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791.
Maria Valentina Dinu Simona Schwarz Ionel Adrian Dinu Ecaterina Stela Dr?gan 《Colloid and polymer science》2012,290(16):1647-1657
Ionic semi-interpenetrating polymer networks composite hydrogels were synthesized by free-radical polymerization using dextran sulphate (DxS), acrylamide as monomer and N,N′-methylene(bis)acrylamide as cross-linking agent. The viscoelastic properties of these composite hydrogels were investigated by oscillatory shear measurements under small deformation conditions comparative with those of polyacrylamide gels. Changes of the rheological properties of composite hydrogels have been studied in terms of polymerization temperature, cross-linker ratio, initial monomer concentration and molar mass of DxS. The results showed that the stability of the composite hydrogels obtained at room temperature (22?°C) was relatively low because the storage modulus (G′) was only eight times higher than the loss modulus (G″), while for those obtained by cryopolymerization (?18?°C), the stability was improved, the G′ values being about 30 times higher than those of G″. This behaviour indicated that, by conducting the synthesis of hydrogels below the freezing point of the reaction solutions, an enhancement of the hydrogels elasticity was achieved. The network parameters, i.e. the average molecular weight between two cross-links and the cross-link density of the composite hydrogels prepared at ?18?°C, were estimated from rheological data. 相似文献
792.
Simona C?nt?-P?nzaru Cristina A Dehelean Codruta Soica Monica Culea Florin Borcan 《Chemistry Central journal》2012,6(1):1-12
A new simple, rapid and sensitive reversed-phase liquid chromatographic method was developed and validated for the simultaneous determination of sulpiride (SUL) and mebeverine Hydrochloride (MEB) in the presence of their impurities and degradation products. The separation of these compounds was achieved within 6 min on a 250 mm, 4.6 mm i.d., 5 m particle size Waters?-C18 column using isocractic mobile phase containing a mixture of acetonitrile and 0.01 M dihydrogenphosphate buffer (45:55) at pH = 4.0. The analysis was performed at a flow rate of 1.0 mL/min with fluorescence-detection at excitation 300 nm and emission at 365 nm. The concentration-response relationship was linear over a concentration range of 10- 100 ng/mL for both MEB and SUL with a limit of detection 0.73 ng/mL and 0.85 ng/mL for MEB and SUL respectively. The proposed method was successfully applied for the analysis of both MEB and SUL in bulk with average recoveries of 100.22 ± 0.757% and 99.96 ± 0.625% respectively, and in commercial tablets with average recoveries of 100.04 ± 0.93% and 100.03 ± 0.376% for MEB and SUL respectively. The proposed method was successfully applied to the determination of MEB metabolite (veratic acid) in real plasma simultaneously with SUL. The mean% recoveries (n = 3) for both MEB metabolite (veratic acid) and SUL were 100.36 ± 2.92 and 99.06 ± 2.11 for spiked human plasma respectively. For real human plasma, the mean% recoveries (n = 3) were and respectively. 相似文献
793.
Luigi Battaglia Elena Peira Simona Sapino Marina Gallarate 《Journal of Dispersion Science and Technology》2013,34(4):565-569
8-Methoxsalen was vehicled in nanoemulsion and in solid lipid nanoparticles (SLN) prepared by the hot homogenization technique in order to be used in topical psoralen UVA (PUVA) therapy. Drug entrapment efficiency in nanoparticles was improved by choosing the appropriate lipid matrix. The use of α-tocopherol in the lipid phase reduces 8-methoxsalen induced photooxidation of porcine skin, which was evaluated in vitro by a malondialdehyde (MDA) test: This result is promising to reduce in vivo human skin irritation after PUVA therapy, which can be attributed to skin photooxidation. 相似文献
794.
Tacke R Bertermann R Burschka C Dragota S Penka M Richter I 《Journal of the American Chemical Society》2004,126(44):14493-14505
A series of zwitterionic lambda(5)Si-silicates with a (2,2,6,6-tetramethylpiperidinio)methyl group and two identical bidentate ligands derived from glycine, (S)-alanine, (S)-phenylalanine, glycolic acid, (S)-lactic acid, (S)-3-phenyllactic acid, or (S)-mandelic acid were synthesized and structurally characterized (solution and solid-state NMR spectroscopy; single-crystal X-ray diffraction). The chiral lambda(5)Si-silicates with ligands derived from optically active alpha-amino acids or alpha-hydroxycarboxylic acids were isolated as enantiomerically and diastereomerically pure compounds that undergo a (Lambda)/(Delta)-epimerization in solution. 相似文献
795.
Eleonora Polo Simona Losio Maria Carmela Sacchi Maurizio Galimberti 《Journal of polymer science. Part A, Polymer chemistry》2013,51(6):1436-1447
New ω‐alkenyl‐substituted ansa‐bridged bisindenyl zirconium complexes are prepared and tested as self‐immobilized catalysts for ethene polymerization. But, even at very high concentration of the tethered complexes and low pressure of ethene, there is no evidence of their insertion into the polyethene chain. A “cross polymerization” test, performed by copolymerizing the tethered complexes with ethene using rac‐Me2Si(2‐MeBenzInd)2ZrCl2 ( MBI ), does not lead to their incorporation into the polyethene chain. However, the corresponding ligand proves to be a suitable comonomer for ethene, and, through copolymerization promoted by MBI, innovative poly(ethene‐co‐2,2′‐bis[(1H‐inden‐3′‐yl)‐hex‐5‐ene) copolymers are prepared and characterized by 13C NMR. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
796.
797.
Treatment with lignin residue 总被引:1,自引:0,他引:1
Björklund Linda Larsson Simona Jönsson Leif J. Reimann Anders Nivebrant Nils-Olof 《Applied biochemistry and biotechnology》2002,98(1-9):563-575
Acid hydrolysis of lignocellulose to hydrolysates intended for production of fuel ethanol results in the formation of byproducts
in addition to fermentable sugars. Some of the byproducts, such as phenolic compounds and furan aldehydes, are inhibitory
to the fermenting microorganism. Detoxification of the hydrolysates may be necessary for production of ethanol at a satisfactory
rate and yield. The lignin residue obtained after hydrolysis is a material with hydrophobic properties that is produced in
large amounts as a byproduct within an ethanol production process based on lignocellulosic raw materials. We have explored
the possibility of using this lignin residue for detoxification of spruce dilute-acid hydrolysates prior to fermentation with
Saccharomyces cerevisiae. Three dilute-acid hydrolysates of spruce were treated with lignin residue, which in all cases resulted in improved fermentability
in terms of productivity and yield of ethanol. The effect was improved by washing the lignin before treatment, by using larger
amounts of lignin in the treatment, and by performing the treatment at low temperature. Treatment with the lignin residue
removed up to 53% of the phenolic compounds and up to 68% of the furan aldehydes in a spruce dilute-acid hydrolysate. A larger
fraction of furfural was removed compared to the less hydrophobic 5-hydroxymethylfurfural. 相似文献
798.
Joanna Anastassopoulou Evridiki Boukaki Carla Conti Paolo Ferraris Elisabetta Giorgini Corrado Rubini Simona Sabbatini Teo Theophanides Giorgio Tosi 《Vibrational Spectroscopy》2009,51(2):270-275
Microimaging Fourier transform infrared spectroscopy is able to monitor differentiation between normal and malignant tissues. All the specimens, previously submitted to histological analysis, displayed abnormal spectra compared with the corresponding normal tissues with changes in many diagnostic bands like those arising from phosphate, C–O and CH stretching vibrational modes. The comparison between cancer (K) and connective (C) spectra evidenced the following differences: in the vCH region 3000–2800 cm−1 no hypomethylation effect was evident in K; the convolution of the bands of connective indicated an expected higher membrane fluidity; in the neoplastic zone, Amide I and II modes showed convoluted bands with maxima at 1651 and 1547 cm−1, respectively, indicating an α-helix conformation of proteins due to changes in the secondary structure proteins upon carcinogenesis. Other signature bands, such as the deformation O–P–O phosphate band at 965 cm−1, suggested DNA conformational changes in solid cancer, infiltrating cancer and neoplasia in the region 1350–800 cm−1. These characteristic bands have been monitored as a function of the degree of cancer progression. Chemometric methods, such as principal component analysis (PCA) and hierarchical clustering analysis (HCA) have been used in order to distinguish spectra of neoplastic and normal zones. 相似文献
799.
Andreina Ricci Simona Piccolella Antonio Fiorentino Federico Pepi Brigida D'Abrosca Pietro Monaco 《Rapid communications in mass spectrometry : RCM》2010,24(11):1543-1556
Mass spectrometric fragmentation data of neo‐clerodane diterpenes are almost inexistent but they can prove helpful for the qualitative and quantitative analysis of these compounds as well as for the identification of unknown compounds belonging to this class of plant secondary metabolites. [M–H]– ions of nine neo‐clerodane diterpenes (1–9), recently isolated from Teucrium chamaedrys, were generated by electrospray ionization and were fragmented in the collision cell of a Triple Quadrupole (TQ) and of a Quadrupole Ion Trap (QIT) mass spectrometer. The deprotonated neo‐clerodane glucosides, chamaedryoside A and B (1, 2), readily lost the sugar residue to give, as their main fragmentation channel, the neo‐clerodane ions, I and II, which were structurally characterized by TQ and QIT MS. The collision‐activated dissociation (CAD) mass spectra of I and II and of deprotonated neo‐clerodanes 3–9 allowed us to reach some general conclusions on the fragmentation pathways of this class of compounds. For example, teuflin and its OH derivatives, teucrin A, teuflidin and 6‐β‐hydroxyteucridin, showed a characteristic fragmentation pattern involving the loss of 94 Da and 124 Da from the lactone moiety, whereas a loss of 44 Da was observed for teucrin E, and of 58 Da for teucrin F and G. In addition, several compound‐specific fragmentations were observed and can be proposed for the identification of individual compounds. The systematic approach allowed us to hypothesize the mechanisms of the most important collision‐activated dissociation/isomerization channels. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
800.
Marko kof Jurij Svete Branko Stanovnik Ljubo Goli
Simona Goli
-Grdadolnik Lovro Seli
《Helvetica chimica acta》1998,81(12):2332-2340
(5S)-1-Benzoyl-3-[(E)-cyanomethylidene]-5-(methoxycarbonyl)pyrrolidin-2-one ( 5 ) was prepared in four steps from L -pyroglutamic acid ( 1 ). 1,3-Dipolar cycloadditions of diazomethane ( 6 ) and 2,4,6-trimethoxybenzonitrile oxide ( 7 ) gave substituted 1,2,7-triazaspiro[4.4]non-1-en-6-one 12 and 1-oxa-2,7-diazaspiro[4,4]non-1-en-6-one 13 in 38 and 20% de, respectively. On the other hand, reaction of 5 with N-phenylbenzonitrile imines 8 and 9 , generated in situ from the corresponding hydrazonoyl chlorides 10 and 11 , respectively, and Et3N, furnished racemic pyrrolo[3,4-c]pyrazoles 14 and 15 in 61 and 56% de, respectively. Cycloaddition of nitrile oxide 7 , when performed in the presence of Et3N, led to pyrrolo[3,4-d]isoxazole 16 in 85% de. 相似文献