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排序方式: 共有119条查询结果,搜索用时 15 毫秒
31.
Carola Tortora Christina Mai Francesca Cascella Dr. Michael Mauksch Prof. Dr. Andreas Seidel-Morgenstern Prof. Dr. Heike Lorenz Prof. Dr. Svetlana B. Tsogoeva 《Chemphyschem》2020,21(16):1775-1787
Viedma deracemization is based on solution phase racemization, dissolution of racemic or scalemic conglomerates and crystal growth through autocatalytic cluster formation. With rate limiting racemization, its acceleration by appropriate catalysts may result in speeding up deracemization. A conglomerate-forming chiral compound may principally racemize directly, or via reverse of its formation reaction. For a hydrazine derivative, we investigated available racemization pathways in presence of pyrrolidine or thiourea amine as base catalysts: via Mannich or aza-Michael reaction steps and their reverse, or by enolization. Racemization by enolization was computationally found to dominate, both under water-free conditions and in presence of water, involving a multitude of different pathways. Faster racemization in presence of water resulted indeed in more rapid deracemization, when the base was pyrrolidine. Under water-free conditions, the role of water as enolization catalyst is assumed by chiral hydrazine itself – in autocatalytic racemization and in which both reactant and product are catalysts. 相似文献
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Tiziana Masullo Riccardo Puccio Mariarosaria Di Pierro Marcello Tagliavia Paolo Censi Valeria Vetri Valeria Militello Angela Cuttitta Paolo Colombo 《Applied biochemistry and biotechnology》2014,172(4):2175-2187
Fluorescent proteins from marine organisms represent potential candidates for biosensor development. In this paper, we described the isolation of a native green fluorescent protein from Anemonia sulcata and the cloning and purification of its equivalent as a recombinant protein in Escherichia coli. Furthermore, the spectroscopic behaviours of the native and recombinant GFPs were investigated as a function of Cu2+, Cd2+, Pb2+ and Ni2+ concentration. Our results suggest the high selectivity of both proteins at copper than the other metals and, for the recombinant protein, a great sensitivity at a very low concentration (0.1–1 μM). Moreover, starting from these data, using the combination of molecular biology techniques and optical setup, we developed a device for the detection of Cu2+ in water solutions. The quenching effect detected with the device showed that the relative attenuation of the signal (0.46?±?0.02 AU) was slightly larger than the data measured by fluorescence spectra (0.65?±?0.03 AU). The good sensitivity in the span of two orders of the magnitude of Cu2+ concentration, the fact that the instrument is made up of low-cost and sturdy parts and the selective quenching of rAsGFP to copper ions make this setup suited as a low cost, on-the-field, copper ion-specific biosensor. 相似文献
35.
Rosa Tundis Mariarosaria Leporini Marco Bonesi Simone Rovito Nicodemo G. Passalacqua 《Molecules (Basel, Switzerland)》2020,25(24)
Salvia officinalis L. (sage) is one of the most appreciated plants for its plethora of biologically active compounds. The objective of our research was a comparative study, in the Mediterranean context, of chemical composition, anticholinesterases, and antioxidant properties of essential oils (EOs) from sage collected in three areas (S1–S3) of Southern Italy. EOs were extracted by hydrodistillation and analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory properties were investigated by employing Ellman’s method. Four in vitro assays, namely, 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric-reducing ability power (FRAP), and β-carotene bleaching tests, were used to study the antioxidant effects. Camphor (16.16–18.92%), 1,8-cineole (8.80–9.86%), β-pinene (3.08–9.14%), camphene (6.27–8.08%), and α-thujone (1.17–9.26%) are identified as the most abundant constituents. However, the content of these constituents varied depending on environmental factors and pedoclimatic conditions. Principal component analysis (PCA) was performed. Based on Relative Antioxidant Capacity Index (RACI), S2 essential oil exhibited the highest radical potential with an IC50 value of 20.64 μg/mL in ABTS test and presented the highest protection of lipid peroxidation with IC50 values of 38.06 and 46.32 μg/mL after 30 and 60 min of incubation, respectively. The most promising inhibitory activity against BChE was found for S3 sample (IC50 of 33.13 μg/mL). 相似文献
36.
M. Ferer Shelley L. Anna Paul Tortora J. R. Kadambi M. Oliver Grant S. Bromhal Duane H. Smith 《Transport in Porous Media》2011,86(1):243-259
Motivated by the need to determine the dependencies of two-phase flow in a wide range of applications from carbon dioxide
sequestration to enhanced oil recovery, we have developed a standard two-dimensional, pore-level model of immiscible drainage,
incorporating viscous and capillary effects. This model has been validated through comparison with several experiments. For
a range of stable viscosity ratios (M = μ
injected,nwf/μ
defending, wf ≥ 1), we had increased the capillary number, N
c and studied the way in which the flows deviate from fractal capillary fingering at a characteristic time and become compact
for realistic capillary numbers. This crossover has enabled predictions for the dependence of the flow behavior upon capillary
number and viscosity ratio. Our results for the crossover agreed with earlier theoretical predictions, including the universality
of the leading power-law indicating its independence of details of the porous medium structure. In this article, we have observed
a similar crossover from initial fractal viscous fingering (FVF) to compact flow, for large capillary numbers and unstable
viscosity ratios M < 1. In this case, we increased the viscosity ratio from infinitesimal values, and studied the way in which the flows deviate
from FVF at a characteristic time and become compact for non-zero viscosity ratios. This crossover has been studied using
both our pore-level model and micro-fluidic flow-cell experiments. The same characteristic time, τ = 1/M
0.7, satisfactorily describes both the pore-level results for a range of large capillary numbers and the micro-fluidic flow cell
results. This crossover should lead to predictions similar to those mentioned above. 相似文献
37.
Paolo Ciambelli Maria Sarno Giuliana Gorrasi Diana Sannino Mariarosaria Tortora 《Journal of Macromolecular Science: Physics》2013,52(5):779-795
Nanocomposite materials were prepared by incorporating multiwall carbon nanotubes (MWNTs), obtained by acetylene catalytic chemical vapor deposition (CCVD) on Co/Fe‐modified MgO, within poly(vinyl alcohol) (PVA). Before incorporation, nanotubes were oxidized to obtain better compatibilization with the polymer. It has been found that the addition of COOH‐functionalized and purified MWNTs improves the mechanical response, increases the glass transition temperature, and delays the thermal oxidation of PVA. Furthermore, the PVA crystallinity seems to be enhanced by the presence of nanotubes. 相似文献
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Any algebraic surface in which is fibered in cubics, so that the generic fibre is a twisted cubic, gives rise to a curve Γ in a suitable compactification
X of the space of smooth rational cubics of In this paper the case n = 4 is addressed and the corresponding space X is studied. We apply our results to complete the classification of smooth, rational surfaces in ruled in cubics.
This work is within the framework of the national research project “Geometry on Algebraic Varieties” Cofin 2006 of MIUR. 相似文献
40.
Mariarosaria Valente Marta Dentoni Fabrizio Bellizzi Fedra Kuris Gian Luigi Gigli 《Molecules (Basel, Switzerland)》2022,27(15)
Specialized pro-resolving mediators (SPMs) are lipid mediators derived from poly-unsaturated fatty acids (PUFAs) which have been demonstrated to have an important role in the inflammation environment, preventing an overreaction of the organism and promoting the resolution of inflammation. Our purpose was to point out the current evidence for specialized pro-resolving mediators, focusing on their role in neuroinflammation and in major neurological diseases. 相似文献