全文获取类型
收费全文 | 1396193篇 |
免费 | 29692篇 |
国内免费 | 7705篇 |
专业分类
化学 | 699761篇 |
晶体学 | 20965篇 |
力学 | 76425篇 |
综合类 | 114篇 |
数学 | 247149篇 |
物理学 | 389176篇 |
出版年
2021年 | 13487篇 |
2020年 | 15927篇 |
2019年 | 16047篇 |
2018年 | 16149篇 |
2017年 | 14831篇 |
2016年 | 29357篇 |
2015年 | 21083篇 |
2014年 | 30386篇 |
2013年 | 74266篇 |
2012年 | 41249篇 |
2011年 | 41567篇 |
2010年 | 40082篇 |
2009年 | 41987篇 |
2008年 | 40043篇 |
2007年 | 36909篇 |
2006年 | 38641篇 |
2005年 | 33878篇 |
2004年 | 33446篇 |
2003年 | 30768篇 |
2002年 | 30984篇 |
2001年 | 30132篇 |
2000年 | 25738篇 |
1999年 | 22976篇 |
1998年 | 21206篇 |
1997年 | 21110篇 |
1996年 | 21175篇 |
1995年 | 19183篇 |
1994年 | 18667篇 |
1993年 | 18201篇 |
1992年 | 18273篇 |
1991年 | 18541篇 |
1990年 | 17748篇 |
1989年 | 17819篇 |
1988年 | 17444篇 |
1987年 | 17343篇 |
1986年 | 16253篇 |
1985年 | 22645篇 |
1984年 | 23885篇 |
1983年 | 20075篇 |
1982年 | 21673篇 |
1981年 | 20902篇 |
1980年 | 20233篇 |
1979年 | 20501篇 |
1978年 | 21776篇 |
1977年 | 21397篇 |
1976年 | 21092篇 |
1975年 | 19819篇 |
1974年 | 19477篇 |
1973年 | 19931篇 |
1972年 | 14431篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
321.
Elasasy M. E. A. Elnaggar D. H. Hafez N. A. Abdel Azab M. E. Amr A. E. Omran M. M. Mohamed A. M. 《Russian Journal of General Chemistry》2021,91(5):915-925
Russian Journal of General Chemistry - Some new fluoro-heterocyclic compounds containing thiazole and pyridine moities have been synthesized and studied for their antiproliferative activity.... 相似文献
322.
Journal of Thermal Analysis and Calorimetry - In the present work, pyrolysis kinetic mechanism was studied for regenerated cellulosic fiber (RCF) and composite RCF containing silicon/nitrogen flame... 相似文献
323.
In this research article, we describe the synthesis and characterization of mononuclear and dinuclear Cu complexes bound by a family of tridentate redox-active ligands with tunable H-bonding donors. The mononuclear Cu-anion complexes were oxidized to the corresponding “high-valent” intermediates by oxidation of the redox-active ligand. These species were capable of oxidizing phenols with weak O−H bonds via H-atom abstraction. Thermodynamic analysis of the H-atom abstractions, which included reduction potential measurements, pKa determination and kinetic studies, revealed that modification of the anion coordinated to the Cu and changes in the H-bonding donor did not lead to major differences in the reactivity of the “high-valent” CuY complexes (Y: hydroxide, phenolate and acetate), which indicated that the tridentate ligand scaffold acts as the H+ and e− acceptor. 相似文献
324.
Colloid Journal - An Erratum to this paper has been published: https://doi.org/10.1134/S1061933X21330024 相似文献
325.
Journal of Thermal Analysis and Calorimetry - This article considers viscoelastic effects on the enhancement of transportation of heat in thin-film flow when the relaxation time phenomenon is... 相似文献
326.
Yuyang Ji Rebekka S. Klausen 《Journal of polymer science. Part A, Polymer chemistry》2021,59(21):2521-2529
The synthesis of vinyl alcohol copolymers is limited due to the poor radical reactivity of vinyl acetate (VAc), the traditional precursor to polyvinyl alcohol (PVA). Main group monomers such as BN 2-vinylnaphthalene (BN2VN) have attracted attention as alternatives to VAc to form side chain hydroxyls via oxidation, but outstanding questions of molecular weight control remain. Herein we report systematic investigation of solvent, temperature, and initiator concentration as factors influencing BN2VN degree of polymerization. We find increased chain transfer to toluene, hypothesized to arise from differences in radical stabilization and reactivity by aromatic and BN aromatic rings. As a result of these combined efforts, high molecular weight (Mw ~ 105 g mol−1) BN2VN homopolymers and BN2VN-styrene copolymers were obtained. 相似文献
327.
Journal of Computer-Aided Molecular Design - Accurate predictions of acid dissociation constants are essential to rational molecular design in the pharmaceutical industry and elsewhere. There has... 相似文献
328.
Yuwei Wang Jia-Jun Yan Shengnan Hu Prof. David James Young Prof. Hong-Xi Li Prof. Zhi-Gang Ren 《化学:亚洲杂志》2021,16(18):2681-2686
A photoluminescent bimetallic cluster [Ag10Cu6(bdppthi)2(C≡CPh)12(MeOH)2(H2O)](ClO4)4 ( 1 , bdppthi=N,N’-bis(diphenylphosphanylmethyl)-tetrahydroimidazole} was synthesized from the PNNP type ligand bdppthi generated in-situ. Upon excitation at 365 nm, 1 exhibited strong phosphorescent emission at 630 nm, which was selectively quenched by NH3 in air or water. The sensing of NH3 was rapid and recoverable, with detection limits of 53 ppm (v/v) in N2 and 21 μmol/L (0.36 ppm, w/w) for NH3 ⋅ H2O in water. Cluster 1 could potentially serve as a bifunctional chemical sensor for the efficient detection of ammonia in waste-gas and waste-water. 相似文献
329.
Farsi R. Mohammadi M. K. Saghanezhad S. J. 《Russian Journal of Organic Chemistry》2021,57(12):2002-2009
Russian Journal of Organic Chemistry - Herein, we report the sulfonamide-functionalized covalent organic framework (COF-SO3H), prepared by condensation of melamine and terephthalaldehyde and... 相似文献
330.
Vyacheslav V. Sentyurin Oleg A. Levitskiy Tatiana V. Magdesieva 《Current Opinion in Electrochemistry》2020
This mini-review highlights key structural features that should be taken into account when creating ambipolar redox-active closed-shell metal-free molecules. This type of compound is strongly required for the fabrication of all-organic ‘poleless’ batteries and semiconductors. The suggested strategies aimed at stabilization of both oxidized (cationic) and reduced (anionic) redox-states are based on the comprehensive analysis of the most successful structures taken from the recent publications. 相似文献