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1.
A recently introduced technique, simultaneous multiple sample light scattering (SMSLS), was used to monitor parallel polymerization reactions in situ. SMSLS is designed for real-time, high-throughput screening and provides a time-dependent light scattering signature for each reaction, which contains both qualitative and semiquantitative information. Qualitatively, the signature immediately indicates whether the reaction occurs or not, whether there is an initial lag period, and how long the reaction takes until it stops. The signature also provides estimates of the reaction rate and weight average molecular mass M(w), and its shape can help identify mechanistic aspects, for example, controlled versus free radical polymerization, presence of impurities, etc. The method is inherently adapted to small sample volumes and requires no special sample preparation or postpolymerization characterization. The demonstration here involved the free radical polymerization of acrylamide under varying conditions and should be readily applicable to a wide variety of other reactions. Results were cross-checked with multi-detector gel permeation chromatography. 相似文献
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M. Bandsept H. Rohrbeck Rob Meyer Wendt Peeschla F. Stolle Purrmann J. H. Büchler F. Allihn Schaller Alb Bruno F. Reiss und Rud Woy 《Fresenius' Journal of Analytical Chemistry》1903,42(4-5):314-318
Ohne Zusammenfassung 相似文献
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Rafael Y. O. Moreira Davi S. B. Brasil Cláudio N. Alves Giselle M. S. P. Guilhon Lourivaldo S. Santos Mara S. P. Arruda Adolfo H. Müller Patrícia S. Barbosa Alcicley S. Abreu Edilene O. Silva Victor M. Rumjanek Jaime Souza Jr. Albérico B. F. da Silva Regina H. de A. Santos 《International journal of quantum chemistry》2008,108(3):513-520
Julocrotine, N‐(2,6‐dioxo‐1‐phenethyl‐piperidin‐3‐yl)‐2‐methyl‐butyramide, is a potent antiproliferative agent against the promastigote and amastigote forms of Leishmania amazonensis (L.). In this work, the crystal structure of Julocrotine was solved by X‐ray diffraction, and its geometrical parameters were compared with theoretical calculations at the B3LYP and HF level of theory. IR and NMR spectra also have been obtained and compared with theoretical calculations. IR absorptions calculated with the B3LYP level of theory employed together with the 6‐311G+(d,p) basis set, are close to those observed experimentally. Theoretical NMR calculations show little deviation from experimental results. The results show that the theory is in accordance with the experimental data. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 相似文献
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Alb Vesterberg 《Fresenius' Journal of Analytical Chemistry》1907,46(2-3):81-93
Ohne Zusammenfassung 相似文献
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Eduard Wiederhold A. Martens Engler Alb Künkler und M. Albrecht 《Fresenius' Journal of Analytical Chemistry》1894,33(1):111-113
Ohne Zusammenfassung 相似文献
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An accurate relativistic universal Gaussian basis set (RUGBS) from H through No without variational prolapse has been developed by employing the Generator Coordinate Dirac-Fock (GCDF) method. The behavior of our RUGBS was tested with two nuclear models: (1) the finite nucleus of uniform proton-charge distribution, and (2) the finite nucleus with a Gaussian proton-charge distribution. The largest error between our Dirac-Fock-Coulomb total energy values and those calculated numerically is 8.8 mHartree for the No atom. 相似文献
9.
The reaction paths for the formation of Si3O3 molecules have been investigated at high level ab initio quantum chemical calculations by using the QCISD method with the 6-311++G(d,p) basis set. The cis-Si2O2 isomer does not participate in the chemical mechanism for the formation of Si3O3 molecules. Although the SiO + cis-Si2O2 reaction is exothermic and spontaneous, it is not expected to explain the growth mechanism of Si3O3 in the interstellar silicate grains of circumstellar envelopes surrounding M-type giants. The reaction of SiO with cyclic Si2O2 molecules is exothermic, is spontaneous, and has a nonplanar transition state. The Gibbs free energy for the transition state formation, (DeltaG0#), is around 5.5 kcal mol-1 at 298 K. The bimolecular rate coefficient for this reaction, kT, is about 1 x 10-12 cm3 molecule-1 s-1 at 298 K and in the collision limit, 1.5 x 10-10 cm3 molecule-1 s-1, at 500 K. The activation energy, Ea, is about 8 kcal mol-1. The enthalpy of Si3O3 fragmentation is 53.9 kcal mol-1 at 298 K. The SiO + cyclic Si2O2 reaction is expected to be the most prominent reaction path for the Si3O3 formation in interstellar environment and fabrication of silicon nanowires. 相似文献
10.
D. Munsche 《Isotopes in environmental and health studies》2013,49(1):32-33
Für die spektroskopische 15N-Bestimmung wird zur Füllung des elektrodenlosen Entladungsrohres der Stickstoff in sehr reinem gasförmigem- Zustand gebraucht. Bei den meisten zu untersuchenden Substanzen liegt der Stickstoff in gebundener Form vor. Die Aufarbeitung kann über Veraschung nach KJELDAHL und Umarbeitung des NH4Cl zu N2 oder durch Verbrennung nach DUMASerfolgen. Dieerste Methode wird sehr haufig angewendet, wobei die Oxydation des Ammoniumchlorids mit alkalischer Hypobromitlauge nach RITTENBERG 1 am verbreitetsten ist. Die Oxydation mit Kupferoxid wurde von HOCH und WEISSER 2 sowie von FAUST 3 beschrieben. ROLLE 4 wendet diese Oxydation des NH4Cl für die Umarbeitung zur massenspektrometrischen Bestimmung an. Bei der Verbrennung der Substanz nach DUMAS fällt die KJELDAHL-Veraschung und die Umarbeitung des NH4Cl weg, was eine Vereinfachung bedeutet. Dennoch wird diese Methode für die spektroskopische 15N-Bestimmung nur wenig angewendet. 相似文献