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51.
Ghizlane Choukrani Jimena Álvarez Freile Natasha Ustyanovska Avtenyuk Wei Wan Kerstin Zimmermann Edwin Bremer Lars Dähne 《Particle & Particle Systems Characterization》2021,38(7):2100012
Nanoparticles may limit off-tumor/on-target ubiquitous activation of signaling by protein-based drugs. However, many challenges still exist in the design of a nanoparticle for protein delivery. In this study, conditions to establish vaterite nanoparticles as a pH-sensitive drug delivery system (DDS) for encapsulated protein drugs are comprehensively evaluated. Low coprecipitation pH of vaterite and protein prevents protein denaturation and yields high loading efficiency. Unprotected vaterite recrystallizes in aqueous solutions within 3 h to calcite and releases the loaded protein completely, but surface-modified particles with carboxyl groups containing polymers prove stable for more than 5 months. Notably, modification of vaterite with sulfonated polymers increases the loading of cationic proteins by a multiple. A system is developed for vaterite exposure to (pH) conditions under body-like-flow rates, with the dissolution of vaterite and simultaneous release of active proteins at tumor microenvironmental pH reaching up to 80% and only 20% at physiological pH within 2 h. Importantly, the immunomodulatory protein tumor necrosis factor preserves its native structure and fully retains functional activity in vitro after release from the particles. In conclusion, the studies described here provide a framework for the development of vaterite-based DDS as a carrier for bioactive protein-based therapeutics. 相似文献
52.
Prof. Javier A. Cabeza Dr. Pablo García‐Álvarez Dr. Enrique Pérez‐Carreño Dr. Vanessa Pruneda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(10):3426-3436
The methylation of the uncoordinated nitrogen atom of the cyclometalated triruthenium cluster complexes [Ru3(μ‐H)(μ‐κ2N1,C6‐2‐Mepyr)(CO)10] ( 1 ; 2‐MepyrH=2‐methylpyrimidine) and [Ru3(μ‐H)(μ‐κ2N1,C6‐4‐Mepyr)(CO)10] ( 9 ; 4‐MepyrH=4‐methylpyrimidine) gives two similar cationic complexes, [Ru3(μ‐H)(μ‐κ2N1,C6‐2,3‐Me2pyr)(CO)10]+( 2 +) and [Ru3(μ‐H)(μ‐κ2N1,C6‐3,4‐Me2pyr)(CO)10]+ ( 9 +), respectively, whose heterocyclic ligands belong to a novel type of N‐heterocyclic carbenes (NHCs) that have the Ccarbene atom in 6‐position of a pyrimidine framework. The position of the C‐methyl group in the ligands of complexes 2 + (on C2) and 9 + (on C4) is of key importance for the outcome of their reactions with K[N(SiMe3)2], K‐selectride, and cobaltocene. Although these reagents react with 2 + to give [Ru3(μ‐H)(μ‐κ2N1,C6‐2‐CH2‐3‐Mepyr)(CO)10] ( 3 ; deprotonation of the C2‐Me group), [Ru3(μ‐H)(μ3‐κ3N1,C5,C6‐4‐H‐2,3‐Me2pyr)(CO)9] ( 4 ; hydride addition at C4), and [Ru6(μ‐H)2{μ6‐κ6N1,N1′,C5,C5′,C6,C6′‐4,4′‐bis(2,3‐Me2pyr)}(CO)18] ( 5 ; reductive dimerization at C4), respectively, similar reactions with 9 + have only allowed the isolation of [Ru3(μ‐H)(μ3‐κ2N1,C6‐2‐H‐3,4‐Me2pyr)(CO)9] ( 11 ; hydride addition at C2). Compounds 3 and 11 also contain novel six‐membered ring NHC ligands. Theoretical studies have established that the deprotonation of 2 + and 9 + (that have ligand‐based LUMOs) are charge‐controlled processes and that both the composition of the LUMOs of these cationic complexes and the steric protection of their ligand ring atoms govern the regioselectivity of their nucleophilic addition and reduction reactions. 相似文献
53.
Abachi S Abbott B Abolins M Acharya BS Adam I Adams DL Adams M Ahn S Aihara H Alitti J Álvarez G Alves GA Amidi E Amos N Anderson EW Aronson SH Astur R Avery RE Baden A Balamurali V Balderston J Baldin B Bantly J Bartlett JF Bazizi K Bendich J Beri SB Bertram I Bezzubov VA Bhat PC Bhatnagar V Bhattacharjee M Bischoff A Biswas N Blazey G Blessing S Boehnlein A Bojko NI Borcherding F Borders J Boswell C Brandt A Brock R Bross A Buchholz D Burtovoi VS Butler JM Casey D Castilla-Valdez H 《Physical review letters》1995,75(6):1023-1027
54.
Lignocellulose–pitch-based composites carbonized at 1000 °C were easily prepared by blending lignocellulose with pretreated pitch in a proportion of 50:50 wt.%. The pretreatment of the pitch was carried out by thermal treatment at temperatures of 250 and 350 °C, both in the absence and in the presence of 10 wt.% of alumina of different surface activities (acid, neutral and basic). The structural and mechanical properties of the composites, evaluated by means of density/porosity determinations, optical microscopy and flexural strength, were found to be enhanced by the presence of alumina. The effects of the addition of alumina in the composite were evaluated by means of thermogravimetric analyses. The results indicate that alumina surface activity plays an important role in the interactions between the composite components. Neutral alumina has the greatest effect during the pretreatment, while acid alumina favors lignocellulose–pitch interactions during the processing of the composite. These effects are more pronounced when the pretreatment is performed at 350 °C. Lignocellulose–pitch-based composites with a water density of 1.75 g cm−3, a porosity of 30 vol.% and a flexural strength of 30 MPa can be obtained when the pitch is pretreated in the presence of neutral alumina. 相似文献
55.
Maria José González-álvarez José Vicente Carmen Ortiz Mellet José Maria García Fernández Francisco Mendicuti 《Journal of fluorescence》2009,19(6):975-988
The thermodynamics of the dimer formation of 2I,3I-O-(o-xylylene)-per-O-Me-γ-cyclodextrin (XmγCD) in aqueous solution was studied by fluorescence techniques, Molecular Mechanics and Molecular Dynamics. Lifetime averages
á t
ñ \left\langle \tau \right\rangle , obtained from fluorescence decay profiles upon excitation of the xylylene appended group, were used as the property sensitive
to the association process. The dimerization equilibrium constants (K
D) were obtained from non-linear regression analysis of the plots of
á t
ñ \left\langle \tau \right\rangle against [XmγCD] at several temperatures and they were compared with the values obtained for the counterparts Xmα- and XmβCDs. The van’t Hoff plot allows us to obtain the ΔH and ΔS showing that the dimerization process was also entropically disfavoured. Molecular Mechanics as well as Molecular Dynamics
calculations in the presence of water were also employed to study the conformational behaviour of isolated XmγCDs, the possible structure of the dimers formed and the driving forces involved in such association processes. Results indicate
that those conformations where Xy moiety does not block the cavity entrance are favoured. Dimers are preferably formed by
head-to-head CD approaching. However, the formation of stable head-to-tail is not dismissed. 相似文献
56.
Alfonso Miranda-Molina Agustín López-Munguía María Luisa San Román Jaime Escalante Marco Antonio Leyva Ana María Puebla Edmundo Castillo Laura Álvarez 《Tetrahedron: Asymmetry》2010,21(1):43-50
The monoglucosyl-inositols α-d-glucopyranosyl-(1→4)-4d-myo-inositol 3 and α-d-glucopyranosyl-(1→1)-1d-myo-inositol 4 were synthesized by a combined enzymatic transglucosylation and hydrolysis strategy, using cyclodextrin glucosyl transferase (CGTase) from Thermoanaerobacter sp., followed by hydrolysis with Aspergillus niger glucoamylase. The glucosides were separated by preparative HPLC and fully characterized by extensive 1D and 2D NMR studies. The structure of the regioisomer 4 was confirmed by X-ray crystallography of its perbenzoylated derivative 4a. Both isomers demonstrated in vivo anti-inflammatory activity at comparative levels to corticosterone on mouse ear oedema induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) and in rat hind paw oedema induced by carrageenan. 相似文献
57.
Natalia Irishina Diego lvarez Oliver Dorn Miguel Moscoso 《Mathematical and Computer Modelling》2009,50(5-6):743
In this paper we investigate the performance of a shape-reconstruction technique as tested on the ‘Marseille data’. This approach, which is based on a level set technique, offers several advantages compared to other approaches, as for example well-defined boundaries and the incorporation of an intrinsic regularization in the form of a priori assumptions regarding the general structures in the medium. The level set strategy (which is an implicit representation of the shapes) frees us from topological restrictions during this reconstruction process. Our algorithm is aiming at, not only detecting the objects, but simultaneously determining their approximate locations, sizes and dielectric properties. The numerical experiments show the utility of this method. 相似文献
58.
Experimental design for optimization of microwave-assisted extraction of benzodiazepines in human plasma 总被引:1,自引:0,他引:1
P. Fernández C. Vázquez R. A. Lorenzo A. M. Carro I. Álvarez P. Cabarcos 《Analytical and bioanalytical chemistry》2010,397(2):677-685
A simple and fast microwave-assisted-extraction (MAE) method has been evaluated as an alternative to solid-phase extraction
(SPE) for the determination of six benzodiazepines widely prescribed in European countries (alprazolam, bromazepam, diazepam,
lorazepam, lormetazepam and tetrazepam) in human plasma. For MAE optimization a Doehlert experimental design was used with
extraction time, temperature and solvent volume as influential parameters. A desirability function was employed in addition
to the simultaneous optimization of the MAE conditions. The analysis of variance showed that the solvent volume had a positive
influence on the extraction of all the analytes tested, achieving a statistically significant effect. Also, the extraction
time had a statistically significant effect on the extraction of four benzodiazepines. The selected MAE conditions—89 °C,
13 min and 8 mL of chloroform/2-propanol (4:1, v/v)—led to recoveries between 89.8 ± 0.3 and 102.1 ± 5.2% for benzodiazepines
using a high performance liquid chromatography method coupled with diode-array detection. The comparison of MAE and SPE shows
better results for MAE, with a lower number of steps in handling the sample and greater efficiency. The applicability of MAE
was successfully tested in 27 plasma samples from benzodiazepine users. 相似文献
59.
60.
Justicia J Álvarez de Cienfuegos L Campaña AG Miguel D Jakoby V Gansäuer A Cuerva JM 《Chemical Society reviews》2011,40(7):3525-3537
This tutorial review highlights the development of radical-based bioinspired synthesis of terpenes from the initial proposal to the development of modern catalytic methods for performing such processes. The power of the radical approach is demonstrated by the straightforward syntheses of many natural products from readily available starting materials. The efficiency of these processes nicely complements the described cationic polyolefin cyclisations and even suggests that modern radical methods provide means to improve upon nature's synthetic pathways. 相似文献