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111.
112.
Javier Magano Brian Conway Jade Nelson Derick D. Winkle Michael H. Chen 《Tetrahedron letters》2009,50(46):6329-1177
The syntheses of β-amino acids 1 and 2 are presented by means of an alternative route to the asymmetric Michael-addition route reported in the preceding article. These two compounds, which bind to the α2δ subunit of calcium channels and have important medical applications, have been prepared on multi-kilogram scale in our pilot plant through a new approach that introduces the chirality at the β-carbon via asymmetric hydrogenation of an enamide precursor. Two Rh-based catalysts, (R)-mTCFP-Rh(COD)BF4 and (R)-binapine-Rh(COD)BF4, were found to be superior in this transformation and gave very high diastereoselectivities. The process development for catalyst selection is described. 相似文献
113.
114.
Dr. Sophie Colombel Dr. Nathalie Van Hijfte Dr. Thomas Poisson Dr. Eric Leclerc Prof. Dr. Xavier Pannecoucke 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(38):12778-12787
A new method for the synthesis of fluorinated α‐C‐glycosides is described. The reactions between highly electrophilic radicals (fluorinated or unfluorinated) and a 2‐benzyloxyglucal or galactal provide 2‐keto‐D ‐arabino‐ or 2‐keto‐D ‐lyxo‐hexopyranosides through an addition/fragmentation process. Sodium borohydride mediated or Meerwein–Ponndorf–Verley (MPV) reduction of these compounds provides α‐C‐glycosides that feature appropriate anchoring groups for further synthetic elaboration. The presence of CF2CO2iPr or CF2Br groups at the pseudo‐anomeric position allows efficient reduction/olefination or Br/Li‐exchange/nucleophilic‐addition sequences. These transformations open the way for the synthesis of fluorinated C‐glycosidic analogues of glycoconjugates. 相似文献
115.
Florian Berthiol Christian Philouze Pierre Y. Chavant Jean-François Poisson 《Tetrahedron letters》2018,59(23):2293-2295
An unprecedented 7-membered ring cyclization of an enamide to a phenol through hypervalent iodine phenolic oxidation was discovered. In the process a molecule of solvent is incorporated on the cycle forming an unusual and stable hemi-aminal ether. 相似文献
116.
Maude Aelterman Tony Biremond Prof. Dr. Philippe Jubault Prof. Dr. Thomas Poisson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(66):e202202194
The electrochemical synthesis of fluorinated allyl silanes and boronates was disclosed. The addition of electrogenerated boryl or silyl radicals onto many α-trifluoromethyl or α-difluoromethylstyrenes in an undivided cell allowed the formation of a large panel of synthetically useful gem-difluoro and γ-fluoroallyl boronates and silanes (64 examples, from 31 % to 95 % yield). In addition, a scale up of the reactions under continuous flow was showcased using an electrochemical reactor with promising volumetric productivity (688 g.L−1.h−1 and 496 g.L−1.h−1). Moreover, the synthetic utility of these building blocks was highlighted through versatile transformations. Finally, plausible reaction mechanisms were suggested to explain the formation of the products. 相似文献
117.
Dr. Fei Zhang Chad R. Simmons Jade Gates Prof. Yan Liu Prof. Hao Yan 《Angewandte Chemie (International ed. in English)》2018,57(38):12504-12507
Programming self‐assembled designer DNA crystals with various lattices and functions is one of the most important goals for nanofabrication using nucleic acids. The resulting porous materials possess atomic precision for several potential applications that rely on crystalline lattices and cavities. Herein, we present a rationally designed and self‐assembled 3D DNA crystal lattice with hexagonal symmetry. In our design, two 21‐base oligonucleotides are used to form a duplex motif that further assembles into a 3D array. The interactions between the strands are programmed using Watson–Crick base‐pairing. The six‐fold symmetry, as well as the chirality, is directed by the Holliday junctions formed between the duplex motifs. The rationally designed DNA crystal provides a new avenue that could create self‐assembled macromolecular 3D crystalline lattices with atomic precision. In addition, the structure contains a highly organized array of well‐defined cavities that are suitable for future applications with immobilized guests. 相似文献
118.
Tony Biremond Dr. Margaux Riomet Prof. Dr. Philippe Jubault Prof. Dr. Thomas Poisson 《Chemical record (New York, N.Y.)》2023,23(11):e202300172
Due to their high versatility borylated and silylated compounds are inevitable synthons for organic chemists. To escape the classical hydroboration/hydrosilylation paradigm, chemists turned their attention to more modern and green methods such as photoredox chemistry and electrosynthesis. This account focuses on novel methods for the generation of boryl and silyl radicals to forge C−B and C−Si bonds from our group. 相似文献
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120.
Weekley CM Aitken JB Vogt S Finney LA Paterson DJ de Jonge MD Howard DL Witting PK Musgrave IF Harris HH 《Journal of the American Chemical Society》2011,133(45):18272-18279
Selenite is an inorganic form of selenium that has a cytotoxic effect against several human cancer cell lines: one or more selenite metabolites are considered to be responsible for its toxicity. X-ray absorption spectroscopy was used to monitor Se speciation in A549 human lung cancer cells incubated with selenite over 72 h. As anticipated, selenodiglutathione and elemental Se both comprised a large proportion of Se in the cells between 4 and 72 h after treatment, which is in accordance with the reductive metabolism of selenite in the presence of glutathione and glutathione reductase/NADPH system. Selenocystine was also present in the cells but was only detected as a significant component between 24 and 48 h concomitant with a decrease in the proportion of selenocysteine and the viability of the cells. The change in speciation from the selenol, selenocysteine, to the diselenide, selenocystine, is indicative of a change in the redox status of the cells to a more oxidizing environment, likely brought about by metabolites of selenite. X-ray fluorescence microscopy of single cells treated with selenite for 24 h revealed a punctate distribution of Se in the cytoplasm. The accumulation of Se was associated with a greater than 2-fold increase in Cu, which was colocalized with Se. Selenium K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy revealed Se-Se and Se-S bonding, but not Se-Cu bonding, despite the spatial association of Se and Cu. Microprobe X-ray absorption near-edge structure spectroscopy (μ-XANES) showed that the highly localized Se species was mostly elemental Se. 相似文献