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171.
We present the results of relativistic and non-relativistic self-consistent field and configuration interaction calculations for the gold atom, using the spin-free no-pair Hamiltonian in a basis set expansion. A new basis set for the gold atom is discussed and its results in relativistic and non-relativistic self-consistent field calculations are compared to those of numerical Dirac-Hartree-Focic and Hartree-Fock calculations, respectively. Excitation energies, electron affinities and ionization potentials were calculated using a multi-reference configuration interaction technique and are in reasonable agreement with experiment in the relativistic case. 相似文献
172.
Crystal Structure Determination of Ammonium catena-Polyphosphate II by X-Ray Powder Techniques The first structure determination of one of the five modifications of ammonium-catena-polyphosphate was performed using X-ray powder diffraction data. (NH4PO3)nII is formed by phase transformation of (NH4PO3)nI which on its part is obtained by condensation of NH4H2PO4 at 200°C in presence of urea. Modification II crystallizes in P212121 (a = 1 207.9(1), b = 648.87(8), c = 426.20(4) pm; Z = 4; 291 observed reflections; R(p) = 0.089; R(wp) = 0.111; R(I, hkl) = 0.088). The chain-anion runs parallel to the shortest axis, the period of identity is two. The ammonium ion is surrounded by a distorted tetrahedron of oxygen atoms (N? O-distances range from 285 to 292 pm, hydrogen bonds of middle strength). 相似文献
173.
Jan F. Keij Jan Th . M. Jansen Frank W. Schultz Jan W. M. Visser 《Photochemistry and photobiology》1994,60(5):503-509
Abstract-During the development of a photodamage cell sorter several photosensitizers were tested for their ability to photoinactivate more than 90% of the sensitized cells after a brief irradiation with a fluence of 10 kJ/m2 . In pilot experiments, yeast cells sensitized with 10-dodecyl acridine orange (DAO) were effectively photoinactivated after receiving a fluence of 10 kJ/m2 delivered in 8 s. However, when the same fluence was delivered in 3 μ s during passage through a focused laser beam in the cell sorter, all cells survived.
Computer simulations of the relevant photophysical and chemical reactions inside the irradiated cell were used to investigate the cause of this phenomenon. The results indicated that the absence of photoinactivation by DAO, after flash irradiations, was caused by the combined effects of (1) limited oxygen diffusion into the cell and (2) a reduced number of collisions between photosensitizer triplet and oxygen molecules during the irradiation due to saturation of the intracellular photosensitizer triplet concentration. The contributions of triplet-triplet annihilation and triplet quenching by ground state photosensitizer molecules were found to be minimal and not significant. These findings indicate that Type II photosensitizers are incapable of rapid selective photoinactivation in cell sorters. 相似文献
Computer simulations of the relevant photophysical and chemical reactions inside the irradiated cell were used to investigate the cause of this phenomenon. The results indicated that the absence of photoinactivation by DAO, after flash irradiations, was caused by the combined effects of (1) limited oxygen diffusion into the cell and (2) a reduced number of collisions between photosensitizer triplet and oxygen molecules during the irradiation due to saturation of the intracellular photosensitizer triplet concentration. The contributions of triplet-triplet annihilation and triplet quenching by ground state photosensitizer molecules were found to be minimal and not significant. These findings indicate that Type II photosensitizers are incapable of rapid selective photoinactivation in cell sorters. 相似文献
174.
The high-pressure iron borate α-FeB2O4 was synthesized under high-pressure and high-temperature conditions in a Walker-type multianvil apparatus at 7.5 GPa and 1100 °C. The monoclinic iron borate crystallizes with eight formula units in the space group P21/c with the lattice parameters a=715.2(2), b=744.5(2), c=862.3(2) pm, and β=94.71(3)°. The compound is built up exclusively from corner-sharing BO4-tetrahedra, isotypic to the monoclinic phases β-SrGa2O4, CaAl2O4-II, and CaGa2O4. Additionally, the structure is closely related to the orthorhombic compound BaFe2O4. The structure consists of layers of six-membered rings, which are interconnected to a three-dimensional network. The iron cations are coordinated by six and seven oxygen atoms. Next to synthesis and crystal structure of the new high-pressure borate, structural coherences to other structure types are discussed. 相似文献
175.
176.
Carsten L. Schmidt Ulrich Wedig Dr. Robert Dinnebier Prof. Dr. Martin Jansen Prof. Dr. 《化学:亚洲杂志》2008,3(11):1983-1990
The new barium nitridoosmate oxide (Ba6O)(OsN3)2 was prepared by reacting elemental barium and osmium (3:1) in nitrogen at 815–830 °C. The crystal structure of (Ba6O)(OsN3)2 as determined by laboratory powder X‐ray diffraction ( , No 148: a=b=8.112(1) Å, c=17.390(1) Å, V=991.0(1) Å3, Z=3), consists of sheets of trigonal OsN3 units and trigonal‐antiprismatic Ba6O groups, and is structurally related to the “313 nitrides” AE3MN3 (AE=Ca, Sr, Ba, M=V–Co, Ga). Density functional calculations, using a hybrid functional, likewise indicate the existence of oxygen in the Ba6 polyhedra. The oxidation state 4+ of osmium is confirmed, both by the calculations and by XPS measurements. The bonding properties of the OsN35? units are analyzed and compared to the Raman spectrum. The compound is paramagnetic from room temperature down to T=10 K. Between room temperature and 100 K it obeys the Curie–Weiss law (μ=1.68 μB). (Ba6O)(OsN3)2 is semiconducting with a good electronic conductivity at room temperature (8.74×10?2 Ω?1 cm?1). Below 142 K the temperature dependence of the conductivity resembles that of a variable‐range hopping mechanism. 相似文献
177.
Electrochemical Synthesis of Perovskites in the System K/Ba/Pr/Bi/O An easy procedure for the synthesis of well crystalline samples of (K,Ba)(Pr,Bi)O3 is provided by anodic oxidation of melts consisting of Ba(OH)2 / KOH / Pr(NO3)3 / Bi(NO3)3, at comparatively low temperatures of about 220 °C. We have explored the influence of different parameters like temperature, potential of the working electrode, and composition of the electrolyte. Chemical and thermal analyses were performed. Products obtained at different experimental conditions revealed different Ba/K and Pr/Bi ratios with a large homogeneity range. X‐Ray powder diffraction and single crystal structure analyses of KxBa1?xPryBi1?yO3 proved these compounds to be cubic perovskites. Barium and potassium ions are disordered occupying the A‐sites while praseodym and bismuth ions share the B‐sites or are ordered, as indicated by a doubling of the lattice parameter. The composition x and y can independently be altered. XPS analysis and physical properties are reported and discussed. 相似文献
178.
Hirtenlehner C Krims C Hölbling J List M Zabel M Fleck M Berger RJ Schoefberger W Monkowius U 《Dalton transactions (Cambridge, England : 2003)》2011,40(38):9899-9910
Gold(I) complexes bearing N-heterocyclic carbenes (NHC) of the type (NHC)AuBr (3a/3b) [NHC = 1-methyl-3-benzylimidazol-2-ylidene (= MeBnIm), and 1,3-dibenzylimidazol-2-ylidene (= Bn(2)Im)] are prepared by transmetallation reactions of (tht)AuBr (tht = tetrahydrothiophene) and (NHC)AgBr (2a/2b). The homoleptic, ionic complexes [(NHC)(2)Au]Br (6a/6b) are synthesized by the reaction with free carbene. Successive oxidation of 3a/3b and 6a/6b with bromine gave the respective (NHC)AuBr(3) (4a/4b) and [(NHC)(2)AuBr(2)]Br (7a/7b) in good overall yields as yellow powders. All complexes were characterized by NMR spectroscopy, mass spectrometry, elemental analysis and single crystal X-ray diffraction. Reactions of the Au(III) complexes towards anionic ligands like carboxylates, phenolates and thiophenolates were investigated and result in a complete or partial reduction to a Au(I) complex. Irradiation of the Au(III) complexes with UV light yield the Au(I) congeners in a clean photo-reaction. 相似文献
179.
Phase Relations and Sodium Ion Conductivity within the Quasi-binary System Na2SiF6/Na2AIF6 . The phase diagram of the Na2SiF6/Na3AlF6 system has been determined by means of x-ray powder diffraction, thermal analysis and conductivity measurements in the sub-solidus region. Na3AlF6 accomodates up to 73 mol.-% Na2SiF6 maintaining the crystal structure type. The sodium ion conductivity increases by about five orders of magnitude upon doping Na3AlF6 with Na2SiF6. 相似文献
180.