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131.
The Deriphat 2-DE was used to visualize polyphenol oxidase (PPO) isoforms of Moscato and Prosecco grape extracts, partially purified and characterized. Catecholase has similar values in the two varieties, whereas Moscato cresolase data are almost 54% higher. In the first dimension, the PPO of both varieties may be detected by SDS-PAGE, but native PAGE (N-PAGE) gave negative results. For this reason, the samples were solubilized in the zwitteronic detergent Deriphat, which was also included in the gel and the cathodic buffer. Deriphat migrated together with the cathodic buffer, maintaining protein solubility and revealing the PPO profiles of Moscato and Prosecco extracts in native conditions. The combination of Deriphat-PAGE (D-PAGE) and SDS-PAGE (2-DE) also resulted in improved separation efficiency in resolving PPO and specialized stains in evaluating PPO activities. The control, represented by IEF for the first-dimensional separation, had a lower number of spots, demonstrating the higher capacity of Deriphat 2-DE to isolate PPO isoforms from grape extracts. The Deriphat 2-DE method described here is simple but powerful, and the resulting information will be a useful tool for further proteomic research. 相似文献
132.
Cordova JM Noack PL Hilcove SA Lear JD Ghirlanda G 《Journal of the American Chemical Society》2007,129(3):512-518
We have designed a functional model membrane protein by engineering a bis-Histidine heme-binding site into a natural membrane protein, glycophorin A (GpA), structurally characterized by the dimerization of a single transmembrane helix. Out of the 32 residues comprising the transmembrane helix of GpA, five amino acids were mutated; the resulting protein, ME1, has been characterized in dodecyl phosphocholin (DPC) micelles by UV-vis, CD spectroscopy, gel electrophoresis, and analytical ultracentrifugation. ME1 binds heme with sub-micromolar affinity and maintains the highly helical secondary structure and dimeric oligomerization state of GpA. The ME1-Heme complex exhibits a redox potential of -128 +/- 2 mV vs SHE, indicating that the heme resides in a hydrophobic environment and is well shielded from the aqueous phase. Moreover, ME1 catalyzes the hydrogen peroxide dependent oxidation of organic substrates such as TMB (2,2',5,5'-tetramethyl-benzidine). This protein may provide a useful framework to investigate how the protein matrix tunes the cofactor properties in membrane proteins. 相似文献
133.
134.
Mandracchia D Piccionello AP Pitarresi G Pace A Buscemi S Giammona G 《Macromolecular bioscience》2007,7(6):836-845
In this preliminary work we have prepared a fluorinated polymer capable of solubilizing an appreciable amount of O(2) and, at the same time, maintaining a higher water solubility than perfluoroalkanes investigated as injectable O(2) carriers. In particular, we describe the synthesis and characterization of a new macromolecular conjugate obtained by derivatization of alpha,beta-poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA) with 5-pentafluorophenyl-3-perfluoroheptyl-1,2,4-oxadiazole, called PHEA-F. This new water soluble fluoropolymer was prepared in high yield using a simple procedure. It was characterized by FT-IR and UV-vis spectrophotometry, (19)F-NMR and SEC measurements. O(2) solubility studies on PHEA-F aqueous solutions were carried out at 25 degrees C and 37 degrees C at atmospheric pressure and showed that PHEA-F conjugate, despite its low degree of derivatization in fluorine containing groups (2.60 mol-%), is capable of dissolving 13-15% more O(2) than non-fluorinated PHEA. Moreover, O(2) release in simulated physiological conditions is faster for PHEA-F than for PHEA. The biocompatibility of this conjugate has been evaluated by performing an in vitro viability assay on human chronic myelogenous leukaemia cells (K-562) chosen as a model cell line and in vitro haemolysis experiments on human RBCs. All these properties suggest the potential use of PHEA-F as an artificial O(2) carrier. 相似文献
135.
Liquid-crystalline rigid-core semiconductor oligothiophenes: influence of molecular structure on phase behaviour and thin-film properties 总被引:1,自引:0,他引:1
Melucci M Favaretto L Bettini C Gazzano M Camaioni N Maccagnani P Ostoja P Monari M Barbarella G 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(36):10046-10054
The design, synthesis and properties of liquid-crystalline semiconducting oligothiophenes containing dithienothiophene (DTT), benzothiadiazole (BTZ) and carbazole (CBZ) rigid cores are described. The effect of molecular structure (shape, size and substitution) on their thermal behaviour and electrical properties has been investigated. Polarised optical microscopy (POM) and differential scanning calorimetry (DSC) analyses have revealed highly ordered smectic mesophases for most of the newly synthesised compounds. X-ray diffraction (XRD) studies performed at various temperatures have shown that the smectic order is retained in the crystalline state upon cooling across the transition temperature, affording cast films with a more favourable morphology for FET applications. 相似文献
136.
Schrekker HS Gelesky MA Stracke MP Schrekker CM Machado G Teixeira SR Rubim JC Dupont J 《Journal of colloid and interface science》2007,316(1):189-195
A surface-enhanced Raman spectroscopy (SERS) study of imidazolium ionic liquid stabilized gold(0) nanoparticles (GNPs) furnished previously unknown knowledge about the coordination and stabilization mode of the imidazolium cation. GNPs were prepared by hydrazine reduction of a chloroauric acid solution in 1-triethylene glycol monomethyl ether-3-methylimidazolium methanesulfonate 2 as ether-functionalized room-temperature ionic liquid (RTIL). UV-vis spectroscopy showed the presence of GNP aggregates as absorptions extended to the NIR region. A parallel coordination mode for the imidazolium cation of RTIL 2 on the GNP surface was observed by SERS, which occurred without the simultaneous coordination of the 1-triethylene glycol monomethyl ether-functionality. Instead of this, the ether-functionality was directed away from the GNP surface and acted as steric barrier between the GNPs/GNP aggregates, thus preventing further aggregation. These new insights suggest that the imidazolium cation is responsible for electrosteric stabilization. 相似文献
137.
Elisa Frederico Seneme Daiane Carla dos Santos Evelyn Marcela Rodrigues Silva Yollanda Edwirges Moreira Franco Giovanna Barbarini Longato 《Molecules (Basel, Switzerland)》2021,26(19)
Natural products have been used by humanity for many centuries to treat various illnesses and with the advancement of technology, it became possible to isolate the substances responsible for the beneficial effects of these products, as well as to understand their mechanisms. In this context, myristicin, a substance of natural origin, has shown several promising activities in a large number of in vitro and in vivo studies carried out. This molecule is found in plants such as nutmeg, parsley, carrots, peppers, and several species endemic to the Asian continent. The purpose of this review article is to discuss data published in the last 10 years at Pubmed, Lilacs and Scielo databases, reporting beneficial effects, toxicity and promising data of myristicin for its future use in medicine. From 94 articles found in the literature, 68 were included. Exclusion criteria took into account articles whose tested extracts did not have myristicin as one of the major compounds. 相似文献
138.
The adsorption of NO, NO/O2 mixtures and NO2 on pure ZrO2 and on two series of catalysts supported on ZrO2, one containing vanadia and the other molybdena (ZV and ZMo, respectively), has been investigated. The V and Mo surface contents
of the latter were ≤3 atoms nm−2 and ≤5 atoms nm−2, respectively. All samples had been previously submitted to a standard oxidation treatment.
On all samples, only extremely minor amounts of NOx surface species are formed by NO interaction at room temperature (RT). NOx surface species are formed in greater amounts on pure ZrO2 when NO and O2 are coadsorbed at RT; they are mainly nitrites, small amounts of nitrates, and small amounts of (O2NO−H)δ− species; when ZrO2 is warmed to 623 K in the NO/O2 mixture, nitrites decrease, nitrates and (O2NO−H)δ− species increase. The same NOx species as on the ZrO2 surface free from V (or Mo) are formed on ZV (or ZMo) samples with surface V (or Mo) density <1.5 atoms nm−2; however, they occur in decreased amount with increasing V (or Mo) coverage. On ZV samples with a surface V density of 1.5–3
atoms nm−2 (or ZMo samples with a surface Mo density of 1.5–5 atoms nm−2) when NO and O2 are coadsorbed at RT, there is formation of small amounts of nitrites, nitrates (both on ZrO2 surface free from V (or Mo) and at the edges of V- or Mo-polyoxoanions) and NO2
δ+ species, associated with V5+ (or Mo6+) of very strong Lewis acidity; when samples are warmed up 623 K in the NO/O2 mixture, nitrites disappear, nitrates increase, NO2
δ+ species remain constant or slightly decrease. When NO2 is allowed into contact at RT with oxidized samples, surface situations almost identical to those obtained for each sample
warmed to 623 K in NO/O2 mixture is reached. The NOx surface species stable at 623 K, the temperature at which catalysts show the best performance in the selective catalytic
reduction (SCR) of NO by NH3, are nitrates, both on ZrO2 and on polyvanadates or polymolybdates at high nuclearity. On the contrary, nitrites and NO2
δ+ species are unstable at 623 K. 相似文献
139.
Bice Fubini Elio Giamello Laura Mollo Giovanna Zanetti Shana K. Eborn Ann E. Aust 《Research on Chemical Intermediates》1999,25(1):95-109
In order to investigate the molecular mechanism whereby iron in asbestos and in other iron containing fibres plays a crucial
role in fibre induced carcinogenicity, two Fe2+-exchanged zeolites (Y and H-ZSM-5) have been prepared and used as model solids. Fe-Y was active both in free radical generation via hydrogen abstraction and in single strand DNA damage, but lost
both these properties when oxidized by hydrogen peroxide. Fe-ZSM-5, on the other hand, was nearly inactive. Iron chelators
and reductants (ascorbate, citrate and EDTA) enhance the activity in DNA single strand breaks. Moreover, they reactivate oxidized
Fe-Y and activate Fe-ZSM-5. Iron is mobilized and Fe3+ is partially reduced to Fe2+. The most pronounced effect was found when citrate was present together with ascorbate. H-abstraction turns out to be a rather
general reaction, occurring also with peptides as target molecules. In this case EPR spectra show that more than one type
of radical moiety is generated. 相似文献
140.
Willy J. M. van Well Xavier Cottin Jan W. de Haan Rutger A. van Santen Berend Smit 《Angewandte Chemie (International ed. in English)》1998,37(8):1081-1083
13 C NMR spectroscopy and computer simulations have shown that the chain length of hydrocarbons has a surprising effect on where these molecules reside in the zeolite FER. Propane and butane can access the entire two-dimensional channel structure, while hexane only the one-dimensional substructure. This difference has important consequences for the catalytic activity and explains some of the experimental observations. 相似文献