全文获取类型
收费全文 | 1090篇 |
免费 | 53篇 |
国内免费 | 1篇 |
专业分类
化学 | 802篇 |
晶体学 | 8篇 |
力学 | 19篇 |
数学 | 72篇 |
物理学 | 243篇 |
出版年
2024年 | 1篇 |
2023年 | 5篇 |
2022年 | 11篇 |
2021年 | 13篇 |
2020年 | 18篇 |
2019年 | 19篇 |
2018年 | 29篇 |
2017年 | 26篇 |
2016年 | 36篇 |
2015年 | 52篇 |
2014年 | 41篇 |
2013年 | 71篇 |
2012年 | 105篇 |
2011年 | 104篇 |
2010年 | 73篇 |
2009年 | 45篇 |
2008年 | 85篇 |
2007年 | 78篇 |
2006年 | 67篇 |
2005年 | 44篇 |
2004年 | 48篇 |
2003年 | 63篇 |
2002年 | 36篇 |
2001年 | 11篇 |
2000年 | 10篇 |
1999年 | 5篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1975年 | 2篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1965年 | 1篇 |
1961年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1144条查询结果,搜索用时 15 毫秒
941.
Prnová Anna Valúchová Jana Mutlu Nurshen Parchovianský Milan Klement Róbert Plško Alfonz Galusek Dušan 《Journal of Thermal Analysis and Calorimetry》2020,142(1):129-138
Journal of Thermal Analysis and Calorimetry - Yttrium aluminate glasses (76.8 mol% of Al2O3, 23.2 mol% of Y2O3) doped with Er3+ and Nd3+ ions at different concentration levels... 相似文献
942.
943.
Dr. Dymytrii Listunov Prof. Ole Hammerich Irving Caballero-Quintana Dr. Albert Poater Cécile Barthes Dr. Carine Duhayon Dr. Mie Højer Larsen Dr. José-Luis Maldonado Dr. Gabriel Ramos-Ortiz Prof. Mogens Brøndsted Nielsen Dr. Valérie Maraval Prof. Remi Chauvin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(47):10707-10711
carbo-Benzene is an aromatic molecule devised by inserting C2 units within each C−C bond of the benzene molecule. By integrating the corresponding carbo-quinoid core as bridging unit in a π-extended tetrathiafulvalene (exTTF), it is shown that a carbo-benzene ring can be reversibly formed by electrochemical reduction or oxidation. The so-called carbo-exTTF molecule was thus experimentally prepared and studied by UV–visible absorption spectroscopy and cyclic voltammetry, as well as by X-ray crystallography and by scanning tunneling microscopy (STM) on a surface of highly oriented pyrolytic graphite (HOPG). The molecule and its oxidized and reduced forms were subjected to a computational study at the density functional theory (DFT) level, supporting carbo-aromaticity as a driving force for the formation of the dication, radical cation, and radical anion. By allowing co-planarity of the dithiolylidene rings and carbo-quinoidal core, carbo-exTTFs present a promising new class of redox-active systems. 相似文献
944.
Thi Kim Hoang Trinh Dr. Jean-Pierre Malval Dr. Fabrice Morlet-Savary Dr. Julien Pinaud Dr. Patrick Lacroix-Desmazes Dr. Corine Reibel Dr. Valérie Héroguez Dr. Abraham Chemtob 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(39):9242-9252
In the search of smarter routes to control the conditions of N-heterocyclic carbene (NHCs) formation, a two-component air-stable NHC photogenerating system is reported. It relies on the irradiation at 365 nm of a mixture of 2-isopropylthioxanthone (ITX) with 1,3-bis(mesityl)imidazoli(ni)um tetraphenylborate. The photoinduced liberation of NHC is evidenced by reaction with a mesitoyl radical to form an NHC-radical adduct detectable by electron spin resonance spectroscopy. The NHC yield can be determined by 1H NMR spectroscopy through the formation of a soluble and stable NHC–carbodiimide adduct. To deprotonate the azolium salt and liberate the NHC, a mechanism is proposed in which the role of base is played by ITX radical anion formed in situ by a primary photoinduced electron-transfer reaction between electronically excited ITX (oxidant) and BPh4− (reductant). An NHC yield as high as 70 % is achieved upon starting with a stoichiometric ratio of ITX and azolium salt. Three different photoNHC-mediated polymerizations are described: synthesis of polyurethane and polyester by organocatalyzed step-growth polymerization and ring-opening copolymerization, respectively, and generation of polynorbornene by ring-opening metathesis polymerization using an NHC-coordinated Ru catalyst formed in situ. 相似文献
945.
Prnová Anna Plško Alfonz Valúchová Jana Švančárek Peter Klement Róbert Michálková Monika Galusek Dušan 《Journal of Thermal Analysis and Calorimetry》2018,133(1):227-236
Journal of Thermal Analysis and Calorimetry - Yttrium aluminate glasses with eutectic AY-E and near-eutectic composition AY-NE were prepared in the form of glass microspheres. Their basic... 相似文献
946.
947.
In this work we investigate by means of dielectric relaxation spectroscopy how segmental motions occurring in poly(vinyl chloride) (PVC) are modified by blending of PVC with small amounts of two different homopolymers: crystalline poly(ϵ‐caprolactone) (PCL) and glassy syndiotactic poly(methylmethacrylate) (sPMMA). The dynamics of the α relaxation of PVC is severely changed by blending it with PCL or sPMMA becoming faster or slower, respectively. Simultaneously, the shape of the relaxation function is being importantly altered. It shows a stronger non‐Debye character being broader and strongly temperature‐dependent. This fact leads us to calculate distributions of relaxation times for the blends that are wider in comparison to the one obtained for pure PVC. Complementary X‐ray diffraction measurements have been performed in order to assure the absence of crystallinity in the blends, and some small variations can be deduced at the level of interchain structural correlations of PVC. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 234–247, 2000 相似文献
948.
949.
950.
Centromeric Alpha‐Satellite DNA Adopts Dimeric i‐Motif Structures Capped by AT Hoogsteen Base Pairs
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Miguel Garavís Dr. Núria Escaja Prof. Valérie Gabelica Prof. Carlos González 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(27):9816-9824
Human centromeric alpha‐satellite DNA is composed of tandem arrays of two types of 171 bp monomers; type A and type B. The differences between these types are concentrated in a 17 bp region of the monomer called the A/B box. Here, we have determined the solution structure of the C‐rich strand of the two main variants of the human alpha‐satellite A box. We show that, under acidic conditions, the C‐rich strands of two A boxes self‐recognize and form a head‐to‐tail dimeric i‐motif stabilized by four intercalated hemi‐protonated C:C+ base pairs. Interestingly, the stack of C:C+ base pairs is capped by T:T and Hoogsteen A:T base pairs. The two main variants of the A box adopt a similar three‐dimensional structure, although the residues involved in the formation of the i‐motif core are different in each case. Together with previous studies showing that the B box (known as the CENP‐B box) also forms dimeric i‐motif structures, our finding of this non‐canonical structure in the A box shows that centromeric alpha satellites in all human chromosomes are able to form i‐motifs, which consequently raises the possibility that these structures may play a role in the structural organization of the centromere. 相似文献