全文获取类型
收费全文 | 521篇 |
免费 | 30篇 |
国内免费 | 2篇 |
专业分类
化学 | 485篇 |
晶体学 | 2篇 |
力学 | 6篇 |
数学 | 22篇 |
物理学 | 38篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 24篇 |
2021年 | 28篇 |
2020年 | 19篇 |
2019年 | 43篇 |
2018年 | 30篇 |
2017年 | 20篇 |
2016年 | 34篇 |
2015年 | 20篇 |
2014年 | 31篇 |
2013年 | 30篇 |
2012年 | 46篇 |
2011年 | 44篇 |
2010年 | 31篇 |
2009年 | 21篇 |
2008年 | 21篇 |
2007年 | 29篇 |
2006年 | 15篇 |
2005年 | 19篇 |
2004年 | 7篇 |
2003年 | 7篇 |
2002年 | 8篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1977年 | 1篇 |
1968年 | 1篇 |
1965年 | 1篇 |
1961年 | 2篇 |
排序方式: 共有553条查询结果,搜索用时 31 毫秒
61.
Martynov AG Gorbunova YG Tsivadze AY 《Dalton transactions (Cambridge, England : 2003)》2011,40(27):7165-7171
Three novel equations were proposed to perform graphical model-free analysis of lanthanide-induced shifts in NMR spectra of axially symmetrical complexes within Bleaney's T(-2) expansion. Application and efficiency of these newly developed approaches were demonstrated on the example of heteroleptic triple-decker crown-phthalocyaninates (Pc)M[(15C5)(4)Pc]M(Pc), where (15C5)--15-crown-5, (Pc(2-))--phthalocyaninato-dianion, M = Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb and Y as diamagnetic reference. By construction of these equations, the proposed analytical techniques are more sensitive to variations of hyperfine coupling terms throughout lanthanide series, in comparison with previously developed approaches, becoming a valuable tool for the investigation of structural and electronic characteristics of lanthanide complexes. 相似文献
62.
Wu X Seo MS Davis KM Lee YM Chen J Cho KB Pushkar YN Nam W 《Journal of the American Chemical Society》2011,133(50):20088-20091
A mononuclear non-heme manganese(IV)-oxo complex has been synthesized and characterized using various spectroscopic methods. The Mn(IV)-oxo complex shows high reactivity in oxidation reactions, such as C-H bond activation, oxidations of olefins, alcohols, sulfides, and aromatic compounds, and N-dealkylation. In C-H bond activation, the Mn(IV)-oxo complex can activate C-H bonds as strong as those in cyclohexane. It is proposed that C-H bond activation by the non-heme Mn(IV)-oxo complex does not occur via an oxygen-rebound mechanism. The electrophilic character of the non-heme Mn(IV)-oxo complex is demonstrated by a large negative ρ value of -4.4 in the oxidation of para-substituted thioanisoles. 相似文献
63.
Getmanenko YA Risko C Tongwa P Kim EG Li H Sandhu B Timofeeva T Brédas JL Marder SR 《The Journal of organic chemistry》2011,76(8):2660-2671
A series of trialkylsilyl-substituted 2,2'-dithiophene, 4,4'-di-n-hexyl-2,2'-dithiophene, 5,5'-dithiazole, and 2,2'-diselenophene with carbonyl (2a-d) and α-dicarbonyl bridges (3a-d) were prepared from readily available dihalides, using double lithiation followed by trapping with N,N-dimethylcarbamoyl chloride or diethyl oxalate (or N,N-dimethylpiperazine-2,3-dione), respectively. Cyclic voltammetry reveals that the first half-wave reduction potentials for this series of compounds span a wide range, from -1.87 to -0.97 V vs the ferrocene/ferrocenium couple at 0 V (0.1 M (n)Bu(4)NPF(6) in THF). A significant increase of the first half-wave reduction potential (by 0.50-0.67 V) was observed on substitution of the monocarbonyl bridge with α-dicarbonyl. Adiabatic electron affinity (AEA, gas phase) trends determined via density functional theory (DFT) calculations are in good agreement with the electrochemical reduction potentials. UV-vis absorption spectra across the series show a weak absorption band in the visible range, corresponding to the HOMO→LUMO transition within a one-electron picture, followed by a more intense, high-energy transition(s). Single-crystal X-ray structural analyses reveal molecular packing features that balance the interplay of the presence of the bulky substituents, intermolecular π-stacking interactions, and S···O intermolecular contacts, all of which affect the DFT-evaluated intermolecular electronic couplings and effective charge-carrier masses for the crystals of the tricyclic cores. 相似文献
64.
S. I. Torunov M. I. Kulish V. M. Mochalova A. V. Utkin V. V. Yakushev 《Russian Journal of Physical Chemistry B, Focus on Physics》2013,7(6):759-764
The instability of detonation waves in a 81 : 19 nitromethane-acetone mixture is experimentally studied. The amplitude of the irregularities caused by detonation instability and the typical reaction time are estimated using a VISAR laser interferometer, which makes it possible to measure the particle velocity profiles at the explosive-window interface. The characteristic transverse dimensions of the irregularities are measured with the help of a CORDIN camera operating in the single shooting mode to record the intrinsic emission of the detonation front or the light of an outside source reflected from it. 相似文献
65.
John Asplund Kossi Edoh Ruth Haas Yulia Hristova Beth Novick Brett Werner 《Discrete Mathematics》2018,341(10):2938-2948
For a graph and, the shortest path reconfiguration graph of with respect to and is denoted by . The vertex set of is the set of all shortest paths between and in . Two vertices in are adjacent, if their corresponding paths in differ by exactly one vertex. This paper examines the properties of shortest path graphs. Results include establishing classes of graphs that appear as shortest path graphs, decompositions and sums involving shortest path graphs, and the complete classification of shortest path graphs with girth 5 or greater. We include an infinite family of well structured examples, showing that the shortest path graph of a grid graph is an induced subgraph of a lattice. 相似文献
66.
Burmistrova Natalia A. Pidenko Pavel S. Pidenko Sergei A. Skibina Yulia S. Monakhova Yulia B. 《Analytical and bioanalytical chemistry》2019,411(27):7055-7059
Analytical and Bioanalytical Chemistry - A new perspective on the relevant problem—creating simple, rapid, and efficient protein sensors based on microstructured optical fibers using a simple... 相似文献
67.
Nikita M. Ankudinov Prof. Dr. Yulia V. Nelyubina Prof. Dr. Dmitry S. Perekalin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(18):e202200195
Diene rhodium complexes are important catalysts in modern organic synthesis. Herein, we report a new approach to such complexes with the uncommon planar chirality. The synthesis is achieved by face-selective coordination of the prochiral 2,5-disubstituted-1,4-benzoquinones (R2-Q) with rhodium precursors containing the chiral auxiliary ligand S-salicyl-oxazoline (S-Salox). Such coordination leads to the formation of (R,R-R2-Q)Rh(S-Salox) complexes in high yields and with exceptional diastereoselectivity (d. r.>20 : 1). Subsequent replacement of the auxiliary ligand provides various benzoquinone rhodium complexes with retention of the planar chirality. Combined theoretical and experimental studies show that due to their electron-withdrawing nature benzoquinones bind metals stronger than the related 1,4-cyclohexadiene, but weaker than other common diene ligands, such as cyclooctadiene. 相似文献
68.
Skotnikova D. S. Mochalova A. E. Smirnova L. A. 《Russian Journal of Applied Chemistry》2019,92(5):634-638
Russian Journal of Applied Chemistry - Chitosan copolymers with vinyl monomers: 4-N-vinylpyridine, acrylamide, and acrylic acid, were synthesized and these sorption properties were investigated.... 相似文献
69.
70.
Mochalova E. N. Galikhanov M. F. Mikryukova Ya. K. 《Russian Journal of Applied Chemistry》2019,92(11):1492-1498
Russian Journal of Applied Chemistry - Electret properties of polymeric materials based on DER-331 epoxy oligomer and amine curing agents, produced in the course of synthesis of the polymer in a... 相似文献