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71.
Two new lucidin type anthraquinone glycosides, putorinoside A (1) and putorinoside B (2) were isolated from Putoria calabrica, in addition to two known anthraquinone glycosides, lucidin 3-O-beta-glucopyranoside (3) and lucidin 3-O-primeveroside (4). Based on spectroscopic data, putorinosides A and B were identified as 2-hydroxymethyl-1-methoxy-3,5,6-trihydroxyanthraquinone 3-O-beta-glucopyranoside and 2-hydroxymethyl-1-methoxy-3,6-dihydroxyanthraquinone 3-O-beta-glucopyranoside, respectively. 相似文献
72.
Energy dispersive X-ray fluorescence technique was used for the determination of As, Sr, Mo, Ba, In and Ce in fly ash Afsin-Elbistan power plants using the standard addition method. An annular241Am source was employed for excitation of the K shell of the elements. 相似文献
73.
74.
K. Usha Deniz E. B. Mirza P. S. Parvathanathan A. V. Patankar A. S. Paranjpe 《Molecular Crystals and Liquid Crystals》2013,570(2-4):271-276
The phase transitions occurring in nBABAs (n = 1 to 5), especially those involving the nematic phase, have been studied by DSC. Schemes of transition are presented and the chain length (n) dependences of the the transition temperatures and entropies are discussed. 相似文献
75.
The obstacle number of a graph G is the smallest number of polygonal obstacles in the plane with the property that the vertices of G can be represented by distinct points such that two of them see each other if and only if the corresponding vertices are
joined by an edge. We list three small graphs that require more than one obstacle. Using extremal graph theoretic tools developed by Pr?mel, Steger, Bollobás, Thomason, and others, we deduce that
for any fixed integer h, the total number of graphs on n vertices with obstacle number at most h is at most 2o(n2){2^{o(n^2)}}. This implies that there are bipartite graphs with arbitrarily large obstacle number, which answers a question of Alpert
et al. (Discret Comput Geom doi:, 2009). 相似文献
76.
77.
78.
Esin Burunkaya Nadir Kiraz Ömer Kesmez H. Erdem Çamurlu Meltem Asiltürk Ertuğrul Arpaç 《Journal of Sol-Gel Science and Technology》2010,55(2):171-176
Aluminum doped zinc oxide (AZO) nanometric particles were synthesized by hydrothermal method. Aluminum nitrate hydrate, aluminum
sec-butoxide and zinc nitrate hydrate were used as the starting materials, and n-propanol and 2-butanol were used as solvents.
Ratio of Al2O3 in ZnO was kept at 10 wt%. Reaction was conducted in a Teflon autoclave at 175–225 °C for 5 h. Ratios of alcohol, H2O and HCl to zinc nitrate hydrate were altered and 6 different sets of parameters were investigated. Obtained products were
subjected to powder-XRD, particle size measurement, TEM examination and AAS analysis. Single phase AZO particles were obtained
at alcohol to zinc nitrate ratio of 35, acid to zinc nitrate ratio of 0.2, at 225 °C. Particle size was determined as 3.2 ± 0.4 nm
from TEM examinations and as 1–2 nm from dynamic light scattering. Synthesized particles have amphiphilic character, thus
they can be dispersed in both polar and non-polar media. It was seen from the UV-diffuse reflectance spectra that the AZO
powder had low reflectance in the UV region and high reflectance in the visible region. The obtained powder has the potential
to be utilized in the form of thin films for optical and electronic purposes. 相似文献
79.
The essential oils (EOs) obtained by solvent-free microwave extraction (SFME) and hydrodistillation (HD) from endemic Origanum husnucanbaseri H. Duman, Aytac & A. Duran were investigated using the gas chromatography-mass spectrometry system. The main constituents of both oils obtained from SFME and HD from O. husnucanbaseri are borneol (15.2-12.8%), α-terpineol (12.3-10.8%) and trans-sabinene hydrate (11.8-9.92%). The EO obtained from SFME contained substantially higher amounts of oxygenated compounds and lower amounts of monoterpenes than that from HD. The antibacterial activities of the EOs from SFME and HD were evaluated by the disc diffusion method against six bacterial strains. The EO extracted by SFME was more effective than the EO extracted by HD against the tested bacteria, except for Klebsiella pneumoniae American type culture collection (ATCC) 13883. Streptococcus pyogenes ATCC 19615 and Staphylococcus aureus ATCC 25923 in particular were more sensitive against the EO extracted by SFME. 相似文献
80.
We report a detailed analysis of the potential energy surface of N-acetyl-l-tryptophan-N-methylamide, (NATMA) both in the gas phase and in solution. The minima are identified using the density-functional-theory (DFT) with the 6-31g(d) basis set. The full potential energy surface in terms of torsional angles is spanned starting from various initial configurations. We were able to locate 77 distinct L-minima. The calculated energy maps correspond to the intrinsic conformational propensities of the individual NATMA molecule. We show that these conformations are essentially similar to the conformations of tryptophan in native proteins. For this reason, we compare the results of DFT calculations in the gas and solution phases with native state conformations of tryptophan obtained from a protein library. In native proteins, tryptophan conformations have strong preferences for the beta sheet, right-handed helix, tight turn, and bridge structures. The conformations calculated by DFT, the solution-phase results in particular, for the single tryptophan residue are in agreement with native state values obtained from the Protein Data Bank. 相似文献