation-based Fourier transform infrared spectroscopy enables access to vibrational information from mid over far infrared to even terahertz domains. This information may prove critical for the elucidation of fundamental bio-molecular phenomena including folding-mediated innate host defence mechanisms. Antimicrobial peptides (AMPs) represent one of such phenomena. These are major effector molecules of the innate immune system, which favour attack on microbial membranes. AMPs recognise and bind to the membranes whereupon they assemble into pores or channels destabilising the membranes leading to cell death. However, specific molecular interactions responsible for antimicrobial activities have yet to be fully understood. Herein we probe such interactions by assessing molecular specific variations in the near-THz 400–40 cm−1 range for defined helical AMP templates in reconstituted phospholipid membranes. In particular, we show that a temperature-dependent spectroscopic analysis, supported by 2D correlative tools, provides direct evidence for the membrane-induced and folding-mediated activity of AMPs. The far-FTIR study offers a direct and information-rich probe of membrane-related antimicrobial interactions.  相似文献   
66.
Carbonized lignin has been proposed as a sustainable and domestic source of activated, amorphous, graphitic, and nanostructured carbon for many industrial applications as the structure can be tuned through processing conditions. However, the inherent variability of lignin and its complex physicochemical structure resulting from feedstock and pulping selection make the Process-Structure-Property-Performance (PSPP) relationships hard to define. In this work, radial distribution functions (RDFs) from synchrotron X-ray and neutron scattering of lignin-based carbon composites (LBCCs) are investigated using the Hierarchical Decomposition of the Radial Distribution Function (HDRDF) modelling method to characterize the local atomic environment and develop quantitative PSPP relationships. PSPP relationships for LBCCs defined by this work include crystallite size dependence on lignin feedstock as well as increasing crystalline volume fraction, nanoscale composite density, and crystallite size with increasing reduction temperature.  相似文献   
67.
Cellulose - In this work, we have developed methods of synthesis of cellulose nanocrystal (CNC) conjugates with chlorotriazine reactive dyes (RDs)—reactive violet, reactive-bright red and...  相似文献   
68.
Russian Chemical Bulletin - New potential biologically active derivatives, in which the sterically hindered pyrocatechol moiety is linked through a 2-thioacetyl covalent bridge to a number of...  相似文献   
69.
Russian Chemical Bulletin - The tandem Knoevenagel—Michael—intramolecular ammonolysis—alkylation reaction was used to synthesize functionalized tetrahydropyridones. The molecular...  相似文献   
70.
Russian Chemical Bulletin - The kinetic regularities of thermal destruction of polycarbonate films containing Pt, Au, Ag, and Ni nanoparticles were studied. Scanning and transmission electron...  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