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51.
Sunil B. Zanje Vishal J. Suryavanshi Arjun N. Kokare Anita A. Ghare Ganesh S. Kamble Pravin N. Kamble Mansing A. Anuse 《Journal of Analytical Chemistry》2018,73(5):438-451
A simple, rapid, selective, sensitive and reliable extractive spectrophotometric method was developed for the determination of ruthenium(III) using 2-nitrobenzaldehyde thiocarbohydrazone (2-NBATCH) as a chromogenic chelating ligand. The ruthenium(III)?2-NBATCH complex is formed in aqueous acetic acid media (0.7 M) containing an organic solvent after 5 min heating on a water bath. The red colored complex is extracted into 1,2-dichloroethane and absorbance is measured at 445 nm against reagent blank. The Beer’s law is obeyed within 1?6 g/mL of ruthenium(III), the optimum concentration range was 2?5 g/mL of ruthenium(III) evaluated by Ringbom’s plot. Molar absorptivity and Sandell’s sensitivity of complex were 1.41 × 104 L/mol/cm and 0.0075 μg/cm2, respectively. The stoichiometry of complex was 1: 3 established from Job’s method of continuous variation, molar ratio method and logarithmic slope method. The proposed method was applied for determination of ruthenium(III) in binary and ternary, synthetic mixtures corresponding to fission product elements alloy and ruthenium(III) catalysts. 相似文献
52.
Kaul N Agrawal H Maske P Rao JR Mahadik KR Kadam SS 《Journal of separation science》2005,28(13):1566-1576
Two sensitive and reproducible methods are described for the quantitative determination of itopride hydrochloride (IH) in the presence of its degradation products. The first method is based on HPLC separation on a reversed phase Kromasil column [C18 (5-microm, 25 cm x 4.6 mm, ID)] at ambient temperature using a mobile phase consisting of methanol and water (70:30, v/v) adjusted to pH 4.0 with orthophosphoric acid with UV detection at 258 nm. The flow rate was 1.0 mL per min with an average operating pressure of 180 kg/cm2. The second method is based on HPTLC separation on silica gel 60 F254 using toluene:methanol:chloroform:10% ammonia (5.0:3.0:6.0:0.1, v/v/v/v) as mobile phase at 270 nm. The analysis of variance (ANOVA) and Student's t-test were applied to correlate the results of IH determination in dosage form by means of HPLC and HPTLC methods. The drug was subjected to acid and alkali hydrolysis, oxidation, dry heat, wet heat treatment, UV, and photodegradation. The proposed HPLC method was utilized to investigate the kinetics of the acidic, alkaline, and oxidative degradation processes at different temperatures and the apparent pseudo-first-order rate constant, half-life, and activation energy were calculated. In addition the pH-rate profile of degradation of IH in constant ionic strength buffer solutions in the pH range 2-11 was studied. 相似文献
53.
P. Madhavan B. M. Rao Pravin Abhishek P. R. Kumar M. Sreenivasulu K. B. Chandrasekhar 《Chromatographia》2007,65(1-2):81-84
A normal phase chiral LC method for chiral purity evaluation of β-amino-β-(4-methoxyphenyl) propionic acid was developed on
donor–acceptor (pirkle) column. The chiral stationary phase used was a 250 × 4.6 mm (R, R) Whelk-01 with 5 μm particle size,
which was accompanied with a 1 cm long guard column. The “hybrid” pi-electron donor–acceptor based stationary phase (R, R)
Whelk-01 was found to be enantiomeric selective for (R) and (S) enantiomers of β-amino-β-(4-methoxyphenyl) propionic acid
with a resolution >2.5. The concentration of 2-propanol and TFA in the mobile phase plays an important role on the chrmatographic
efficiency and resolution between the enantiomers. The limit of detection and limit of quantification of (S) enantiomer was
0.3 and 1.0 μg mL-1 for 20 μL injection volume. The percentage RSD of the peak area of six replicate injections of (S) enantiomer at LOQ concentration
was 4.5. The percentage recovery of (S) enantiomer from (R) enantiomer samples ranged from 92 to 100. The test solution was
observed to be stable up to 24 h after the preparation. The developed method was also checked by different analysts and on
different lots of columns, reagents and it was proved to be rugged. The developed normal phase chiral LC method can be used
for the determination of the enantiomeric purity of R-β-amino-β-(4-methoxyphenyl) propionic acid. 相似文献
54.
Complexes of ammonia with propane and cyclopropane: electrostatic guidelines for ab initio treatment
A model based on the molecular electrostatic potential (MESP) is employed for the investigation of structures and energies
of complexes of ammonia with propane and cyclopropane. The electrostatic model geometries are employed as starting points
for an ab initio investigation at the self-consistent field and second-order M?ller-Plesset (MP2) levels. The most stable
structures of C3H6..NH3 and C3H8..NH3 complexes have the interaction energies of 10.07 kJ/mol and 8.15 kJ/mol, respectively, at the MP2/6-31G(d,p) level. The energy rank order of the structures is not altered with the use of the 6-31++G(d,p) basis set, and the basis␣set superposition error has little effect. The interaction energy decomposition analysis shows
that the electrostatic component is dominant over the other ones. MESP topography thus seems to offer valuable hints for predicting
the structures of weakly bonded complexes.
Received: 8 July 1998 / Accepted: 4 August 1998 / Published online: 2 November 1998 相似文献
55.
2,4,5-Trisubstituted pyrrole derivatives were efficiently synthesized by one-pot condensation of 1,3-diones, α-bromoacetophenones, and ammonium acetate in ionic liquid [bmim]BF4. The new synthetic method offers multisubstituted pyrroles with the advantages of mild reaction conditions, operational simplicity, higher yield, and environmental friendliness. 相似文献
56.
The interchangeability of the isoindolinone group as a nitrogen protecting group for amino acid intermediates is demonstrated by the preparation of several natural and unnatural α-amino acid derivatives using a two-carbon N-isoindolinone (phthalimidine) scaffold. Using a selective benzylic oxidation, the N-isoindolinone group is then converted to the N-phthaloyl group for convenient removal (65–98%). For preparation of the isoindolinone products which were to be the substrates for benzylic oxidation, a range of side chains were installed on the isoindolinone-protected glycine equivalent on deprotonation to demonstrate the utility of the N-protected isoindolinone synthon (51–93%). While the ensuing benzylic oxidation is employed successfully for converting the N-isoindolinone group to the N-phthaloyl group in simple substrates, substrates bearing unsaturated or electron-rich side chains respond poorly to the oxidation. 相似文献
57.
Bhagyashri B. Kamble Tawade Anita K. Kamble Pravin Padavi Mukesh N. Sharma Kiran Kumar K. Ajalkar Balu D. Tayade Shivaji N. 《Russian Journal of Electrochemistry》2020,56(9):766-774
Russian Journal of Electrochemistry - A micro-bricks shaped tungsten oxide (WO3) was prepared by hydrothermal method. The prepared material was characterized by field emission scanning electron... 相似文献
58.
59.
P. H. Veena Subhash Abel K. Rajagopal V. K. Pravin 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2006,57(3):447-463
This paper deals with the study of heat transfer characteristics in the laminar boundary layer flow of a visco-elastic fluid
over a linearly stretching continuous surface with variable wall temperature subjected to suction or blowing. The study considers
the effects of frictional heating (viscous dissipation) and internal heat generation or absorption. An analysis has been carried
out for two different cases of heating processes namely: (i) Prescribed surface temperature (PST) and (ii) Prescribed wall
heat flux (PHF) to get the effect of visco-elastic parameter for various situations. Further increase of visco-elastic parameter
is to decrease the skin friction on the sheet. The solutions for the temperature and the heat transfer characteristics are
obtained in terms of Kummers function.
Received: June 16, 2004; revised: February 8, 2005 相似文献
60.
An efficient and greener protocol for the synthesis of poly functionalized pyridines using tetra‐n‐butyl ammonium fluoride (TBAF) in water is established. Remarkable advantages of the present synthetic strategy over the others are shorter reaction times, higher isolated yields, reuse of catalytic system, simple work‐up procedure and more especially its applicability to heteryl and aliphatic aldehydes. 相似文献