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991.
Mindaugas Radziunas Anissa Zeghuzi Jürgen Fuhrmann Thomas Koprucki Hans-Jürgen Wünsche Hans Wenzel Uwe Bandelow 《Optical and Quantum Electronics》2017,49(10):332
We extend a 2 (space) + 1 (time)-dimensional traveling wave model for broad-area edge-emitting semiconductor lasers by a model for inhomogeneous current spreading from the contact to the active zone of the laser. To speedup the performance of the device simulations, we suggest and discuss several approximations of the inhomogeneous current density in the active zone. 相似文献
992.
Javed Ahmad Hidetoshi Minami Sher Alam Jianding Yu Yasutomo Arai Hiromoto Uwe 《中国物理快报》2008,25(12):4421-4424
Optical transmittance and reflectance on ferroelectric BaTi2O5 glasses prepared recently by a containerless synthesis technique are measured at room temperature in the wavelength range 190-800nm. The fundamental absorption edge located around 340nm demonstrates the colourless and transparent character of the glass. The optical band gap of 3.32eV has been estimated. The tail of the optical absorption near the fundamental absorption edge is found to follow the Urbach rule. Our analysis of the experimental spectra supports an indirect allowed interband transition between the valence band formed by O-2p orbitals and the conduction band formed by Ti-3d orbitals. 相似文献
993.
Size-dependent intrinsic radiative decay rates of silicon nanocrystals at large confinement energies
Sykora M Mangolini L Schaller RD Kortshagen U Jurbergs D Klimov VI 《Physical review letters》2008,100(6):067401
We study ultrafast photoluminescence (PL) dynamics of Si nanocrystals (NCs). The early-time PL spectra (<1 ns), which show strong dependence on NC size, are attributed to emission involving NC quantized states. The PL spectra recorded for long delays (>10 ns) are almost independent of NC size and are likely due to surface-related recombination. Based on instantaneous PL intensities measured 2 ps after excitation, we determine intrinsic radiative rate constants for NCs of different sizes. These constants sharply increase for confinement energies greater than approximately 1 eV indicating a fast, exponential growth of the oscillator strength of zero-phonon, pseudodirect transitions. 相似文献
994.
Rainer Richter Uwe Schrder Lothar Beyer Jorge Angulo‐Cornejo Maria Lino‐Pacheco 《无机化学与普通化学杂志》2001,627(8):1877-1881
Mononuclear Copper(II) Complexes of Dioxaalkylene and Alkylene Bridged Bis‐isoureas By reaction of N‐benzoylthiocarbamic‐O,S‐diethylester with primary diamines (oxa)alkylene bridged isoureas 1 have been prepared. They yield with CuII neutral chelates 2 with tetradentate ligand coordination. The structures of the ligand 1 a and of the related CuII complex 2 a have been determined by X‐ray crystal structure analysis. They show an enamine tautomer in the ligand and a slightly tetrahedrally distorted coordination with an (oxa)alkylene bridge between the trans arranged N ligator atoms in the complex. 相似文献
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998.
Uwe Karst 《Nachrichten aus der Chemie》2001,49(6):845-847
Unter dem Motto „A Voyage of Discovery”︁ lud die 52. Pittsburgh Conference (Pittcon) Anfang März zu einer Entdeckungsreise durch die Analytische Chemie nach New Orleans, der Hauptstadt des Jazz, ein. Wiederum wurde ein reichhaltiges wissenschaftliches Programm mit der größten jährlichen Ausstellung analytisch‐chemischer Geräte verknüpft. 相似文献
999.
1000.
Mehmet Somer Uwe Herterich Jan urda Wilder Carrillo‐Cabrera Anke Zürn Karl Peters Hans Georg von Schnering 《无机化学与普通化学杂志》2000,626(3):625-633
Ternary Nitridoborates. 2. Synthesis, Crystal Structure, and Vibrational Spectra of New Ternary Compounds with the [N–B–N]3– Anion The isotypic compounds LiM4[BN2]3 (M = Ca, Sr, Ba, Eu) and NaM4[BN2]3 (M = Sr, Ba) are formed as colorless to pale yellow prismatic crystals (black with Eu) by reaction of the binary components Li3N, M3N2, EuN and Na, NaN3, Ba3N2 and BN in sealed niobium ampoules at 1375 and 1275 K, respectively. The linear anions [N–B–N]3– have bond lengths d(B–N) between 132.6 and 136.6 pm. Vibrational frequencies and force constants f(B–N) = 7.25–7.89 Ncm–1 reveal significant drifts related to bond length and effective anionic charge. The cubic crystal structures (Im3m (No. 229), Z = 2; LiM4[BN2]3: a(Ca) = 711.5 pm; a(Sr) = 745.6 pm; a(Eu) = 742.5 pm, a(Ba) = 788.0 pm and NaM4[BN2] structure type, and the range of existence of this cubic structure is derived from the molar volume and the ionic radii. The cations form a partial structure of centered cubes E1(E2)8 which are condensed to a [E1(E2)8/2] network (E1 = Li, Na; E2 = Ca, Sr, Ba, Eu). The remaining open cubes are filled by the [BN2]3– anions yielding two interpenetrating [E1(BN2)6/2] networks. Periodic Nodal Surfaces (PNS) of Im3m symmetry show the regions of different interactions. 相似文献