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61.
62.
Detection of propranolol in pharmaceutical formulations by diffuse reflectance spectroscopy 总被引:1,自引:0,他引:1
Gotardo MA Tognolli JO Pezza HR Pezza L 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,69(4):1103-1109
This paper describes an analytical reflectometric method that has an objective not only the industrial quality control but also to detect possible falsifications and/or adulterations of propranolol in pharmaceutical formulations. The method is based on the diffuse reflectance measurements of the colored product (III) of the spot test reaction between propranolol hydrochloride (I) and 2,6-dichloroquinone-4-chloroimide (II) using filter paper as solid support. Spot test conditions have been investigated using experimental design in order to identify and optimize the critical factors. The factors evaluated were DCQ concentration, propranolol solvent and DCQ solvent. The best reaction conditions were achieved with the addition of 30 microL of propranolol solution in ethanol 35% (v/v) and 30 microL of DCQ solution at 70 mg mL(-1) in acetone, in this order. All reflectance measurements were carried out at 500 nm and the linear range was from 8.45x10(-4) to 8.45x10(-2)mol L(-1) (r=0.998). The limit of detection was 1.01x10(-4)mol L(-1). No interference was observed from the assessed excipients and drugs. The method was applied to determine propranolol in commercial brands of pharmaceuticals. The results obtained by the proposed method were favorably compared with those given by the British Pharmacopoeia procedure. 相似文献
63.
Elisa M. N. de Oliveira Felipe L. Coelho Dr. Mara L. Zanini Dr. Ricardo M. Papaléo Dr. Leandra F. Campo 《Chemphyschem》2016,17(20):3176-3180
Excited‐state intramolecular proton transfer (ESIPT) is a particularly well known reaction that has been very little studied in magnetic environments. In this work, we report on the photophysical behavior of a known ESIPT dye of the benzothiazole class, when in solution with uncoated superparamagnetic iron oxide nanoparticles, and when grafted to silica‐coated iron oxide nanoparticles. Uncoated iron oxide nanoparticles promoted the fluorescence quenching of the ESIPT dye, resulting from collisions during the lifetime of the excited state. The assembly of iron oxide nanoparticles with a shell of silica provided recovery of the ESIPT emission, due to the isolation promoted by the silica shell. The silica network gives protection against the fluorescence quenching of the dye, allowing the nanoparticles to act as a bimodal (optical and magnetic) imaging contrast agent with a large Stokes shift. 相似文献
64.
Yamaguti-Sasaki E Ito LA Canteli VC Ushirobira TM Ueda-Nakamura T Dias Filho BP Nakamura CV de Mello JC 《Molecules (Basel, Switzerland)》2007,12(8):1950-1963
Chemical evaluation of the semi-purified fraction from the seeds of guaraná, Paullinia cupana H.B.K. var. sorbilis (Mart.) Ducke, yielded the following compounds: caffeine, catechin, epicatechin, ent-epicatechin, and procyanidins B1, B2, B3, B4, A2, and C1. Measurement of the antioxidant activity by reduction of the DPPH radical confirmed the anti-radical properties of the aqueous (AqE) and crude (EBPC) extracts and semi-purified (EPA and EPB) fractions. The EPA fraction showed radical-scavenging activity (RSA) and protected DPPH from discoloration at 5.23 +/- 0.08 (RSD% = 1.49) microg/mL, and for the phosphomolybdenum complex showed a higher Relative Antioxidant Capacity (RAC) at 0.75 +/- 0.01 (1.75). The EPA fraction had a total polyphenolics content of 65.80% +/- 0.62 (RSD% = 0.93). The plant drug showed 5.47% +/- 0.19 (RSD% = 3.51) and 6.19% +/- 0.08 (RSD% = 1.29) for total polyphenolics and methylxanthines, respectively. In vitro assessment of the antibacterial potential of the Paullinia cupana extracts against Streptococcus mutans showed that these could be used in the prevention of bacterial dental plaque. 相似文献
65.
Croci L Suffredini E Cozzi L Paniconi M Ciccaglioni G Colombo MM 《Journal of AOAC International》2007,90(6):1588-1597
Control of contamination by Vibrio parahaemolyticus in fishery products is often hampered by the lack of standardized methods and by the uncertainty associated with biochemical identification of the isolates. In this study, 5 polymerase chain reaction (PCR) methods for the identification of V. parahaemolyticus to the species level were evaluated by using 25 Vibrio reference strains and 163 isolates from fishery products, environmental sources, and clinical samples. Sequence targets of the methods were toxR, gyrB, and tlh genes (tested with 2 protocols), and the fragment pR72H. Isolate identification was confirmed by sequencing of the 16S rRNA gene and by PCR protocols for the identification of other Vibrio species. The PCR assay targeting the toxR gene achieved the highest performance (100% inclusivity and exclusivity). The 2 PCR protocols based on tlh gene detection, although showing the same inclusivity (100%), differed in the exclusivity (50 and 91%, respectively). Finally, the results provided by the PCR assays targeting the gyrB gene and pR72H fragment were less reliable and, in some cases, difficult to assess. According to the results of this study, the characteristics of accuracy expressed by the toxR identification method make it a suitable candidate as a reference method for the molecular identification of V. parahaemolyticus strains. 相似文献
66.
Surface tensions of imidazolium based ionic liquids: anion, cation, temperature and water effect 总被引:1,自引:0,他引:1
Freire MG Carvalho PJ Fernandes AM Marrucho IM Queimada AJ Coutinho JA 《Journal of colloid and interface science》2007,314(2):621-630
This work addresses the experimental measurements of the surface tension of eight imidazolium based ionic liquids (ILs) and their dependence with the temperature (288-353 K) and water content. The set of selected ionic liquids was chosen to provide a comprehensive study of the influence of the cation alkyl chain length, the number of cation substitutions and the anion on the properties under study. The influence of water content in the surface tension was studied for several ILs as a function of the temperature as well as a function of water mole fraction, for the most hydrophobic IL investigated, [omim][PF(6)], and one of the more hygroscopic IL, [bmim][PF(6)]. The surface thermodynamic functions such as surface entropy and enthalpy were derived from the temperature dependence of the surface tension values. 相似文献
67.
Mara D. Neusel Mü fit Sezer 《Proceedings of the American Mathematical Society》2007,135(8):2347-2354
Let be a faithful representation of a finite group . In this paper we proceed with the study of the image of the associated Noether map In our 2005 paper it has been shown that the Noether map is surjective if is a projective -module. This paper deals with the converse. The converse is in general not true: we illustrate this with an example. However, for -groups (where is the characteristic of the ground field ) as well as for permutation representations of any group the surjectivity of the Noether map implies the projectivity of .
68.
The simple chemistry and structure of quartz together with its abundance in nature and its piezoelectric properties make convenient its employment for several applications, from engineering to Earth sciences. For these purposes, the quartz equations of state, thermoelastic and thermodynamic properties have been studied since decades. Alpha quartz is stable up to 2.5 GPa at room temperature where it converts to coesite, and at ambient pressure up to 847 K where it transforms to the beta phase. In particular, the displacive phase transition at 847 K at ambient pressure is driven by intrinsic anharmonicity effects (soft-mode phase transition) and its precise mechanism is difficult to be investigated experimentally. Therefore, we studied these anharmonic effects by means of ab initio calculations in the framework of the statistical thermodynamics approach. We determined the principal thermodynamic quantities accounting for the intrinsic anharmonicity and compared them against experimental data. Our results up to 700 K show a very good agreement with experiments. The same procedures and algorithms illustrated here can also be applied to determine the thermodynamic properties of other crystalline phases possibly affected by intrinsic anharmonic effects, that could partially invalidate the standard quasi-harmonic approach. 相似文献
69.
Eduarda S. Morais Mara G. Freire Carmen S. R. Freire Armando J. D. Silvestre 《Molecules (Basel, Switzerland)》2021,26(23)
The addition of alkali metal halide salts to acidic deep eutectic solvents is here reported as an effective way of boosting xylan conversion into furfural. These salts promote an increase in xylose dehydration due to the cation and anion interactions with the solvent being a promising alternative to the use of harsh operational conditions. Several alkali metal halides were used as additives in the DES composed of cholinium chloride and malic acid ([Ch]Cl:Mal) in a molar ratio of 1:3, with 5 wt.% of water. These mixtures were then used as both solvent and catalyst to produce furfural directly from xylan through microwave-assisted reactions. Preliminary assays were carried out at 150 and 130 °C to gauge the effect of the different salts in furfural yields. A Response Surface Methodology was then applied to optimize the operational conditions. After an optimization of the different operating conditions, a maximum furfural yield of 89.46 ± 0.33% was achieved using 8.19% of lithium bromide in [Ch]Cl:Mal, 1:3; 5 wt.% water, at 157.3 °C and 1.74 min of reaction time. The used deep eutectic solvent and salt were recovered and reused three times, with 79.7% yield in the third cycle, and the furfural and solvent integrity confirmed. 相似文献
70.
Mara Cristina Almeida Carlos Campaner Doralice Maria Cella 《Micron (Oxford, England : 1993)》2009,40(5-6):586-596
Omophoita belongs to the tribe Oedionychini and is endemic from Neotropical region. The species of the tribe Oedionychini have revealed certain singular chromosomal features, such as sex chromosomes with extremely large size, asynapsis, and synthelic or amphithelic orientation during meiosis. Additionally, some species also showed post-reductional segregation of the gigantic sex chromosomes in meiotic division. The purpose of this work was to characterize cytogenetically four Omophoita species (O. magniguttis, O. octoguttata, O. personata, and O. sexnotata) in relation to their diploid number, chromosomal morphology, type of sex chromosome system, and constitutive heterochromatin pattern in mitotic and meiotic cells, and compare the obtained data with those of related species to establish the mechanism involved in the chromosomal differentiation of these species during the evolutionary process. The diploid number, 2n = 22 = 20 + X + y, and meiotic formulae, 10II + X + y, observed in these species were similar to those of the same genus and other species related. The autosomal morphology was acrocentric in O. magniguttis and O. octoguttata, metacentric in O. personata, and predominantly metacentric in O. sexnotata. In all these species, the sex chromosomes were metacentric. The secondary constriction occurred in pair 6 and X chromosome of O. personata, and in pair 6 and y chromosome of O. sexnotata. The constitutive heterochromatin was pericentromeric in O. magniguttis and centromeric in O. sexnotata, with the exception of the mitotic sex chromosomes of O. sexnotata, in which centromeric C band was lacking. Additional C bands in the sex chromosomes of O. magniguttis and certain autosomes and sex chromosomes of O. sexnotata were observed. Collochores were indirectly identified in the spermatocytes of O. octoguttata, O. personata, and O. sexnotata. The main mechanisms involved in the karyotype evolution of these species were discussed. 相似文献