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101.
Qingqing Sun Dr. Gemma Aragay Andrea Pinto Dr. Elisabet Aguiló Prof. Dr. Laura Rodríguez Prof. Dr. Pablo Ballester 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(15):3348-3357
We report the synthesis of an unprecedented mono-gold(I) phosphine complex based on a “two-wall” aryl-ethynyl extended calix[4]pyrrole. We describe and compare the binding properties of the parent 10α,20α-bis-aryl-ethynyl calix[4]pyrrole ligand and the prepared organometallic compound as receptors for tetraalkylammonium chloride salts in dichloromethane and acetone. We describe the results of 1H NMR, UV–Vis titrations and isothermal titration calorimetry (ITC) experiments in dichloromethane and acetone, aiming to thermodynamically characterize the formed complexes. The obtained results indicate a noticeable decrease in the binding affinity of the chloride for the mono-gold(I) receptor 1 compared to the parent ligand 2 . The increase in the negative value of the electrostatic surface potential at the center of the aromatic ring of the gold(I) meso-aryl-ethynyl substituent serves to explain the observed results and the presence in solution of the chloride complex of 1 as a mixture of two conformers. 相似文献
102.
The Ligand (E)-[4,4,4-Trifluoro-1-(trifluoromethyl)-1,3-bis(trimethylsiloxy)-2-butenyl]di-phenylphosphine The tertiary phosphine (E)-Ph2PC(OSiMe3)(CF3)CH = C(OSiMe3)CF3 (L), 1 and the carbonyl Fe2(CO)9 react to give (OC)4FeL, 2. Bis( 1,1,1,5,5,5-hexafluoropentane-2,4-dionato)palladium(II) and 1 furnish the diphenylphosphido group bridged palladium(II) complex 3 crystallizing from chloroform triclinic in the space group P1 with a = 12.600(3), b = 13.298(3), c = 13.975(3) Å, α = 93.27(2), β = 111.67(2), γ = 106.71(2)° The elementary cell contains Z = 2 formular units and two molecules CHCl3 with two independent molecules 3 each showing an inversion centre. The planar [PdP], four membered ring system and the planar chelate units, exhibit a torsional angle of 6.75° 相似文献
103.
Mariateresa Giustiniano Sveva Pelliccia Ettore Novellino Gian Cesare Tron 《Tetrahedron letters》2018,59(13):1196-1199
N-Substituted α-amino acid amides can be easily obtained in two steps using the four-component Ugi reaction followed by chemoselective cleavage of the resulting tertiary amide. The use of the sacrificial acid, 2-hydroxymethylbenzoic acid is associated to shorter reaction times, higher yields, and safer and greener reaction conditions compared to strategies based on trifluoroacetic acid, a toxic and environmental hazardous reagent. The optimized procedure was easily scaled up to gram amounts. 相似文献
104.
Stereochemically defined enantioenriched molecules were, are and will always be playing a pivotal role in the development of novel pharmaceutical agents. On this line, compounds having tertiary benzylic stereocenter are of special note. This has led to an increase in the development of novel synthetic strategies for accessing molecules having this structural moiety. The current critical discussion proposes to describe the various synthetic methodologies for the enantioselective synthesis of diaryl methanols, diarylmethyl amines and other related scaffolds with tertiary benzylic stereogenic center that came up during 1995–2016. Through this critical view, we would not only like to give the readers a brief outlook on the different techniques that can be followed for the synthesis of a vast array of entities having this structural core, but also would like to highlight the limitations the protocols that need to be addressed. 相似文献
105.
Mizuho Sugiuchi Dr. Yukatsu Shichibu Prof. Katsuaki Konishi 《Angewandte Chemie (International ed. in English)》2018,57(26):7855-7859
2,3‐bis(diphenylphosphino)butane enantiomers (chiraphos, L) used as chiral auxiliaries results in the preferential formation of an unprecedented Au24 framework with inherent chirality. The crystal structure of [Au24L6Cl4]2+ ( 1 ) has a square antiprism‐like octagold core twinned by two helicene‐like hexagold motifs, where the inherent chirality is associated with the helical arrangement. The clusters carrying (R,R)‐ and (S,S)‐ diphosphines had right‐ and left‐handed strands, respectively. Circular dichroism spectra showed peaks in the visible to near‐IR region, some of which did not coincide with absorption bands, suggesting the enantiomeric Au24 frameworks possess unique chiroptical properties. The Au24 frameworks were thermally robust, which could be attributed to the superatomic concept (18 e? system) and the steric constraint effects of the bridging ligand units. 相似文献
106.
Nucleophilic Activation of Sulfur Hexafluoride: Metal‐Free,Selective Degradation by Phosphines
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Florenz Buß Dr. Christian Mück‐Lichtenfeld Paul Mehlmann Dr. Fabian Dielmann 《Angewandte Chemie (International ed. in English)》2018,57(18):4951-4955
The development of new methods for the chemical activation of the extremely inert greenhouse gas sulfur hexafluoride (SF6) not only is of current environmental interest, but also offers new opportunities for applications of SF6 as a reagent in organic synthesis. We herein report the first nucleophilic activation of SF6 by Lewis bases, namely by phosphines, which results either in its complete degradation to phosphine sulfides and difluorophosphoranes or in the selective conversion of SF6 into a bench‐stable, crystalline salt containing the SF5? anion. Quantum chemical calculations reveal a nucleophilic substitution mechanism (SN2) for the initial fluorine abstraction from SF6 by the phosphine. Furthermore, a scalable one‐pot procedure for the complete decomposition of SF6 into solid, nonvolatile products is presented based on cheap and commercially available starting materials. 相似文献
107.
A Sterically Constrained Tricyclic PC3 Phosphine: Coordination Behavior and Insertion of Chalcogen Atoms into P−C Bonds
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Dr. Anne Hentschel M. Sc. Alexander Brand Dr. Philipp Wegener Prof. Dr. Werner Uhl 《Angewandte Chemie (International ed. in English)》2018,57(3):832-835
A tricyclic phosphine has been generated that has a rigid molecular backbone with the P atoms exclusively bound to C(sp2) atoms as well as a very large Tolman angle and buried volume. It is an interesting new ligand in coordination chemistry (Au, Pd complexes) and shows unusual insertion reactions into its endocyclic P?C bonds facilitated by its inherent molecular strain. 相似文献
108.
A large macrocyclic compound with six para-phenylene rings and six amide moieties, which are alternately secondary and tertiary, was synthesized. In a stepwise synthesis, the final cyclization step was successful because a combination of three tertiary amides, which prefer a cis conformation, and two linear secondary amides would arrange both amino and carboxyl ends close to each other, while various sizes of macrocyclic compounds including the target cyclic trimer were generated in one-pot synthesis where three secondary amide bonds were formed. 相似文献
109.
Hao Deng Marco Bengsch Nico Tchorz Dr. Constanze N. Neumann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(51):e202202074
The fine-tuning of metal-phosphine-catalyzed reactions relies largely on accessing ever more precisely tuned phosphine ligands by de-novo synthesis. Late-stage C−H functionalization and diversification of commercial phosphines offers rapid access to entire libraries of derivatives based on privileged scaffolds. But existing routes, relying on phosphorus-directed transformations, only yield functionalization of C −H bonds in a specific position relative to phosphorus. In contrast to phosphorus-directed strategies, herein we disclose an orthogonal functionalization strategy capable of introducing a range of substituents into previously inaccessible positions on arylphosphines. The strongly coordinating phosphine group acts solely as a bystander in the sterically controlled borylation of bulky phosphines, and the resulting borylated phosphines serve as the supporting ligands for palladium during diversification through phosphine self-assisted Suzuki-Miyaura reactions. 相似文献
110.