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111.
We apply smoothing procedures to response functions for isoscalar vibrations. For collective motion, we find a transition from a structured strength distribution to one corresponding to one incoherent, strongly overdamped mode. It is argued that the latter may be interpreted as macroscopic motion exhibiting, to some extent, features of the hydrodynamical model. We discuss the physical origin of this behaviour, in particular its relation to the disappearance of shell structure.Supported in part by the Deutsche Forschungsgemeinschaft 相似文献
112.
A. N. Andreyev D. D. Bogdanov V. I. Chepigin A. P. Kabachenko O. N. Malyshev Yu. Ts. Oganessian R. N. Sagajdak G. M. Ter-Akopian A. V. Yeremin F. P. Hessberger S. Hofmann V. Ninov M. Florek S. Saro M. Veselsky 《Zeitschrift für Physik A Hadrons and Nuclei》1992,344(2):225-226
The neutron-deficient isotopes257,258105 were produced in the reaction27Al+236u in 6n and 5n evaporation channels, respectively. The evaporation residues emerging from the target were separated in-flight from the projectiles and from products of different nuclear reactions by the electrostatic separator VASSILISSA [1]. The isotopes were then implanted into position-sensitive silicon detectors and identified using the --correlation method. The measured production cross-section is (5n)=(0.45±0.20)nb atE
P
=154 MeV and (6n)=(0.075±0.055) nb atE
P
=163 MeV. These cross-sections are compared with data measured for the same isotopes in the more symmetrical reaction50Ti+209Bi. 相似文献
113.
Anthony D. Wright Gabriele M. Knig Otto Sticher Paolo Lubini Patrick Hofmann Max Dobler 《Helvetica chimica acta》1991,74(8):1801-1807
Reinvestigation of the brown alga Dictyota pardalis f. pseudohamata CRIBB led to the crystallization of 1 and to the isolation of the two new dolabellane derivatives 2 and 3 . X-Ray analysis of 1 and 2 , together with detailed 1D-and 2D-NMR studies on 2 and 3 , allowed their structures to be elucidated as (1R*,3S*,7S*,11R*,4Z)-dolabella-4,8(17), 12(18)-triene-3,7-diol ( 1 ), (1R*,3S*,4S*,7S*,8S*,11R*,14R*,12E)-3,4:7,8-diepoxydolabe11-12-ene-14, 18-diol ( 2 ), and (1R*,3S*,4S*,7S*,8S*,11R*,14R*)-3,4:7,8-diepoxy-l,4,8,12,12-pentamethylbicyclo[9. 3. 0]tetra-decan-14-ol( 3 ). 相似文献
114.
The enantiomeric separation of various kinds of basic pharmaceuticals has been investigated in nonaqueous capillary electrophoresis (NACE) systems using an ion-pairing reagent in combination with cyclodextrins (CDs). The simultaneous addition to the methanolic background electrolyte (BGE) of (+)-S-camphorsulfonate or alkanesulfonates and an anionic beta-cyclodextrin derivative, heptakis(2,3-dimethyl-6-sulfato)-beta-cyclodextrin (HDMS-beta-CD), led to partial or complete enantioresolution in most cases. In the absence of ion-pairing reagent, the enantiomeric resolution obtained with this CD derivative was most often completely lost or strongly reduced, indicating the important role of ion-pairing in the chiral recognition mechanism in these NACE systems. The influence of the nature and concentration of the counterion and the anionic CD derivative on the enantioseparation of basic compounds was studied. Synergistic effects between these two kinds of charged additives were clearly observed. 相似文献
115.
F. Vogt H. Bremer F. Hofmann Ja. I. Isakov Ch. M. Minaßev T. A. Isakova 《无机化学与普通化学杂志》1985,521(2):145-152
Studies on Oxide Catalysts. XLii. Redox Behaviour of Nickel in Zeolites NiNa? Y. 4. Influence of Composition on the Reducibility of Nickel in Zeolites NiNa? Y By chemical analysis (reaction with K2Cr2O7) and ESCA investigations we determined the degree of reduction in reduced samples NiNa-Y as function of the mole ratio SiO2/Al2O3 (module), of the Ni2+ degree of exchange and the kind of the second cations. (NH4+, Ca2+, Co2+, and Nd3+) in the temperature region of 620–770 K. The degree of nickel reduction increases with increasing module, decreasing degree of exchange and decreasing number of Brönsted acidic centres. This behaviour is caused by the influence of the interaction between cations Ni2+ and zeolite lattice on the reduction equilibrium. 相似文献
116.
Convenient high-yield syntheses of the primary and di-primary heteroaryl-phosphines R-PH2 and H2P-R'-PH2(with R = 2-thienyl, 2-furyl, and R'= 2,5-thiophenediyl, 2,5-furandiyl, respectively) are presented. The products and a set of precursor molecules have been characterized by analytical and spectral data, and the crystal structures of selected molecules have been determined: 2-C4H3O-PCl2, 2,5-(Cl2P)2C4H2O, 2,5-[(Et2N)2P]2C4H2E (with E = O, S). In the crystals, the two molecules with -PCl2 substituents adopt trans conformations, while the other two have the -P(NEt2)2 groups rotated into a twist conformation. The reaction of the thienyl compounds with tris[(tert-phosphine)gold]oxonium tetrafluoroborates gave almost quantitative yields of the tri- and hexanuclear gold complexes, respectively: {2-C4H3S-P[Au(PR3)]3}+BF4- and [2,5-{[(R3P)Au]3P}2C4H2S]2+(BF4(-)2, (R =tBu, Ph). The structures of the compounds with R3P =tBu3P ligands have been determined. In both cases the [2-C4H3/2S-P] units cap triangles of gold atoms in an array that can be described as three [Au(PR3)]+ cations bridged by a phosphido dianion (RP)2-. 相似文献
117.
Hubert Huppertz 《Journal of solid state chemistry》2004,177(10):3700-3708
This paper reports about two new hydrogen-containing rare-earth oxoborates RE4B6O14(OH)2 (RE=Dy, Ho) synthesized under high-pressure/high-temperature conditions from the corresponding rare-earth oxides, boron oxide, and water using a Walker-type multianvil equipment at 8 GPa and 880 °C. The single crystal structure determination of Dy4B6O14(OH)2 showed: Pbcn, a=1292.7(2), b=437.1(2), , Z=2, R1=0.0190, and wR2=0.0349 (all data). The isotypic holmium species revealed: Pbcn, a=1292.8(2), b=436.2(2), , Z=2, R1=0.0206, and wR2=0.0406 (all data). The compounds exhibit a new type of structure, which is built up from layers of condensed BO4-tetrahedra. Between the layers, the rare-earth cations are coordinated by 7+2 oxygen atoms. Furthermore, we report about temperature-resolved in situ powder diffraction measurements, DTA/TG, and IR-spectroscopic investigations into RE4B6O14(OH)2 (RE=Dy, Ho). 相似文献
118.
We have extended to molecules a density functional previously parametrized for atomic computations. The Coulombhole-Hartree-Fock functional, introduced by Clementi in 1963, estimated the dynamic correlation energy by the computation of a Hartree-Fock type single-determinant wavefunction, where the Hartree-Fock potential was augmented with an effective potential term, related to a hard Coulomb hole enclosing each electron. The method was later revised by S. Chakravorty and E. Clementi, Phys. Rev. A, 38 (1989) 2290, so that a Yukawa-type soft Coulomb hole replaced the previous hard hole. Atomic correlation energies, computed for atoms with Z = 2 to 54, as well as for a number of excited states, validated the method. In this work we have parametrized for molecules a function which controls the width of the soft Coulomb hole by fitting the first and second atomic ionization potentials of atoms with 1 Z 18 and the binding energies of a few diatomic molecules. The parametrization was successfully validated by computing the dissociation energy for a number of molecules. A few-determinant version of the Coulomb-Hartree-Fock method (CHF-N) necessary to account for the non-dynamic correlation correction and to ensure proper dissociation products, is briefly discussed with reference to a previous proposal by G.C. Lie and E. Clementi, J. Chem. Phys., 60 (1974) 1275 and 60 (1974) 1288. 相似文献
119.
Hexanethiolate monolayer-protected gold nanoclusters (MPCs) were used as redox quenchers at the polarizable water/1,2-dichloroethane (DCE) interface. Photocurrent responses originating from the heterogeneous quenching of photoexcited water soluble porphyrin complexes by MPCs dissolved in the DCE phase were observed. As MPCs can function as both electron acceptors and donors, the photocurrent results from the superposition of two simultaneous processes, which correspond to the oxidation and reduction of MPCs. The magnitude of the net photocurrent is essentially determined by the balance of the kinetics of these two processes, which can be controlled by tuning the Galvani potential difference between the two phases. We show that, within the available potential window, the apparent electron-transfer rate constants follow classical Butler-Volmer dependence on the applied potential difference. 相似文献
120.
A. Breakstone H. B. Crawley A. Firestone M. Gorbics J. W. Lamsa W. T. Meyer D. L. Parker D. Drijard F. Fabbri H. G. Fischer H. Frehse P. Hanke P. G. Innocenti O. Ullaland W. Hofmann M. Panter K. Rauschnabel J. Spengler D. Wegener W. Geist M. Heiden E. E. Kluge T. Nakada A. Putzer K. Doroba R. Gokieli R. Sosnowski 《Zeitschrift fur Physik C Particles and Fields》1981,11(3):203-209
We present an analysis of minimum bias events from proton-proton collisions at \(\sqrt s = 7GeV\) in the CERN ISR. We remove the effects of both the leading protons and compare theB=0 mesonic residue of the events to the hadronic events of similar energy produced ine + e ? collisions. This comparison is presented in terms of the standard jet-type analyses involving quantities such as sphericity and aplanarity. We find significant differences between these data and the data frome + e ? annihilations. The data of this experiment are consistent with the predictions of a longitudinal phase space model. 相似文献