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91.
In the present study a second-order calibration strategy for high performance liquid chromatography with diode-array detection (HPLC-DAD) has been developed using parallel factor analysis (PARAFAC) and has been applied for simultaneous determination of aflatoxins B1, B2, G1 and G2 in pistachio nuts in the presence of matrix interferences. Sample preparation was based on solvent extraction (SE) followed by solid phase extraction (SPE) on Bond Elut C18 cartridges. Since the sample preparation procedure was not selective to the analytes of interest, exploiting second-order advantage to obtain concentrations of individual analytes in the presence of uncalibrated interfering compounds seemed necessary. Appropriate pre-processing steps have been applied to correct background signals and the effect of retention time shifts. Transferred calibration data set obtained from standardization of solvent based calibration data has been used in prediction step. The results of PARAFAC on a set of spiked and naturally contaminated pistachio nuts indicated that the four aflatoxins could be successfully determined. The method was validated and multivariate analytical figures of merit were calculated. The advantages of the proposed method are using a low-cost SPE step relative to standard method of aflatoxin analysis (immune affinity column assay), a unique and simple isocratic elution program for all samples and a calibration transfer for saving both chemicals and time of analysis. This study show that coupling of SPE-HPLC-DAD with PARAFAC as a powerful second-order calibration method can be considered as an alternative method for resolution and quantification of aflatoxins in the presence of unknown interferences obtained through analysis of highly complex matrix of pistachio samples and cost per analysis can be reduced significantly. 相似文献
92.
Maryam Ezoddin Farzaneh Shemirani Mohammad Reza Jamali 《Journal of Analytical Chemistry》2010,65(2):153-158
In this research, simple, rapid and efficient method, dispersive liquid-liquid microextraction (DLLME) combined fiber optic
-linear array detection spectrophotometry (FO-LADS) was developed using a cylindrical micro-cell for preconcentration and
determination of Cu(II) in samples. DLLME and FO-LADS methods have good matching conditions for being combined since FO-LADS
is a suitable method for the determination of analytes in low volume of the remained phase obtained after DLLME. Molar absorptivity
of complex Cu with (4-benzylp iperidineditiocarbamate potassium salt) (BPDC) was determined as 2.75 × 104 L mol-1 cm-1 at 7nmax = 436 nm. Under the optimum conditions the calibration graph was linear in the rage of 2–70 fug L-1 with detection limit of 0.34 fug L-1. The proposed procedure was successfully applied to the determination of Cu(II) in real water samples and human urine sample. 相似文献
93.
Nahid Shahabadi Soheila Kashanian Marzieh Khosravi Maryam Mahdavi 《Transition Metal Chemistry》2010,35(6):699-705
The water-soluble Ni(II) complex, [Ni(bipy)2(phen-dione)](OAc)2·2H2O (bipy = 2,2′-bipyridine and phen-dione = 1,10-phenanthroline-5,6-dione) has been synthesized and characterized by physico-chemical
and spectroscopic methods. The binding interactions of this complex with calf thymus DNA (CT-DNA) were investigated using
fluorimetry, spectrophotometry, circular dichroism and viscosimetry. In fluorimetric studies, the enthalpy and entropy of
the reaction between the complex and CT-DNA showed that the reaction is exothermic (ΔH = −123.9 kJ mol−1; ΔS = −323.5 J mol−1 K−1). The competitive binding studies showed that the complex could not release methylene blue completely. The complex showed
absorption hyperchromism in its UV–Vis spectrum with DNA. The calculated binding constant, K
b obtained from UV–Vis absorption studies was 2 × 105 M−1. Moreover, the complex induced detectable changes in the CD spectrum of CT-DNA, as well as changes in its viscosity. The
results suggest that this nickel(II) complex interact with CT-DNA via a groove-binding mode. 相似文献
94.
Iman Manavi-Tehrani Mohammad Rabiee Maryam Parviz Mohammad Reza Tahriri Zahra Fahimi 《Macromolecular Symposia》2010,296(1):457-465
In the present research hydrogel films based on polyvinyl alcohol (PVA) and polyacrylic acid (PAA) blend, with various crosslink densities, have been prepared through different thermal treatment. The results of FTIR and DSC confirmed quality and quantity of conclusion on miscibility of PVA/PAA blends, respectively. Besides, biocompatibility of the samples has been proved in cytotoxicity tests using L929 cells, according to ISO10993–5. Water uptake of the hydrogel blends is measured. pH sensitivity properties of blends are studied with and without boiling in NaOH solutions where the effect of swelling in water before boiling has also been investigated. Preswellings in water and NaOH concentration have been found to be mainly effective on pH sensitivity of PVA/PAA blends. Biocompatibility and pH sensitivity behavior make these hydrogels appropriate candidates to orally deliver drugs such as insulin and peptides that can be released in basic pH of intestine. The stability of these films in acidic solutions and its expansion and also the consequent release of drugs in basic solutions have been studied by using Teofilin as a model drug by UV-spectrophotometeric measurements. 相似文献
95.
Mozaffar Asadi Maryam Mohammadikish Khosro Mohammadi 《Central European Journal of Chemistry》2010,8(2):291-299
Four Schiff base ligands, salabza-H2 = N,N′-bis(salicylidene)-2-aminobenzylamine, were synthesized by condensation of one mole of 2-aminobenzylamine and two moles of
salicylaldehyde and/or two moles of substituted salicylaldehyde (5-OMe, 5-Br, 5-NO2). All the four Schiff bases and their Mn(II), Co(II), Cu(II) and Zn(II) complexes are characterized by UV-Vis, FT-IR, 1H NMR spectroscopy, mass spectrometry and elemental analysis. The formation constants and the Gibbs free energies were measured
spectrophotometrically for 1:1 complexes in methanol in constant ionic strength (I = 0.1 mol dm−3 NaClO4) and at 25°C. The data refinement was carried out with the SQUAD program. The trend of formation constants of H2L1 with M(II) follows the order: Mn(II) (3.97) < Zn(II) (4.30) < Co(II) (4.89) < Cu(II) (5.73) 相似文献
96.
Younes Ghasemi Abdolali Mohagheghzadeh Zahra Ostovan Maryam Moshavash Sara Rasoul-Amini Mohammad Hossein Morowvat 《Chemistry of Natural Compounds》2010,46(5):734-737
Biotransformation of several monoterpene ketones, including carvone, pulegone, piperitone, menthone, and fenchone, was carried
out by the locally isolated unicellular microalgae Chlorella vulgaris. The microalgal strain was isolated during a screening program from soil samples collected from paddy-fields of Fars Province,
in the south of Iran. Chlorella vulgaris was cultured in 250 mL conical flasks, each containing 50 mL of BG-11 liquid medium and 20 μL levels of terpene substrates,
incubated at a temperature of 28±2°C and illuminated continuously with fluorescent lamps with shaking at 80 rpm. The metabolites
were identified by thin-layer chromatography and GC-MS. Chlorella vulgaris has the ability to reduce the C=C double bond of carvone to yield trans-dihydrocarvone and cis-dihydrocarvone. The cell line reduced menthone and pulegone to the same product and gave menthol. Study of Chlorella vulgaris with substrates of piperitone and fenchone showed no reaction in these substrates. Chlorella vulgaris MCCS 012 was assigned according to the 18S rRNA gene sequence. The DNA sequence of the 18S rRNA gene of Chlorella vulgaris MCCS 012 was recorded in the NCBI under the accession number EU374170. 相似文献
97.
Abolghasem Davoodnia Mehdi Bakavoli Raheleh Moloudi Niloofar Tavakoli-Hoseini Maryam Khashi 《Monatshefte für Chemie / Chemical Monthly》2010,122(3):867-870
Abstract
A simple, efficient, and green method for synthesis of 2,4,6-triarylpyridines by one-pot three-component reaction of acetophenones, aryl aldehydes, and ammonium acetate using 3-methyl-1-(4-sulfonylbutyl)imidazolium hydrogen sulfate [HO3S(CH2)4MIM][HSO4], a Br?nsted-acidic ionic liquid, as an effective and reusable catalyst under solvent-free conditions is described. This method has several advantages, for example simple procedure with an easy work-up, shorter reaction times, and high yields. 相似文献98.
A selective and sensitive method for simultaneous determination of lead, zinc and copper by adsorptive differential pulse
cathodic stripping voltammetry is presented. The method is based on adsorptive accumulation of the complexes of Pb(II), Zn(II),
and Cu(II) ions with dopamine onto hanging mercury drop electrode (HMDE), followed by reduction of adsorbed species by differential
pulse cathodic stripping voltammetry. The effect of experimental parameters such as pH, dopamine concentration, accumulation
time and potential and scan rate were examined. Under the optimized conditions, linear calibration curves were established
for the concentration of Pb, Zn, and Cu in the ranges of 5–150, 5–250, and 1–150 ng/mL, respectively. Detection limits of
0.06, 0.25, and 0.04 ng/mL for Pb, Zn, and Cu were obtained. An application of the proposed method is reported for the determination
of these elements in some real samples such as natural waters and alloys. 相似文献
99.
A simple and efficient method for the iodination of aromatic compounds has been achieved in the presence of iodine and 1,4-bis(triphenylphosphonium)-2-butene peroxodisulfate. 相似文献
100.
Hydroxylamine was found to be a mild reagent for conversion of arylboronic acids and their pinacolyl boronate esters into phenols. This procedure works on most arylboronic acids at room temperature, yielding phenols in moderate to good yields, and efficiently on arylboronates also yielding phenols in good yields. 相似文献