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21.
22.
Stuart Clough John Gupton Adepeju Ligali Matthew Roberts David Driscoll Scott Annett Alisa Hewitt Matthew Hudson Edward Jackson Robert Miller Bradley Norwood Rene Kanters Hadley Wyre Heather Petruzzi 《Tetrahedron》2005,61(31):7554-7561
The highly stereoselective conversions of (Z)-3-aryl-3-chloropropenals to (E)-3-alkoxy-3-arylpropenals, to (E)-3-aryl-3-morphorlinopropenals, and to vinamidinium salts are reported. The stereochemical assignments were based on 2D-NMR experiments. 相似文献
23.
Klaus Burger Lothar Hennig Annett Fuchs Dieter Greif Jan Spengler Fernando Albericio 《Monatshefte für Chemie / Chemical Monthly》2005,136(10):1763-1779
Summary. A new approach to trifluoromethyl substituted butenolides and their thioanalogues is described starting from 2-fluoro-3-trifluoromethylfurans
and -thiophenes, respectively. The reaction sequence includes three steps – nucleophilic displacement reaction, Claisen, and finally Cope rearrangement – which can be run as domino reaction. A modification of the domino reaction (transesterification instead of
Cope rearrangement) provides a concise access to α-trifluoromethyl-γ-ketoacids. 相似文献
24.
25.
[chemical reaction: see text]. The catalytic asymmetric Claisen rearrangement (CAC) of a highly substituted and functionalized alpha-alkoxycarbonyl-substituted allyl vinyl ether has been exploited to gain access to an advanced building block for the projected total synthesis of (-)-xeniolide F, the enantiomer of a xenicane diterpene isolated from a coral of the genus Xenia. 相似文献
26.
27.
Carina Lemke Dr. Adéla Jílková Dominic Ferber Dr. Annett Braune Anja On Dr. Patrick Johe Dr. Alena Zíková Prof. Dr. Tanja Schirmeister Dr. Michael Mareš Dr. Martin Horn Prof. Dr. Michael Gütschow 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(62):e202201636
Rhodesain is the major cysteine protease of the protozoan parasite Trypanosoma brucei and a therapeutic target for sleeping sickness, a fatal neglected tropical disease. We designed, synthesized and characterized a bimodal activity-based probe that binds to and inactivates rhodesain. This probe exhibited an irreversible mode of action and extraordinary potency for the target protease with a kinac/Ki value of 37,000 M−1s−1. Two reporter tags, a fluorescent coumarin moiety and a biotin affinity label, were incorporated into the probe and enabled highly sensitive detection of rhodesain in a complex proteome by in-gel fluorescence and on-blot chemiluminescence. Furthermore, the probe was employed for microseparation and quantification of rhodesain and for inhibitor screening using a competition assay. The developed bimodal rhodesain probe represents a new proteomic tool for studying Trypanosoma pathobiochemistry and antitrypanosomal drug discovery. 相似文献
28.
Pollex A Millet A Müller J Hiersemann M Abraham L 《The Journal of organic chemistry》2005,70(14):5579-5591
[structure: see text] An ester dienolate [2,3]-Wittig rearrangement was utilized to access the alkylated citric acid skeleton 6 that is characteristic for the viridiofungins and other members of the alkyl citrate family of secondary natural products. The [2,3]-sigmatropic rearrangement of (Z,Z)-15 provided the rearrangement product (+/-)-syn-16 in moderate yield and with very good diastereoselectivity. A Julia-Kocienski olefination efficiently served to connect the polar head (+/-)-syn-26 with the lipophilic tail (32a-c) of the viridiofungins. Amide formation between the racemic viridiofungin precursors 35a-c and the enantiomerically pure amino acid L-tyrosine methyl ester followed by preparative reversed-phase HPLC provided the isopropyl dimethyl ester of viridiofungin A ((+)-39a), A2 ((+)-39b), and A4 ((+)-39c) as well as the nonnatural diastereomers (-)-38a-c. 相似文献
29.
Klaus Burger Brigitte Helmreich Lothar Hennig Jan Spengler Fernando Albericio Annett Fuchs 《Monatshefte für Chemie / Chemical Monthly》2007,31(4):227-236
An efficient synthesis of 2-fluoro-3-(trifluoromethyl)furans was developed. Keystep of the reaction sequence is a [4 + 1]
cycloaddition reaction of tin(II)chloride to 4,4-bis(trifluoromethyl)-1-oxabuta-1,3-dienes. At elevated temperatures the tin
heterocycles are transformed into 1-aryl-4,4-difluoro-3-(trifluoromethyl)but-3-en-1-ones which on treatment with sodium hydride
in dry DMF give 2-fluoro-3-(trifluoromethyl)furans. The single fluorine bound to C-(2) can be readily replaced by various N-, O-, S-,
and C-nucleophiles and dinucleophiles. 相似文献
30.
Jakub Adam Koza Sascha Mühlenhoff Margitta Uhlemann Kerstin Eckert Annett Gebert Ludwig Schultz 《Electrochemistry communications》2009,11(2):425-429
The effect of a magnetic field in the perpendicular-to-electrode configuration on the hydrogen evolution reaction (HER) was investigated during the deposition of Co. An enhanced desorption of hydrogen in the form of numerous small bubbles was found by combining potentiostatic investigations, coupled with an electrochemical quartz crystal microbalance (EQCM), and simultaneous microscopic observations of the electrode surface. The results are consistent with the recently proposed qualitative model [J.A. Koza, M. Uhlemann, A. Gebert, L. Schultz, Electrochem. Commun. 10 (2008) 1330]. 相似文献