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41.
Thais Francine Ribeiro Alves Cecília Torqueti Barros Denicezar Baldo Venâncio Alves Amaral Mirella Sever Carolina Santos 《Journal of Dispersion Science and Technology》2019,40(4):546-554
The aim of the present study was to improve the solubility and dissolution rate of ibuprofen and to evaluate, ex vivo, the intestinal permeation. Solid dispersions (SD) were prepared with Kollicoat IR® by solvent evaporation technique in different drug:carrier ratios. The permeation intestinal of ibuprofen was evaluated by inverted intestinal sac method. The SD was characterized by solubility equilibrium, FT-IR, DSC, PXRD, SEM, and dissolution rate. The solubility, dissolution rate, and permeability were significantly greater for SD 1:2. The PXRD, SEM and DSC indicated a partial change in the crystalline state of ibuprofen. The solubility equilibrium of SD (1:2) was approximately 15 times greater than the solubility of ibuprofen. Dissolution rate enhancement was attributed to the decreased crystallinity of the ibuprofen, and increase of wettability and decrease of particle size. In conclusion, dissolution rate and intestinal permeability of ibuprofen were enhanced by the use of Kollicoat IR® carrier in the SD formulation. 相似文献
42.
The kinetics of growth and exopolysaccharide (EPS) production from Streptococcus thermophilus were studied and optimized for different physical (temperature, pH, aeration rate) and chemical (carbon/nitrogen ratio) factors in milk medium. From these experiments, it was clear that EPS production displays primary metabolite kinetics. Using the optimized conditions, EPS production could also be established in de Man Rogosa Sharpe medium. Growth-associated EPS production, bacterial growth and other fermentation data were translated into a mathematical model. 相似文献
43.
A novel method utilising comprehensive two-dimensional liquid chromatography interfaced to electrospray ionisation time-of-flight mass spectrometry was developed for the determination of organic acids in atmospheric aerosols. The system was applied to the analysis of methanolic extracts of filters from a high volume sampler. The enhanced separation power of two-dimensional separation was demonstrated in the analysis of both rural and urban samples. Quantification was performed for compounds for which standards were available. Limit of detection was 2-200ng/ml. Average reproducibility of retention times in each dimensions was 0.1%, and average reproducibility of peak areas was 8% (10mug/ml, n=3). 相似文献
44.
Murro Simone van de Ven Christiaan J. F. 《Mathematical Physics, Analysis and Geometry》2022,25(1):1-40
Mathematical Physics, Analysis and Geometry - We consider the existence of the topological entropy of shift spaces on a finitely generated semigroup whose Cayley graph is a tree. The considered... 相似文献
45.
This paper describes an integrated setup for fluorescence recovery after photobleaching (FRAP) for determining translational and rotational Brownian diffusion simultaneously, ensuring that these two quantities are measured under exactly the same conditions and at the same time in dynamic experiments. The setup is based on translational-FRAP with a fringe pattern of light for both the bleaching and monitoring of fluorescently labeled particles, and rotational-FRAP, which uses the polarization of a short bleach light pulse to create a polarization anisotropy. The fringe pattern of the probe beam is modulated in conjunction with a synchronized lock-in amplifier giving a fast, sensitive, ensemble-averaged measurement compared to microscope-image based techniques. The experimental polarization geometry we used ensures that the fluorescence emission is collected without polarization bias. Therefore, only the orientation of the absorption dipole moment of the fixed dye in the particles is measured, which simplifies interpretation of the data. The polarization is modulated rapidly between two orthogonal polarization states, giving the polarization anisotropy in one, single measurement. The rotational and translational Brownian diffusion of anisotropic colloids is measured for ellipsoids of revolution. This experiment shows that in this case the rotational correlation function matches a three-exponential decay in accordance with theoretical predictions. 相似文献
46.
Ligand substitution of the mixed-metal clusters FeRu2(CO)12 and Fe2Ru(CO)12 with triphenylphosphine and trimethylphosphite has been studied. Mono- and di-substituted derivatives have been synthesized and characterized structurally. The following crystal and molecular structures are reported: Fe2Ru(CO)11PPh3: triclinic, space group P, a 9.203(2), b 11.903(3), c 15.117(4) Å, α 81.54(2), β 87.28(2), γ 66.72(2)°, Z = 2; Fe2Ru(CO)11P(OMe)3: orthorhombic, space group Pna21, a 17.220(5), b 14.572(4), c 8.708(6) Å, Z = 4, FeRu2(CO)11PPh3: monoclinic, space group P21/n, a 11.435(3), b 16.034(5), c 16.642(4) Å, β 93.35(2)°, Z = 4; FeRu2(CO)10(PPh3)2: orthorhombic, space group Pccm, a 14.854(4), b 17.180(7), c 16.786(12) Å, Z = 4.Ligand substitution is found to occur preferentially at the ruthenium centers of the FeRu2 and Fe2Ru clusters. Monosubstitution causes expansion of both of the clusters while the overall geometry is practically unchanged. Disubstitution of FeRu2(CO)12 causes contraction of the cluster and leads to a formation of carbonyl bridges. The structural trends have been interpreted in terms of electronic and packing effects of ligand substitution. The X-ray structures of Fe2Ru(CO)12 and FeRu2(CO)12 are not known; the ligand substitution studies indicate that Fe2Ru(CO)12 has the same structure as Fe3(CO)12, and that FeRu3(CO)12 does not have a Ru3(CO)12 structure as postulated previously from the IR studies. 相似文献
47.
48.
There is an analogue of the Ferrand construction for smooth surfaces in 4: if the normal bundle of such a surface X has a suitable 1-subbundle, then a 2-vector bundle can be constructed, which has a section vanishing doubly on X. In this way the Horrocks-Mumford bundle is recovered from the quintic scroll.K. Stein, dem B ahnbrecher der Funktionen-theorie, gewidmet 相似文献
49.
Four trapping methods for pressurised hot water extraction were compared in terms of recovery and selectivity. Also, robustness, repeatability and solvent consumption of the trapping systems were investigated. The trapping methods were collection into solvent following liquid-liquid extraction, solid-phase trapping into Tenax TA (SPE), flat sheet microporous membrane liquid-liquid extraction and hollow fibre microporous membrane liquid-liquid extraction. Polycyclic aromatic hydrocarbons were extracted with these systems from four soil and sediment matrices and the extracts were analysed by GC-MS and size-exclusion chromatography. Clear differences were observed in the selectivity and extraction efficiencies of the trapping systems. 相似文献
50.
Nataša Novak Tušar Dr. Alenka Ristić Dr. Gregor Mali Dr. Matjaž Mazaj Dr. Iztok Arčon Prof. Denis Arčon Prof. Venčeslav Kaučič Prof. Nataša Zabukovec Logar Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(19):5783-5793
A two‐step synthesis of a novel mesostructured silicate, KIL‐2, and its manganese‐containing analogue, Mn/KIL‐2, has been developed. KIL‐2 possesses interparticle mesopores with pore dimensions between 5 and 60 nm and a surface area of 448 m2. The mesopores are formed by the aggregation of silica nanoparticles, which creates a network with interparticle voids. The particle size and the pore diameters depend on the temperature of the ageing step (first step) and on the solvothermal treatment in ethanol (second step), respectively. Mn/KIL‐2 contains octahedrally coordinated Mn3+ (80 %) and tetrahedrally coordinated Mn2+ (20 %) ions. Mn3+ ions are present in the extra‐framework MnOx nanoparticles with typical dimensions of 2 nm, which are homogeneously distributed throughout the material. Mn2+ ions occur as isolated manganese framework sites. The material is also able to retain its structure characteristics after the hydrothermal treatment in boiling water. Because of its non‐toxic nature and cost‐effective synthesis, Mn/KIL‐2 thus exhibits properties that are needed for an environment‐friendly catalyst. 相似文献