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61.
M. Hafez I. S. Yahia S. Taha 《Applied Physics A: Materials Science & Processing》2014,116(3):1445-1453
Optical, microstructural, and thermal properties of the investigated silver nitrate samples were characterized by various techniques, such as X-ray analysis, scanning electron microscopy, UV–Vis–NIR absorption and differential scanning calorimetry (DSC). The presence of structural phase transition [orthorhombic structure (phase II) to rhombohedral structure (phase I)] was checked by DSC and X-ray analysis measurements. The thermal energy required for such transformation is found to be 11.6 J/g. The optical band gaps of AgNO3 are 1.4 and 2.02 eV for phase II and phase I, respectively, at the low-energy region. But at high-energy region, the optical band gaps are 3.41 and 3.43 eV for phase II and phase I, respectively. Characteristic peaks for AgNO3 corresponding to (2 1 1), (0 0 4) and (3 5 1) for phase II and (0 0 4), (3 1 1) and (0 2 4) for phase I have been observed. The average crystalline size for AgNO3 samples and the values of dislocation density δ and the strain ε for the planes of two phases II and I are calculated and also the texture coefficient is determined. Such information can considerably aid in understanding the process of phase transformations in AgNO3. 相似文献
62.
Taha A 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2003,59(6):1373-1386
Solvatochromic mixed ligand complexes of copper(II) with malonate and diamine derivatives, Cu(n)(RMal)(diam)(n)X(m) (where n=1 or 2, m=1-4, RMal, malonic acid (H(2)Mal), diethylmalonate (HDEtMal) or diethylethoxyethylenemalonate (DEtEMal), and diam, ethylenediamine (en), 1,3-propylenediamine (1,3-pn), N,N,N'-trimethylethylenediamine (Me(3)en), N,N,N'-triethylethylenediamine (Et(3)en), N,N,N',N'-tetramethylethylenediamine (Me(4)en), N,N,N',N'-tetramethylpropylenediamine (Me(4)pn), or N-methyl-1,4-diazacycloheptane (medach); and X=ClO(4)(-) or Cl(-)), has been synthesized and characterized by spectroscopic, magnetic, molar conductance and electrochemical measurements. The mass spectra along with the analytical data of the complexes show peaks with m/e corresponding to a bridged binuclear structure for the chloride complexes, while perchlorate complexes showed either mononuclear structure for DEtMal and DEtEMal or bridged binuclear structure for Mal complexes. These results correspond to IR spectral data, which indicated that the modes of ester and carboxylato coordination sites are mono- and/or bidentate. The d-d absorption bands in weak donor solvents suggest square-planar and distorted square pyramidal-trigonal bipyramid geometries for the perchlorate and chloride complexes; respectively. On the other hand, an octahedral structure is identified for complexes in strong donor solvents. Perchlorate complexes show a drastic color change from violet to green as the donation ability of solvent increases, whereas chloride complexes are highly affected by the acceptor properties of the solvent. Cyclic voltammetric measurements on the complexes, proposed a quasi-reversible or irreversible and mainly diffusion controlled reduction process. Such behavior has been explained according to the ECE mechanism. A linear correlation has been found between the Cu(II) reduction potential and the spectral data. Molecular orbital calculations were performed for the ligands on the bases of PM3 level and the results corresponded to the experimental data. The data are discussed in terms of chromotropic concept and its applications as a Lewis acid-base color indicator. 相似文献
63.
Khalid Mohammed Khan Muhammad Taha Fazal Rahim Waqas Jamil Shahnaz Perveen Muhammad Iqbal Choudhary 《Journal of the Iranian Chemical Society》2012,9(1):81-83
Treatment of indole with substituted aldehyde in the presence of equimolar amount of sodium bromate and sodium hydrogen sulfite mixture in water yielded corresponding substituted bis(indolyl)methanes in good yields. This provides a facile and environmentally friendly method towards the synthesis of an important class of organic compounds. 相似文献
64.
Two rare metal coordination complexes of yttrium(III) including 1,10‐phenanthroline, Y(phen)2(NO3)3 and (phenH)2[Y2(pydc)3(NO3)2·6H2O] (phen=1,10‐phenanthroline, pydc=2,6‐pyridinedicarboxylate), and a proton transfer compound (phenH+)2(pydc2?) were synthesized and characterized by elemental analysis, molar conductance, infrared spectra (IR), nuclear magnetic resonance (NMR) and thermal analysis. The proposed structures of yttrium complexes were exhibited. The in vitro biological activities of the newly synthesized complexes have also been investigated against Bacillus coli, Staphylococcus aureus and Candida albicans. The results showed that yttrium(III) complexes including 1,10‐phenanthroline exhibited better antibacterial/antifungal activity than their ligands and corresponding compounds. 相似文献
65.
Thomas Heinze Taha Genco Katrin Petzold-Welcke Holger Wondraczek 《Cellulose (London, England)》2012,19(4):1305-1313
Amino cellulose sulfate (ACS); namely 6-deoxy-6-(ω-aminoethyl) amino cellulose-2,3(6)-O-sulfate (AECS) and 6-deoxy-6-(2-(bis-N′,N′-(2-aminoethyl)aminoethyl)) amino cellulose-2,3(6)-O-sulfate (BAECS) were prepared by a three step synthesis starting with the functionalization of microcrystalline cellulose with p-toluenesulfonyl (tosyl) groups (degree of substitution, DSTos between 0.55 and 1.37). Subsequently the introduction of the sulfate moieties was carried out (DSSulf between 1.09 and 1.27) and the tosyl groups at position 6 were replaced by a nucleophilic substitution reaction. As nucleophilic agents 1,2-diaminoethane and tris-(2-aminoethyl)amine were applied, yielding AECS (DSAEA values between 0.41 and 0.86) and BAECS (DSBAEA values between 0.32 and 0.74), respectively. The ACS samples were characterized by means of elemental analysis, 13C-NMR-, FT-IR-, and UV–Vis spectroscopy. Moreover, the solubility of the samples in water at different pH values and the molecular weights of the samples in aqueous solution were studied. 相似文献
66.
A simple, facile, efficient and three-components procedure for the synthesis of pyrimido[1,2-a]benzimidazoles and pyrazolo[3,4-b]pyridines utilizing phenylsulfone synthon, under ultrasonic irradiation was developed. 相似文献
67.
New eight lanthanide metal complexes were prepared. These complexes were characterized by elemental analysis, molar conductivity measurements, spectral analysis (1H NMR, FT-IR, UV–vis), luminescence and thermal gravimetric analysis. All Ln(III) complexes were 1:1 electrolytes as established by their molar conductivities. The microanalysis and spectroscopic analysis revealed eight-coordinated environments around lanthanide ions with two nitrate ligands behaving in a bidentate manner. The other four positions were found to be occupied with tetradentate LIII ligand. Tb–LIII and Sm–LIII complexes exhibited characteristic luminescence emissions of the central metal ions and this was attributed to efficient energy transfer from the ligand to the metal center. The LIII and Ln–LIII complexes showed antibacterial activity against a number of pathogenic bacteria. 相似文献
68.
Trimethylamine N-oxide (TMAO) is a compatible or protective osmolyte that stabilizes the protein native structure through non-bonding mechanism between TMAO and hydration surface of protein. However, we have shown here first time the direct binding mechanism for naturally occurring osmolyte TMAO with hydration structure of poly(N-isopropylacrylamide) (PNIPAM), an isomer of polyleucine, and subsequent aggregation of PNIPAM. The influence of TMAO on lower critical solution temperature (LCST) of PNIPAM was investigated as a function of TMAO concentration at different temperatures by fluorescence spectroscopy, viscosity (η), multi angle dynamic light scattering, zeta potential, and Fourier transform infrared (FTIR) spectroscopy measurements. To address some of the basis for further analysis of FTIR spectra of PNIPAM, we have also measured FTIR spectra for the monomer of N-isopropylacrylamide (NIPAM) in deuterium oxide (D(2)O) as a function of TMAO concentration. Our experimental results purportedly elucidate that the LCST values decrease with increasing TMAO concentration, which is mainly contributing to the direct hydrogen bonding of TMAO with the water molecules that are bound to the amide (-CONH) functional groups of the PNIPAM. We believed that the present work may act as a ladder to reach the heights of understanding of molecular mechanism between TMAO and macromolecule. 相似文献
69.
Drug abuse is both an age-old and a constantly evolving problem in society. Trends in illicit drug use are highly fluid, with new formulations increasing in popularity. For this reason, methods for illicit drug detection and analysis need to be continually updated so they remain useful and relevant. A recent trend in street heroin production has seen it diluted with large amounts of tramadol in addition to the classical diluents such as acetaminophen and caffeine. This study describes a sensitive, simple and accurate high-performance liquid chromatographic method with ultraviolet detection for the simultaneous detection of heroin, 6-acetylmorphine, morphine, tramadol and O-desmethyltramadol in the blood of rats using a liquid-liquid back-extraction method. The separation was performed on LichroCART RP-18e with particle size of 5 μm (250 × 4.6 mm) with mobile phase acetonitrile-50 mM KH(2)PO(4) buffer, pH 7.1, using a gradient mode with a 1.0 mL/min flow rate. The calibration curves were linear in the concentration ranges 0.25-100 and 0.1-100 μg/mL for morphine and other analytes, respectively. Recovery values for the substances ranged between 59 and 83%. This technique was successfully used in pharmacokinetic studies measuring 6-acetylmorphine, morphine, tramadol and O-desmethyltramadol in the blood of rats intraperitoneally treated with a blend of 10 mg/kg heroin and 70 mg/kg tramadol. This technique shows promise for analysis of confiscated street heroin. 相似文献
70.
Jean Fotie Jessica L. Rhodus Hashem A. Taha Carolyn S. Reid 《Heteroatom Chemistry》2012,23(6):598-604
Two C,N‐linked dimeric 1,2‐dihydro‐2,2,4‐trimethylquinolines, namely 6‐chloro‐1‐(6‐chloro‐1,2‐dihydro‐2,2,4‐trimethylquinolin‐8‐yl)‐1,2‐dihydro‐2,2,4‐trimethylquinoline ( 3a ) and 6‐ethoxy‐1‐(6‐ethoxy‐1,2‐dihydro‐2,2,4‐trimethylquinolin‐8‐yl)‐1,2‐dihydro‐2,2,4‐trimethylquinoline ( 3b ), have been prepared through a silver‐catalyzed dimerization of their corresponding monomers. The effect of different silver salts on the reaction was also investigated, and the obtained results suggest that silver ions effectively catalyzed the formation of a C–N bond under these mild conditions. This represents one of the rare reports on the silver‐catalyzed C–N bond formation through a coupling of a secondary amine and an activated aromatic system, via a direct C–H functionalization. Theoretical studies showed that these dimeric structures favor a conformation in which their monomer units are oriented approximately perpendicular to each other, with an intramolecular hydrogen bond (N–H distance of 2.33 Å) forming between the hydrogen atom of the amine in one of the monomeric units and the tertiary nitrogen atom of the other one. 相似文献