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161.
Wenz G Strassnig C Thiele C Engelke A Morgenstern B Hegetschweiler K 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(24):7202-7211
Inclusion compounds of cationic, anionic, and neutral p-substituted derivatives of tert-butylbenzene complexed in beta-cyclodextrin and its ionic 6-mono and 6-hepta derivatives were systematically investigated by isothermal titration calorimetry (ITC). All inclusion compounds showed 1:1 stoichiometry with binding constants ranging from 10 to 3 x 10(6) M(-1). The binding free energies could be subdivided into apolar and electrostatic contributions. The electrostatic interactions could be quantitatively described by Coulomb's law by taking into account the degree of protonation of hosts and guests, the orientations of the guests within the hosts, and ion shielding as described by the Debye-Hückel-Onsager theory. The orientations of the guests within the cyclodextrin cavities were determined by ROESY NMR spectroscopy. 相似文献
162.
Isoprenoid Biosynthesis in Pathogenic Bacteria: Nuclear Resonance Vibrational Spectroscopy Provides Insight into the Unusual [4Fe‐4S] Cluster of the E. coli LytB/IspH Protein
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Dipl.‐Biophys. Isabelle Faus Dr. Annegret Reinhard Dr. Sergej Rackwitz Dr. Juliusz A. Wolny Dr. Kai Schlage Dr. Hans‐Christian Wille Dr. Aleksandr Chumakov Dr. Sergiy Krasutsky Dr. Philippe Chaignon Prof. C. Dale Poulter Dr. Myriam Seemann Prof. Volker Schünemann 《Angewandte Chemie (International ed. in English)》2015,54(43):12584-12587
The LytB/IspH protein catalyzes the last step of the methylerythritol phosphate (MEP) pathway which is used for the biosynthesis of essential terpenoids in most pathogenic bacteria. Therefore, the MEP pathway is a target for the development of new antimicrobial agents as it is essential for microorganisms, yet absent in humans. Substrate‐free LytB has a special [4Fe‐4S]2+ cluster with a yet unsolved structure. This motivated us to use synchrotron‐based nuclear resonance vibrational spectroscopy (NRVS) in combination with quantum chemical‐molecular mechanical (QM/MM) calculations to gain more insight into the structure of substrate‐free LytB. The apical iron atom of the [4Fe‐4S]2+ is clearly linked to three water molecules. We additionally present NRVS data of LytB bound to its natural substrate, (E)‐4‐hydroxy‐3‐methylbut‐2‐en‐1‐yl diphosphate (HMBPP) and to the inhibitors (E)‐4‐amino‐3‐methylbut‐2‐en‐1‐yl diphosphate and (E)‐4‐mercapto‐3‐methylbut‐2‐en‐1‐yl diphosphate. 相似文献
163.
Annegret Wagler 《Journal of Graph Theory》1999,32(4):394-404
A perfect graph is critical, if the deletion of any edge results in an imperfect graph. We give examples of such graphs and prove some basic properties. We relate critically perfect graphs to well-known classes of perfect graphs, investigate the structure of the class of critically perfect graphs, and study operations preserving critical perfectness. © 1999 John Wiley & Sons, Inc. J Graph Theory 32: 394–404, 1999 相似文献
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167.
Annegret Tillack 《Tetrahedron letters》2006,47(50):8881-8885
An improved method for the N-alkylation of primary amines with primary and secondary alcohols has been developed. Novel, effective catalyst systems, for example, Ru3(CO)12 combined with tri-o-tolylphosphine or n-butyl-di-1-adamantylphosphine, allow for aminations in a good yield under comparatively mild conditions. 相似文献
168.
G. Ullrich P. Burtscher U. Salz N. Moszner R. Liska 《Journal of polymer science. Part A, Polymer chemistry》2006,44(1):115-125
Aromatic amines are known to give very poor performance as coinitiators for camphorquinone in the photopolymerization of acidic aqueous formulations. Differential scanning photocalorimetry investigations using N‐phenylglycine (NPG) as an alternative coinitiator proved the suitability of this derivative. Furthermore, it was demonstrated that the generally poor photoreactivity had to be assigned to the presence of water and not to the acidity of the formulation. The poor storage stability of NPG‐containing formulations was significantly improved by derivatives containing electron‐withdrawing substituents in the para position of the aromatic moiety, and the photoreactivity was kept at a very high level. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 115–125, 2006 相似文献
169.
Zusammenfassung. Im Sommer 2002 stellten Agrawal, Kayal und Saxena den ersten deterministischen Primzahltest mit polynomieller Laufzeit vor, den nun nach ihnen benannten AKS-Algorithmus. Wir wollen dieses Ereignis zum Anlass nehmen, einen Überblick über bisher bekannte Algorithmen zur Identifizierung von Primzahlen darzustellen. Nach einem kurzen Abriss über die Primzahltheorie und einigen klassischen Tests in Kapitel 1 werden wir in Kapitel 2 moderne praxisrelevante Verfahren vorstellen. In Kapitel 3 behandeln wir schließich den AKS-Algorithmus. Da Primzahlen bei der Erzeugung kryptographischer Schlüssel eine wichtige Rolle spielen, sind effiziente Tests auch für unser tägliches Leben von Bedeutung.Eingegangen: 9. Januar 2004 / Angenommen: 20. April 2004 相似文献
170.
Annegret Ulke-Lemée David Hao Sun Hiroaki Ishida Hans J. Vogel Justin A. MacDonald 《BMC biochemistry》2017,18(1):5