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921.
Yunxing Yan 《Journal of solid state chemistry》2003,172(2):364-369
Three new chromophores and trans-4-(N-(ethyl 4″-nitrobenzoate)-N-ethyl amino)-4′-(dimethyl amino) stilbene (DMANHAS) have been synthesized and whose chemical structures have been characterized by 1H NMR, IR, and elemental analyses. Linear absorption, single-photon-induced fluorescence and two-photon-induced fluorescence are experimentally studied. Trans-4-(N-2-hydroxyethyl-N-ethyl amino)-4′-(dimethyl amino)stilbene (DMAHAS) and trans-4-(N-2-hydroxyethyl-N-ethyl amino)-4′-(diethyl amino)stilbene (DEAHAS) have effective two-photon absorption cross-sections of σ2=0.91×10−46 cm4 s/photon and σ2=1.19×10−46 cm4 s/photon at 532 nm by using an open aperture Z-scan technique, respectively. When pumped with 800 nm laser irradiation, DMAHAS and DEAHAS indicate strong two-photon-induced blue fluorescence of 436 and 440 nm, respectively, while trans-4-(N-(ethyl 4″-nitrobenzoate)-N-ethyl amino)-4′-(diethyl amino) stilbene (DEANHAS) and DMANHAS exhibit no fluorescence. 相似文献
922.
Studies of the electrochemical behavior of epinephrine at a homocysteine self-assembled electrode 总被引:6,自引:0,他引:6
The self-assembled electrode with the homocysteine monolayer (Hcy/Au) has been characterized by infrared spectroscopy and ac impedance spectroscopy in electrolyte. The Hcy/Au electrode is demonstrated to promote the electrochemical response of epinephrine (E) by cyclic voltammetry. A pair of well-defined redox waves was obtained and the calculated standard rate constant (ks) is 2.1×10−2 cm s−1 at the self-assembled electrode. The reduction peak of E can be used to determine the concentration of E in presence of ascorbic acid (AA) owing to the Hcy/Au also promoting the electrochemical oxidation of AA. 相似文献
923.
The structure of Ph[PhC(O)NH]2P=NC(O)Ph (2) in solid state and in solution is discussed on the basis of a crystal structure analysis and IR and Raman spectra. In crystalline state 2 forms dimers which are associated via two pairs of bifurcated (N–H)2O=C hydrogen bonds. The spectroscopic data are in good agreement with the crystallographic results with respect to the hydrogen bonding and they suggest that 2 also in solution is associated. 相似文献
924.
Xiaoqing Zeng Maofa Ge Zheng Sun Jiang Bian Dianxun Wang 《Journal of Molecular Structure》2007,840(1-3):59-65
Gaseous nitryl azide N4O2 is generated by the heterogeneous reaction of gaseous ClNO2 with freshly prepared AgN3 at −50 °C. The geometric and electronic structure of the molecule in the gas phase has been characterized by in situ photoelectron spectroscopy (PES) and quantum chemical calculations. The experimental first vertical ionization energy of N4O2 is 11.39 eV, corresponding to the ionization of an electron on the highest occupied molecular orbital (HOMO) {4a″(πnb(N4–N5–N6))}−1. An apparent vibrational spacing of 1600 ± 60 cm−1 (νasO1N2O3) on the second band at 12.52 eV (πnb(O1–N2–O3)) further confirms the preference of energetically stable chain structure in the gas phase. To complement the experimental results, the potential-energy surface of this structurally novel transient molecule is discussed. Both calculations and spectroscopic results suggest that the molecule adopts a trans-planar chain structure, and a five-membered ring decomposition pathway is more favorable. 相似文献
925.
New organohalogermanes RGe(OCH2CH2NMe2)2X (R = Ph, X = I (5); R = Me, X = Cl (6) or I (7)) with an intramolecular N→Ge coordination bond were synthesized. According
to the 1H and 13C NMR spectroscopic data, iodides 5 and 7 exist in solution as ionic compounds with the pentacoordinated germanium atom. In
solution of compound 4 (R = Ph, X = Cl), there is an equilibrium between the ionic and covalent forms. The equilibrium shifts
toward the ionic form with increasing solvent polarity or temperature. In solution, chloride 6 is a covalent compound. The
structures and relative stabilities of different isomers of compounds 4–7 were studied by quantum chemical calculations at
the density functional level of theory.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 892–900, May, 2007. 相似文献
926.
The alkali sodium ferrate (IV) Na4FeO4 has been prepared by solid-state reaction of sodium peroxide Na2O2 and wustite Fe1−xO, in a molar ratio Na/Fe=4, at 400°C under vacuum. Powder X-ray and neutron diffraction studies indicate that Na4FeO4 crystallizes in the triclinic system P−1 with the cell parameters= a=8.4810(2) Å, b=5.7688(1) Å, c=6.5622(1) Å, α=124.662(2)°, β=98.848(2)°, γ=101.761(2)° and Z=2. Na4FeO4 is isotypic with the other known phases Na4MO4 (M=Ti, Cr, Mn, Co and Ge, Sn, Pb). The solid solution Na4FexCo1−xO4 exists for x=0-1 and we have followed the evolution of the cell parameters with x to determine the lattice parameters of the triclinic cell of Na4FeO4. A three-dimensional network of isolated FeO4 tetrahedra connected by Na atoms characterizes the structure. This compound is antiferromagnetic below TN=16 K. At 2 K the magnetic cell is twice the nuclear cell and the magnetic structure is collinear (μFe=3.36(12) μB at 2 K). This black compound is highly hygroscopic. In water or on contact with the atmospheric moisture it is disproportionated in Fe3+ and Fe6+. The Mössbauer spectra of Na4FeO4 are fitted with one doublet (δ=− 0.22 mm/s, Δ=0.41 mm/s at 295 K) in the paramagnetic state and with a sextet at 8K. These parameters characterize Fe4+ high-spin in tetrahedral FeO4 coordination. 相似文献
927.
On Chalcogenolates. 206. N-Thioacetyl Dithiocarbamates and Esters of N-Thioacetyl Dithiocarbamic Acid Thioacetamide reacts with carbon disulfide in the presence of KH to form via the tetrabutyl ammonium salt dark yellow N-thioacetyl dithiocarbamates M[S2C? NH? CS? CH3], where M = K, Rb, Cs. The salts as well as the methyl and ethyl ester have been characterized by means of electron absorption, infrared, nuclear magnetic resonance (1H and 13C), and mass spectra. Attempts to synthesize N-thioacetyl dithiocarbamic acid were not successful. 相似文献
928.
Synthesis and Reactivity of Triflate Substituted Siloxane Derivatives The reaction of amino substituted siloxane derivatives with trifluoromethanesulfonic acid leads under elimination of ammonium trifluoromethanesulfonate to the formation of siloxanyl triflates. The compounds are characterised by NMR-spectroscopy (29Si, 13C, 1H). The synthetic potential of these siloxanes is shown on selected examples. One interesting point of view is the synthesis of silicon containing oligo- and polymeres, in which siloxane and silylenealkine units are combined. 相似文献
929.
930.
C. Damas M. Adibnejad A. Benjelloun A. Brembilla M. C. Carré M. L. Viriot P. Lochon 《Colloid and polymer science》1997,275(4):364-371
Cationic amphiphilic polymers (e.g. polyvinylpyridinium bromides and polyvinylimidazo-lium bromides) adopt a compact coiled
form in aqueous solutions. In the case of former polymers, the resulting hydrophobic microdomains are evidenced only by fluorescence
spectroscopy if a molecular rotor (DMAC) is used as a fluorescent probe, while the behaviour of the latter can be studied
in aqueous solution by using both types of fluorescent probes, i.e., pyrene and the molecular rotor. The purpose of the present
investigation deals with a comparative study between the magnitude of the local viscosity and the polarity of the hydrophobic
microdomains generated by poly(3-hexadecyl-1-vinylimidazolium bromide) in an aqueous medium using pyrene and DMAC as fluorescent
probes. Moreover, the results are compared with the data obtained with micelles of conventional surfactants such as the homopolymer
repetitive unit model and CTAB.
Received: 3 June 1996 Accepted: 29 September 1996 相似文献