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排序方式: 共有188条查询结果,搜索用时 31 毫秒
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Dr. Gijs M. ter Huurne Dr. Pongphak Chidchob Dr. Augustin Long Prof. Alexandre Martinez Prof. Anja R. A. Palmans Dr. Ghislaine Vantomme 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(44):9964-9970
The design and the characterization of supramolecular additives to control the chain length of benzene-1,3,5-tricarboxamide (BTA) cooperative supramolecular polymers under thermodynamic equilibrium is unraveled. These additives act as chain cappers of supramolecular polymers and feature one face as reactive as the BTA discotic to interact strongly with the polymer end, whereas the other face is nonreactive and therefore impedes further polymerization. Such a design requires fine tuning of the conformational preorganization of the amides and the steric hindrance of the motif. The chain cappers studied are monotopic derivatives of BTA, modified by partial N-methylation of the amides or by positioning of a bulky cyclotriveratrylene cage on one face of the BTA unit. This study not only clarifies the interplay between structural variations and supramolecular interactions, but it also highlights the necessity to combine orthogonal characterization methods, spectroscopy and light scattering, to elucidate the structures and compositions of supramolecular systems. 相似文献
3.
Daniel Wechsler Cynthia Carolina Fernndez Julia Kbl Lisa-Marie Augustin Corinna Stumm Norbert Jux Hans-Peter Steinrück Federico Jos Williams Ole Lytken 《Molecules (Basel, Switzerland)》2021,26(10)
Porphyrins are large organic molecules that are interesting for different applications, such as photovoltaic cells, gas sensors, or in catalysis. For many of these applications, the interactions between adsorbed molecules and surfaces play a crucial role. Studies of porphyrins on surfaces typically fall into one of two groups: (1) evaporation onto well-defined single-crystal surfaces under well-controlled ultrahigh vacuum conditions or (2) more application-oriented wet chemical deposition onto less well-defined high surface area surfaces under ambient conditions. In this study, we will investigate the wet chemical deposition of 5-(monocarboxyphenyl)-10,15,20-triphenylporphyrin (MCTPP) on well-defined rutile TiO2(110) single crystals under ambient conditions. Prior to deposition, the TiO2(110) crystals were also cleaned wet-chemically under ambient conditions, meaning none of the preparation steps were done in ultrahigh vacuum. However, after each preparation step, the surfaces were characterized in ultrahigh vacuum with X-ray photoelectron spectroscopy (XPS) and the result was compared with porphyrin layers prepared in ultrahigh vacuum (UHV) by evaporation. The differences of both preparations when exposed to zinc ion solutions will also be discussed. 相似文献
4.
André U. Augustin Prof. Dr. Peter G. Jones Prof. Dr. Daniel B. Werz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(50):11620-11624
A 1,3-aminothiolation was realized by reacting 2-substituted cyclopropane 1,1-dicarboxylates with sulfonamides and N-(arylthio)succinimides. Under Sn(OTf)2 catalysis the transformation proceeded smoothly to the corresponding ring-opened products bearing the sulfonamide in the 1-position next to the donor and the arylthio residue in the 3-position next to the acceptor. The procedure was extended to the corresponding selenium analogues by employing N-(phenylseleno)succinimides as an electrophilic selenium source. 相似文献
5.
W.-D. Rudorf M. Augustin 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):329-335
Abstract Acylacetonitrile 1 reagieren mit Schwefelkohlenstoff in Gegenwart von Natriumhydrid zu den Dinatriumsalzen 2. Behandlung von 2 mit einem Alkylierungsreagens ergibt die offenkettigen oder cyclischen Acyl-cyanketen-S,S-acetale 3, 4, 8 bzw. 10. Arylierung zu 11 gelingt mit 2,4-Dinitrochlorbenzen. Fügt man zu2 nur ein Äquivalent Methyliodid hinzu und säuert das Reaktionsgemisch an, so entstehen die monoalkylierten Verbindungen 7, während β-Hydroxythioanilide 12 durch Umsetzung von 1 mit Phenylisothiocyanat zugänglich sind. Ein Vergleich der δ-Werte zeigt, daß in 7 und 12 der gleiche Typ für die Chelatisierung des Protons der OH-Gruppe vorliegt. Acyl acetonitriles 1 react with carbon disulfide in the presence of sodium hydride to give disodium salts 2. Treatment of 2 with an alkylation reagent yields the open chain or cyclic acyl cyanketene S,S-acetals 3,4,8 and 10, respectively. Arylation to 11 is successful with 2,4-dinitro-chlorobenzene. Adding only one equivalent of methyl iodide to 2 and acidifying the reaction mixture lead to the monoalkylated compounds 7, whereas β-hydroxythioanilides 12 are available by reaction of 1 with phenyl isothiocyanate. A comparison of the δ-values shows that there exists the same type of the proton's chelation of the OH-group in 7 and 12. 相似文献
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J. Augustin St. Graf B. Müller W. Greiner 《Zeitschrift für Physik A Hadrons and Nuclei》1990,336(3):353-356
The rates forX ° creation by photons and electrons channeling along a crystal axis are estimated. The process is found to depend strongly on the parameters of the crystal fields. PromisingX ° production rates can therefore be obtained for germanium rather than for lighter elements. 相似文献
8.
J. -E. Augustin G. Cosme F. Couchot B. Dudelzak F. Fulda B. Grelaud G. Grosdidier B. Jean-Marie S. Jullian D. Lalanne V. Lepeltier B. Louis F. Mané C. Paulot R. Riskalla Ph. Roy F. Rumpf G. Szklarz Z. Ajaltouni A. Falvard J. Jousset B. Michel J. C. Montret R. Baldini S. Calcaterra G. Capon D. Bisello G. Busetto S. Limentani M. Nigro L. Pescara M. Posocco P. Sartori L. Stanco DM Collaboration 《Zeitschrift fur Physik C Particles and Fields》1987,36(3):369-376
The radiative decayJ/ψ → γ π+ π? has been studied using the 8.6 millionJ/ψ produced in the DM2 experiment at the DCIe +e? storage rings at Orsay. The π+ π? mass spectrum shows a cleanf 2 (1270) signal, and the possible presence of two other states at thef 2 (1720) andf 4 (2030) masses. For thef 2 (1270), the branching ratio BR(J/ψ →γf)xBR(f→π+ π?) is measured to be (7.50±0.30±1.12)×10?4, and the spin analysis prefers theJ=2 assignment, with helicity parametersx=0.83±0.06 andy=0.01±0.06. The existence of higher mass states is discussed. 相似文献
9.
10.
Nanocrystalline CuFe2O4 and CuFe2O4/xSnO2 nanocomposites (x=0, 1, 5 wt%) have been successfully synthesized by one-pot reaction of urea-nitrate combustion method. The transmission electron microscope study reveals that the particle size of the as synthesized CuFe2O4 and CuFe2O4/5 wt%SnO2 are 10 and 20 nm, respectively. The SnO2 coating on the nanocrystalline CuFe2O4 was confirmed from HRTEM studies. The resultant products were sintered at 1100 °C and characterized by XRD and SQUID for compound formation and magnetic studies, respectively. The X-ray diffraction pattern shows the well-defined sharp peak that confirms the phase pure compound formation of tetragonal CuFe2O4. The zero field cooled (ZFC) and field cooled (FC) magnetization was performed using SQUID magnetometer from 2 to 350 K and the magnetic hysteresis measurement was carried out to study the magnetic properties of nanocomposites. 相似文献