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71.
Visible Light‐Promoted Decarboxylative Di‐ and Trifluoromethylthiolation of Alkyl Carboxylic Acids 下载免费PDF全文
Dr. Lisa Candish Lena Pitzer Dr. Adrián Gómez‐Suárez Prof. Dr. Frank Glorius 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(14):4753-4756
Described herein is a new and straightforward decarboxylative di‐ and trifluoromethylthiolation of alkyl carboxylic acids promoted by visible light. This approach enables the synthesis of biologically relevant alkyl SCF2H and SCF3 compounds from cheap and abundant carboxylic acids. The method is operationally simple, using irradiation from household light sources, and its mild reaction conditions make it tolerant of a range of functional groups. The strategy employs electrophilic phthalimide‐derived di‐ and trifluoromethylthiolation reagents and exploits the ability of the imidyl radical to carry a radical chain. 相似文献
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73.
Lena Freimuth Prof. Dr. Jens Christoffers 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(22):8214-8221
The fluorescent diaminoterephthalate scaffold was equipped by amidation with three types of reactive functions: thiols for metal‐surface binding, alkynes for click reactions, and maleimides for ligation with proteins. Starting from a succinyl succinate derivative with two orthogonally cleavable ester functions, three monoamides (38–57 % yield over three steps) and two bisamides (19 and 25 % yield over five steps) were prepared. Although alkyne and thiol derivatized compounds showed reasonable luminescence behavior (Φ≈1–4 %), the fluorescence was quenched by the maleimide moiety. It was turned on (10‐ to 20‐fold increase of fluorescence quantum yield) by conjugate addition of thiols. 相似文献
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A microwave-assisted, one-pot, iridium-catalyzed aromatic C-H borylation/rhodium-catalyzed 1,4-conjugate addition sequence provides a highly robust protocol suitable for high-throughput array synthesis. Selective formation of either β-aryl-substituted ketones or the corresponding alcohols can be achieved in good overall yields by simple variation of the reaction conditions. 相似文献
76.
Mohammad-Reza Zamani-Meymian Lena Jentjens Niels L. Raeth Konrad Peithmann Karl Maier 《Applied Physics A: Materials Science & Processing》2010,98(4):909-912
Irradiation of congruently melting, nominally undoped lithium niobate crystals (LiNbO3) with high-energy, low-mass 3He ions, which are transmitted through the crystal, causes large and stable changes of the refractive index. In the irradiated
regions, the extraordinary index is increased whereas the ordinary index is diminished. The decay of these changes upon annealing
treatments up to 400°C is investigated, exhibiting a strongly non-monoexponential decay behaviour. Long-term measurements
of the refractive index changes yield no pattern erasure on a timescale of four years. 相似文献
77.
Lena G Lallemand E Gruner AC Boeglin J Roussel S Schaffner AP Aubry A Franetich JF Mazier D Landau I Briand JP Didierjean C Rénia L Guichard G 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(33):8498-8512
The development of the 1,3,5-triazepane-2,6-dione system as a novel, conformationally restricted, and readily accessible class of dipeptidomimetics is reported. The synthesis of the densely functionalized 1,3,5-triazepane-2,6-dione skeleton was achieved in only four steps from a variety of simple linear dipeptide precursors. To extend the practical value of 1,3,5-triazepane-2,6-diones, a general polymer-assisted solution-phase synthesis approach amenable to library production in a multiparallel format was developed. The conformational preferences of the 1,3,5-triazepane-2,6-dione skeleton were investigated in detail by NMR spectroscopy and X-ray diffraction. The ring exhibits a characteristic folded conformation which was compared to that of related dipeptide-derived scaffolds including the more planar 2,5-diketopiperazine (DKP). Molecular and structural diversity was increased further through post-cyclization appending operations at urea nitrogens. Preliminary biological screens of a small collection of 1,3,5-triazepane-2,6-diones revealed inhibitors of the underexplored malaria liver stage and suggest strong potential for this dipeptide-derived scaffold to interfere with and to modulate biological pathways. 相似文献
78.
Ding F Rosén A Campbell EE Falk LK Bolton K 《The journal of physical chemistry. B》2006,110(15):7666-7670
A new model is proposed for the encapsulation of catalyst metal particles by graphite layers that are obtained, for example, in low-temperature chemical vapor deposition production of carbon nanotubes (CNTs). In this model graphite layers are primarily formed from the dissolved carbon atoms in the metal-carbide particle when the particle cools. This mechanism is in good agreement with molecular dynamics simulations (which show that precipitated carbon atoms preferentially form graphite sheets instead of CNTs at low temperatures) and experimental results (e.g., encapsulated metal particles are found in low-temperature zones and CNTs in high-temperature regions of production apparatus, very small catalyst particles are generally not encapsulated, and the ratio of the number of graphitic layers to the diameter of the catalyst particle is typically 0.25 nm(-1)). 相似文献
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80.
Finet L Candela Lena JI Kaoudi T Birlirakis N Arseniyadis S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(16):3813-3820
This article describes the design of olefin-generated/reagent-modulated consecutive hetero-domino reactions of 1,2-unsaturated bicyclic diols, which are potentially of great use, initiated by PhI(OAc)(2), continued by [Pb(OAc)(4)], and completed by use of a mild base (K(2)CO(3)). Inversion of a quaternary center has been achieved through a three-reaction sequence: a domino transformation followed by an m-CPBA-mediated Baeyer-Villiger oxidation and subsequent reductive lactone ring opening. 相似文献