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31.
Dr. Lenka Štacková Marina Russo Dr. Lucie Muchová Vojtěch Orel Prof. Libor Vítek Dr. Peter Štacko Prof. Petr Klán 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(58):13184-13190
Carbon monoxide (CO) is an endogenous signaling molecule that controls a number of physiological processes. To circumvent the inherent toxicity of CO, light-activated CO-releasing molecules (photoCORMs) have emerged as an alternative for its administration. However, their wider application requires photoactivation using biologically benign visible and near-infrared (NIR) light. In this work, a strategy to access such photoCORMs by fusing two CO-releasing flavonol moieties with a NIR-absorbing cyanine dye is presented. These hybrids liberate two molecules of CO in high chemical yields upon activation with NIR light up to 820 nm and exhibit excellent uncaging cross-sections, which surpass the state-of-the-art by two orders of magnitude. Furthermore, the biocompatibility and applicability of the system in vitro and in vivo are demonstrated, and a mechanism of CO release is proposed. It is hoped that this strategy will stimulate the discovery of new classes of photoCORMs and accelerate the translation of CO-based phototherapy into practice. 相似文献
32.
Dr. Aleksandra Markovic Luca Gerhards Dr. Pia Sander Dr. Carsten Dosche Prof. Dr. Thorsten Klüner Prof. Dr. Rüdiger Beckhaus Prof. Gunther Wittstock 《Chemphyschem》2020,21(22):2506-2514
Multinuclear transition metal complexes bridged by ligands with extended π-electronic systems show a variety of complex electronic transitions and electron transfer reactions. While a systematic understanding of the photochemistry and electrochemistry has been attained for binuclear complexes, much less is known about trinuclear complexes such as hexaphenyl-5,6,11,12,17,18-hexaazatrinaphthylene-tristitanocene [(Cp2Ti)3HATN(Ph)6]. The voltammogram of [(Cp2Ti)3HATN(Ph)6] shows six oxidation and three reduction waves. Solution spectra of [(Cp2Ti)3HATN(Ph)6] and of the electrochemically formed oxidation products show electronic transitions in the UV, visible and the NIR ranges. Density functional theory (DFT) and linear response time-dependent DFT show that the three formally titanium(II) centers transfer an electron to the HATN ligand in the ground state. The optically excited transitions occur exclusively between ligand-centered orbitals. The charged titanium centers only provide an electrostatic frame to the extended π-electronic system. Complete active self-consistent field (CASSCF) calculation on a structurally simplified model compound, which considers the multi-reference character imposed by the three titanium centers, can provide an interpretation of the experimentally observed temperature-dependent magnetic behavior of the different redox states of the title compound in full consistency with the interpretation of the electronic spectra. 相似文献
33.
R. Klíma 《Czechoslovak Journal of Physics》1970,20(2):182-195
The stationary state of a collisionless plasma in a magnetic mirror is analyzed provided that a strong h.f. field is present. The h.f. field frequency is somewhat higher than the electron cyclotron frequency. The pressure acting on the plasma and the height of the h.f. potential barrier are derived in particular. The h.f. potential yields the possibility of eliminating the loss cone in the velocities distribution. The upper limits, which the electron temperature must not exceed, are derived. If an appropriate stationary magnetic field is used, the required incident wave power can be diminished and the allowable electron temperature can be increased. Some new results concerning the case of a homogeneous magnetic field are presented. 相似文献
34.
Using the classical dipole representation for the gas molecules, an approximate kinetic equation is derived including radiation pressure forces. The energy-momentum tensor for a quasimonochromatic electromagnetic wave packet is constructed. Electrostrictive forces and nonlinear perturbations of the gas rest energy density are taken into account. Certain particle-like properties of the wave packet are demonstrated. Radiation pressure forces are given for some simple models of fluid inhomogeneities. 相似文献
35.
The article describes a computational model for the simulation of the emergence of social structure or social order, respectively. The model is theoretically based on the theory of social typifying by Berger and Luckmann. It consists of interacting artificial actors (agents), which are represented by two neural networks, an action net, and a perception net. By mutually adjusting of their actions, the agents are able to constitute a self‐organized social order in dependency of their personal characteristics and certain features of their environment. A fictitious example demonstrates the applicability of the model to problems of extra‐terrestrial robotics. © 2007 Wiley Periodicals, Inc. Complexity 12: 41–52, 2007 相似文献
36.
Temperature dependences of the dielectric permittivity of betaine phosphite crystals are studied both without and under application of an electric bias. It is shown that, in view of the fact that the high-temperature improper ferroelastic (antiferrodistorsive) phase transition at T c1=355 K is nearly tricritical, the nonlinear temperature dependence of inverse dielectric permittivity in the paraelectric phase and the effect of the field on the dielectric permittivity can be described within a phenomenological model containing two coupled (polar and nonpolar) order parameters with a negative coupling coefficient. An analysis of the model revealed that, in the case where two phase transitions, a nonpolar and a ferroelectric one, can occur in the crystal, all of its dielectric properties, including the polarization response in a field, can be described by one dimensionless parameter a. For the crystal under study, we have a=?2.5. This value of the parameter corresponds to a second-order ferroelectric transition far from the tricritical point, at which a=?1. It is shown that the polarization response in the paraelectric phase in an electric field calculated within this model differs radically from that in the ferroelectric phase-transition model for which the Curie-Weiss law holds in the paraelectric phase. 相似文献
37.
38.
L. Koester K. Knopf W. Waschkowski A. Klüver 《Zeitschrift für Physik A Hadrons and Nuclei》1985,320(4):661-668
Coherent neutron scattering lengths and total cross sections have been measured for elemental Zn,Zn-compounds and on isotopicly enriched samples for neutron energies from 0.5 meV up to 143 keV using different techniques. From the experimental data the following quantities were obtained: the coherent scattering lengths (b in fm) of Zn (5.689±0.014);64Zn (5.23±0.04);66Zn (5.98±0.05);67Zn (7.58±0.08;b +=9.4±0.5/5.8±0.5;b ?=5.0±0.7/10.1±0.7);68Zn (6.04 ±0.03); the potential scattering radii (R′ in fm) of Zn (6.2±0.2),64Zn (6.0±0.3) and66Zn (6.2 ±0.3); the absorption cross sections (σ γ at 0.025 eV in barn) of Zn (1.11±0.02);64Zn (1.1 ±0.1) and66Zn (0.62±0.06). Derived quantities are the “zero energy” scattering cross sections (σ 0 in barn) for Zn (4.128±0.010) and67Zn (7.8±0.3) and the incoherent bound cross sections of Zn (0.061 ±0.023) and67Zn (0.6±0.4). In the epithermal region the Zn-cross section can be described by introduction of two strong bound levels of67Zn+n for which estimated parameters are given. 相似文献
39.
G.?Kl?mkeEmail author K.?M?nig 《The European Physical Journal C - Particles and Fields》2005,42(3):261-270
A Monte-Carlo analysis on production and decay of supersymmetric charginos at a future photon-collider is presented. A photon collider offers the possibility of a direct branching-ratio measurement. In this study, the process
has been considered for a specific mSUGRA scenario. Various backgrounds and a parameterised detector simulation have been included. Depending on the centre-of-mass energy, a statistical error for the directly measurable branching ratio BR(
) of up to 3.5% can be reached.Received: 14 March 2005, Revised: 31 May 2005, Published online: 28 June 2005G. Klämke: Now at: Institut für Theoretische Physik, Universität Karlsruhe, Wolfgang-Gaede-Str. 1, 76131 Karlsruhe, Germany 相似文献
40.
RGDS‐ and SIKVAVS‐Modified Superporous Poly(2‐hydroxyethyl methacrylate) Scaffolds for Tissue Engineering Applications 下载免费PDF全文
Hana Macková Zdeněk Plichta Vladimír Proks Ilya Kotelnikov Jan Kučka Helena Hlídková Daniel Horák Šárka Kubinová Klára Jiráková 《Macromolecular bioscience》2016,16(11):1621-1631
Three‐dimensional hydrogel supports for mesenchymal and neural stem cells (NSCs) are promising materials for tissue engineering applications such as spinal cord repair. This study involves the preparation and characterization of superporous scaffolds based on a copolymer of 2‐hydroxyethyl and 2‐aminoethyl methacrylate (HEMA and AEMA) crosslinked with ethylene dimethacrylate. Ammonium oxalate is chosen as a suitable porogen because it consists of needle‐like crystals, allowing their parallel arrangement in the polymerization mold. The amino group of AEMA is used to immobilize RGDS and SIKVAVS peptide sequences with an N‐γ‐maleimidobutyryloxy succinimide ester linker. The amount of the peptide on the scaffold is determined using 125I radiolabeled SIKVAVS. Both RGDS‐ and SIKVAVS‐modified poly(2‐hydroxyethyl methacrylate) scaffolds serve as supports for culturing human mesenchymal stem cells (MSCs) and human fetal NSCs. The RGDS sequence is found to be better for MSC and NSC proliferation and growth than SIKVAVS.