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61.
We consider the decay rate of energy of the 1D damped original nonlinear wave equation. We first construct a new energy function. Then, employing the perturbed energy method and the generalized Young’s inequality, we prove that, with a general growth assumption on the nonlinear damping force near the origin, the decay rate of energy is governed by a dissipative ordinary differential equation. This allows us to recover the classical exponential, polynomial, or logarithmic decay rate for the linear, polynomial or exponentially degenerating damping force near the origin, respectively. Unlike the linear wave equation, the exponential decay rate constant depends on the initial data, due to the nonlinearity. 相似文献
62.
S. Czajkowski M. Bernas P. Armbruster H. Geissel C. Kozhuharov G. Münzenberg D. Vieira Ph. Dessagne Ch. Miehe E. Hanelt G. Audi J. K. P. Lee 《Zeitschrift für Physik A Hadrons and Nuclei》1994,348(4):267-272
Neutron-rich Co and Fe isotopes produced by86Kr projectile fragmentation at 500 MeV/u were separated and identified using the fragment separator (FrS) in a bunched energy mode.66Co and65Fe ions were selectively implanted in a double PIN-diode array where the-decay signals were measured. The half-lives were deduced from time correlations between implantation and-decay signals. The remeasurement of the66Co half-life confirms the isotope identification. The value of the65Fe half-life was found to be 0.45±0.15 s. 相似文献
63.
H. Navarro T. Timusk W. R. Datars D. C. Houghton 《Applied Physics A: Materials Science & Processing》1994,59(4):373-379
We have applied the technique of Photo Thermal Ionization Spectroscopy (PTIS) to the study of an erbium-doped p-Ge epitaxial layer, grown by MBE on an undoped n-type germanium substrate. The Er-doped Ge layer shows continuum photoconductivity response in the far-infrared region extending from 70 cm–1 to 900 cm–1. This type of epitaxial Er-doped Ge layers is a potentially attractive system for photoconductivity detectors of far-infrared radiation. Below 900 cm–1 three acceptor-like charged states can be distinguished with ionization energies of 9, 26.6 and 50 meV. Additionally, a study of the photoconductive response of the same sample for radiation from 1000 cm–1 to 10000 cm–1, i.e., for radiation energies well inside the forbidden gap to energies above it, shows a wealth of levels, some of which have previously been associated with erbium.On leave from: Instituto de Física, Universidad Autónoma de Puebla, Puebla, México 相似文献
64.
65.
M. Forrer M. Frenz V. Romano H. J. Altermatt H. P. Weber A. Silenok M. Istomyn V. I. Konov 《Applied physics. B, Lasers and optics》1993,56(2):104-112
Bone ablation using different pulse parameters and four emission lines of 9.3, 9.6, 10.3, and 10.6 m of the CO2 laser exhibits effects which are caused by the thermal properties and the absorption spectrum of bone material. The ablation mechanism was investigated with light- and electron-microscopy at short laser-pulse durations of 0.9 and 1.8 s and a long pulse of 250 s. It is shown that different processes are responsible for the ablation mechanism either using the short or the long pulse durations. In the case of short pulse durations it is shown that, although the mineral components are the main absorber for CO2 radiation, water is the driving force for the ablation process. The destruction of material is based on explosive evaporation of water with an ablation energy of 1.3 kJ/cm3. Histological examination revealed a minimal zone of 10–15 m of thermally altered material at the bottom of the laser drilled hole. Within the investigated spectral range we found that the ablation threshold at 9.3 and 9.6 m is lower than at 10.3 and 10.6 m. In comparison the ablation with a long pulse duration is determined by two processes. On the one side, the heat lost by heat conduction leads to carbonization of a surface layer, and the absorption of the CO2 radiation in this carbonized layer is the driving force of the ablation process. On the other side, it is shown that up to 60% of the pulse energy is absorbed in the ablation plume. Therefore, a long pulse duration results in an eight-times higher specific ablation energy of 10 kJ/cm3. 相似文献
66.
Absorbance values between 300 and 800 nm of aqueous solutions of poly(N-isopropyl acrylamide-co-itaconic acid-9.80), poly(N-isopropyl acrylamide-co-itaconic acid-52.05) and poly(N-isopropyl acrylamide)s containing Tegomer H-Si 2111 end groups and/or blocks were measured using a Shimadzu 160-A UV-visible spectrometer. Turbidities obtained from these absorbance values were used to interpret the macromolecular phase transition from a hydrophilic to a hydrophobic structure of the polymers. The effects of comonomer type and content, concentration of the solutions, pH and temperature on the coil-globule transition were discussed in terms of turbidity form factor, β related to size and shapes of particles and calculated by using the simplified form of Debye equation.The results presented in this work show that the presence of Tegomer H-Si 2111 (Si containing end groups and/or blocks) or high amount of itaconic acid (IA) in the chains prevent a collapse transition from hydrated extended coils to hydrophobic globules, which aggregate and form a separate phase (β<2). Furthermore, it was observed that in the case of concentrated solutions intermolecular hydrophobic interactions between isopropyl groups overcame the repulsive forces resulting from the ionized carboxylic acid groups of IA or surface active nature of Si containing hydrophobic groups (β>2). This stage of the transition corresponds to macroscopic phase separation after an intramolecular process. 相似文献
67.
纳米级NiTiO3粉体的合成 总被引:3,自引:0,他引:3
以H2TiO3,H2O2及NiCl2为主要原料,用化学共沉淀法制备了纳米级NiTiO3。确定了反应物H2TiO3,H2O2,NH3的最佳摩尔比为1:8:2,用不同的退火温度和退火时间对样品处理得到相应粒径的纳米级粉体。 相似文献
68.
A family of of open subsets of the real line is called an ω-cover of a set X iff every finite subset of X is contained in an element of . A set of reals X is a γ-set iff for every ω-cover of X there exists such that In this paper we show that assuming Martin's axiom there is a γ-set X of cardinality the continuum. 相似文献
69.
Mavroudis A Demertzis 《Analytica chimica acta》2004,505(1):73-76
An efficient, more sensitive and accurate spectrophotometric process is possible and can be used to obtain qualitative or quantitative results for analytes at limiting concentrations lower than usual. Transmission measurements (incident light power, P0, or transmitted, P) are performed with a fluorescence spectrometer. One cell only is used to measure standards or unknown solutions, placed between the standard holder cuvette and the emission monochromator of the instrument. The source of the radiant power (P0) is not the xenon lamp but the fluorescence or scattered radiation from the holder cuvette filled with an appropriate solution. The analyte concentration is found from a calibration graph, based upon Beer’s law or the approximate formula P0−P=2.303P0εbc, which is valid for dilute solutions. Determination of iron in a reference material, using 1,10-phenanthroline as the chromogenic reagent, was chosen as an example to demonstrate the suitability of the proposed method and clarify several important statistical questions. Also discussed is why and to what extent molecular fluorescence methods are more sensitive than molecular absorption methods. 相似文献
70.
Z. Guennoun A. Coupeaud I. Couturier-Tamburelli N. Pitri S. Coussan J.-P. Aycard 《Chemical physics》2004,300(1-3):143-151
The structures and energies of the 1:1 acetylene/cyanoacetylene, acetylene/dicyanoacetylene and cyanoacetylene/dicyanoacetylene complexes in solid argon matrices have been investigated using FT-IR spectroscopy and ab initio calculations, at the B3LYP/6-31G** level of theory. For the three complexes, predicted frequency shifts for the L shaped structures, characterized by a hydrogen bond between the nitrogen of the cyano group and the acetylenic proton, were found to be in good agreement with those experimental. Only in the case of acetylene/cyanoacetylene complex, we obtained a second minimum with a T shaped structure characterized by an interaction between the proton of cyanoacetylene and the Π system of acetylene. It appears clearly that HC3N acts as an electrophile or as a nucleophile in these complexes. 相似文献