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71.
Kmak Kelly N. Shaughnessy Dawn A. Vujic Jasmina 《Journal of Radioanalytical and Nuclear Chemistry》2020,323(2):931-945
Thorium-230 has many research applications, but there is not a commercial source of this isotope. However, since 230Th is part of the 238U decay chain, it can be separated from naturally occurring uranium. In this work, a novel procedure was developed to separate thorium from uranium ore, consisting of leaching, liquid–liquid extraction, precipitations and ion exchange chromatography. The final product was 91.32?±?0.77 mg of thorium with a purity of 99.5?±?1.2 wt%. Of that, 7.65?±?0.10 mg was 230Th and the remainder 232Th. The total yield of 230Th was 71.1?±?5.4%. Ways to improve the yield by further processing the back-extraction solution are suggested.
相似文献72.
73.
A. Baldea D. Axente M. Abrudean V. Mercea C. Bratu 《Journal of Radioanalytical and Nuclear Chemistry》1987,111(2):423-428
Thermal decomposition of uranium double fluoride in a screw reactor in the temperature range of 250–500 °C is presented. Using integral reactor relation, kinetic parameters are discussed in terms of the shrinking core grain model. Arrhenius global activation energy is also determined. 相似文献
74.
In this Article we present enthalpies of fusion and melting points obtained from new thermochemical measurements of tris(acetylacetonato)metal(III), M(acac)(3), complexes (M = Fe, Al, Cr, Mn, Co) using differential scanning calorimetry (DSC) and evaluate them in relation to their different values found in the literature. An enthalpy of fusion of 27.67 kJ mol(-)(1) was derived for Mn(acac)(3) from a symmetrical DSC thermogram captured for the first time. The enthalpy value was indirectly confirmed with the solubility measurements of Mn(acac)(3) in acetylacetone. A hypothesis has been stated that the enthalpy of fusion and the potential energy of M(acac)(3) in the crystal state may be related. To calculate molecular in-crystal potential energy, in this Article we proposed a molecular mechanics model for the M(acac)(3) class of compounds. Nine X-ray crystal structures of M(acac)(3) complexes (M = Fe, Al, V, Mn, Co, Cr, Sc) were included in the modeling. The conformational potential energy was minimized for a molecule surrounded by other molecules in the crystal lattice. The partial charges from two schemes, the electrostatic potential (ESP) fit and the natural population analysis (NPA), were used to construct two types of force fields to examine which force field type would yield a better fit with the experimental thermal properties. The final force fields were named FF-ESP and FF-NPA. Both force field sets reproduced well the experimental crystal data of nine M(acac)(3) complexes as well as of tris(3-methyl-2,4-pentanedionato-O,O')cobalt(III). Only in-crystal potential energies derived by FF-NPA yielded a significant correlation (correlation coefficient R = -0.71) with the measured enthalpies of fusion. The enthalpy of fusion for Co(acac)(3) could not be determined experimentally because of simultaneous decomposition and fusion, and it is predicted to be 33.2 kJ mol(-)(1) from the correlation regression line. 相似文献
75.
Marius Bruvoll Selma Dizdarevic Nina Fimland Jasmina Hafizovic Carl Henrik Grbitz Helen Therese Kalfjs Kristian Vestli Alexander Krivokapic 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(1):o22-o25
The structures of the title dipeptides, C9H18N2O4·0.33H2O, C12H16N2O4 and C8H16N2O4S·0.34H2O, complete a series of investigations focused on l ‐Xaa‐l ‐serine peptides, where Xaa is a hydrophobic residue. All three structures are divided into hydrophilic and hydrophobic layers. The hydrophilic layers are thin for l ‐phenylalanyl‐l ‐serine, rendered possible by an unusual peptide conformation, and thick for l ‐isoleucyl‐l ‐serine and l ‐methionyl‐l ‐serine, which include cocrystallized water molecules on the twofold axes. 相似文献
76.
Jasmina S. Brbori? Sote Vladimirov Mirjana S. Jovanovi? Nikola Dogovi? 《Monatshefte für Chemie / Chemical Monthly》2004,28(11):1009-1014
The synthesis and characterization of N-[2-[[4-iodo-2,6-bis(1-methylethyl)phenyl]amino]-2-oxoethyl]-N-(carboxymethyl)glycine and N-[2-[(4-iodo-2,6-diethylphenyl)amino]-2-oxoethyl]-N-(carboxymethyl)glycine is presented, as well as a modified and improved synthesis of N-[2-[(2,4-diiodo-6-methylphenyl)amino]-2-oxoethyl]-N-(carboxymethyl)glycine. These compounds are new agents for hepatobiliary imaging. 相似文献
77.
Boris Pejin Ana Ciric Ivo Karaman Mladen Horvatovic Jasmina Glamoclija Milos Nikolic 《Natural product research》2016,30(16):1847-1850
The antibiofilm and possible antiquorum sensing effects against the strain Pseudomonas aeruginosa PAO1 of five crude extracts of the freshwater bryozoan Hyalinella punctata (Hancock, 1850) were evaluated in vitro for the first time. H. punctata ethyl acetate extract (HpEtAc) exhibited the highest antibiofilm activity reducing the biofilm formation of P. aeruginosa PAO1 in the range of 80.63–88.13%. While all tested extracts reduced the twitching motility of the aforementioned bacterial strain, HpEtAc showed to be the most effective. Finally, at a concentration of 0.5 MIC, the same extract mostly inhibited the production of pyocyanin by P. aeruginosa PAO1 (71.53%). In comparison both with the positive controls used (streptomycin and ampicillin, 67.13 and 69.77%, respectively), HpEtAc was found to inhibit pyocyanin in a higher extent. An extensive chemical characterisation of this particular extract may result in isolation and identification of novel lead compounds targeting P. aeruginosa, an opportunistic human pathogen. 相似文献
78.
Matijasević J Hassler N Reiter G Fringeli UP 《Langmuir : the ACS journal of surfaces and colloids》2008,24(6):2588-2596
The development and optimization of biomimetic surfaces required for biosensors and medical assays are made more efficient by quantitatively monitoring the surface chemical reactions in situ by means of attenuated total reflection (ATR) FTIR spectroscopy. single-beam-sample-reference (SBSR) ATR, as well as modulated excitation (ME), techniques have been applied to get physicochemical information on growth and structure of the surface layer. SBSR and ME methods result in optimum background compensation and signal-to-noise ratio. Surface modification was performed on a germanium multiple internal reflection element (Ge-MIRE). Activation of the surface resulted in free Ge-OH groups used for a spontaneous chemical reaction with 7-octenyltrichlorosilane (7-OTCS) in toluene. Formation of Ge-O-Si bonds was enabled by hydrolization of Si-Cl3 after partial elimination of a tightly bound thin water layer covering the MIRE. Unwanted side-reaction by hydrolization of Si-Cl3 in solution followed by polymerization paralleled this process. Steady growing of the silane layer to multilayer thickness with increasing time was observed in all experiments. Most unexpectedly, in some experiments the end-standing double bond of the silane layer was found to be partly oxidized even after being exposed only to toluene, probably because of catalysis by molecular sieve nanoparticles remaining in toluene after drying. Finally, theoretical means are presented enabling the calculation of the spectrum of dissolved 7-OTCS in toluene, a prerequisite for background compensation during in situ studies of the growing layer. 相似文献
79.
Veaceslav Boldescu Irina Kacso Gheorghe Borodi Ioan Bratu Gheorghe Duca 《Journal of inclusion phenomena and macrocyclic chemistry》2008,62(1-2):143-148
Complexation of sanguinarine with hydroxy-propyl-β-cyclodextrin (HPβCD) in the presence and absence of hydrophilic polymer—polyvinylpyrrolidone K30 was studied. Respective binary and ternary systems were prepared using two techniques, physical mixture and lyophilization, and characterized by FT-infrared spectrometry, differential scanning calorimetry and X-ray diffractometry. The Fourier Transform Infrared spectra of the lyophilized binary and ternary systems showed significant shifts in the regions of 1240–1300 cm?1, 1450–1525 cm?1 and 1600–1650 cm?1, where absorptions of –C–O–C– asymmetrical stretching of sanguinarine rings A and F and νC=C ring vibrations of sanguinarine benzo[c]phenanthridine system can be observed respectively. Moreover, in the case of ternary products νC=O amide band absorption of polyvinylpyrrolidone (1600–1750 cm?1) shifted to the lower wavenumbers in both the physical mixture and the lyophilized product. These changes in the spectra of the studied systems proved the involvement of the respective molecular groups in complexation process. Differential scanning calorimetry and X-ray diffractometry indicated different states of drug amorphization and entrapment in HPβCD in the presence and without polyvinylpyrrolidone. The obtained results let us conclude that obtained binary and ternary systems represent sanguinarine-HPβCD molecular complexes, with different rate of inclusion in the presence and without polyvinylpyrrolidone. 相似文献
80.
Kübra Kaygisiz Adriana M. Ender Jasmina Gačanin L. Alix Kaczmarek Dimitrios A. Koutsouras Abin N. Nalakath Pia Winterwerber Franz J. Mayer Hans-Joachim Räder Tomasz Marszalek Paul W. M. Blom Christopher V. Synatschke Tanja Weil 《Macromolecular bioscience》2023,23(2):2200294
Amyloid-like fibrils are a special class of self-assembling peptides that emerge as a promising nanomaterial with rich bioactivity for applications such as cell adhesion and growth. Unlike the extracellular matrix, the intrinsically stable amyloid-like fibrils do not respond nor adapt to stimuli of their natural environment. Here, a self-assembling motif (CKFKFQF), in which a photosensitive o-nitrobenzyl linker (PCL) is inserted, is designed. This peptide (CKFK-PCL-FQF) assembles into amyloid-like fibrils comparable to the unsubstituted CKFKFQF and reveals a strong response to UV-light. After UV irradiation, the secondary structure of the fibrils, fibril morphology, and bioactivity are lost. Thus, coating surfaces with the pre-formed fibrils and exposing them to UV-light through a photomask generate well-defined areas with patterns of intact and destroyed fibrillar morphology. The unexposed, fibril-coated surface areas retain their ability to support cell adhesion in culture, in contrast to the light-exposed regions, where the cell-supportive fibril morphology is destroyed. Consequently, the photoresponsive peptide nanofibrils provide a facile and efficient way of cell patterning, exemplarily demonstrated for A549, Chinese Hamster Ovary, and Raw Dual type cells. This study introduces photoresponsive amyloid-like fibrils as adaptive functional materials to precisely arrange cells on surfaces. 相似文献