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101.
Complexation of morin with three kinds of cyclodextrin. A thermodynamic and reactivity study 总被引:1,自引:0,他引:1
Jullian C Orosteguis T Pérez-Cruz F Sánchez P Mendizabal F Olea-Azar C 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,71(1):269-275
Properties of inclusion complexes between morin (M) and beta-cyclodextrin (betaCD), 2-hydroxypropyl-beta-cyclodextrin (HPbetaCD) and Heptakis (2,6-O-di methyl) beta-cyclodextrin (DMbetaCD) such as aqueous solubility and the association constants of this complex have been determined. The water solubility of morin was increased by inclusion with cyclodextrins. The phase-solubility diagrams drawn from UV spectral measurements are of the A(L)-type. Also ORAC(FL) studies were done. An increase in the antioxidant reactivity is observed when morin form inclusion complex with the three cyclodextrin studied. Finally, thermodynamics studies of cyclodextrin complexes indicated that for DMbetaCD the inclusion is primarily enthalpy-driven process meanwhile betaCD and HPbetaCD are entropy-driven processes. This is corroborated by the different inclusion geometries obtained by 2D-NMR. 相似文献
102.
Gregory B. Kharas Amanda M. Claro Youya Gao Jay S. Bhanot Paulina Bosek Timothy R. Corwin 《高分子科学杂志,A辑:纯化学与应用化学》2016,53(10):595-599
Trisubstituted ethylenes, alkyl ring-substituted propyl 2-cyano-3-phenyl-2-propenoates, RPhCH?C(CN)CO2C3H7 (where R is H, 2-methyl, 3-methyl, 4-methyl, 4-ethyl, 4-propyl, 4-i-propyl, 4-butyl, 4-i-butyl, 4-t-butyl) were prepared and copolymerized with styrene. The monomers were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and propyl cyanoacetate, and characterized by CHN analysis, IR, 1H and 13C-NMR. All the ethylenes were copolymerized with styrene (M1) in solution with radical initiation (ABCN) at 70°C. The compositions of the copolymers were calculated from nitrogen analysis and the structures were analyzed by IR, 1H and 13C-NMR. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 250–500°C range with residue (2–4% wt.), which then decomposed in the 500–800°C range. 相似文献
103.
104.
Justyna Sekuła Joanna NiziołMaria Misiorek Paulina DecAgnieszka Wrona Adrian ArendowskiTomasz Ruman 《Analytica chimica acta》2015
Gold nanoparticle-enhanced target (AuNPET) was used for detailed investigation of various materials of biological origin – human fingerprint, onion bulb and chicken liver. Analysis of these objects was focused on toxic and harmful compounds – designer drug containing pentedrone, diphenylamine in onion and potentially cancerogenic metronidazole antibiotic in liver. Detection of large quantity of endogenous compounds from mentioned objects is also shown. Most of analyzed compounds were also localized with MS imaging and relationship between their function and location was discussed. Detected compounds belong to a very wide range of chemical compounds such as saccharides, ionic and non-ionic glycerides, amino acids, fatty acids, sulfides, sulfoxides, phenols etc. Fingerprint experiments demonstrate application of AuNPET for detection, structure confirmation and also co-localization of drug with ridge patterns proving person-drug contact. 相似文献
105.
Paulina Dreyse Mireya Santander-Nelli David Zambrano Luis Rosales Luis Sanhueza 《International journal of quantum chemistry》2020,120(12):e26167
The structures and electronic properties of a series of cyclometalated Ir(III) complexes with substituted dppz ancillary ligand (dppz: dipyrido[3,2-a:2′,3′-c]phenazine) including tert-butyl, pyrrolidine ring, and alkoxys substituents as donor group have been theoretically study. With the aim of highlight the attractive qualities of each system for their use as luminescent material, the effects of the electron-donor substituents onto dppz was evaluated on the structural, charge transport, absorption, and phosphorescent properties. The effect of the substituent was studied on the modulation of the bright and dark triplet states. Main results show that ortho-methoxy and tert-butyl substituents act as lower electron-donating groups, then, efficient electron donation ability was displayed with alkoxy (ethoxy and propoxy) substituents. The best performance was found in a complex with pyrrolidine ring according since their phosphorescence is favored, highlighting their larger electric transition dipole moment value, proposing this system as potential candidate to LEC technology. 相似文献
106.
McGoverin CM Engelbrecht P Geladi P Manley M 《Analytical and bioanalytical chemistry》2011,401(7):2283-2289
Undesired germination of cereal grains diminishes process utility and economic return. Pre-germination, the term used to describe
untimely germination, leads to reduced viability of a grain sample. Accurate and rapid identification of non-viable grain
is necessary to reduce losses associated with pre-germination. Viability of barley, wheat and sorghum grains was investigated
with near-infrared hyperspectral imaging. Principal component analyses applied to cleaned hyperspectral images were able to
differentiate between viable and non-viable classes in principal component (PC) five for barley and sorghum and in PC6 for
wheat. An OH stretching and deformation combination mode (1,920–1,940 nm) featured in the loading line plots of these PCs;
this water-based vibrational mode was a major contributor to the viable/non-viable differentiation. Viable and non-viable
classes for partial least squares-discriminant analysis (PLS-DA) were assigned from PC scores that correlated with incubation
time. The PLS-DA predictions of the viable proportion correlated well with the viable proportion observed using the tetrazolium
test. Partial least squares regression analysis could not be used as a source of contrast in the hyperspectral images due
to sampling issues. 相似文献
107.
Multivariate analysis of HT/GC-(IT)MS chromatographic profiles of triacylglycerol for classification of olive oil varieties 总被引:1,自引:0,他引:1
Cristina Ruiz-Samblás Luis Cuadros-Rodríguez Antonio González-Casado Francisco de Paula Rodríguez García Paulina de la Mata-Espinosa Juan Manuel Bosque-Sendra 《Analytical and bioanalytical chemistry》2011,399(6):2093-2103
The ability of multivariate analysis methods such as hierarchical cluster analysis, principal component analysis and partial
least squares-discriminant analysis (PLS-DA) to achieve olive oil classification based on the olive fruit varieties from their
triacylglycerols profile, have been investigated. The variations in the raw chromatographic data sets of 56 olive oil samples
were studied by high-temperature gas chromatography with (ion trap) mass spectrometry detection. The olive oil samples were
of four different categories (“extra-virgin olive oil”, “virgin olive oil”, “olive oil” and “olive-pomace” oil), and for the
“extra-virgin” category, six different well-identified olive oil varieties (“hojiblanca”, “manzanilla”, “picual”, “cornicabra”,
“arbequina” and “frantoio”) and some blends of unidentified varieties. Moreover, by pre-processing methods of chemometric
(to linearise the response of the variables) such as peak-shifting, baseline (weighted least squares) and mean centering,
it was possible to improve the model and grouping between different varieties of olive oils. By using the first three principal
components, it was possible to account for 79.50% of the information on the original data. The fitted PLS-DA model succeeded
in classifying the samples. Correct classification rates were assessed by cross-validation. 相似文献
108.
Li W Estrada-de los Santos P Matthijs S Xie GL Busson R Cornelis P Rozenski J De Mot R 《Chemistry & biology》2011,18(10):1320-1330
Under control of the Gac regulatory system, Pseudomonas putida RW10S1 produces promysalin to promote its own swarming and biofilm formation, and to selectively inhibit many other pseudomonads, including the opportunistic pathogen Pseudomonas aeruginosa. This amphipathic antibiotic is composed of salicylic acid and 2,8-dihydroxymyristamide bridged by a unique 2-pyrroline-5-carboxyl moiety. In addition to enzymes for salicylic acid synthesis and activation, the biosynthetic gene cluster encodes divergent type II fatty acid biosynthesis components, unusual fatty acid-tailoring enzymes (two Rieske-type oxygenases and an amidotransferase), an enzyme resembling a proline-loading module of nonribosomal peptide synthetases, and the first prokaryotic member of the BAHD family of plant acyltransferases. Identification of biosynthetic intermediates enabled to propose a pathway for synthesis of this bacterial colonization factor. 相似文献
109.
Labet V Gonzalez-Morelos P Hoffmann R Ashcroft NW 《The Journal of chemical physics》2012,136(7):074501
In the first of a series of four papers on hydrogen under pressure, and its transitions from an initiating molecular state, we begin by defining carefully the problem, and setting the distance scale of interactions of protons and electrons in molecular aggregates of the first of the elements. Following a review of the experimental situation, in particular the phase diagram of hydrogen, in as much as it is known, and the behavior of its vibrons and rotons, we move onto the setting up of a numerical laboratory for probing the underlying physics and chemistry of interactions in hydrogen as the pressure increases. The laboratory consists of the preferred static structures emerging from calculations on the system in the range of 1 atm to 500 GPa, those of Pickard and Needs. The intermolecular (inter-pair) H···H separations naturally decrease with increasing pressure, first rapidly so, then more slowly. The intramolecular (intra-pair) H-H distances vary over a much smaller scale (0.05 A?) as the pressure increases, first decreasing, then increasing, and finally decreasing. We define an equalization function to gauge the approach to equality of the first neighbor and shortest next neighbor H (proton) separations in this numerical laboratory. And we find that metallization is likely to occur before bond equalization. 相似文献
110.
Lopes IC Santos PV Diculescu VC Peixoto FM Araújo MC Tanaka AA Oliveira-Brett AM 《The Analyst》2012,137(8):1904-1912
Microcystins (MCs) are cyclic hepatotoxic heptapeptides produced by certain strains of freshwater cyanobacteria toxic for humans and animals. The electrochemical behaviour of microcystin-LR (MC-LR) at a glassy carbon electrode (GCE) was investigated using cyclic voltammetry (CV), square wave voltammetry (SWV) and differential pulse voltammetry (DPV). The oxidation of MC-LR is a diffusion-controlled irreversible and pH-independent process that occurs with the transfer of only one electron and does not involve the formation of any electroactive oxidation product. Upon incubation in different pH electrolytes, homogeneous degradation of MC-LR in solution was electrochemically detected by the appearance of a new oxidation peak at a lower potential. The electrochemical behaviour of chemically degraded MC-LR is an irreversible, pH-dependent process, and involves the formation of two redox products that undergo reversible oxidation. The formation of degradation products of MC-LR was confirmed by HPLC with UV detection at room temperature. Experiments were also carried out in solutions containing constituent MC-LR amino acids, which enabled the understanding of the MC-LR electron transfer reaction and degradation. An oxidation mechanism for MC-LR is proposed. 相似文献