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排序方式: 共有339条查询结果,搜索用时 46 毫秒
61.
Janine Kowalke Dr. Jörg Wagler Christine Viehweger Dr. Erica Brendler Prof. Edwin Kroke 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(36):8003-8006
Reactions of SiCl4 with R2PO(OH) (R=Me, Cl) yield compounds with six-fold coordinated silicon atoms. Whereas R=Me afforded the hexacoordinated tetra-cationic silicon complex [Si(Me2PO(OH))6]4+ with chloride counter-ions, R=Cl caused release of HCl with formation of a cyclic dimeric silicon complex [Si(Cl2PO(OH))(Cl2PO2)3(μ-Cl2PO2)]2 with bridging bidentate dichlorophosphates. 相似文献
62.
Nicolas Gillaizeau-Simonian Dr. Etienne Barde Dr. Amandine Guérinot Prof. Janine Cossy 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(12):4004-4008
A cobalt-catalyzed 1,4-aryl migration/disulfonylation cascade applied to α-bromo N-sulfonyl amides was developed. The reaction was highly chemoselective, allowing the preparation of α-aryl amides possessing a variety of functional groups. The method was used as the key step to synthesize an alkaloid, (±)-deoxyeseroline. Mechanistic investigations suggest a radical process. 相似文献
63.
Dr. Camille Lecourt Sabrina Dhambri Khalil Yamani Dr. Guillaume Boissonnat Dr. Simon Specklin Dr. Etienne Fleury Karim Hammad Eric Auclair Serge Sablé Dr. Antonio Grondin Dr. Paola B. Arimondo Dr. François Sautel Dr. Georges Massiot Dr. Christophe Meyer Prof. Dr. Janine Cossy Dr. Geoffroy Sorin Dr. Marie-Isabelle Lannou Prof. Dr. Janick Ardisson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(11):2745-2749
A strategy for the assembly of the entire carbon backbone of a stereoisomer of the antitumor marine natural product hemicalide has been investigated. The devised convergent approach relies on Horner–Wadsworth–Emmons and Julia–Kocienski olefination reactions for the construction of the C6=C7 and C34=C35 double bonds, respectively, an aldol reaction to create the C27−C28 bond, and a Suzuki–Miyaura cross-coupling as the endgame to form the C15−C16 bond. 相似文献
64.
Sarah HisChristophe Meyer Janine Cossy Gibert EmericAlfred Greiner 《Tetrahedron letters》2003,44(47):8581-8584
In the presence of trifluoroacetic acid, ketoxime benzyl carbonates undergo a Beckmann rearrangement to the corresponding amides. This reaction was translated to a solid support by immobilizing oximes in the form of mixed carbonates derived from hydroxymethylpolystyrene in order to produce a diversity of amides with high efficiency. 相似文献
65.
Rhodium‐Catalyzed Cyclization of O,ω‐Unsaturated Alkoxyamines: Formation of Oxygen‐Containing Heterocycles
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Julien Escudero Prof. Véronique Bellosta Prof. Janine Cossy 《Angewandte Chemie (International ed. in English)》2018,57(2):574-578
O,ω‐Unsaturated N‐tosyl alkoxyamines undergo unexpected RhIII‐catalyzed intramolecular cyclization by oxyamination to produce oxygen‐containing heterocycles. Mechanistic studies show that an aziridine intermediate seems to be responsible for the formation of the heterocycles, possibly via a RhV species. 相似文献
66.
E. Zrkov K. Bouchal D. Zdenkov Z. Pelzbauer F. Svec J. Klal H. G. Batz 《Journal of polymer science. Part A, Polymer chemistry》1983,21(10):2949-2960
Latexes based on styrene-glycidyl methacrylate copolymers were prepared by the emulsifier-free dispersion copolymerization technique. The main factors affecting the size and morphology of the latex particles and their distribution are the initiator concentration (K2S2O8), the total ionic strength of the aqueous phase, and the total monomer concentration. The existence of critical values for these variables was demonstrated. In the range in which these factors had values below the critical, the synthesized latex particles were spherical, homogeneous, and in varied sizes, depending on the abovementioned parameters in the range of 220–500 nm. Above the critical values of these variables the latex particles consisted of spherical aggregates of smaller particles. The reactive oxirane groups of the latex particles were modified later by hydrolysis, ammonolysis, reaction with Na2S, or periodic acid oxidation of the hydrolyzed or ammonolyzed forms of the latex particles. 相似文献
67.
O'Shea JN Swarbrick JC Nilson K Puglia C Brena B Luo Y Dhanak VR 《The Journal of chemical physics》2004,121(20):10203-10208
The adsorption of isonicotinic acid on rutile TiO(2)(110) has been investigated using synchrotron-based valence band photoemission. Structural ordering in multilayer films of the molecules is found to give rise to a strong angular dependence in the valence band intensities when measured using linearly polarized radiation. Molecular ordering in this case is proposed to be induced by intermolecular hydrogen bonding which is found to be highly dependent upon the deposition rate of the isonicotinic acid. Through comparison of the experimental data with density functional calculated valence band spectra of hydrogen-bonded isonicotinic acid molecules, we can account for the angular dependence in terms of the spatial distribution of the molecular orbitals. 相似文献
68.
Clemens Fritsch Janine Batz Klaus Bolsen Klaus-Werner Schulte Matthias Zumdick Thomas Ruzicka Giinter Goerz 《Photochemistry and photobiology》1997,66(1):114-118
Abstract— In photodynamic therapy with topically applied δ-aminolevulinic acid porphyrins are acting as photosensitiz-ers. The profile of porphyrin metabolites in normal or in neoplastic skin after administration of δ-aminolevulinic acid has not been determined in detail yet. Thus, to study porphyrin biosynthesis in human skin an organ culture model was developed. Explant pieces of normal skin, ker-atoacanthoma, and basal cell carcinoma were incubated with 1 niM δ-aminolevulinic acid for 36 h. Levels of δ-aminolevulinic acid, porphyrins and porphyrin metabolites were measured in tissues and supernatants. After incubation with δ-aminolevulinic acid, higher porphyrin levels were demonstrated in tumors as compared to normal skin. In supernatants, most of formed porphyrins, preferentially highly carboxylated porphyrin metabolites, were measured. The pattern of synthesized porphyrins differed between normal and neoplastic skin explants. In tissues of basal cell carcinomas protoporphyrin was preferentially shown and tissues of keratoacanthomas were characterized by a predominance of coproporphyrin as compared to normal skin. The results show that explant cultures offer an easy approach to examine the porphyrin biosynthesis of various tissues. The tumor-specific δ-aminolevulinic acid metabolism indicates additional porphyrin metabolites such as coproporphyrin apart from protoporphyrin as effective photosensitizers and may offer a novel approach to tumor-selective photodynamic damage. 相似文献
69.
Two enantioselective formal syntheses of (−)-swainsonine have been achieved from l-proline by using an enantioselective ring enlargement of substituted prolinols as the key step. The more efficient synthesis has been achieved in 14 steps with an overall yield of 14%. 相似文献
70.
The enantioselective synthesis of the C14-C25 subunit of bafilomycin A1 was realized in a convergent route. The sequence involves two dynamic kinetic resolution steps of 2-alkyl 1,3-diketones that use optically active ruthenium complexes, an anti-selective reduction of a beta-hydroxyketone to control the C23 stereogenic center, and an aldol-type reaction under Evans' conditions, which sets the C17 and C18 stereogenic centers. 相似文献