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排序方式: 共有325条查询结果,搜索用时 9 毫秒
1.
TiCx-PECVD-layers were characterized by TEM. EDX analysis and electron diffraction. TiCx-layers deposited using benzene showed a columnar structure, at which the column size decreases with rising excess carbon content. TiCx-layers deposited using n-heptane presented a lamellar structure, at which the lamellar thickness diminishes with an increasing excess carbon content. In dependence on the layer thickness a periodic progress of the element contents was observed, at which a maximum for Ti and Cl correlates with a minimum for C. It was found that the incorporated chlorine is bonded to titanium. The lattice parameter depends on the chlorine content. Using TiCl4/H2/Ar-gas mixtures without any hydrocarbon, layers containing TiH2 are formed. 相似文献
2.
Pop D Winter B Freyer W Widdra W Hertel IV 《The journal of physical chemistry. B》2005,109(16):7826-7833
Photoemission measurements were performed on a series of stepwise benzoannelated zinc porphyrazine molecules in thin films. The electronic structure of tert-butyl-substituted zinc tetraazaporphyrin, phthalocyanine, and naphthalocyanine is investigated using mainly EUV synchrotron radiation. A detailed analysis of the zinc satellites in the spectra of the valence region is performed in an attempt to infer the effect of ligand size extension on the metal-ligand interactions. No differences in the character of the bond between zinc and ligand were detected as a function of ligand size. The results are compared with those for the respective metal-free and copper-containing molecules. 相似文献
3.
J. C. Greer R. Ahlrichs I. V. Hertel 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1991,18(4):413-426
A theoretical study of the energetics and intramolecular dynamics for ammonia cluster cations (NH3) 2 + and (NH3) 3 + is presented. The proton transfer mechanism after a vertical ionisation is followed in detail. Structural and energetic calculations are performed near the Hartree-Fock self consistent field (HF-SCF) limit; all open shell calculations are spin restricted (RHF). The calculations reconcile experimental results from thermochemical and photoionisation measurements: discrepancies in the energetics are shown to be due to the probing of different regions of the potential energy surface (PES). For the dynamics calculations, it is impractical to determine a large region of the multidimensional PES and then integrate Newton's equations. The calculations therefore incorporate a quantum mechanical determination of the electronic energy of the system after each time increment while nuclear degrees of freedom are handled classically. In this way, the classical reaction path across the Born-Oppenheimer surface is obtained. 相似文献
4.
Ozonation of polycyclic aromatic hydrocarbons (PAHs) in soil is a process that can be used for in-situ soil remediation or in combination with bioremediation techniques. First steps to a comprehensive ecotoxicological evaluation of this method is done by ozonation of radioactively labeled (14C) pyrene and benzo[a]pyrene in a silty soil (LUFA 2.2) under mass-balancing conditions and GC-MS analysis of aromatic ozonation products. 14C-Mass-balances for pyrene and benzo[a]pyrene (b[a]p) in soil showed that, apart from 14CO2 formation, considerable percentages of both PAHs are oxidized to water soluble substances (20–30%) or to non-extractable or bound residues (10% for pyrene, 30% for b[a]p). TLC and GC-MS analysis of ozonation products extractable from artificially contaminated silica and soil by organic solvents revealed a large number of aromatic substances. PAH-quinones and ten ring fission products with formyl- and carboxy-groups of both pyrene and b[a]p could be identified. 相似文献
5.
Eike Hertel 《Geometriae Dedicata》1994,52(3):215-220
A subsetS of a metric space (X,d) is calledd-convex if for any pair of pointsx,y S each pointz X withd(x,z) +d(z,y) =d(x,y) belongs toS. We give some results and open questions concerning isometric and convexity-preserving embeddings of finite metric spaces into standard spaces and the number ofd-convex sets of a finite metric space. 相似文献
6.
A. Bähring E. Meyer I. V. Hertel H. Schmidt 《Zeitschrift für Physik A Hadrons and Nuclei》1985,320(1):141-149
Pronounced polarization effects have been observed in inelastic collisions of laser state-prepared Na*(3p,M L) with Na+ leading to Na*(3d) for the energy rangeE CM=20–45 eV. Using linearly polarized light the dependence of the inelastic process on the alignment of the electronic charge cloud of the Na*(3p) prior to the collision has been measured. In studies with left and right hand circularly polarized light the angular momentum transferred in the collision process has been determined. The results are compared with similar data for the 3p→3s deexitation process studied previously [6]. The density matrix of the Na*(3p) state has been evaluated with respect to the collisional excitation to Na*(3d). Semiclassical calculations based on the coupled channel impact parameter approximation using pseudopotentials [7] and nonadiabatic rotational coupling elements for the Na 2 * system [12] have been performed. The agreement with the experimental results is good, in particular for the higher collision energies. 相似文献
7.
R. Witte E. E. B. Campbell C. Richter H. Schmidt I. V. Hertel 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1987,5(2):101-111
A collisional alignment and orientation study with planar symmetry is described, determining the complete density matrix for resonant charge transfer from laser excited atoms. Results are reported for the Na++Na*(3p) system over the collision energy rangeE c.m.=50?100 eV. We communicate the optimal alignment angle γ and linear polarisationP l + of the charge cloud as well as its relative height ρ00 and the angular momentumL ⊥ + transferred in the collision as a function of the scattering angle. For preparation of the sodium 3p orbital in the scattering plane (positive reflection symmetry) we observe that at small reduced scattering angles (<20 eV°) the preparation of apσ at large internuclear distances contributes most to the scattering intensity whereas at larger reduced scattering angles (>60 eV°) apπ+ preparation is more important. In contrast, preparation of thepπ? orbital (perpendicular to the scattering plane) is large at small and vanishes at larger scattering angles. We conclude that orbital following cannot be assumed in this resonant charge transfer process. The angular momentum transfer is observed to be small, indicating only little coherence in the process, but shows nevertheless an interesting behaviour as a function of scattering angle. 相似文献
8.
Alexander Goerke Gregor Leipelt Hartmut Palm C. P. Schulz I. V. Hertel 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1995,32(4):311-320
The first reactive differential scattering study for atomic clusters is reported. Oxidation of Na
x
(x8) with O2 is investigated in a crossed beam apparatus. Sodium oxide (Na
n
O,n4) and sodium dioxide (Na
n
O2,n6) are produced with a total reactive cross section from 50 to 80 Å2, depending on the cluster size. The excess energies for these reactions are estimated by an SCF type ab initio calculation and range from 0.5 to 5 eV. The large cross section may then be understood quantitatively in terms of a harpooning mechanism as a first step in the reaction path. Angular distributions have been determined for the most abundant products, showing strong forward scattering. Two different schemes are discussed for the reaction: while the dioxides Na
n
O2 may be formed by an evaporative cooling process from a highly excited collision complex, formation of Na
n
O appears to originate from a direct process. In both cases the experimental data suggest that most of the exothermicity remains in the reaction products. 相似文献
9.
E. E. B. Campbell R. R. Schneider A. Hielscher A. Tittes R. Ehlich I. V. Hertel 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1992,22(2):521-527
The collisional velocity dependence of the cross sections for fragmentation of mass-selected (CO2) n + (n+2...7) clusters in collisions with Ar atoms is presented. Interesting structure can be observed in the cross sections which indicate that the collision occurs between the Ar atom and one CO2 molecule within the cluster. The results may be explained by assuming that the collision leads to either vibrational excitation of a loosely bound CO2 monomer which then leaves the cluster or excitation of the entire cluster to a dissociative state. 相似文献
10.