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71.
Dr.-Ing. K. P. Großkurth 《Colloid and polymer science》1981,259(2):163-170
Zusammenfassung Im vorfibrillaren Stadium besitzt die Crazematerie eine in Verformungsrichtung deformierte Netzwerkstruktur, die sich bei Polystyrol und Styrol-Acrylnitril-Copolymerisat elektronenoptisch an Oberflächenabdrücken sauerstoffionengeätzter Proben nachweisen läßt. Während die durchschnittlichen Globulitverformungen zumeist deutlich unterhalb von 50% liegen, werden partiell Spitzenwerte von bis zu 300% erreicht. Am Beispiel des Polystyrols verdeutlichen quantitative Strukturvergleiche mit warmgerecktem Material, daß die molekulare Beweglichkeit während des Crazewachstums und der Schulter-Hals-Verstreckung derjenigen entspricht, die für thermisch aktiviertes Material oberhalb der Glastemperatur charakteristisch ist.Mit 7 Abbildungen und 2 Tabellen 相似文献
72.
The novel versatile cobalt(I) tris-carbene complex [(TIMEN(xyl))Co]Cl (1) (where TIMEN = (tris[2-(3-arylimidazol-2-ylidene)ethyl]amine) reacts with CO, one-electron oxidizers such as CH(2)Cl(2), and O(2) to yield the cobalt complexes [(TIMEN(xyl))Co(CO)]Cl (2), [(TIMEN(xyl))Co(Cl)]Cl (3), and peroxo species [(TIMEN(xyl))Co(O(2))](BPh(4)) (5). All new complexes were fully characterized by (1)H NMR, UV/vis, and IR spectroscopy as well as superconducting quantum interference device (SQUID) magnetization measurements and single-crystal X-ray crystallography. The nucleophilic character of the eta(2)-bound dioxygen ligand in 5 was confirmed by density functional theory (DFT) studies and allows for oxygen-transfer reactions with electron-deficient organic substrates, such as benzoyl chloride. 相似文献
73.
A. S. Aynacioglu A. -H. Meißner F. Walachowicz G. v. Oppen 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1991,18(1):85-91
The magnetic depolarization of the impact radiation at λ(41 D?21 P)=492 nm and λ(31 D?21 P) = 668 nm as well as the splitting of the magnetic depolarisation signals in electric fields were investigated for 10–25 keV H 2 + (D 2 + )-He collisions (only 492 nm line) and for 5-22.5 keV He-He collisions (both lines). The results are compared with analogous measurements for He+- He and Ne+ - He collisions and the dynamics of the excitation process are qualitatively discussed. In particular, we emphasize the importance of inertia for the evolution of the electron cloud during the final phase of the collision process. 相似文献
74.
Isotope shifts have been measured in Sm II from which the shifts between pure configurations 4f 6 s and 4f 65d can be determined. The specific mass shift for such a “transition” was estimated to be (?1±2)mK for a change of two neutrons. The values derived for the change in the nuclear charge distribution,δ〈r 2〉, are in good agreement with the results obtained from isotope shift measurements in Sm I (H. Brand et al.: J. Phys. B11, L99, 1978). The weighted mean values representing the best information onδ〈r 2〉 presently available are in fm2: [144, 148] 0.488(23); [148, 150] 0.285(14); [150, 152] 0.400(19); [152, 154] 0.217(11). 相似文献
75.
Jolanta Klocek Krzysztof Kolanek Dieter Schmeißer 《Journal of Physics and Chemistry of Solids》2012,73(5):699-706
Fullerene based materials may open a new horizon in many fields of science. In this study we fabricated thin films of the hybrid materials formed as a result of interactions between C60 fullerenes and 3-aminopropyltrimethoxysilane (APTMS). The deposition technique was a combination of spin-coating and evaporation methods. Interactions within the films were investigated by means of X-ray photoelectron spectroscopy and near edge X-ray absorption fine structure spectroscopy (NEXAFS). Surface morphology was measured by atomic force microscopy (AFM). We found that there are strong chemical reactions between the nucleophilic nitrogen atoms from APTMS and electrophilic fullerene molecules. Results of NEXAFS investigations suggest that due to direct interactions between APTMS and C60 the electronic structure of the fullerene molecules changes while at the same time AFM proved that the C60 molecule diameter is not altered. 相似文献
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79.
Dr. Qingquan Lu Steffen Greßies Felix J. R. Klauck Prof. Dr. Frank Glorius 《Angewandte Chemie (International ed. in English)》2017,56(23):6660-6664
A MnI-catalyzed regioselective C−H allenylation is reported that allows a broad range of 2-allenylindoles to be synthesized regioselectively on a gram scale under simple conditions. Notably, a highly efficient chirality transfer was observed (up to 93 % ee) in this transformation. This procedure was further found to allow, for the first time, the direct preparation of ketones by MnI-catalyzed C−H activation. Mechanistic investigations revealed that the precoordination of the oxygen atom to the manganese center as well as the congested tertiary carbon atom in the propargylic carbonates play a crucial role. 相似文献
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