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排序方式: 共有144条查询结果,搜索用时 15 毫秒
1.
Bala Ritu Das Debabrata Karanveer Naskar Nabanita Lahiri Susanta 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(6):2561-2572
Journal of Radioanalytical and Nuclear Chemistry - Natural radionuclide levels are studied in alluvial sediments upto the depth of 900 cm. Eighteen profiles are selected from agricultural... 相似文献
2.
Devi Ritu Singh Jaydip Potukuchi Baba 《International Journal of Theoretical Physics》2022,61(10):1-14
International Journal of Theoretical Physics - We successfully realized symmetric and asymmetric cyclic quantum teleportation by using different controllers for each receiver. In this study, Alice... 相似文献
3.
Ranjana Aggarwal Rajiv Kumar Sunil Kumar Gaurav Garg Ritu Mahajan Jitender Sharma 《Journal of fluorine chemistry》2011,132(11):965-972
5-Hydroxy-5-trifluoromethyl-4,5-dihydropyrazol-1-thiocarboxamides 3 and 3-trifluoromethylpyrazol-1-thiocarboxamides 4, regioselectively obtained by the condensation of trifluoromethyl-β-diketones with thiosemicarbazide under neutral and acidic conditions, on further reaction with phenacyl bromides 5 afforded 4-aryl-(5-trifluoromethyl-pyrazol-1-yl)thiazoles 6 and 4-aryl-(3-trifluoromethyl-pyrazol-1-yl)thiazoles 7, respectively. Five 4,5-dihydropyrazoles (3a–e) and two pyrazolylthiazoles (6a and 6c) were tested against one Gram-positive and one Gram-negative bacteria to assess their in vitro antibacterial activity. Compounds 3a, 3b and 3e showed moderate antibacterial activity against Gram-positive bacterium, Bacillus pumilus. 相似文献
4.
Ritu Ahuja Munirathinam Nethaji Ashoka G. Samuelson 《Journal of organometallic chemistry》2009,694(7-8):1144-1152
The ligand bis(diphenylphosphino)isopropylamine (dppipa) has been shown to be a versatile ligand sporting different coordination modes and geometries dictated by copper(I). Most of the molecular structures were confirmed by X-ray crystallography. It is found in a chelating mode, in a monomeric complex when the ligand to copper ratio is 2:1. A tetrameric complex is formed when low ratios of ligand to metal (1:2) were used. But with increasing ratios of ligand to metal (1:1 and 2:1), a trimer or a dimer was obtained depending on the crystallization conditions. Variable temperature 31P{1H} NMR spectra of these complexes in solution showed that the Cu–P bond was labile and the highly strained 4-membered structure chelate found in the solid state readily converted to a bridged structures. On the other hand, complexes with the ligand in a bridging mode in the solid state did not form chelated structures in solution. The effect of adding tetra-alkylammonium salts to solutions of various complexes of dppipa were probed by 31P{1H} NMR and revealed the effect of counter ions on the stability of complexes in solution. 相似文献
5.
Ligand protonation and stepwise dissociation constants, formation constants and speciation of four pyridyl sulfonamide ligands
(Congreeve et al., New J. Chem. 27:98–106, 2003) were assessed, using potentiometric and UV/Visible spectrophotometric pH titrations (in 80% MeOH − 20% H2O). The suitability of these ligands as Cu(II) and Zn(II) sensors for physiological applications was assessed. Two ligands
L1 and L4 were p-toluenesulfonamide derivatives while L2 and L3 were triflurosulfonamide derivatives. Additionally L3 and L4 were appended with α-methyl groups. The most stable complex was formed by L1 with Cu(II) owing to the fact that this complex was square planar (log 10
K
1=12.15±0.004 and log 10
β
2=15.42±0.006). The rest of the complexes invariably formed distorted tetrahedron geometry and complexation was weaker. Speciation
diagrams show the effect of ligand to metal concentration, revealing that the L2 and L3 ligands are the most suitable for forming ML2 complexes at physiological pH. 相似文献
6.
Ritu Agarwal Sunil D. Purohit Kritika 《Mathematical Methods in the Applied Sciences》2019,42(18):7160-7171
In calcium signalling, activation of receptor is a very significant aspect. To understand the mechanism of calcium signalling, receptors are the important components. The mobilization of intracellular calcium from intracellular stores depends upon binding of agonist to cell surface receptor. Thrombin is chosen as model ligand. In order to understand thrombin receptor activation, we analyze fractional model incorporating derivative of arbitrary order and nonsingular kernel which can precisely describe the effect of memory and can explain the model in better and more efficient manner as compared with fractional operators with singular kernels. The problem has been solved by perturbation iterative method. Using fixed‐point theorem, it is proved that solution of the system will exist and also it will be unique. 相似文献
7.
Synthesis,characterization and role of zero-valent iron nanoparticle in removal of hexavalent chromium from chromium-spiked soil 总被引:3,自引:0,他引:3
Chromium is an important industrial metal used in various products/processes. Remediation of Cr contaminated sites present
both technological and economic challenges, as conventional methods are often too expensive and difficult to operate. In the
present investigation, Zero-valent iron (Fe0) nanoparticles were synthesized, characterized, and were tested for removal of Cr(VI) from the soil spiked with Cr(VI). Fe0 nanoparticles were synthesized by the reduction of ferric chloride with sodium borohydride and were characterized by UV–Vis
(Ultra violet–Visible) and FTIR (Fourier transform infrared) spectroscopy. The UV–Vis spectrum of Fe0 nanoparticles suspended in 0.8% Carboxymethyl cellulose showed its absorption maxima at 235 nm. The presence of one band
at 3,421 cm−1 ascribed to OH stretching vibration and the second at 1,641 cm−1 to OH bending vibration of surface-adsorbed water indicates the formation of ferrioxyhydroxide (FeOOH) layer on Fe0 nanoparticles. The mean crystalline dimension of Fe0 nanoparticles calculated by XRD (X-ray diffraction) using Scherer equation was 15.9 nm. Average size of Fe0 nanoparticles calculated from TEM (Transmission electron microscopy) images was found around 26 nm. Dynamic Light Scattering
(DLS) also showed approximately the same size. Batch experiments were performed using various concentration of Fe0 nanoparticles for reduction of soil spiked with 100 mg kg−1 Cr(VI). The reduction potential of Fe0 nanoparticles at a concentration of 0.27 g L−1 was found to be 100% in 3 h. Reaction kinetics revealed a pseudo-first order kinetics. Factors like pH, contact time, stabilizer,
and humic acid facilitates the reduction of Cr(VI). 相似文献
8.
Ritu B. Dixit Satish F. Vanparia Tarosh S. Patel Chandresh L. Jagani Hiren V. Doshi Bharat C. Dixit 《应用有机金属化学》2010,24(5):408-413
Looking at the pharmacological importance of 8‐hydroxyquinolines and sulfonamides, in the present study, a novel bi‐dentate ligand 4‐amino‐N′‐[(8‐hydroxyquinoline‐5‐yl)methyl] benzenesulfonohydrazide (AHQMBSH) having above both moieties within a single molecular framework was synthesized by the reaction of N‐acetamidobenzene sulfonohydrazide with 5‐chloromethyl‐8‐hydroxyquinoline hydrochloride. Its metal(II) oxinates were also prepared with Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) salts. All the above compounds were investigated by physicochemical analyses, thermogravimetric analysis and spectroscopic techniques. Antimicrobial activities for the above prepared compounds were carried out using the agar‐plate method against various strains of bacteria (Staphylococcus aureus, Bacillus subtillis, Pseudomonas aerugionsa, Escherichia coli) and fungi (Aspergillus niger and Aspergillus flavous). The results show a significant increase in antimicrobial and antifungal activities of AHQMBSH compared with the parent 8‐hydroxyquinoline and sulfonamides. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
9.
Alka Tiwari Ritu Tiwari A. K. Bajpai 《Journal of Dispersion Science and Technology》2013,34(8):1208-1215
Binary biopolymeric beads of alginate and pectin were prepared and characterized by FTIR spectra. On to the surfaces of the prepared beads were performed static and dynamic adsorption studies of Cu(II) ions at fixed pH and ionic strength of the aqueous metal ion solutions. The adsorption data were applied to Langmuir and Freundlich isotherm equations and various adsorption parameters were calculated. The influence of various experimental parameters such as effect of time, pH, temperature, solid to liquid ratio, and the presence of salts were investigated on the adsorption of copper ions. 相似文献
10.
The Schmidt reaction is the acid-catalyzed analogue of the Curtius reaction and is extensively used in organic synthesis. In this work, the mechanism of this reaction has been explored using DFT calculations at the B3LYP/6-311+G(d,p) level. Protonated formyl azide may undergo rearrangement to the product, protonated isocyanic acid, with simultaneous extrusion of molecular nitrogen (concerted mechanism), or undergo rearrangement to the anti conformer, followed by removal of nitrogen to form the nitrenium ion, which then rearranges to the final product, protonated isocyanic acid (step-wise mechanism). Like the Curtius reaction, it is found that the concerted pathway is definitely preferred. The key role of acidification in decreasing the overall energy barrier is more highlighted in case of phenyl substitution, with negligible effect on the lower homologues. For methoxy and amine substituents, there is very little difference in the activation energies of the concerted and step-wise reactions, with the former being still slightly preferred. Unlike the parent compound, the rearrangement of substituted nitrenium ion in some cases involves side reactions like C-H insertion and cyclization. 相似文献