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81.
El?bieta Hejchman Dorota Maciejewska Irena Wolska 《Monatshefte für Chemie / Chemical Monthly》2008,18(3):1337-1348
The microwave-assisted synthesis of four new 5-acetyl-4,7-dimethoxy-6-hydroxybenzofuran (khellinone) analogs is described.
The structures of the obtained derivatives in the solid state are evaluated on the basis of 13C CP/MAS NMR spectra and theoretical calculations at DFT level. A single crystal X-ray diffraction structure is presented
for 8-acetyl-7-hydroxy-4-methylcoumarin. 1,4-Bis(5-acetyl-4,7-dimethoxybenzofuran-6-yloxy)butane was evaluated for potential
anticancer activity in an in vitro screening panel of 60 human tumor cell lines. Selected leukemia, non-small cell lung cancer, CNS, melanoma, ovarian, and
breast cancer cell lines were sensitive to this compound. 相似文献
82.
Simon Backx Andreas Dejaegere Andreas Simoens Jef Van de Poel Dr. Dorota Krasowska Prof. Dr. Christian V. Stevens Prof. Dr. Sven Mangelinckx 《European journal of organic chemistry》2023,26(26):e202300172
Organophosphorus compounds such as phosphonamidates are gaining attention across different fields of chemistry, with interesting applications as pharmaceuticals, or pesticides. However, practical application of phosphonamidates is complicated by their difficult syntheses which often involve expensive or unstraightforward reagents and harsh conditions. To remedy these issues, we present a flexible, room temperature synthesis for novel P-alkylphosphonamidates without the need for intermediary purification. Commonly available phosphonates are first chlorinated by use of oxalyl chloride and phosphonylaminium salts are used to mediate the harsh reactivity of phosphonochloridates, giving rise to the desired products. We demonstrate the compatibility of our protocol with primary and secondary amines, as well as with different phosphonate esters. The proposed pathway also enables the synthesis of primary phosphonamidates using ammonium acetate as a cheap and safe alternative for ammonia. In future research, this protocol will also enable the synthesis of bioactive targets that are incompatible with current protocols. 相似文献
83.
Anna Żywicka Dorota Peitler Rafał Rakoczy Adam Feliks Junka Karol Fijałkowski 《Applied biochemistry and biotechnology》2016,180(4):805-816
The present study aimed to explore and describe the properties of bacterial cellulose (BC) membranes obtained from three different strains of Gluconacetobacter xylinus for 72, 120, and 168 h, used as a carrier support for the immobilization of Saccharomyces cerevisiae. The experiments also included the analysis of glucose consumption and alcohol production during the fermentation process displayed by yeasts immobilized on the BC surface. The results of the present study demonstrate that the number of immobilized yeast cells is dependent on the type of cellulose-synthesizing strain, cellulose form, and duration of its synthesis. The BC in the form of wet membranes obtained after 3 days of synthesis displayed the most favorable properties as a carrier for yeast immobilization. The immobilization of yeast cells on BC, regardless of its form, increased the amount of the produced alcohol as compared to free cells. The yeast cells immobilized in BC were able to multiply on its surface during the fermentation process. 相似文献
84.
Simultaneous separation of 14 antiarrhythmic drugs and determination of mexiletine and flecainide by capillary zone electrophoresis 总被引:1,自引:0,他引:1
A method using capillary zone electrophoresis was developed for the simultaneous separation of 14 antiarrhythmic drugs belonging to various classes. The drugs are separated on a fused-silica capillary, 90 cm x 75 microm (72 cm effective length), with phosphate and acetate buffers as background electrolytes and UV detection at 217 nm. The effects of buffer pH, temperature, and applied voltage on the migration of the drugs were studied. The pH was found to be the most significant factor determining effective separation. The antiarrhythmic compounds are completely separated within a relatively short time (< 7 min) by using 70 mM phosphate buffer at pH 7.91, an applied voltage of 28 kV, and a temperature of 32 degrees C. Mexiletine (MEX) and flecainide (FLE) were quantified under conditions of the optimum separation. The calibration graphs were constructed over the concentration range of 4.0-14.0 microg/mL for both drugs with good correlation (r > or = 0.9999). Detection and quantitation limits were found to be 0.5 and 1.5 microg/mL for FLE and 0.7 and 2.1 microg/mL for MEX, respectively. The proposed method was used for the determination of both drugs in their commercial forms with satisfactory precision (relative standard deviations of 0.36-1.21% for FLE and 0.78-1.66% for MEX) and accuracy (relative standard errors of 0.13-1.17% for FLE and 0.35-1.18% for MEX). 相似文献
85.
Benniston AC Harriman A Rewinska DB Yang S Zhi YG 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(36):10194-10203
The synthesis is described for a small series of oligomers built from (2, 3, 4 or 6) ethynyl-naphthalene repeat units and end-capped with solubilising 1,2,3-tris-dodecyloxy-benzene groups. These compounds absorb in the near-UV region and exhibit strong fluorescence in both fluid solution and a glassy matrix at 77 K. The spectral profiles are fully consistent with a structurally heterogeneous ground state becoming more planar upon excitation and with the low-temperature glass further stabilising the co-planar orientation. The absorption and fluorescence maxima move towards lower energy with increasing number of repeat units and there is a corresponding increase in the Huang-Rhys factor for the radiative process. The non-radiative rate constants also depend on molecular length and are well explained in terms of the energy-gap law. In contrast, very weak phosphorescence is observed at 77 K for which the peak maximum and lifetime remain insensitive to the number of naphthalene units. The triplet lifetimes recorded at ambient temperature are also independent of the molecular length but the triplet-triplet absorption spectra change throughout the series. These results are discussed in terms of the degree of electronic coupling between adjacent repeat units for each of the relevant excited states. During these studies it was noted that the rate of intersystem crossing to the triplet manifold is but weakly affected by heavy-atom perturbers. A non-fluorescent complex is formed between iodoethane and the molecular rod but the corresponding bimolecular process occurs at well below the diffusion-controlled limit. This behaviour is considered in terms of spin-orbit coupling between the excited states and takes account of the differing conjugation lengths. 相似文献
86.
Dorota Prukala 《Journal of heterocyclic chemistry》2007,44(5):1207-1211
87.
The use of protonated l-prolinethioamide instead of the free base derivative 1 as the organocatalyst for the direct aldol addition has a profound and appreciable effect on both the yield and the stereochemical course of the reaction. 4-Nitrobenzaldehyde (2) reacts with acetone in the presence of the protonated catalyst 1.TFA, affording aldol product 3 with a yield up to 99% and an ee up to 98%. The catalyst loading can be lowered to 2.5 mol %. More than 20 different acids were investigated as an additive, and its role as cocatalyst has been discussed. Furthermore, reactions of l-prolinethioamide salts with acetone have been monitored using ESI-MS and 1H NMR techniques, giving insight into the mechanism of the direct aldol reaction. The presumed formation of the iminium salt 10 has been unambiguously confirmed. 相似文献
88.
Cristiano A Lim CW Rozkiewicz DI Reinhoudt DN Ravoo BJ 《Langmuir : the ACS journal of surfaces and colloids》2007,23(17):8944-8949
This paper describes the adsorption and spreading of beta-cyclodextrin (CD) vesicles on hydrophobic and hydrophilic substrates, which involves a transition from bilayer vesicles to planar molecular monolayers or bilayers. On substrates that are patterned with self-assembled monolayers by microcontact printing (muCP), the CD vesicles preferentially adsorb on hydrophobic areas instead of hydrophilic (nonionic) areas, and on cationic areas instead of hydrophilic (nonionic) areas. Supported monolayers of amphiphilic cyclodextrins CD1 and CD2 were obtained by adsorption of CD vesicles to hydrophobic substrates, and supported bilayers of amphiphilic cyclodextrins CD1 and CD2 were prepared by adsorption of CD vesicles on cationic substrates. Contact angle goniometry, atomic force microscopy and confocal fluorescence microscopy (CFM) were used to analyze the supported CD layers. The fluidity of the supported CD layers was verified using fluorescence recovery after photobleaching experiments. The supported layers function as a supramolecular platform that can bind suitable guest molecules through inclusion in the CD host cavities. Additionally, the CD host layers were patterned with fluorescent guest molecules by supramolecular muCP on the supported CD layers. The host-guest interactions were investigated with CFM and fluorescence resonance energy transfer experiments. 相似文献
89.
Thid D Bally M Holm K Chessari S Tosatti S Textor M Gold J 《Langmuir : the ACS journal of surfaces and colloids》2007,23(23):11693-11704
The influence of lateral ligand mobility on cell attachment and receptor clustering has previously been explored for membrane-anchored molecules involved in cell-cell adhesion. In this study, we considered instead a cell binding motif from the extracellular matrix. Even though the lateral mobility of extracellular matrix ligands in membranes does not occur in vivo, we believe it is of interest for cell engineering in vitro. As is the case for cell-cell adhesion molecules, lateral mobility of extracellular matrix ligands could influence cell attachment and, subsequently, cell behavior in cell culture. In this paper, the accessibility and functionality of extracellular matrix ligands presented at surfaces were evaluated for the conditions of laterally mobile versus non-mobile ligands by studying ligand-antibody binding events and early cell attachment as a function of ligand concentration. We compare the initial attachment of rat-derived adult hippocampal progenitor (AHP) cells on laterally mobile, supported phospholipid bilayer membranes to non-mobile, poly-L-lysine-grafted-poly(ethylene glycol) (PLL-g-PEG) polymer films functionalized with a range of laminin-derived IKVAV-containing peptide densities. To this end, synthesis of a new PLL-g-PEG/PEG-IKVAV polymer is described. The characterization of available IKVAV peptides on both surface presentations schemes was explored by studying the mass uptake of anti-IKVAV antibodies using a combination of the surface-sensitive techniques quartz crystal microbalance with dissipation monitoring, surface plasmon resonance spectroscopy, and optical waveguide lightmode spectroscopy. IKVAV-containing peptides presented on laterally mobile, supported phospholipid bilayers and non-mobile PLL-g-PEG were recognized by the anti-IKVAV antibody in a dose-dependent manner, indicating that the amount of available IKVAV ligands increases proportionally with ligand density over the concentrations tested. Attachment of AHP cells to IKVAV-functionalized PLL-g-PEG and supported phospholipid bilayers followed a sigmoidal dependence on peptide concentration, with a critical concentration of approximately 3 pmol/cm2 IKVAV ligands required to support initial AHP cell attachment for both surface modifications. There appeared to be little influence of IKVAV peptide mobility on the initial attachment of AHP cells. Although the spread in the cell attachment data was larger for the PLL-g-PEG surface modification, this was reduced when observed after 24 h, indicating that the cells might need longer times to establish attachment strengths equivalent to those observed on peptide-functionalized supported lipid bilayers. The present study is a step toward understanding the influence of extracellular-matrix-derived ligand mobility on cell fate. Further analysis should focus on the systematic tuning of lateral ligand diffusion, as well as a comparison between the response of non-spreading cells (i.e., AHPs), versus spreading cells (i.e., fibroblasts). 相似文献
90.
DHA-induced changes of supported lipid membrane morphology 总被引:1,自引:0,他引:1
Thid D Benkoski JJ Svedhem S Kasemo B Gold J 《Langmuir : the ACS journal of surfaces and colloids》2007,23(11):5878-5881
Docosahexaenoic acid (DHA) is a polyunsaturated long fatty acid known to have fundamental effects on cell membrane function. Here, the effect of DHA on phosphocholine-supported lipid bilayers was measured using the quartz crystal microbalance with dissipation monitoring (QCM-D) technique. Above a concentration of 60 muM (i.e., near the critical micelle concentration), DHA had drastic effects on the viscoelastic properties of the supported membranes, suggesting a more complex process and structure than simple insertion of molecules in the bilayer. Fluorescence microscopy revealed the spontaneous formation of elongated out-growths from the bilayers, which were remarkable for their length ( approximately 100 mum) and extensive coverage of the surface. These results demonstrate the applicability of QCM-D as a method to screen for conditions where membrane remodeling occurs but also that complementary techniques are required to describe in more detail the changes in viscoelastic properties of the membrane. These results are highly relevant for the present rapid development in the field of model lipid membranes aiming toward increased knowledge about processes occurring at biological surfaces. 相似文献