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991.
We characterize the domain of the realizations of a linear parabolicoperator defined in L2 spaces with respect to a suitable measurethat is invariant for the associated evolution semigroup. Asa byproduct, we obtain optimal L2 regularity results for evolutionequations with time-dependant Ornstein–Uhlenbeck operators. 相似文献
992.
Cotí KK Wang Y Lin WY Chen CC Tak For Yu Z Liu K Shen CK Selke M Yeh A Lu W Tseng HR 《Chemical communications (Cambridge, England)》2008,(29):3426-3428
A new type of dynamic micromixer combining the concepts of parallel multi-lamination and hydrodynamic focusing was developed for arbitrary control of disguised chemical selectivity. 相似文献
993.
994.
The geometry of Re2Cl82− has been optimized for the eclipsed (D
4h
) equilibrium conformation and for the staggered (D
4d
) conformation at BP86/TZ2P. The nature of the Re–Re bond which has a formal bond order four has been studied with an energy
decomposition analysis (EDA). The EDA investigation indicates that the contribution of the b
2 (δ
xy
) orbitals to the Re–Re bond in the ground state is negligibly small. The vertical excitation of one and two electrons from the bonding δ orbital into the antibonding δ* orbitals yielding the singly and doubly excited states and gives a destabilization of 17.5 and 36.1 kcal/mol, respectively, which is nearly the same as the total excitation energies.
The preference for the D
4h
geometry with eclipsing Re–Cl bonds is explained in terms of hyperconjugation rather than δ bonding. This is supported by the calculation of the triply bonded Re2Cl8 which also has an eclipsed energy minimum structure. The calculations also suggest that the Re–Re triple bond in Re2Cl8 is stronger than the Re–Re quadruple bond in Re2Cl82−. A negligible contribution of the δ orbital to the metal–metal bond strength is also calculated for Os2Cl8 which is isoelectronic with Re2Cl82−.
Contribution of the Mark S. Gordon 65th Birthday Festschrift Issue.
Theoretical Studies of Inorganic Compounds. 38. Part 37 (2006) Bessac F, Frenking G, Inorg Chem 45:6956. 相似文献
995.
996.
997.
998.
999.
Matthias Busker Michael Nispel Dr. Thomas Häber Dr. Karl Kleinermanns Prof. Dr. Mihajlo Etinski Timo Fleig Dr. 《Chemphyschem》2008,9(11):1570-1577
Electronic and vibrational gas phase spectra of 1‐methylthymine (1MT) and 1‐methyluracil (1MU) and their clusters with water are presented. Mass selective IR/UV double resonance spectra confirm the formation of pyrimidine‐water clusters and are compared to calculated vibrational spectra obtained from ab initio calculations. In contrast to Y. He, C. Wu, W. Kong; J. Phys. Chem. A, 2004 , 108, 94 we are able to detect 1MT/1MU and their water clusters via resonant two‐photon delayed ionization under careful control of the applied water‐vapor pressure. The long‐living dark electronic state of 1MT and 1MU detected by delayed ionization, survives hydration and the photostability of 1MT/1MU cannot be attributed solely to hydration. Oxygen coexpansions and crossed‐beam experiments indicate that the triplet state population is probably small compared to the 1nπ* and/or hot electronic ground state population. Ab initio theory shows that solvation of 1MT by water does not lead to a substantial modification of the electronic relaxation and quenching of the 1nπ* state. Relaxation pathways via 1ππ*1–nπ*1 and 1ππ *–S0 conical intersections and barriers have been identified, but are not significantly altered by hydration. 相似文献
1000.
Rapid screening of membrane protein activity: electrophysiological analysis of OmpF reconstituted in proteoliposomes 总被引:1,自引:0,他引:1
Solvent-free planar lipid bilayers were formed in an automatic manner by bursting of giant unilamellar vesicles (GUVs) after gentle suction application through micron-sized apertures in a borosilicate glass substrate. Incubation of GUVs with the purified ion channel protein of interest yielded proteoliposomes. These proteoliposomes allow for immediate recording of channel activity after GUV sealing. This approach reduces the time-consuming, laborious and sometimes difficult protein reconstitution processes normally performed after bilayer formation. Bilayer recordings are attractive for investigations of membrane proteins not accessible to patch clamp analysis, like e.g. proteins from organelles. In the presented work, we show the example of the outer membrane protein OmpF from Escherichia coli. We reconstituted OmpF in proteoliposomes and observed the characteristic trimeric conductance levels and the typical gating induced by pH and transmembrane voltage. Moreover, OmpF is the main entrance for beta-lactam antibiotics and we investigated translocation processes of antibiotics and modulation of OmpF by spermine. We suggest that the rapid formation of porin containing lipid bilayers is of potential for the efficient electrophysiological characterization of the OmpF protein, for studying membrane permeation processes and for the rapid screening of antibiotics. 相似文献