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排序方式: 共有378条查询结果,搜索用时 31 毫秒
111.
Elin Oscarsson Tim Lindberg Kathrin S. Zeller Malin Lindstedt Daniel Agardh sa Hkansson Karolina
stbring 《Molecules (Basel, Switzerland)》2020,25(24)
Food additives such as emulsifiers are used in increasing quantities in the food industry. The aim of this study was to compare three different emulsifiers (polysorbate 80 (P80), carboxymethyl cellulose (CMC), and β-lactoglobulin (β-lac) with regards to their effect on the stimulation of immune cells and intestinal permeability. The immune stimulatory effects were studied in the myeloid cell line MUTZ-3-cells, while the change in intestinal permeability was studied in the Caco-2 cell line and ex vivo in the Ussing chamber system using small intestinal fragments from rats. The tested concentrations of the emulsifiers ranged from 0.02% up to 1%, which are concentrations commonly used in the food industry. The results showed that P80 affected both the myeloid cells and the intestinal permeability more than CMC (p < 0.05) and β-lac (p < 0.05) at the highest concentration. CMC was found to neither affect the permeability in the intestine nor the MUTZ-3 cells, while β-lac changed the permeability in the total part of the small intestine in rats. These findings indicate that P80 might be more cytotoxic compared to the other two emulsifiers. 相似文献
112.
Rafa Jerzy Kopiasz Waldemar Tomaszewski Aleksandra Ku
miska Karolina Chreptowicz Jolanta Mierzejewska Tomasz Ciach Dominik Jaczewski 《Macromolecular bioscience》2020,20(7)
The antimicrobial properties of polycations are strongly affected by the structural features such as the backbone flexibility and topology (isomerism) through the polymer ability to attain proper conformation in interaction with the cell membrane. In this paper, a synthesis and biocidal properties evaluation of ionenes characterized by different backbone topology (isomerism) and flexibility are presented. The findings reveal influence of variation in topology on activity against different microorganisms, and general positive effect of improved flexibility. Furthermore, one of the obtained ionenes displays degradable properties in near physiological environment (phosphate‐buffered saline pH 7.4, 37 °C). The degradation proceeds via Hofmann elimination reaction and the products are not of acidic character. For the first time a new class of degradable ionenes with a high antimicrobial potential is presented. 相似文献
113.
Claudia Aparicio Jan Filip Karolina Machalova-Siskova Miroslav Mashlan Lubomir Spanhel 《Journal of Sol-Gel Science and Technology》2014,72(3):655-662
Hot ethanolic mixtures of hydrated Zn(II)- and Fe(II)-carboxylates (acetate and lactate) react to form yellow-orange colored Fe(III)xZnyOzOHw heteroclusters showing pronounced electronic resonances in the optical UV absorption spectra. On the addition of LiOH to these polymolecular sols, stable nanoparticulate Fe(III)–ZnO colloids are formed. During colloidal growth, 2–4 nm sized weakly crystallized Wurtzite nanoparticles are exclusively formed even in the presence of high Fe content up to 20 at.%. The presence of Fe(III) in the ZnO condensation process retards the nanoparticle growth and blocks the thermal crystallization and size enhancement up to 250 °C. The produced 0.5 M Fe(III)–ZnO sols are useful for film formation processes. From atomic force microscopy-AFM, scanning electron microscopy-SEM and X-ray diffraction-XRD studies, we note important differences in shape and morphology of the thermally annealed Fe(III)–ZnO layers depending on the iron carboxylate employed. Surprisingly, Fe(II)-lactate derived coatings are carrying vertically oriented cone-shaped aggregates composed of 60–120 nm long primary nanorods. Contrary, Fe(II)-acetate based synthesis gave sand-dune like film morphologies containing spherical 12 nm sized nanocrystallites. All film samples possess mesoporosity with pore size ranging between 5 and 20 nm. 相似文献
114.
Addition of chlorotrimethylsilane (Me3SiCl) to the mixture of a carbamoyl‐substituted Meldrum's acid, i.e., a 5‐[(arylamino)hydroxymethylene]‐2,2‐dimethyl‐1,3‐dioxane‐4,6‐dione of type 1 and a secondary amine as nucleophile strongly accelerated the rate of their reaction. The reason for this phenomenon observed, during our previous research, remained, however, unclear. To elucidate the mechanism of this reaction, we assumed and verified three possible pathways for the action of Me3SiCl (cf. Scheme 2): The acceleration of the reaction is caused i) by formation of a O‐trimethylsilylated Meldrum's acid of type 2 , ii) by the silylated amine 3 , or iii) by the presence of HCl liberated from Me3SiCl. The performed experiments revealed that the faster course of reaction is caused by the formation of N‐trimethylsilylated amines of type 3 . 相似文献
115.
Michel Fleck Karolina Schwendtner Ana Hensler 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(4):m122-m125
In bis(glycine) lithium chromate monohydrate {systematic name: poly[aquadi‐μ‐glycinato‐μ‐tetraoxochromato(VI)‐dilithium(I)]}, [CrLi2(C2H5NO2)2O4(H2O)]n, (I) (space group P212121), and bis(glycine) lithium molybdate {systematic name: poly[di‐μ‐glycinato‐μ‐tetraoxomolybdato(VI)‐dilithium(I)]}, [Li2Mo(C2H5NO2)2O4]n, (II) (space group P21), all atoms are located on general positions. The crystal structure of (I) is characterized by infinite chains of corner‐sharing [LiO4] tetrahedra, which are connected by glycine molecules to form layers. [CrO4] tetrahedra are attached to the [LiO4] tetrahedra. Compound (II) contains dimers of [LiO4] tetrahedra which are connected by [MoO4] tetrahedra to form chains, which are in turn connected by glycine molecules to form double layers. 相似文献
116.
117.
The procedures for measuring dissociation constants (pK(a)) of twenty 1-substituted pyrrolidin-2-one derivatives are described. The dissociation constants of the compounds tested were determined using potentiometric titration, reversed-phase thin-layer chromatography (RP-TLC) and calculated using Pallas and Marvin programs. It was found that the RP-TLC method of determination of pK(a) could be considered as a feasible alternative to potentiometric titration. The Marvin program is a better tool for preliminary estimation of dissociation constant than the Pallas one. 相似文献
118.
Karolina Wahlström 《Tetrahedron letters》2008,49(23):3779-3781
The Boc-N-methyl-N-[2-(methylamino)ethyl]carbamoyl group (Boc-Nmec) is reported as a new side chain-protective group for tyrosine in Fmoc solid-phase peptide synthesis. Tyrosine is incorporated into the peptide as Fmoc-Tyr(Boc-Nmec)-OH by standard coupling methods. During the cleavage of the peptide from the resin with TFA the Boc group is simultaneously cleaved while the cationic N-methyl-N-[2-(methylamino)ethyl]carbamoyl group remains attached to the tyrosine residue, thereby increasing the solubility of the peptide. After purification of the peptide, the Nmec protective group can be cleaved under neutral or mild alkaline conditions via an intramolecular cyclization reaction. 相似文献
119.
The dipeptide Fmoc-Val-(2-hydroxy-4-methoxybenzyl)Gly-OBzl was synthesized and the 2-hydroxyl group carbamoylated to give a Boc-N(CH3)CH2CH2N(CH3)CO–, (Boc-Nmec-) modification of the 2-hydroxy-4-methoxybenzyl (Hmb) group. After catalytic hydrogenation and purification, the resulting dipeptide Fmoc-Val-(Boc-Nmec-Hmb)Gly-OH was used in solid phase peptide synthesis. During treatment with TFA, the peptide was released from the resin and the Boc group cleaved. The peptide could then be purified with an alkylated peptide bond carrying a cationic charge that both increased the solubility of the peptide during the purification steps and facilitated analysis by MALDI-TOF mass spectrometry. The Nmec group was cleaved by intramolecular cyclization under slightly alkaline conditions, followed by cleavage of the Hmb group by TFA to give the fully deprotected peptide. 相似文献
120.
This study was undertaken to identify factors exerting the strongest influence on the adsorption of dye. The maximum adsorption
capacity (at the adopted operating conditions) was the main parameter used to evaluate the process. In addition, the feasible
adsorption capacity of chitosan was evaluated. Breakthrough experiments were carried out in a circulating air-lift reactor
at a constant concentration of reactive dye Black 8 (100 mg/dm3). The tests studied different chitosan concentrations in the reactor and a range of flow intensities. The results of the
breakthrough tests were compared by means of apparent mass transfer coefficients, determined by slopes at C/C
0=1/2. The adsorption capacity of chitosan was affected to the greatest extent by the flow rate of the medium to the reactor.
In turn, the utilization of the maximum adsorption capacity of chitosan, at the assumed efficiency of dye removal, was determined
by chitosan concentration in the reactor. 相似文献