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71.
The hydrogen vibrational modes in LaHx samples have been investigated by pulsed neutron spectroscopy. The results are compared with a simple model emphasizing strong HH forces and the lack of stoichiometry in LaH2.28. 相似文献
72.
B. Roussière F. Le Blanc J. Pinard L. Cabaret J. Crawford H. T. Duong J. Genevey G. Huber F. Ibrahim M. Krieg J. K. P. Lee J. Obert J. Oms J. C. Putaux C. Richard-Serre J. Sauvage V. Sebastian 《Acta Physica Hungarica A》1998,7(1):97-100
Isotope shift and hyperfine structure measurements have been performed on the short lived184Au nucleus using the COMPLIS apparatus installed at ISOLDE. The charge radius change and the magnetic and quadrupole moments of both isomeric and ground states have been deduced. The184Au ground state appears to be slightly more deformed than the isomeric state. 相似文献
73.
K. -L. Kratz H. Ohm H. Gabelmann G. I. Crawford G. Jung B. Pfeiffer 《Zeitschrift für Physik A Hadrons and Nuclei》1982,305(1):93-94
Beta-delayed neutron measurements on95Rb have indicated evidence for two heretofore unknown excited O+ states in94Sr which are not fed by ß -decay from the Jπ = 3? ground state of94Rb. 相似文献
74.
75.
Tasić U Alexeev Y Vayner G Crawford TD Windus TL Hase WL 《Physical chemistry chemical physics : PCCP》2006,8(40):4678-4684
Ab initio calculations at the CCSD(T)/aug-cc-pVTZ level of theory were used to characterize the Ar-CH(3)OH intermolecular potential energy surface (PES). Potential energy curves were calculated for four different Ar + CH(3)OH orientations and used to derive an analytic function for the intermolecular PES. A sum of Ar-C, Ar-O, Ar-H(C), and Ar-H(O) two-body potentials gives an excellent fit to these potential energy curves up to 100 kcal mol(-1), and adding an additional r(-n) term to the Buckingham two-body potential results in only a minor improvement in the fit. Three Ar-CH(3)OH van der Waals minima were found from the CCSD(T)/aug-cc-pVTZ//MP2/aug-cc-pVTZ calculations. The structure of the global minimum is in overall good agreement with experiment (X.-C. Tan, L. Sun and R. L. Kuczkowski, J. Mol. Spectrosc., 1995, 171, 248). It is T-shaped with the hydroxyl H-atom syn with respect to Ar. Extrapolated to the complete basis set (CBS) limit, the global minimum has a well depth of 0.72 kcal mol(-1) with basis set superposition error (BSSE) correction. The aug-cc-pVTZ basis set gives a well depth only 0.10 kcal mol(-1) smaller than this value. The well depths of the other two minima are within 0.16 kcal mol(-1) of the global minimum. The analytic Ar-CH(3)OH intermolecular potential also identifies these three minima as the only van der Waals minima and the structures predicted by the analytic potential are similar to the ab initio structures. The analytic potential identifies the same global minimum and the predicted well depths for the minima are within 0.05 kcal mol(-1) of the ab initio values. Combining this Ar-CH(3)OH intermolecular potential with a potential for a OH-terminated alkylthiolate self-assembled monolayer surface (i.e., HO-SAM) provides a potential to model Ar + HO-SAM collisions. 相似文献
76.
Summary Improved analytical procedures are presented for the simultaneous determination of carbon, hydrogen, and nitrogen in solid organic materials by the gas volumetric method. The accuracy is improved, and the method is less dependent upon the analyst's technique.
Work was performed under the auspices of the U. S. Atomic Energy Commission. 相似文献
Zusammenfassung Verbesserte Verfahren für die gleichzeitige gasvolumetrische Bestimmung von Kohlenstoff, Wasserstoff und Stickstoff in festen organischen Verbindungen werden beschrieben. Die Genauigkeit wurde verbessert, und die Ergebnisse sind weniger von der Arbeitstechnik des Analytikers abhängig.
Résumé On présente une amélioration des procédés analytiques pour le dosage simultané du carbone, de l'hydrogène et de l'azote dans les matériaux solides organiques par la méthode volumétrique gazeuse. La précision est meilleure et la méthode dépend moins de la technique de l'analyste.
Work was performed under the auspices of the U. S. Atomic Energy Commission. 相似文献
77.
Apostolico L Braunschweig H Crawford AG Herbst T Rais D 《Chemical communications (Cambridge, England)》2008,(4):497-498
The first catalytic application of the Group VI metal borylene complexes [(CO)(5)M[double bond]BN(SiMe(3))(2)] involves the demercuration reaction of bis(alkynyl)mercurials, [Hg(C[triple bond]CR)(2)], with formation of a series of buta-1,3-diynes. 相似文献
78.
J. La Rosa I. Outola E. Crawford S. Nour H. Kurosaki K. Inn 《Journal of Radioanalytical and Nuclear Chemistry》2008,277(1):11-18
A radiochemical procedure is described for the measurement of 0.1 Bq 237Np in a solution containing similar activity concentrations of Th, U, Pu and Am as well as activity concentrations of 60Co, 90Sr and 137Cs one hundred times higher. A tracer of 239Np (milked from 243Am) was used as an isotopic spike for chemical yield determination. The relationship between gamma-counting geometries for
ampoule (liquid) and NdF3 (solid) 239Np sources was established so that Np chemical yields could be measured by a comparative method. Efficiencies of alpha-spectrometers
for 237Np in NdF3 sources were measured by a bootstrap technique. Two sets of experiments were designed and used to test out the procedure. 相似文献
79.
A comparison of the abilities of time-dependent density-functional theory (TDDFT) and coupled cluster (CC) theory to reproduce experimental sodium D-line specific rotations for 13 conformationally rigid organic molecules is reported. The test set includes alkanes, alkenes, and ketones with known absolute configurations. TDDFT calculations make use of gauge-including atomic orbitals and give origin-independent specific rotations. CC rotations are computed using both the origin-independent dipole-velocity and origin-dependent dipole-length representations. The mean absolute deviations of calculated and experimental rotations are of comparable magnitudes for all three methods. The origin-independent DFT and CC methods give the same sign of [alpha]D for every molecule except norbornanone. For every large-rotation ketone and alkene for which DFT and CC yield the incorrect sign as compared to liquid-phase experimental data, the corresponding optical rotatory dispersion (ORD) curve is bisignate, suggesting that the two models cannot reliably reproduce the relative excitation energies and antagonistic rotational strengths of multiple competing electronic states that contribute to the total long-wavelength rotation. Several potential sources of error in the theoretical treatments are considered, including basis set incompleteness, vibrational and temperature effects, electron correlation, and solvent effects. 相似文献
80.
Crawford P Burch R Hardacre C Hindle KT Hu P Rooney DW 《The Journal of chemical physics》2008,128(10):105104
The carbazole moiety is a component of many important pharmaceuticals including anticancer and anti-HIV agents and is commonly utilized in the production of modern polymeric materials with novel photophysical and electronic properties. Simple carbazoles are generally produced via the aromatization of the respective tetrahydrocarbazole (THCZ). In this work, density functional theory calculations are used to model the reaction pathway of tetrahydrocarbazole aromatization over Pd(111). The geometry of each of the intermediate surface species has been determined and how each structure interacts with the metal surface addressed. The reaction energies and barriers of each of the elementary surface reactions have also been calculated, and a detailed analysis of the energetic trends performed. Our calculations have shown that the surface intermediates remain fixed to the surface via the aromatic ring in a manner similar to that of THCZ. Moreover, the aliphatic ring becomes progressively more planer with the dissociation of each subsequent hydrogen atom. Analysis of the reaction energy profile has revealed that the trend in reaction barriers is determined by the two factors: (i) the strength of the dissociating ring-H bond and (ii) the subsequent gain in energy due to the geometric relaxation of the aliphatic ring. 相似文献