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951.
In this paper the acoustic forces on particles and agglomerates caused by high-intensity ultrasound in gaseous atmosphere are derived by means of computational fluid dynamics (CFD). Sound induced forces cause an oscillating stress scenario where the primary particles of an agglomerate are alternatingly pressed together and torn apart with the frequency of the applied wave. A comparison of the calculated acoustic forces with respect to the inter particle adhesion forces from Van-der-Waals and liquid bridge interactions reveals that the separation forces may reach the same order of magnitude for 80 μm sized SiO2-particles. Hence, with finite probability acoustically agitated gases may de-agglomerate/disperse solid agglomerate structures. This effect is confirmed by dispersion experiments in an acoustic particle levitation setup. 相似文献
952.
We show that any Weyl curvature model can be geometrically realized by a Weyl manifold. 相似文献
953.
Udo Dinglreiter 《Heat and Mass Transfer》2011,47(8):991-999
In many industrial processes as well as in air conditioning systems heat and moisture is transferred by rotary heat exchangers
from the warm exhaust air flow to the cold supply air flow. Rotary heat exchangers are classified as sorption rotors, hygroscopic
rotors and condensation rotors. Basic mechanisms of heat and moisture transfer are presented. By means of the condensation
potential as the difference between the moisture content of the warm air flow and the moisture content of the cold air flow
at saturation the humidity transfer at the different rotor types is investigated. The condensation potential as a reference
parameter provides the possibility to describe the influence of various air conditions in exhaust air and supply air flow
on the humidity transfer of different rotary heat exchangers and to compare these rotors with each other. In order to give
an overview of relevant design parameters, the influence of the speed of turning, the flute height of the rotor matrix and
the velocity of the air flow regarding the heat and mass transfer is considered. 相似文献
954.
Chemical behavior of carbenes (adamantylidenes) generated by photolysis of adamantanediazirines has been investigated while they were incarcerated within an organic container in water and on silica surfaces. Confined carbenes behave differently from the free ones, and their behavior is dictated by the nature and the structure of the host-guest complexes. The substituent present on the adamantyl skeleton controls the stoichiometry (1:1 or 2:2) and the orientation of guest molecules within the host. 相似文献
955.
956.
Ethanol clusters are generated in a continuous He seeded supersonic expansion and doped with sodium atoms in a pick-up cell. By this method clusters of the type Na(C(2)H(5)OH)(n) are formed and characterized by determining size selectively their ionization potentials (IPs) for n = 2-40 in photoionization experiments. A continuous decrease to 3.1 eV is found from n = 2 to 6 and a constant value of 3.07 ± 0.06 eV for n = 10-40. This IP evolution is similar to the sodium-water and the sodium-methanol system. Quantum chemical calculations (B3LYP and MP2) of the IPs indicate adiabatic contributions to the photoionization process for the cluster sizes n = 4 and 5, which is similar to the sodium-methanol case. The results of the extrapolated IPs and the vertical binding energies (VEBs) of cluster anions are compared with the recently reported VEBs of solvated electrons in liquid water, methanol, and ethanol solutions in the range of 3.1-3.4 eV. The new results imply that the extrapolated VBEs of solvated electrons in anionic clusters match the VBE in liquid water, while they are about 0.5 eV too low for methanol. The influence of the presence of counterions on these findings is discussed. 相似文献
957.
Verkerk UH Zhao J Van Stipdonk MJ Bythell BJ Oomens J Hopkinson AC Siu KW 《The journal of physical chemistry. A》2011,115(24):6683-6687
Collision-induced dissociations of protonated (18)O-labeled tetraglycines labeled separately at either the first or the second amide bond established that water loss from the backbone occurs from the N-terminal residue. Density functional theory at B3LYP/6-311++G(d,p) predicted that the low-energy [G(4) + H - H(2)O](+) product ion is an N(1)-protonated 3,5-dihydro-4H-imidazol-4-one. The ion at the lowest energy, III, is 24.8 kcal mol(-1) lower than the protonated oxazole structure, II, proposed by Bythell et al. (J. Phys. Chem A2010, 114, 5076-5082). In addition, structure III has a predicted IR spectrum that provides a better match with the published experimental IRMPD spectrum than that of structure II. 相似文献
958.
First-principles calculations have been used to investigate the electronic structure and energetics of the simple tetragonal SrCuO? (P4=mmm) and its high-pressure tetragonal superstructure (P4=mmm). Based on the calculations, the high-pressure phase is metastable as compared with the low pressure tetragonal phase, with an energy difference of 0.13 eV per SrCuO? formula unit. The energy barrier to the transition from the superstructure to the simple tetragonal structure is 0.24 eV at 7 GPa; thus, high temperatures are required to synthesize the latter. Among the possible structural configurations resulting from the partially occupied oxygen site in the superstructure phase, the most stable structure has a space group PN4m2, reduced from that of the simple tetragonal structure P4=mmm. The detailed analysis of the electronic band structures of the simple tetragonal and superstructure phases suggests that the out-of-plane buckling of the O atoms in the superstructure leads to significant decrease in the O p-Cu d orbital overlap, allowing the energy of the system to be lowered, which is necessary for the structural stability. An understanding of the electronic structure and energetics of the high-pressure superstructure phase and its relation to the simple tetragonal phase provides a basis for exploring the physical properties of the infinite layer, high-TC superconductor. 相似文献
959.
Wind energy conversion devices (WECDs) are sensitive structures subjected to high force fluctuations, making them prone to damage. Thus, a global identification and damage detection technique is important to keep track of any changes in the structural characteristics of the WECD. In this contribution, a previously-developed structural identification and damage detection algorithm, namely: the M odified A daptive Ha R mony Searc H AL gorithm (MARSHAL), is used to perform structural identification and damage detection to a laboratory test model of a WECD supported by a tripile. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
960.
Cem Gok Udo Gerstmann Sule Aytas 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(1):777-788
Radioactive strontium is one of the major radioactive contaminant and its contamination is a very serious concern. Therefore, there is a need for economic, effective, non-toxic, readily available and abundant adsorbent or biosorbent to remove strontium from solutions. In this study, biosorption of 85Sr as a surrogate for 90Sr onto alginate beads was investigated in a batch system. Alginate beads were prepared from Na-alginate via cross-linking with divalent calcium ions according to the egg box model. The effect of several parameters such as pH, initial strontium concentration, contact time, dosage of alginate beads and temperature were investigated. In order to optimize the design of biosorption system for the removal of strontium, it is important to establish the most appropriate correlation for equilibrium curves. The experimental isotherm data were described by 6 different biosorption isotherm models, namely Langmuir, Freundlich, Dubinin–Radushkevich, Temkin, Flory–Huggins and Brunauer, Emmer and Teller, with constants obtained from linear and non-linear regression methods. The thermodynamic parameters (?H°, ?S° and ?G°) for strontium biosorption were also determined. The results indicate that these alginate beads have a good potential for the biosorption of strontium from solutions. 相似文献