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121.
Prashanta K. Mishra Vivekananda Chakravortty Kailash C. Dash 《Transition Metal Chemistry》1991,16(1):73-75
Summary Zr(acac)4 undergoes ligand exchanges with various tri- and tetradentate Schiff base ligands, forming compounds of the Zr(L)2 type (H2L=tetradentate H2Sal2en, H2Sal2pn, H2Sal2
o-phen and the tridentate H2SAP) and Zr(acac)2L (H2L=H2SAN. H2SAE). Upon reaction with a combination of tri- and tetradentate ligands, Zr(acac)4 yields Zr(L)(L) complexes (H2L=H2Sal2en or H2Sal2
o-phen; H2L=H2SAN, H2SAE, or H2SAP), which have been characterised by analytical data, m.ps, electrical conductivities, i.r. and n.m.r (1H and13C) spectra, they have a coordination number of 6, 7 or 8. 相似文献
122.
Summary The kinetics and mechanism of reversible complexation of NiII with (2-imidazoleazo)benzene (IAB), 2,2-biimidazole (Biim) and 2,2-bibenzimidazole (Bibzm) have been investigated at 15–35 °C, I = 0.30 mol dm–3. The stability constants, K
M, of the [NiL]2+ species vary in the sequence: [Ni(IAB)]2+ < [Ni(Bibzm)]2+ < [Ni(Biim)]2+. The values of the spontaneous dissociation rate constant (k
r) at 25 °C decrease in the sequence: [Ni(IAB)]+ > [Ni(Biim)]2+ > [Ni(Bibzm)]2+. The aquation of [Ni(IAB)]2+ is insensitive to acid catalysis, whilst [Ni(Biim)]2+ is relatively more susceptible towards acid-catalysed aquation than [Ni(Bibzm)]2+. The chelate ring in [NiL]2+ (L = IAB, Biim or Bibzm) is sterically strained. The formation of [Ni(IAB)]2+ and [Ni(Bibzm)]2+ may be chelation controlled while the normal I
d mechanism is supported by our data for [Ni(Biim)]2+. 相似文献
123.
Summary The aquation of pentaammine (substituted salicylato) cobalt(III) complexes [(NH3)5CoO2CC6H3(X)OH]2+,X = 5-SO3, 5-Br, 5-NO2, and 3-NO2 in the presence of ferric ion was studied spectrophotometrically in the 65°–80° range. Ferric ion catalyses the aquation of the substratesvia formation of a reactive binuclear species.Reprints of this article are not available. 相似文献
124.
The solubility and solubility product of silver permanganate in water have been determined at the temperatures ranging from 15 to 35°C over 5°C intervals in the presence of an added electrolyte, sodium perchlorate. The solubility of silver permanganate ranges from 0.966 x 10?5 mol 1?1 at 15°C to 1.420x10?5 moll?1 at 35°C and the corresponding solubility product 0.933 x 10?10 mol2 1?2 at 15°C to 2.017 x 10?10 mol2 1?2 at 35°C. The standard potentials of the Ag(s)/AgMnO4(s)/ MnO?4 electrode have been calculated at these temperatures. The mean activity coefficients of silver permanganate at various rounded molarities of sodium perchlorate solutions, and the standard thermodynamic quantities for the process AgMnO4(s)→Ag+ (aq)+MnO?4(aq) have been calculated at these temperatures. 相似文献
125.
The solubility and solubility product of silver iodate in formamide in sodium perchlorate solutions have been determined at 25, 30 and 35°C. The solubilities in pure formamide are found to be 2.169 × 10?4, 2.488 × 10?4, and 2.943 × 10?4 mole I?1, respectively, at these temperatures, and the corresponding solubility products are 4.609 × 10?8, 6.053 × 10?8, and 8.448 × 10?8 mole2 1?2. The standard potential of the Ag(s)/AgIO3(s)/IO3? electrode has been calculated and found to be 0.2562 V at 25°C. The mean activity coefficients of silver iodate at various rounded molarities of sodium perchlorate solutions, and the standard thermodynamic quantities for the process AgIO3(s)åAg+ (solvated) + IO3? (solvated) have been calculated at these three temperatures. 相似文献
126.
The MnIV complex of 1,8-bis(2-hydroxybenzamido)-3,6-diazaoctane (MnIVL) with phenolate-amido-amine coordination is reduced by l-ascorbic acid and oxalic acid obeying overall 1:1 stoichiometry. The reactions are biphasic and MnIIIL− is the reactive intermediate. The product of oxidation of ascorbic acid (H2Asc) is dehydroascorbic acid and that of oxalic acid (H2OX) is CO2, while MnII is the end product from MnIV. Both MnIVL and MnIIIL− form outer sphere adducts with H2Asc and H2OX with high values of equilibrium constants of formation (Q>102 dm3 mol−1, I = 0.5 mol dm−3, 25.8 °C, 1.5% v/v MeOH+H2O). The adduct formation is diffusion controlled and is attributed to hydrogen bonding interactions between the reactants.
The rate constants for the electron transfer in (MnIV/IIIL, H2A), (MnIV/IIIL, HA−) (H2A = H2Asc, H2OX) and for (MnIVL, H2Asc)+H2Asc, (MnIIIL−, HAsc−)+HAsc− are reported. There was no evidence of direct coordination of the reductants to the MnIV/III center indicating an outer sphere (ET) mechanism. 相似文献
127.
A highly oxygenated, novel pentacyclic bis-oxa-bridged compound 8 was synthesized with remarkable efficiency starting from readily available tetrachloro-5,5-dimethoxyclopentadiene and 1,4-cyclohexadiene in three steps. The ruthenium-catalyzed oxidation of 2:1 bis-adduct 1 followed by a one-pot transformation of the resulting bis-alpha-diketone 3 furnished (after esterification) the title compound in an overall yield of 29.1%. The versatility of this simple method was further demonstrated with other norbornyl alpha-diketones to obtain the corresponding strained oxa-bridged derivatives. 相似文献
128.
The synthesis
of conducting polymers based on m-nitroaniline, m-chloroaniline and m-aminophenol
by aniline initiated ammonium peroxydisulfate oxidation, has been attempted.
The IR spectra of the polymers have been studied. Thermogravimetric analysis
of the conducting polymers has been followed using a computer analysis method
LOTUS PACKAGE, developed by us for assigning the degradation mechanism. A
number of equations have been used to evaluate the kinetic parameters. The
mechanism of degradation of the conducting polymers has been explained on
the basis of their kinetic parameters. 相似文献
129.
Pion mass and its decay constant have been studied in a chiral symmetric potential model of independent quarks. The non-perturbative
multi-gluon interaction which is responsible for quark confinement in a hadron is phenomenologically represented here by an
effective potentialU(r) = 1/2(1 +γ
0)(ar
2 +V
0). The residual interactions due to quark-pion coupling arising out of the chiral symmetry preservation and that due to quark-gluon
coupling arising out of single-gluon exchange are treated as low order perturbations. The centre of mass correction is also
taken into account appropriately. This leads to the
mass in consistency with that of the PCAC-pion and the pion decay constant in reasonable agreement with experiment. 相似文献
130.
Faiz Ahmed Khan Jyotirmayee Dash Rashmirekha Satapathy Sarasij K. Upadhyay 《Tetrahedron letters》2004,45(15):3055-3058
Knoevenagel condensation proceeds efficiently in recyclable [bmim]PF6 and [bmim]BF4 without any catalyst, and hydrotalcites in ionic liquid serve as a safe and recyclable reaction system for both Knoevenagel as well as nitroaldol condensations. 相似文献