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111.
Fátima Duarte Freire C. Flávio Soares Aragão T. Flávio Accioly de Lima e Moura Fernanda Nervo Raffin 《Journal of Thermal Analysis and Calorimetry》2009,97(1):355-357
Chlorpropamide ((4-chloro-N-(propylamino)-carbonyl)-benzenesulfonamide) belongs to compounds having sulfonylurea group and is widely used as an oral
antidiabetic agent. In this work differential scanning calorimetry (DSC) was used during pre-formulation of chlorpropamide
tablets to determine the drug-excipients compatibility. The DSC curves of chlorpropamide and binary mixtures with excipients
(sodium croscarmellose, sodium lauryl sulfate, microcrystalline cellulose, magnesium stearate and calcium carbonate) showed
that chlorpropamide exhibited interaction with magnesium stearate and sodium lauryl sulfate. The binary mixtures of chlorpropamide–magnesium
stearate presented a single endothermic process at 96–108 °C and chlorpropamide–sodium lauryl sulfate showed a wide endotherm
at 99–120 °C. 相似文献
112.
Alexander A. Davydov Stefano Marcugini Fernanda Pambianco 《Designs, Codes and Cryptography》2009,50(3):359-372
An infinite family of complete (q
2 + q + 8)/2-caps is constructed in PG(3, q) where q is an odd prime ≡ 2 (mod 3), q ≥ 11. This yields a new lower bound on the second largest size of complete caps. A variant of our construction also produces
one of the two previously known complete 20-caps in PG(3, 5). The associated code weight distribution and other combinatorial properties of the new (q
2 + q + 8)/2-caps and the 20-cap in PG(3, 5) are investigated. The updated table of the known sizes of the complete caps in PG(3, q) is given. As a byproduct, we have found that the unique complete 14-arc in PG(2, 17) contains 10 points on a conic. Actually, this shows that an earlier general result dating back to the Seventies fails
for q = 17.
相似文献
113.
Bertorelle F Rodrigues F Fery-Forgues S 《Langmuir : the ACS journal of surfaces and colloids》2006,22(20):8523-8531
The reprecipitation method is a simple and useful way to prepare microcrystals through a solvent exchange process. It was applied to three fluorescent dyes of the 4-amino-7-nitrobenz-2-oxa-1,3-diazole series. Compounds 1, 2, and 3 differ by the length of the alkyl chain, which comprises 8, 12, and 18 carbon atoms, respectively. The reprecipitation process was first studied in water, in the absence of additives. The kinetics was monitored by UV/vis absorption spectroscopy. The size and shape of the microparticles were analyzed by fluorescence microscopy and transmission electron microscopy. Dyes 1 and 2 lead to microcrystals, the whole process taking much more time for 2 than for 1. The long-chained dye 3 only gave stable aggregates. Therefore, it appears that the hydrophobicity of the organic dye markedly influenced the reprecipitation process. The latter was then studied in the presence of additives. Poly(amidoamine) dendrimers, terminated by 64 carboxylate or amino groups were placed in the reprecipitation medium. They had little effect upon the formation of aggregates for dye 3. In contrast, they drastically accelerated the reprecipitation of 1 and 2 and tuned the size and shape of the microcrystals. Platelets and spindles were thus obtained by varying the nature of the dendrimer, and their optical properties were briefly investigated. 相似文献
114.
115.
Antonio Galdámez Fernanda López-Vergara Patricia Barahona Victor Manríquez Ricardo E. ávila 《Journal of Solid State Electrochemistry》2012,16(2):697-702
The new solid solutions AgPbSb1 − x
Bi
x
S3 were prepared by solid state reactions. The phases were characterized by powder X-ray diffractions (XRD), scanning electron
microscopy, and thermal analysis. The XRD patterns of different members (x = 0.5, 0.7, 0.8, and 1.0) are consistent with pure phases crystallizing in the cubic PbS-type structure. The electrical characterization
was carried out using ac impedance spectroscopy and dc methods. The temperature dependence of the dc conductivity shows typical
semiconductor Arrhenius behavior. The impedance measurements were performed in the frequency range of 0.1 Hz to 10 MHz and
at the temperature range of 15 °C to 350 °C. The ac conductivity conforms to Jonscher’s universal power law. The frequency
dependence of the dielectric permittivity follows the normal dielectric material behavior, and the relaxation is thermally
activated. The frequency and temperature dependences of the electrical data are found to follow Summerfield scaling formalism. 相似文献
116.
In this paper we investigate adiabatic charge and spin pumping through interacting quantum dots using non-equilibrium Green's function techniques and the equation-of-motion method. We treat the electronic correlations inside the dot using a Hartree-Fock approximation and succeed in obtaining closed analytic expressions for the Keldysh Green's functions. These allow us to compute charge and spin currents through the quantum dot. Depending on the parameters of the quantum dot and its coupling to the reservoirs, we show that it can be found in two different regimes: the magnetic regime and the non-magnetic regime. In the magnetic regime we find a non-vanishing spin current in addition to the charge current present in both cases. 相似文献
117.
Ray L. Frost Yunfei Xi Ricardo Scholz Fernanda M. Belotti 《Transition Metal Chemistry》2012,37(8):777-782
In this research, we have used vibrational spectroscopy to study the phosphate mineral kosnarite KZr2(PO4)3. Interest in this mineral rests with the ability of zirconium phosphates (ZP) to lock in radioactive elements. ZP have the capacity to concentrate and immobilize the actinide fraction of radioactive phases in homogeneous zirconium phosphate phases. The Raman spectrum of kosnarite is characterized by a very intense band at 1,026?cm?1 assigned to the symmetric stretching vibration of the PO4 3? ??1 symmetric stretching vibration. The series of bands at 561, 595 and 638?cm?1 are assigned to the ??4 out-of-plane bending modes of the PO4 3? units. The intense band at 437?cm?1 with other bands of lower wavenumber at 387, 405 and 421?cm?1 is assigned to the ??2 in-plane bending modes of the PO4 3? units. The number of bands in the antisymmetric stretching region supports the concept that the symmetry of the phosphate anion in the kosnarite structure is preserved. The width of the infrared spectral profile and its complexity in contrast to the well-resolved Raman spectrum show that the pegmatitic phosphates are better studied with Raman spectroscopy. 相似文献
118.
Davi Fernando BackManfredo Hörner Fernanda BrochGelson Manzoni de Oliveira 《Polyhedron》2012,31(1):558-564
The new ligand 1,3-bis(3-methoxy-4-methylbenzoate) triazene (1, bmmbt), and the already known ligand 1,3-bis(4-acetylphenyl)triazene (bapht), yield the two new palladium(II) complexes [(bmmbt)Pd(PPh3)2Cl]·DMSO (2) and [(bapht)Pd(PPh3)2Cl] (3) (Ph = phenyl; DMSO = dimethylsulfoxide). Compound 1 shows the existence of more than one interaction promoting the coupling between the triazene chains. Other remarkable types of interactions in 1 are bifurcated hydrogen contacts and non-classical CH···π bonding. Complexes 2 and 3 present a planar geometry, supported also through bifurcated intramolecular Cl···H-C interactions, as well as the occurrence of trifurcated Cl···H-C intermolecular interactions. 相似文献
119.
We explore the mechanism responsible for the ergodicity breaking in systems with long-range forces. In thermodynamic limit such systems do not evolve to the Boltzmann-Gibbs equilibrium, but become trapped in an out-of-equilibrium quasi-stationary-state. Nevertheless, we show that if the initial distribution satisfies a specific constraint-a generalized virial condition-the quasistationary state is very close to ergodic and can be described by Lynden-Bell statistics. On the other hand, if the generalized virial condition is violated, parametric resonances are excited, leading to chaos and ergodicity breaking. 相似文献
120.
Magdi E.A. Zaki A. Paula Bettencourt Francisco M. Fernandes M. Fernanda Proença 《Tetrahedron》2012,68(24):4628-4634
Substituted 4-(2,5-dihydro-1H-pyrrol-3-yl)-1H-imidazoles were prepared from 5-amino-1-aryl-4-cyanoformimidoylimidazoles and cyanoacetamide, under mild experimental conditions. The pyrrolyl-imidazoles were cyclized to the corresponding 7,8-dihydroimidazo[4,5-b]pyrrolo[3,4-d]pyridines by reflux in ethanol, with catalysis by DBU. The same pyrrolyl-imidazoles were reacted with orthoesters, at room temperature and in the presence of sulfuric acid, to generate 3,7-dihydro-8H-imidazo[4,5-d]pyrrolo[3,2-f]diazepines in very good yield. Electrochemical studies of the imidazo[4,5-d]pyrrolo[3,2-f][1,3] diazepine derivatives were carried out. The reduction potential of 7-ethyl-3-(4-methoxyphenyl)-8-oxo-7,8-dihydro-3H-imidazo[4,5-d]pyrrolo[3,2-f][1,3] diazepine-9-carbonitrile was in the adequate range for presenting bioreduction properties. 相似文献