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671.
Gabriela Oksdath‐Mansilla Alicia B. Peñéñory 《Journal of Physical Organic Chemistry》2011,24(12):1136-1143
The reactions of 2‐(4‐Z‐phenyl)‐1,3‐dithiane anions (Z = H, OMe, Cl, CN) with neopentyl, neophyl and phenyl iodides were studied in DMSO, taking into consideration the effect of the Z substituent on the dithiane anions reactivity as well as on the product distribution. These substitution reactions proceed by an SRN1 mechanism with radicals and radical anions as intermediates. Two competitive pathways are possible for the radical anion of the substitution product, namely electron transfer (ET) to the substrate giving the substitution product and C–S bond fragmentation to yield a distonic radical anion. ET is the main pathway for the reactions between dithiane anions bearing electron‐donor substituents and neopentyl or its analogue iodides affording the substitution products in moderate yields (41–53%). Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
672.
Harvey Amorín Teresa Hungría Angel R. Landa-Cánovas María Torres Mickael Dollé Miguel Algueró Alicia Castro 《Journal of nanoparticle research》2011,13(9):4189-4200
Piezoelectric oxides are currently being considered in combination with magnetic materials for the development of magnetoelectric
composites, in which stress transfer across the interface is a key issue. In this context, we report here a detailed study
of the mechanochemical activation processes of the ferroelectric perovskite BiScO3–PbTiO3 and of the ferrimagnetic spinel NiFe2O4. Highly sinterable, single-phase nanopowders of both ferroic oxides are synthesised, and used for the preparation of high-density
materials and two-phase composites by hot pressing. Emphasis is put on studying chemical reactions at and interdiffusion across
the interface between the two phases using high spatial resolution techniques such as micro X-ray diffraction and piezoresponse
force microscopy. The feasibility of preparing magnetoelectric composites by this approach is demonstrated, for which the
necessity of controlling physicochemical processes at the interface is key to obtain functionality. 相似文献
673.
674.
Adsorption of Methylene Blue and Tetracycline by Zeolites Immobilized on a PBAT Electrospun Membrane
David Picn Alicia Vergara-Rubio Santiago Estevez-Areco Silvina Cerveny Silvia Goyanes 《Molecules (Basel, Switzerland)》2023,28(1)
The detection of emerging contaminants in bodies of water has steadily increased in recent years, becoming a severe problem threatening human and ecosystem health. Developing new materials with adsorption properties to remove these pollutants represents an important step toward a potential solution. In this paper, a polybutylene adipate terephthalate (PBAT) nanofibrous membrane incorporating clinoptilolite zeolite was developed and its excellent performance in removing tetracycline (TC) and methylene blue (MB) from water was demonstrated. The composite membrane was prepared in two steps: firstly, a homogeneous dispersion of clinoptilolite (1 wt% respect to polymer) in a PBAT solution (12.6 wt%) was electrospun; secondly, the electrospun membrane was subjected to an acid treatment that improved its wettability through the protonation of the surface silanol groups of clinoptilolite. The resulting membrane was hydrophilic and showed higher adsorption for TC (800 mg/g) and MB (100 mg/g), using a low dose (90 mg/L) powdered zeolite. The maximum removal capacity was obtained at neutral pH, being the cation exchange reaction the main adsorption mechanism. Pseudo-second-order kinetics and Henry’s law agree well with the proposed chemisorption and the high affinity of TC and MB for the adsorbent. The material can be reused after the removal process without generating additional contamination, although losing some effectivity. 相似文献
675.
Alicia Dobn-Surez María J. Gimnez Salvador Castillo María E. García-Pastor Pedro J. Zapata 《Molecules (Basel, Switzerland)》2021,26(11)
Green pepper fruit is often consumed before it is completely ripe. However, the influence of the phenological stage in which the green pepper is consumed as a potential influencing factor in its bioactive compounds content and antioxidant capacity remains unknown. In addition, no literature is available concerning the bioactive compounds changes in ‘Lamuyo’ green peppers along its developmental and growth cycle. For this, two different approaches have been carried out, one using twelve different phenological stages (S1 to S12), and in the other, seven different harvest dates (from 27 February to 20 April). Moreover, bioactive compounds changes during 21 days of postharvest storage at 8 °C were investigated. In this study, bioactive compounds (ascorbic acid, dehydroascorbic acid, and total phenolic content) and the total hydrophilic and lipophilic (TAA-H and TAA-L) antioxidant activity were analysed. In addition, total soluble solids, total acidity, individual sugars, and organic acids were determined. Vitamin C levels increased along the phenological stages and harvest dates due to significant increases in ascorbic and dehydroascorbic acid levels. Our results show that the total phenol content decreases as vegetables develop and subsequently increases both as ripening begins and by the last harvest date. Furthermore, TAA-H was also greater by the phenological stage S12 and the 20 April harvest date. In conclusion, the phenological stage and harvest date are key factors that significantly influence the bioactive compounds of green peppers, and those that appear by S12 and 20 April could be more beneficial to health. 相似文献
676.
Steady state viscosity and viscoelasticity of HMHEC solutions were studied. Viscosity increases with concentration due to a reinforcement of the micellar network. High shear rate viscosities are independent of temperature. Two relaxation processes were observed, the long one related to the lifetime of the hydrophobic junction and the short related to rapid Rouse-like relaxations of the free chains. When SDS is added, mixed micelles form that reinforce the network up to an optimum [SDS]/[HMHEC] ratio. Above this ratio, the micelles in excess isolate the polymer chains, the long relaxation process disappears and Rouse-like relaxations occur, corresponding to rapid movements of free chains. 相似文献
677.
678.
Dr. Wentao Xu Dr. Nikita Hanikel Dr. Kirill A. Lomachenko Dr. Cesare Atzori Dr. Alicia Lund Dr. Hao Lyu Zihui Zhou Prof. Dr. C. Austen Angell Prof. Dr. Omar M. Yaghi 《Angewandte Chemie (International ed. in English)》2023,62(16):e202300003
We report a synthetic strategy to link titanium-oxo (Ti-oxo) clusters into metal-organic framework (MOF) glasses with high porosity though the carboxylate linkage. A new series of MOF glasses was synthesized by evaporation of solution containing Ti-oxo clusters Ti16O16(OEt)32, linkers, and m-cresol. The formation of carboxylate linkages between the Ti-oxo clusters and the carboxylate linkers was confirmed by Fourier-transform infrared (FT-IR) spectroscopy. The structural integrity of the Ti-oxo clusters within the glasses was evidenced by both X-ray absorption near edge structure (XANES) and 17O magic-angle spinning (MAS) NMR. After ligand exchange and activation, the fumarate-linked MOF glass, termed Ti-Fum, showed a N2 Brunauer–Emmett–Teller (BET) surface areas of 923 m2 g−1, nearly three times as high as the phenolate-linked MOF glass with the highest BET surface area prior to this report. 相似文献
679.
Side-Chain Chemistry Governs Hierarchical Order of Charge-Complementary β-sheet Peptide Coassemblies
Dr. Renjie Liu Xin Dong Dr. Dillon T. Seroski Dr. Bethsymarie Soto Morales Dr. Kong M. Wong Alicia S. Robang Lucas Melgar Prof. Thomas E. Angelini Prof. Anant K. Paravastu Prof. Carol K. Hall Prof. Gregory A. Hudalla 《Angewandte Chemie (International ed. in English)》2023,62(51):e202314531
Self-assembly of proteinaceous biomolecules into functional materials with ordered structures that span length scales is common in nature yet remains a challenge with designer peptides under ambient conditions. This report demonstrates how charged side-chain chemistry affects the hierarchical co-assembly of a family of charge-complementary β-sheet-forming peptide pairs known as CATCH(X+/Y−) at physiologic pH and ionic strength in water. In a concentration-dependent manner, the CATCH(6K+) (Ac-KQKFKFKFKQK-Am) and CATCH(6D−) (Ac-DQDFDFDFDQD-Am) pair formed either β-sheet-rich microspheres or β-sheet-rich gels with a micron-scale plate-like morphology, which were not observed with other CATCH(X+/Y−) pairs. This hierarchical order was disrupted by replacing D with E, which increased fibril twisting. Replacing K with R, or mutating the N- and C-terminal amino acids in CATCH(6K+) and CATCH(6D−) to Qs, increased observed co-assembly kinetics, which also disrupted hierarchical order. Due to the ambient assembly conditions, active CATCH(6K+)-green fluorescent protein fusions could be incorporated into the β-sheet plates and microspheres formed by the CATCH(6K+/6D−) pair, demonstrating the potential to endow functionality. 相似文献
680.
M. Carmen Matías Alicia Larena M. De La Ulagares Orden Joaquín Martinez Urreaga 《Macromolecular Symposia》1995,94(1):273-282
The effect of glass fiber reinforcements on the curing behavior of unsaturated polyester commercial resins was investigated by Fourier transform infrared spectroscopy. Two different E-glass fibers and two commercial resins were employed. The results indicate that both the glass fiber content and the fiber size have a pronounced effect on the ultimate values of the styrene conversion. Some complications found in the infrared analysis of commercial resins are also presented. 相似文献