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1.
I. H. Qureshi M. S. Chaudhary S. Ahmad 《Journal of Radioanalytical and Nuclear Chemistry》1982,68(1-2):209-218
Instrumental neutron activation analysis technique has been used to determine the concentration levels of 12 trace elements
in human head hair samples collected from 105 individuals living in various areas of Rawalpindi-Islamabad. The data show that
the average concentrations of Mn, Co, Ag and Au are higher in the female group as compared to the male group. Four individuals
were found to have elevated levels of Se due to the use of anti-dandruff shampoos, whereas two individials had elevated levels
of Hg. 相似文献
2.
M. S. Chaudhary S. Ahmad A. Mannan I. H. Qureshi 《Journal of Radioanalytical and Nuclear Chemistry》1984,83(2):387-396
An instrumental neutron activation analytical (INAA) technique is described for the determination of 26 toxic and other trace elements in Eastern Coal (NBS SRM-1632a), local coal and its ash. The coal ash was produced by heating coal at 750°C in a muffled furnace. The transfer of these elements to the environment on the complete compustion of coal is estimated from the difference between the elemental concentration of coal and its ash. 相似文献
3.
Samuel K Yin W Stearns RA Tang YS Chaudhary AG Jewell JP Lanza T Lin LS Hagmann WK Evans DC Kumar S 《Journal of mass spectrometry : JMS》2003,38(2):211-221
Metabolic activation of drug candidates to electrophilic reactive metabolites that can covalently modify cellular macromolecules may result in acute and/or idiosyncratic immune system-mediated toxicities in humans. This presents a significant potential liability for the future development of these compounds as safe therapeutic agents. We present here an example of an approach where sites of metabolic activation within a new drug candidate series were rapidly identified using online liquid chromatography/multi-stage mass spectrometry on an ion trap mass spectrometer. This was accomplished by trapping the reactive intermediates formed upon incubation of compounds with rat and human liver microsomes as their corresponding glutathione conjugates and mass spectral characterization of these thiol adducts. Based on the structures of the GSH adducts identified, potential sites and mechanisms of bioactivation within the chemical structure were proposed. These metabolism studies were interfaced with iterative structural modifications of the chemical series in order to block these bioactivation sites within the molecule. This strategy led to a significant reduction in the propensity of the compounds to undergo metabolic activation as evidenced by reductions in the irreversible binding of radioactivity to liver microsomal material upon incubation of tritium-labeled compounds with this in vitro system. With the efficiency and throughput achievable with such an approach, it appears feasible to identify and address the metabolic activation potential of new drug leads during routine metabolite identification studies in an early drug discovery setting. 相似文献
4.
2‐Acetyl thiophenethiocynate (ATT) was synthesized and its characterization study was carried out using elemental analysis, IR and NMR techniques. The new reagent was proposed as an extractant for the development of the extractive spectrophotometric method for determination of Pt(IV) metal. The reagent complexes with the metal to produce a yellow colored complex which was then extracted into ethyl acetate at pH 11.2–11.6 having an absorption maxima at 400 nm. The thermal study showed that the extraction reactions are exothermic in nature with the reagent, and the stoichiometric ratio of Pt(IV) to 2‐acetyl thiophenethiocynate in the organic phase was 1:2. The method permits separation and determination of platinum from real and binary mixtures. The separation of Pt(IV) from bivalent metal ions has been also studied. 相似文献
5.
S. Ahmad M. S. Chaudhary A. Mannan I. H. Qureshi 《Journal of Radioanalytical and Nuclear Chemistry》1983,78(2):375-383
The concentration of certain toxic and essential elements in various brands of tea consumed locally were determined using instrumental neutron activation analysis. Transference of these elements into the drinkable portion was studied by brewing and boiling tea leaves for two minutes and the approximate intake was calculated from this data. The toxic effects of Hg, Se, As, Br and Sb are briefly discussed. 相似文献
6.
Sorption of europium on zirconium oxide has been studies as a function of shaking time, concentration and nature of electrolyte. The effect of initial europium concentration and the amount of adsorbent has been investigated in the range from 6.6·10–10 to 6.6·10–8 mol·dm–3 and between 10 to 200 mg of the oxide. Maximum sorption (>99.8%) from pH 10 buffer and low sorption (<3%) was observed from 0.01 mol·dm–3 nitric or perchloric acid solution. Citrate, sulfate, EDTA and carbonate reduced the sorption significantly. Under optimal conditions Ag(I), Cs(I), Tc(VII), Sb(V), Cu(II), Nd(III), Fe(III), and especially Nd and Fe showed low distribution coefficients. The data followed both Dubinin-Radushkevich and Langmuir-type isotherms. The mean free energy, of sorption was evaluated to be 10.1 kJ mol–1 and the sorption capacity was found to be 22.2 mmol g–1, using the Dubinin-Radushkevich isotherm. 相似文献
7.
Ramesh C. Kapoor Raj N. Mehrotra Shared K. Vajpai Purnima Chaudhary 《Transition Metal Chemistry》1991,16(1):65-70
Summary The kinetics of the OsVIII-catalysed oxidation of glycols by alkaline hexacyanoferrate(III) ion exhibits zerothorder dependence in [Fe(CN)
6
3–
] and first-order dependence in [OsO4]. The order with respect to glycols is less than unity, whereas the rate dependence on [OH–] is a combination of two rate constants; one independent of and the other first-order in [OH–]. These observations are commensurate with a mechanism in which two complexes, [OsO4(H2O)G]– and [OsO4(OH)G]2–, are formed either from [OsO4(H2O)(OH)]– or [OsO4(OH)2]2– and the glycol GH, or by [OsO4(H2O)2] and [OsO4(H2O)(OH)]– and the glycolate ion, G–, which is in equilibrium with the glycol GH through the reaction between GH and OH–. Hence there is an ambiguity about the true path for the formation of the two OsVIII-glycol complexes. A reversal in the reactivity order of glycols in the two rate-determining steps, despite the common attack of OH– ion on the two species of OsVIII-complexes, indicates that the two complexes are structurally different because S changes from the negative (corresponding to k11) to positive (related to k2). 相似文献
8.
Abstract A biocompatible zinc (II) complex based on a tetradentate N,N,O,O-type salen ligand was synthesized, characterized and used for the solvent-free ring-opening polymerization (ROP) of L-lactide in bulk at 180?°C to prepare high molecular weight poly(L-lactide) (Mn : 82,600?Da; Mw : 140,000?Da; PDI: 1.70). Poly(L-lactide) (PLLA) was characterized using FTIR, 1H NMR, 13C NMR, GPC, TGA, DSC, WAXD, and MALDI-ToF. Kinetic measurement was carried out and first-order behavior to monomer was observed. The k app was found as 6?±?0.001?×?10?4?s?1. The biocompatibility of the PLLA was confirmed by in vitro cytotoxicity against NIH/3T3 fibroblast cell line and can be used in biomedical applications. 相似文献
9.
Chen Hui Sharma Sunil K. Sharma Priyanka R. Chi Kai Fung Eric Aubrecht Katherine Keroletswe Ngonye Chigome Samuel Hsiao Benjamin S. 《Cellulose (London, England)》2021,28(13):8611-8628
Cellulose - Mercury contamination in drinking water is a worldwide problem due to its severely harming effects on the human body. A nanostructured natural bioadsorbent, carboxycellulose nanofiber... 相似文献
10.
Mixed Polymer‐Coated Magnetic Nanoparticles as Forward Osmosis Draw Agents of Tuned Hydrophilicity 下载免费PDF全文
Dr. Priyanka Dey Dr. Emad L. Izake 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(32):11253-11260
We recently reported a polymer‐coated magnetic nanoparticle (MNP) draw agent for the forward osmosis (FO) water desalination process. The water flux was found to increase when the polymer poly(sodium acrylate) (PSA) was anchored to the MNP surface as compared to the polymer (or polyelectrolyte solution) alone, due to the polymer chains being stretched out and most of the hydrophilic groups on the polymer contributing to water flux. We herein report the use of a secondary polymer poly(N‐isopropylacrylamide) PNIPAM to manipulate the PSA polymer conformation and influence inter‐ and intrachain interactions to enhance the efficiency of the FO draw agent. These PSA–PNIPAM‐coated MNPs generated a much higher water flux of ~11.66 LMH when compared to the 100 % PSA‐coated MNPs featuring a value of ~5.32 LMH under identical FO conditions. The osmotic pressure and water flux driven by the mixed polymer‐coated MNPs were found to be a strong function of the net polymer coverage on MNPs, that is, net available hydrophilic groups. Our new draw agent demonstrates potential for use in the water industry due to its improved efficiency and cost effectiveness as it uses only ~0.062 % (w/v) of the draw agent solution. 相似文献