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排序方式: 共有343条查询结果,搜索用时 15 毫秒
241.
Sreenath Nair Abigail Davis Olivia Campagne John D. Schuetz Clinton F. Stewart 《Molecules (Basel, Switzerland)》2022,27(17)
IWR-1-endo, a small molecule that potently inhibits the Wnt/β-catenin signaling pathway by stabilizing the AXIN2 destruction complex, can inhibit drug efflux at the blood–brain barrier. To conduct murine cerebral microdialysis research, validated, sensitive, and reliable liquid chromatography–tandem mass spectrometry (LC-MS/MS) methods were used to determine IWR-1-endo concentration in the murine plasma and brain microdialysate. IWR-1-endo and the internal standard (ISTD) dabrafenib were extracted from murine plasma and microdialysate samples by a simple solid-phase extraction protocol performed on an Oasis HLB µElution plate. Chromatographic separation was executed on a Kinetex C18 (100A, 50 × 2.1 mm, 4 µm particle size) column with a binary gradient of water and acetonitrile, each having 0.1% formic acid, pumped at a flow rate of 0.6 mL/min. Detection by mass spectrometry was conducted in the positive selected reaction monitoring ion mode by monitoring mass transitions 410.40 > 344.10 (IWR-1-endo) and 520.40 > 307.20 (ISTD). The validated curve range of IWR-1-endo was 5–1000 ng/mL for the murine plasma method (r2 ≥ 0.99) and 0.5–500 ng/mL for the microdialysate method (r2 ≥ 0.99). The lower limit of quantification (LLOQ) was 5 ng/mL and 0.5 ng/mL for the murine plasma and microdialysate sample analysis method, respectively. Negligible matrix effects were observed in murine plasma and microdialysate samples. IWR-1-endo was extremely unstable in murine plasma. To improve the stability of IWR-1-endo, pH adjustments of 1.5 were introduced to murine plasma and microdialysate samples before sample storage and processing. With pH adjustment of 1.5 to the murine plasma and microdialysate samples, IWR-1-endo was stable across several tested conditions such as benchtop, autosampler, freeze–thaw, and long term at −80 °C. The LC-MS/MS methods were successfully applied to a murine pharmacokinetic and cerebral microdialysis study to characterize the unbound IWR-1-endo exposure in brain extracellular fluid and plasma. 相似文献
242.
Renee L. Timmins Olivia R. Wilson Andrew J. D. Magenau 《Journal of polymer science. Part A, Polymer chemistry》2020,58(10):1463-1471
An alkylborane initiated reversible addition-fragmentation chain transfer (AI-RAFT) process was developed for the synthesis of star-polymers using a one-pot approach at room-temperature in the presence of oxygen. Linear poly(tert-butyl acrylate) arms were first polymerized using a latent trialkylborane-amine initiator, which generated trialkylborane, in situ, and subsequently radicals after reaction with oxygen. Polymerizations were optimized to maximize monomer conversion (~70–80%) and minimize arm-dispersity (~1.10) through the oxygen concentration, initiator concentration, and polymerization time. The oxygen concentration was a critical AI-RAFT parameter, providing maximum conversion at a ~0.5:1 molar ratio of oxygen-to-initiator. After arm-polymerization, multifunctional acrylates were injected into the reactor to commence crosslinking without intermediate purification. The impact of the crosslinking time and the crosslinker's functionality, concentration, and injection time were investigated to enhance arm incorporation and diminish star-polymer dispersity, quantified by deconvolution of size-exclusion chromatography data. Crosslinker concentration had the largest influence on arm conversion with optimal concentrations at a 20-25-fold excess to chain transfer agent. Under optimal conditions, arm conversions were maximized to ~75–85% and star-dispersity minimized to ~1.35–1.50. Herein an initial effort is made toward the synthesis of star-polymers with well-defined structures and high-arm conversions, while also striving for oxygen tolerance, minimal purification, low-temperatures, and metal-free conditions. 相似文献
243.
Dr. Xiaolei Zhu Dr. Guangcan Xu Dr. Lise-Marie Chamoreau Dr. Yongmin Zhang Dr. Virginie Mouriès-Mansuy Prof. Louis Fensterbank Dr. Olivia Bistri-Aslanoff Dr. Sylvain Roland Prof. Matthieu Sollogoub 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(68):15901-15909
A series of water-soluble encapsulated copper(I), silver(I) or gold(I) complexes based on NHC-capped permethylated cyclodextrins ( ICyDMe ) were developed and used as catalysts in pure water for hydration, lactonization, hydroarylation and cycloisomerization reactions. ICyDMe ligands gave cavity-based high regioselectivity in hydroarylations, and high enantioselectivities in gold-catalyzed cycloisomerizations reactions giving up to 98 % ee in water. These ICyDMe are therefore useful ligands for selective catalysis in pure water. 相似文献
244.
Guangcan Xu Dr. Sébastien Leloux Dr. Pinglu Zhang Dr. Jorge Meijide Suárez Dr. Yongmin Zhang Dr. Etienne Derat Dr. Mickaël Ménand Dr. Olivia Bistri-Aslanoff Dr. Sylvain Roland Prof. Tom Leyssens Prof. Olivier Riant Prof. Matthieu Sollogoub 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(19):7661-7667
The encapsulation of copper inside a cyclodextrin capped with an N-heterocyclic carbene (ICyD) allowed both to catch the elusive monomeric (L)CuH and a cavity-controlled chemoselective copper-catalyzed hydrosilylation of α,β-unsaturated ketones. Remarkably, (α-ICyD)CuCl promoted the 1,2-addition exclusively, while (β-ICyD)CuCl produced the fully reduced product. The chemoselectivity is controlled by the size of the cavity and weak interactions between the substrate and internal C−H bonds of the cyclodextrin. 相似文献
245.
Gilda M. Iova Horia Calniceanu Adelina Popa Camelia A. Szuhanek Olivia Marcu Gabriela Ciavoi Ioana Scrobota 《Molecules (Basel, Switzerland)》2021,26(5)
Background: There is a growing interest in the correlation between antioxidants and periodontal disease. In this study, we aimed to investigate the effect of oxidative stress and the impact of two antioxidants, curcumin and rutin, respectively, in the etiopathology of experimentally induced periodontitis in diabetic rats. Methods: Fifty Wistar albino rats were randomly divided into five groups and were induced with diabetes mellitus and periodontitis: (1) (CONTROL)—control group, (2) (DPP)—experimentally induced diabetes mellitus and periodontitis, (3) (DPC)—experimentally induced diabetes mellitus and periodontitis treated with curcumin (C), (4) (DPR)—experimentally induced diabetes mellitus and periodontitis treated with rutin (R) and (5) (DPCR)—experimentally induced diabetes mellitus and periodontitis treated with C and R. We evaluated malondialdehyde (MDA) as a biomarker of oxidative stress and reduced glutathione (GSH), oxidized glutathione (GSSG), GSH/GSSG and catalase (CAT) as biomarkers of the antioxidant capacity in blood harvested from the animals we tested. The MDA levels and CAT activities were also evaluated in the gingival tissue. Results: The control group effect was statistically significantly different from any other groups, regardless of whether or not the treatment was applied. There was also a significant difference between the untreated group and the three treatment groups for variables MDA, GSH, GSSG, GSH/GSSG and CAT. There was no significant difference in the mean effect for the MDA, GSH, GSSG, GSH/GSSG and CAT variables in the treated groups of rats with curcumin, rutin and the combination of curcumin and rutin. Conclusions: The oral administration of curcumin and rutin, single or combined, could reduce the oxidative stress and enhance the antioxidant status in hyperglycemic periodontitis rats. 相似文献
246.
Zachary Mathe Olivia McCubbin Stepanic Sergey Peredkov Serena DeBeer 《Chemical science》2021,12(22):7888
Phosphorus is ubiquitous in biochemistry, being found in the phosphate groups of nucleic acids and the energy-transferring system of adenine nucleotides (e.g. ATP). Kβ X-ray emission spectroscopy (XES) of phosphorus has been largely unexplored, with no previous applications to biomolecules. Here, the potential of P Kβ XES to study phosphate-containing biomolecules, including ATP and NADPH, is evaluated, as is the application of the technique to aqueous solution samples. P Kβ spectra offer a detailed picture of phosphate valence electronic structure, reporting on subtle non-covalent effects, such as hydrogen bonding and ionic interactions, that are key to enzymatic catalysis. Spectral features are interpreted using density functional theory (DFT) calculations, and potential applications to the study of biological energy conversion are highlighted.Phosphorus X-ray emission spectroscopy probes non-covalent interactions and electronic structure of phosphate biomolecules in both solid and solution samples. 相似文献
247.
Tongtong Zhang Dr. Laurent Le Corre Prof. Olivia Reinaud Dr. Benoit Colasson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(1):434-443
The design of biomimetic models of metalloenzymes needs to take into account many factors and is therefore a challenging task. We propose in this work an original strategy to control the second coordination sphere of a metal centre and its distal environment. A biomimetic complex, reproducing the first coordination sphere, is encapsulated in a self-assembled hydrogen-bonded capsule. The cationic complex is co-encapsulated with its counter-anion or with solvent molecules. The capsule is dynamic, allowing a fast in/out exchange of the co-encapsulated species. It also provides both a hydrogen-bonding site in the second coordination sphere and a source of proton as it can be deprotonated in the presence of the complex, providing a globally neutral host-guest assembly. This simple and broad scope strategy is unprecedented in biomimetic studies. The approach appears to be a very promising method for the stabilisation of reactive species and for the study of their reactivity. 相似文献
248.
Olivia Ngeno Chebet Leonidah Kerubo Omosa Sevgan Subramanian Vaderament-A Nchiozem-Ngnitedem John Onyari Mmari Komivi Senyo Akutse 《Molecules (Basel, Switzerland)》2021,26(18)
Endophytic fungal isolates Hypocrea lixii F3ST1 and Beauveria bassiana G1LU3 were evaluated for their potential to endophytically colonize and induce active compounds in Phaseolus vulgaris, as a defense mechanism against pea leafminer (Liriomyza huidobrensis) and fall armyworm (Spodoptera frugiperda). Endophytic colonization was achieved through seed inoculation with the volatile emissions from P. vulgaris plants being analyzed using GC-MS. The crude extracts of P. vulgaris obtained using methanol and dichloromethane were assayed against leafminer and fall armyworm larvae using leaf dipping and topical application, respectively. The two isolates successfully colonized the entire host plant (roots, stems, and leaves) with significant variation (p < 0.001) between fungal isolates and the controls. The results showed qualitative differences in the volatile profiles between the control plants, endophytically colonized and insect-damaged plants attributed to fungal inoculation and leafminer damage. The crude methanol extracts significantly reduced the percentage pupation of 2nd instar leafminer larvae (p < 0.001) and adult-flies emergence (p < 0.05). The survival of the 1st instar fall armyworm larvae was also significantly reduced (p < 0.001) compared to the controls. This study demonstrated the high potential of endophytic fungi H. lixii and B. bassiana in inducing mainly specific defense compounds in the common bean P. vulgaris that can be used against pea leafminer and fall armyworm. 相似文献
249.
Abstract— Simple measurement of germicidal (2537 Å) u.v. in a geometrically complex system is described. The radiant energy incident upon thin egg white films in a rapidly spinning centrifuge was integrated over time periods with NBS light-sensitive paper. The radiant killing of contaminant Salmonella was found to be one microorganism per 1011 quanta absorbed by the medium. 相似文献
250.
Patil AV Premaraban T Berthoumieu O Watts A Davis JJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(18):5632-5636
Bacteriorhodopsin, BR, is a natural, photoresponsive, biomolecule that has potential application in data storage, imaging and sensing. Being membrane-bound, however, it is coupled with metallic electronic surfaces only with some difficulty. We report herein a facile method to generate uniformly orientated, anchored and active monolayers of BR on metallic electrodes. In the present study, the cytoplasmic side of the BR is equipped with an engineered cysteine to achieve largely lipid-free, orientation-specific, highly stable, covalent immobilization on gold surfaces. By using non-invasive Kelvin probe force microscopy, it is possible to measure the light-induced proton accumulation at the extracellular protein surface at truly molecular scales. The intimate probe-BR interaction possible on lipid removal facilitates the detection of photoinduced surface potential switching substantially larger ((20.4 ± 7.5) mV) with functional single delipidated mutant BR trimers than for the wild-type protein. The proton pumping detected is also notably highly unidirectional with the orientated protein. 相似文献