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151.
O. Keller C. Mang M. Nikola G. Schulz 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1996,37(4):315-322
Emission spectra following electron impact on CH3F, CH2F2 and CHF3 at various energies have been investigated in the spectral region from 200 nm to 700 nm. Emission thresholds and excitation functions for atomic and molecular fragments have been determined. Absolute emission cross sections were obtained for two band systems, A 2 Δ → X 2 Π, C 2 Σ+ → X 2 Π, observed in the emission spectrum of CH3F and for the H-Balmer radiation, H α ? H γ, in the spectra of all compounds. The continuous emission between 200 nm and 400 nm in the spectra of CH2F2 and CHF3 has been examined systematically. It was found that CF2(Ã) is the main precursor in both spectra. 相似文献
152.
Asima Davidovi? Ibro Tabakovi? Dušan Sladi? Nikola Dogovi? Miroslav J. Gašic 《Journal of Electroanalytical Chemistry》1991,321(3):457-468
The electrochemical reduction of avarone (Q), an antitumor sesquiterpenoid quinone, was investigated at various pH in aqueous ethanol containing a cationic surfactant, cetyltrimethylammonium bromide (CTAB) by cyclic and rotating disc electrode voltammetry, using a glassy carbon electrode. Comparison of the electrochemical reduction of Q in presence of CTAB with the same process in a homogeneous water + ethanol solution shows an anodic shift of the reduction potential in the presence of CTAB; at pH > 9.5 and in presence of CTAB, two well-defined reduction peaks are observed, thus confirming one-electron reduction of Q, whereby the intermediate radical-anion is stabilized by the cationic micellar medium. The electrochemical oxidation of BNAH was investigated by cyclic voltammetry, and the anodic shift of the peak potential in presence of CTAB was observed. From the electrochemical behaviour of Q and BNAH, and the kinetics of the oxidation of BNAH with Q, it is suggested that the reaction takes place in two successive one-electron transfer steps. The application of the Marcus theory gives additional proof that, in this case, the first electron transfer is the rate determining step. 相似文献
153.
Jasmina S. Brbori? Sote Vladimirov Mirjana S. Jovanovi? Nikola Dogovi? 《Monatshefte für Chemie / Chemical Monthly》2004,28(11):1009-1014
The synthesis and characterization of N-[2-[[4-iodo-2,6-bis(1-methylethyl)phenyl]amino]-2-oxoethyl]-N-(carboxymethyl)glycine and N-[2-[(4-iodo-2,6-diethylphenyl)amino]-2-oxoethyl]-N-(carboxymethyl)glycine is presented, as well as a modified and improved synthesis of N-[2-[(2,4-diiodo-6-methylphenyl)amino]-2-oxoethyl]-N-(carboxymethyl)glycine. These compounds are new agents for hepatobiliary imaging. 相似文献
154.
AbstractSelective binding of fluoride anion and its alkali metal cation ion pairs by a fluorescent calix[4]arene (L) derivative bearing tryptophan moieties was studied in acetonitrile at 25 °C. It was found that LF? and LF22? complexes were formed and their stability constants were determined by means of UV and 1H NMR titrations. Both amide and indole NH groups were involved in the stabilisation of the fluoride complexes, i.e. L afforded two anion-binding sites. 1H NMR titrations provided evidence of simultaneous complexation of both Na+ cation and fluoride anion resulting in the formation of a ternary NaLF complex. In this ion pair complex, the Na+ cation was most probably bound primarily by the calixarene ether and amide oxygen atoms, whereas the indole NH groups interacted with the fluoride ion. A highly favourable ion pairing between Na+ and F– in acetonitrile was studied using potentiometric measurements. The results pointed out the importance of fluoride pairing with alkali metal cations in aprotic organic solvents and the necessity of taking these reactions into account in the course of speciation studies of such solutions. 相似文献
155.
The surface potential at the silver chloride aqueous interface was measured by means of a single-crystal silver chloride electrode (SCr-AgCl). The measurements were conducted by titration of the KCl solution with AgNO3, and vice versa. The SCr-AgCl electrode potentials were converted to surface potentials psi(0) by setting zero at the point of zero charge at pCl = 5.2. The psi(0)(pCl) function was linear, with a slope 12% lower with respect to the Nernst equation. It was demonstrated that the surface potential at the silver halide aqueous interface could be interpreted by means of the surface complexation model, originally developed for metal oxides. 相似文献
156.
Zhang F Trbovic N Wang J Brüschweiler R 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2005,174(2):219-222
A novel processing scheme is presented that converts a two-dimensional double-quantum NMR spectrum into a single-quantum correlation spectrum. The covariance-like spectrum is computed from the 2D Fourier transform spectrum by emphasizing contributions that fulfill the double-quantum condition resulting in a symmetric spectrum that is easier to analyze. The method is demonstrated for the 2D INADEQUATE experiment. 相似文献
157.
158.
159.
Entanglement evolution is studied in open systems represented by rings of qubits with the Ising interaction and variously oriented external field and with Markov environments. The effect of thermal or dephasing environment is manifested as exponential decrease of the entanglement superposed on its dynamics in the isolated system. 相似文献
160.
Zusammenfassung Durch die mitgeteilten Versuche wird gezeigt, da? optisch aktive Antipoden von kapillar aktiven Substanzen, sich in verschiedenem
Grade an optisch aktiven Flüssigkeitsoberfl?chen ansammeln und dadurch verschiedene Grenzfl?chenspannungen und verschiedene
Emulgierungštendenzen der beiden Phasen bedingen. Aus dieser Tatsache folgt dann eine ungleiche Abtrennungsgeschwindigkeit
der beiden Antipoden von der optisch aktiven Flüssigkeitsoberfl?che, welche zu einer Spaltung von kapillaraktiven Razematen
ausgenutzt wird.
Die bekannten pharmakologischen Unterschiede im Verhalten von Antipoden auf den Organismus, wie z. B. die st?rkere Wirkung
desl-Adrenalins im Vergleich zu derd-Form, der verschiedene Geruch und Geschmack mancher Antipoden, werden in Beziehung gesetzt zu den beschriebenen Emulgierungsversuchen
und sind gewi? zum Teil durch die Unterschiede der Grenzfl?chenspannungen und somit der Resorptionsgeschwindigkeiten der Antipoden
gegenüber der aus optisch aktivem Material aufgebauten Zellwand bedingt. 相似文献