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1.
Shoeib T Cunje A Hopkinson AC Siu KW 《Journal of the American Society for Mass Spectrometry》2002,13(4):408-416
Collision-induced dissociation experiments on the Ag+-phenylalanine complex using several collision energies were shown to yield ten different fragment ions. Unambiguous assignment of these fragment ions were made by careful analysis of deuterium labeling experiments. The losses of H2O, CO, CO2, and AgH were commonly observed; also encountered were the losses of H2, Ag, and H. Deuterium labeling experiments and density functional calculations have been employed to probe fragmentation mechanisms that account for all experimental results. 相似文献
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S. Ö. Akdemir S. D. Eryilmaz E. Öztekin 《International journal of quantum chemistry》2012,112(6):1585-1591
In this article, extremely simple analytical formulas are obtained for rotational overlap integrals which occur in integrals over two reduced rotation matrix elements. The analytical derivations are based on the properties of the Jacobi polynomials and beta functions. Numerical results and special values for rotational overlap integrals are obtained by using symmetry properties and recurrence relationships for reduced rotation matrix elements. The final results are of surprisingly simple structures and very useful for practical applications. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012 相似文献
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Tamer Shoeib Junfang Zhao Houssain EI Aribi Alan C. Hopkinson K. W. Michael Siu 《Journal of the American Society for Mass Spectrometry》2013,24(1):38-48
The fragmentations of [AA + M]+ complexes, where AA = Phe, Tyr, Trp, or His, and M is a monovalent metal (Li, Na, or Ag), have been exhaustively studied through collision-induced dissociation (CID) and through deuterium labeling. Dissociations of the Li- and Ag-containing complexes gave a large number of fragment ions; by contrast, the sodium/amino acid complexes have lower binding energies, and dissociation resulted in much simpler spectra, with loss of the entire ligand dominating. Unambiguous assignments of these fragment ions were made and formation mechanisms are proposed. Of particular interest are fragmentations in which the charge was retained on the organic fragment and the metal was lost, either as a metal hydride (AgH) or hydroxide (LiOH) or as the silver atom (Ag?). Caption for Graphical Abstract
CID products of Li+, Na+, and Ag+ complexes of Phe, Tyr, Trp, and His are reported and mechanisms by which they are formed are proposed. 相似文献
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Galal H. Elgemeie Wafaa A. Zaghary Tamer M. Nasr Kamelia M. Amin 《Journal of carbohydrate chemistry》2013,32(6):345-356
Reported is the first method to prepare a new class of thienopyrazole thioglycosides via a one‐pot reaction of the sodium thienopyrazolthiolate salts with 2,3,4,6‐tetra‐O‐acetyl‐α‐D‐gluco‐and galactopyranosyl bromides. The sodium thienopyrazolthiolate salts are prepared using pyrazoldithioic acids and their corresponding mono ‐ and dithiolate salts. 相似文献
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This paper presents size exclusion chromatography data with on-line coupling to UV and inductively coupled plasma mass spectrometry (ICP-MS) of water soluble metal-binding compounds present in zinc, copper, chromium and iodine enriched yeast nutritional supplements. Molecular weight estimates of the extracted metal-containing compounds are given and are shown to vary substantially from 1.2 kDa to larger than 668 kDa. Seven proteins suspected of containing chromium were identified from one of the chromium-containing fractions. Four of these identified proteins are known to form complexes with other metal ions. The metal chromatographic profiles of zinc, copper and chromium-enriched yeasts were compared to their respective native metal profiles in non-enriched yeast samples. The chromium profiles are shown to be markedly different while those of zinc and copper are qualitatively similar. Only iodide ions or weakly bound, non-aromatic, low molecular weight ( 1.2 kDa) iodine species were observed in the iodine-enriched yeast samples. 相似文献
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Filiz Taneri Tamer Güneri Zolt%aacute;n Aigner Michael Kata 《Journal of inclusion phenomena and macrocyclic chemistry》2002,44(1-4):257-260
Highly-soluble cyclodextrin derivatives, such as hydroxypropyl--cyclodextrin(HP--CD) and methyl--cyclodextrin (MEB), were tested as solubilizingagents for ketoconazole, with the aim of improving the physicochemical andbiopharmaceutical properties of this lipophilic imidazole antifungal agent. Productswere prepared in four molecular ratios by physical mixing, kneading and spray-dryingmethods. The kneaded products in a ratio of 1:2 and the spray-dried products exhibitedthe highest dissolution rates. The phase solubility diagrams of ketoconazole with thesecyclodextrins at 25 °C in water and in simulated intestinal medium wereconstructed. A solubility diagram of AL type was obtained with HP--CD, and one of AP type with MEB. The complexes were characterized by thermal methods(DSC, TG, DTG and DTA). Multicomponent systems were prepared with tartaric acid.The effects of water-soluble polymers, e.g., polyvinylpyrrolidone, on the aqueous solubility of ketoconazole were investigated. Particle size distribution, surface area, partition coefficient, heat of dissolution and wettability studies were also carried out. The formation of inclusion complexes was observed by means of thermoanalytical studies. 相似文献
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Reaction of the organoactinide complexes (C5Me5)2AnMe2 (An = Th, U) with catecholborane yields an inclusion complex where the actinide is encapsulated inside a 15-membered, hexaoxo, trianionic macrocycle built from alternating catechol and catecholborate fragments. In the presence of LiOH, a dimer of two encapsulated actinide macrocycles is formed. The X-ray molecular structure for all the complexes is presented. 相似文献