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Patil ST Bhoir IC Bhagwat AM Sundaresan M 《Fresenius' Journal of Analytical Chemistry》2000,367(1):91-93
Tolnaftate, an antifungal drug (TF) and related impurities arising from synthesis, viz., N-methyl-m-toluidine (NMmT) and beta-naphthol-1-chlorothio carbamate (beta-NCTC) can be determined by supercritical fluid chromatography. Even though it was possible to elute TF completely with neat SCF CO2, the peaks of the impurities were found to merge. The chromatographic figures of merit of the three analytes such as retention time (tR), capacity factor (k), selectivity factor (alpha), no. of theoretical plates (N), were optimized. The three compounds can be resolved in 5 min on a Hypersil (250 x 4.0 mm) 5 mu, C18 column with supercritical carbon dioxide, modified with 1.96% methanol as the mobile phase at 9.81 MPa and at 40 degrees C. Detection was carried out at 220 nm. The data as evaluated by the linear regression least squares fit method gave linearity ranges from 0.2 to 10.0 microg/mL for TF and NMmT and 0.3 to 10.0 microg/mL for beta-NCTC with correlation coefficients > 0.99. The method was successfully employed to estimate levels of 0.01% for NMmT and 0.02% for beta-NCTC with respect to TF. 相似文献
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Bhagwat PrasadAmit Garg Hardik TakwaniSaranjit Singh 《Trends in analytical chemistry : TRAC》2011,30(2):360-387
Metabolite identification (Met ID) is important during the early stages of drug discovery and development, as the metabolic products may be pharmacologically active or toxic in nature. Liquid chromatography-mass spectrometry (LC-MS) has a towering role in metabolism research.This review discusses current approaches and recent advances in using LC-MS for Met ID. We critically assess and compare various mass spectrometers, highlighting their strengths and limitations. Citing appropriate examples, we cover recent LC and ion sources, isotopic-pattern matching, hydrogen/deuterium-exchange MS, data dependent analyses, MSE, mass defect filter, 2D and 3D approaches for the elucidation of molecular formula, polarity switching, and background-subtraction and noise-reduction algorithms. A flow chart outlines a comprehensive strategy for Met ID, including a focus on reactive metabolites. 相似文献
4.
Grzegorz Kosowski Dawid Mikulski Prashant Bhagwat Santhosh Pillai 《Molecules (Basel, Switzerland)》2022,27(18)
One of the key elements influencing the efficiency of cellulosic ethanol production is the effective pretreatment of lignocellulosic biomass. The aim of the study was to evaluate the effect of microwave-assisted pretreatment of wheat stillage in the presence of sodium cumene sulphonate (NaCS) hydrotrope used for the production of second-generation bioethanol. As a result of microwave pretreatment, the composition of the wheat stillage biomass changed significantly when compared with the raw material used, before treatment. Microwave-assisted pretreatment with NaCS effectively reduced the lignin content and hemicellulose, making cellulose the dominant component of biomass, which accounted for 42.91 ± 0.10%. In post pretreatment, changes in biomass composition were also visible on FTIR spectra. The peaks of functional groups and bonds characteristic of lignins (C–O vibration in the syringyl ring, asymmetric bending in CH3, and aromatic skeleton C–C stretching) decreased. The pretreatment of the analyzed lignocellulosic raw material with NaCS resulted in the complete conversion of glucose to ethanol after 48 h of the process, with yield (in relation to the theoretical one) of above 91%. The highest observed concentration of ethanol, 23.57 ± 0.10 g/L, indicated the high effectiveness of the method used for the pretreatment of wheat stillage that did not require additional nutrient supplementation. 相似文献
5.
Satish Bhagwat Myron B. Allen 《Numerical Methods for Partial Differential Equations》1988,4(4):315-318
Downstream-weighted implicit difference schemes for pure advection are stable for Courant numbers λ ≥ 1. They are numerically diffusive when λ > 1. 相似文献
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Summary A scheme of cation analysis is presented where phosphate and organic acids do not interfere with the course of analysis. The method is standardised on 2–3 mg level, and the procedure is rapid. Group separations are neat and in no case the precipitate is gelatinous. Some confirmatory tests of the elements have been modified.
Zusammenfassung Ein Analysengang für Kationen wird angegeben, der durch Phosphat und organische Säuren nicht gestört wird und mit 2 bis 3 mg Probe rasch durchführbar ist. Die Gruppentrennungen verlaufen sauber, die Niederschläge sind in keinem Fall gallertig. Einzelne Nachweisreaktionen wurden modifiziert.相似文献
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A generalized version of Gordon's M-diffusion model for reorientation of molecules in dense phase was proposed by Duttagupta and Sood. They calculated the IR correlation function and compared it with a few experimental data. We calculate the Raman correlation function for this model and compare it with experimental data for OCS, N2O in CCl4, and CH3I. We find that at short times, the agreement with the experimental data is much better than that for Gordon's M-diffusion model. We have also shown that, at long times the correlation function decays as an inverse power of time. However, the experimental correlation function at long times decays much faster. 相似文献
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A point-defect model of structural phase transitions in YBa2Cu3O6 + x is proposed. The model treats the basal-plane oxygen atoms as point defects. The treatment parallels the work of Alefeld and coworkers on ferroelasticity due to hydrogen in metals. The model predicts that the tetragonal-to-orthorhombic phase transition should be accompanied by precipitation into regions of high and low oxygen density, as well as high and low oxygen ordering. This is in agreement with experiment, as well as with the predictions of Khachaturyan's concentration-wave model. A new feature of the present model is the prediction of two characteristic temperatures related, respectively, to Snoek-type and Gorsky-type diffusive relaxations. Practical implications of the high diffusivity of the basal-plane oxygens include the easy fabricability of a bicrystal of Y-Ba-Cu-O such that the two components of the bicrystal are rotated by 90° with respect to each other, and are separated by a non-superconducting layer. Such a bicrystal can find applications as a Josephson-tunneling device. 相似文献
10.
H. Naik S. V. Surayanarayana V. K. Mulik P. M. Prajapati B. S. Shivashankar K. C. Jagadeesan S. V. Thakare D. Raj S. C. Sharma P. V. Bhagwat S. D. Dhole S. Ganesan V. N. Bhoraskar A. Goswami 《Journal of Radioanalytical and Nuclear Chemistry》2012,293(2):469-478
The 238U(n, ??)239U reaction cross-section at average neutron energy of 3.7?±?0.3?MeV from the 7Li(p, n)7Be reaction has been determined using activation and off-line ??-ray spectrometric technique. The 238U(n, ??)239U and 238U(n, 2n)237U reaction cross-sections at average neutron energy of 9.85?±?0.38?MeV from the same 7Li(p, n)7Be reaction have been also determined using the above technique. The experimentally determined 238U(n, ??)239U and 238U(n, 2n)237U reaction cross-sections were compared with the evaluated data of ENDF/B-VII, JENDL-4.0, JEFF-3.1 and CENDL-3.1. The experimental values were found to be in general agreement with the evaluated value based on ENDF/B-VII, and JENDL-4.0 but not with the JEFF-3.1 and CENDL-3.1. The present data along with literature data in a wide range of neutron energies were interpreted in terms of competition between different reaction channels including fission. The 238U(n, ??)239U and 238U(n, 2n)237U reaction cross-sections were also calculated theoretically using the TALYS 1.2 computer code and were also found to be in agreement experimental data. 相似文献