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排序方式: 共有319条查询结果,搜索用时 31 毫秒
1.
Elarbi Chatir Dr. Martial Boggio-Pasqua Prof. Frederique Loiseau Dr. Christian Philouze Prof. Guy Royal Dr. Saioa Cobo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(7):e202103755
A phenanthrene unit has been functionalized by several methylthiophene units in order to bring it a photochromic behavior. These compounds were characterized by NMR, absorption and emission spectroscopies, theoretical calculations as well as cyclic voltammetry. The association of a phenanthrene group with a photochromic center could open the door to a new generation of organic field-effect transistors. 相似文献
2.
A Multi‐Addressable Switch Based on the Dimethyldihydropyrene Photochrome with Remarkable Proton‐Triggered Photo‐opening Efficiency 下载免费PDF全文
Dr. Diego Roldan Dr. Saioa Cobo Dr. Frédéric Lafolet Dr. Neus Vilà Dr. Constance Bochot Dr. Christophe Bucher Prof. Dr. Eric Saint‐Aman Dr. Martial Boggio‐Pasqua Dr. Marco Garavelli Prof. Dr. Guy Royal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):455-467
A series of photochromic derivatives based on the trans‐10b,10c‐dimethyl‐10b,10c‐dihydropyrene (DHP, “closed form”) skeleton has been synthesized and their photoisomerization leading to the corresponding cyclophanediene (CPD, “open form”) isomers has been investigated by UV/Vis and 1H NMR spectroscopies. Substitution of the DHP core with electron‐withdrawing pyridinium groups was found to have major effects on the photoisomerization efficiency, the most remarkable examples being to enhance the quantum yield of the opening reaction and to allow fast and quantitative conversions at much lower radiant energies. This effect was rationalized by theoretical calculations. We also show that the reverse reaction, that is, going from the open form to the closed form, can be electrochemically triggered by oxidation of the CPD unit and that the photo‐opening properties of pyridine‐substituted DHPs can be efficiently tuned by protonation, the system behaving as a multi‐addressable molecular switch. These multi‐addressable photochromes show promise for the development of responsive materials. 相似文献
3.
Carboxylic‐Acid‐Passivated Metal Oxide Nanocrystals: Ligand Exchange Characteristics of a New Binding Motif 下载免费PDF全文
Jonathan De Roo Dr. Yolanda Justo Katrien De Keukeleere Freya Van den Broeck Prof. Dr. José C. Martins Prof. Dr. Isabel Van Driessche Prof. Dr. Zeger Hens 《Angewandte Chemie (International ed. in English)》2015,54(22):6488-6491
Ligand exchange is central in the processing of inorganic nanocrystals (NCs) and requires understanding of surface chemistry. Studying sterically stabilized HfO2 and ZrO2 NCs using 1H solution NMR and IR spectroscopy as well as elemental analysis, this paper demonstrates the reversible exchange of initial oleic acid ligands for octylamine and self‐adsorption of oleic acid at NC surfaces. Both processes are incompatible with an X‐type binding motif of carboxylic acids as reported for sulfide and selenide NCs. We argue that this behavior stems from the dissociative adsorption of carboxylic acids at the oxide surface. Both proton and carboxylate moieties must be regarded as X‐type ligands yielding a combined X2 binding motif that allows for self‐adsorption and exchange for L‐type ligands. 相似文献
4.
Jessica Orrego Hernandez Jaime Portilla Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(5):363-368
Cyclohexylamine reacts with 5‐chloro‐3‐methyl‐1‐(pyridin‐2‐yl)‐1H‐pyrazole‐4‐carbaldehyde to give 5‐cyclohexylamino‐3‐methyl‐1‐(pyridin‐2‐yl)‐1H‐pyrazole‐4‐carbaldehyde, C16H20N4O, (I), formed by nucleophilic substitution, but with 5‐chloro‐3‐methyl‐1‐phenyl‐1H‐pyrazole‐4‐carbaldehyde the product is (Z)‐4‐[(cyclohexylamino)methylidene]‐3‐methyl‐1‐phenyl‐1H‐pyrazol‐5(4H)‐one, C17H21N3O, (II), formed by condensation followed by hydrolysis. Compound (II) crystallizes with Z′ = 2, and in one of the two independent molecular types the cyclohexylamine unit is disordered over two sets of atomic sites having occupancies of 0.65 (3) and 0.35 (3). The vinylogous amide portion in each compound shows evidence of electronic polarization, such that in each the O atom carries a partial negative charge and the N atom of the cyclohexylamine portion carries a partial positive charge. The molecules of (I) contain an intramolecular N—H...N hydrogen bond, and they are linked by C—H...O hydrogen bonds to form sheets. Each of the two independent molecules of (II) contains an intramolecular N—H...O hydrogen bond and each molecular type forms a centrosymmetric dimer containing one R22(4) ring and two inversion‐related S(6) rings. 相似文献
5.
Daniela M. Ridolfi Ana Paula Lemes Sheila de Oliveira Giselle Z. Justo Marcelly V. Palladino Nelson Durán 《Cellulose (London, England)》2017,24(8):3353-3365
Chitosan/poly(ethylene oxide) (PEO) (5:1) nanofibers with cellulose nanocrystals (CNCs) were produced using an electrospinning technique. The addition of CNCs to the chitosan/PEO solutions allowed the production of uniform fibers (without beads) with a high proportion of chitosan. The fiber diameters were influenced by the concentration of CNCs in the chitosan/PEO solutions. The solutions containing 10% (w/w) of CNCs produced thinner fibers compared to solutions containing 5% (w/w) of CNCs. Thermogravimetric analysis indicated that the nanofibers were thermally stable, despite the CNCs having an effect on the PEO decomposition. Results from the cell assay in cultures of 3T3 fibroblasts indicated that the chitosan/PEO nanofibers (with 10% CNCs) promoted cell attachment with changes in the cytoskeletal organization. The results obtained in this work highlight the favorable effect of CNCs in electrospinning of chitosan/PEO. As expected, the influence of nanofibers on 3T3 fibroblasts F-actin and β-tubulin network revealed alterations in cytoskeleton, leading to changes in cell morphology and spreading. 相似文献
6.
Alberto Insuasty Braulio Insuasty Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(1):74-76
The molecules of the title compound, C17H21N3OS, are characterized by a wide C—C—C angle at the methine C atom linking the aryl and thiazolidine rings, associated with a short repulsive intramolecular S...H contact between atoms in these two rings. A single piperidine–arene C—H...π hydrogen bond links pairs of molecules into centrosymmetric dimers. 相似文献
7.
Juan C. Castillo Rodrigo Abonía Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(7):798-802
In dibenzylammonium hydrogen maleate [or dibenzylammonium (2Z)‐3‐carboxyprop‐2‐enoate], C14H16N+·C4H3O4−, (I), the anion contains a fairly short and nearly linear O—H...O hydrogen bond, with an O...·O distance of 2.4603 (16) Å, but with the H atom clearly offset from the mid‐point of the O...O vector. The counter‐ions in (I) are linked by two N—H...O hydrogen bonds to form C22(6) chains and these chains are weakly linked into sheets by a C—H...O hydrogen bond. Bis(dibenzylamino)methane, C29H30N2, (II), crystallizes with two independent molecules lying across twofold rotation axes in the space group C2/c, and the molecules are conformationally chiral; there are no direction‐specific intermolecular interactions in the crystal structure of (II). 相似文献
8.
Juan C. Castillo Rodrigo Abonía Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(5):544-548
In the molecule of 4‐(2‐chlorophenyl)pyrrolo[1,2‐a]quinoxaline, C17H11ClN2, (I), the bond lengths are consistent with electron delocalization in the two outer rings of the fused tricyclic system, with a localized double bond in the central ring. The molecules of (I) are linked into chains by a π–π stacking interaction. In (4RS)‐4‐(1,3‐benzodioxol‐6‐yl)‐4,5‐dihydropyrrolo[1,2‐a]quinoxaline, C18H14N2O2, (II), the central ring of the fused tricyclic system adopts a conformation intermediate between screw‐boat and half‐chair forms. A combination of N—H...O and C—H...π(arene) hydrogen bonds links the molecules of (II) into a sheet. Comparisons are made with related compounds. 相似文献
9.
10.
Dr. Christophe Kahlfuss Dr. Raymond Grüber Prof. Elise Dumont Prof. Guy Royal Floris Chevallier Dr. Saioa Cobo Prof. Eric Saint-Aman Dr. Christophe Bucher 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(6):1573-1580
A dynamic supramolecular approach is developed to promote the π-dimerization of viologen radicals at room temperature and in standard concentration ranges. The approach involves cis- or trans-protected palladium centers serving as inorganic hinges linking two functionalized viologens endowed with metal-ion coordinating properties. Based on detailed spectroscopic, electrochemical and computational data, we show that the one-electron electrochemical reduction of the viologen units in different dynamic metal/ligand mixtures leads to the formation of the same intramolecular π-dimer, regardless of the initial environment around the metallic precursor and of the relative ratio between metal and ligand initially introduced in solution. The large-scale electron-triggered reorganization of the building blocks introduced in solution thus involves drastic changes in the stoichiometry and stereochemistry of the palladium/viologen complexes proceeding in some cases through a palladium centered trans→cis isomerization of the coordinated ligands. 相似文献