全文获取类型
收费全文 | 149797篇 |
免费 | 1582篇 |
国内免费 | 378篇 |
专业分类
化学 | 79953篇 |
晶体学 | 1637篇 |
力学 | 6589篇 |
综合类 | 7篇 |
数学 | 15172篇 |
物理学 | 48399篇 |
出版年
2020年 | 1112篇 |
2019年 | 1169篇 |
2018年 | 1475篇 |
2017年 | 1452篇 |
2016年 | 2466篇 |
2015年 | 1548篇 |
2014年 | 2422篇 |
2013年 | 6313篇 |
2012年 | 4929篇 |
2011年 | 6257篇 |
2010年 | 4278篇 |
2009年 | 4290篇 |
2008年 | 5691篇 |
2007年 | 5763篇 |
2006年 | 5403篇 |
2005年 | 4993篇 |
2004年 | 4395篇 |
2003年 | 3767篇 |
2002年 | 3577篇 |
2001年 | 4162篇 |
2000年 | 3108篇 |
1999年 | 2347篇 |
1998年 | 2042篇 |
1997年 | 2032篇 |
1996年 | 1838篇 |
1995年 | 1844篇 |
1994年 | 1842篇 |
1993年 | 1671篇 |
1992年 | 1943篇 |
1991年 | 2076篇 |
1990年 | 1867篇 |
1989年 | 1875篇 |
1988年 | 1822篇 |
1987年 | 1718篇 |
1986年 | 1657篇 |
1985年 | 2157篇 |
1984年 | 2299篇 |
1983年 | 1866篇 |
1982年 | 2051篇 |
1981年 | 1937篇 |
1980年 | 1857篇 |
1979年 | 2009篇 |
1978年 | 2177篇 |
1977年 | 2050篇 |
1976年 | 2090篇 |
1975年 | 2004篇 |
1974年 | 2059篇 |
1973年 | 2044篇 |
1972年 | 1341篇 |
1971年 | 1197篇 |
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
81.
Nikiforova E. A. Baibarodskikh D. V. Kirillov N. F. Dmitriev M. V. Zverev D. P. 《Russian Journal of Organic Chemistry》2020,56(12):2074-2078
Russian Journal of Organic Chemistry - 1-Aryl-3-(2-hydroxy-5-R-phenyl)prop-2-en-1-ones reacted with the Reformatsky reagent derived from methyl 1-bromocyclohexanecarboxylate to give... 相似文献
82.
Meccanica - The numerical solution of the steady-state response of a uniform taut string on visco-elastic support under a concentrated transverse moving load is addressed. By recasting the... 相似文献
83.
Rational design of methacrylate monomers containing oxadiazole moieties for single‐layer organic light emitting devices 下载免费PDF全文
Bogdan Zdyrko Yuriy Bandera Volodymyr Tsyalkovsky Christopher F. Huebner Jamie A. Shetzline Parul Rungta Ryan D. Roeder Charles Tonkin Stephen E. Creager Stephen H. Foulger 《Journal of Polymer Science.Polymer Physics》2015,53(23):1663-1673
Methacrylate derived monomers functionalized with pendant oxadiazole moieties were synthesized and copolymerized with carbazole containing monomers to form polymers with electron and hole transporting fragments in the same molecule. Substituents on the oxidazole moiety were varied with the purpose of bandgap tuning and performance optimization when employed in single‐layer organic light emitting devices (OLED). Quantum mechanical calculations of the HOMO‐LUMO levels of the oxidazole derivatives were used to down‐select promising candidates for chemical synthesis and testing in single‐layer OLEDs. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1663–1673 相似文献
84.
85.
86.
87.
Hydroxyl Radical Generation and DNA Nuclease Activity: A Mechanistic Study Based on a Surface‐Immobilized Copper Thioether Clip‐Phen Derivative 下载免费PDF全文
Adolfo I. B. Romo Dieric S. Abreu Dr. Tércio de F. Paulo Dr. Marta S. P. Carepo Prof. Eduardo H. S. Sousa Prof. Luis Lemus Prof. Carolina Aliaga Prof. Alzir A. Batista Prof. Otaciro R. Nascimento Prof. Héctor D. Abruña Prof. Izaura C. N. Diógenes 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(29):10081-10089
Coordination compounds of copper have been invoked as major actors in processes involving the reduction of molecular oxygen, mostly with the generation of radical species the assignment for which has, so far, not been fully addressed. In the present work, we have carried out studies in solution and on surfaces to gain insights into the nature of the radical oxygen species (ROS) generated by a copper(II) coordination compound containing a thioether clip‐phen derivative, 1,3‐bis(1,10‐phenanthrolin‐2‐yloxy)‐N‐(4‐(methylthio)benzylidene)propan‐2‐amine (2CP‐Bz‐SMe), enabling its adsorption/immobilization to gold surfaces. Whereas surface plasmon resonance (SPR) and electrochemistry of the adsorbed complex indicated the formation of a dimeric CuI intermediate containing molecular oxygen as a bridging ligand, scanning electrochemical microscopy (SECM) and nuclease assays pointed to the generation of a ROS species. Electron paramagnetic resonance (EPR) data reinforced such conclusions, indicating that radical production was dependent on the amount of oxygen and H2O2, thus pointing to a mechanism involving a Fenton‐like reaction that results in the production of OH.. 相似文献
88.
Square‐Planar Ruthenium(II) Complexes: Control of Spin State by Pincer Ligand Functionalization 下载免费PDF全文
Dr. Bjorn Askevold Dr. Marat M. Khusniyarov Dr. Wolfgang Kroener Dr. Klaus Gieb Prof. Paul Müller Dr. Eberhardt Herdtweck Dr. Frank W. Heinemann Dr. Martin Diefenbach Prof. Max C. Holthausen Veacheslav Vieru Prof. Liviu F. Chibotaru Prof. Sven Schneider 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(2):579-589
Functionalization of the PNP pincer ligand backbone allows for a comparison of the dialkyl amido, vinyl alkyl amido, and divinyl amido ruthenium(II) pincer complex series [RuCl{N(CH2CH2PtBu2)2}], [RuCl{N(CHCHPtBu2)(CH2CH2PtBu2)}], and [RuCl{N(CHCHPtBu2)2}], in which the ruthenium(II) ions are in the extremely rare square‐planar coordination geometry. Whereas the dialkylamido complex adopts an electronic singlet (S=0) ground state and energetically low‐lying triplet (S=1) state, the vinyl alkyl amido and the divinyl amido complexes exhibit unusual triplet (S=1) ground states as confirmed by experimental and computational examination. However, essentially non‐magnetic ground states arise for the two intermediate‐spin complexes owing to unusually large zero‐field splitting (D>+200 cm?1). The change in ground state electronic configuration is attributed to tailored pincer ligand‐to‐metal π‐donation within the PNP ligand series. 相似文献
89.
90.