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排序方式: 共有171条查询结果,搜索用时 484 毫秒
91.
Hoegger D Morier P Vollet C Heini D Reymond F Rossier JS 《Analytical and bioanalytical chemistry》2007,387(1):267-275
A micro-analytical system for rapid and quantitative analysis by inhibition immunoassay is presented and applied to the detection of folic acid. Eight polymer microchannels of 65-nL volume each and containing microelectrodes are embedded in a cartridge so that they can be operated simultaneously. All fluidic steps as well as the amperometric detection in the channels are operated by an instrument and software developed in-house. The fluidic steps of the immunoassay occur through hydrodynamic loading of the different solutions through the channels. The speed and duration of the flow and incubation parameters can thus be adapted to the biological and testing requirements. The effectiveness of the system was demonstrated by analysing folic acid concentrations in real infant formula samples within 5 min. In an effort to get a fully monitored assay, each fluidic step is monitored thanks to continuous amperometric detection of oxygen in the microchannel. 相似文献
92.
(1R,2R,3R,4S,5R)-4-amino-5-methylcyclopentane-1,2,3-triol ( 1 ) was prepared stereoselectively from D -ribose (Scheme). Aminocyclopentanetriol 1 , which by its design may be considered an analog of the fucosyl cation, inhibits α-L -fucosidase selectively (Ki=28 μM ) over α- and β-glucosidase, α- and β-mannosidase, and α- and β-galactosidase (Table). 相似文献
93.
Aminocyclopentitol analogs of α‐L ‐fucose were synthesized stereoselectively from D ‐ribose. Alkyl substituents were attached at the NH2 group to mimic the glycosidic leaving group. The resulting (alkylamino)cyclopentitols inhibited α‐L ‐fucosidases selectively with inhibition constants in the range of Ki=10−7 M . Comparisons with stereoisomers and acyclic analogs showed that this inhibition only occurs with N‐alkyl substitution and proper configuration at the cyclopentane, as expected for transition‐state‐analog‐type inhibition. These observations were supported by molecular‐modeling comparisons between inhibitor and transition state. 相似文献
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96.
Mayya Sundukova Efthymia Prifti Annalisa Bucci Kseniia Kirillova Joana Serrao Luc Reymond Miwa Umebayashi Ruud Hovius Howard Riezman Kai Johnsson Paul A. Heppenstall 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(8):2363-2366
Optical monitoring of neuronal voltage using fluorescent indicators is a powerful approach for the interrogation of the cellular and molecular logic of the nervous system. Herein, a semisynthetic tethered voltage indicator (STeVI1) based upon nile red is described that displays voltage sensitivity when genetically targeted to neuronal membranes. This environmentally sensitive probe allows for wash‐free imaging and faithfully detects supra‐ and sub‐threshold activity in neurons. 相似文献
97.
Hydrogenic (two-body) systems are the only atomic systems for which uncertainties in calculations of the energy levels approach the current state of the art in frequency measurement. This article discusses progress in the theory and measurement of transition frequencies in hydrogenic systems. These studies have relevance to the determination of fundamental constants and the testing of physical theories, especially quantum electrodynamics. A set of high accuracy calculable frequency standards could also be realized by using hydrogenic systems. 相似文献
98.
Solid phase peptide synthesis (SPPS) provides peptides with a dendritic topology when diamino acids are introduced in the sequences. Peptide dendrimers with one to three amino acids between branches can be prepared with up to 38 amino acids (MW ~ 5,000 Da). Larger peptide dendrimers (MW ~ 30,000) were obtained by a multivalent chloroacetyl cysteine (ClAc) ligation. Structural studies of peptide dendrimers by CD, FT-IR, NMR and molecular dynamics reveal molten globule states containing up to 50% of α-helix. Esterase and aldolase peptide dendrimers displaying dendritic effects and enzyme kinetics (k(cat)/k(uncat) ~ 10(5)) were designed or discovered by screening large combinatorial libraries. Strong ligands for Pseudomonas aeruginosa lectins LecA and LecB able to inhibit biofilm formation were obtained with glycopeptide dendrimers. Efficient ligands for cobalamin, cytotoxic colchicine conjugates and antimicrobial peptide dendrimers were also developed showing the versatility of dendritic peptides. Complementing the multivalency, the amino acid composition of the dendrimers strongly influenced the catalytic or biological activity obtained demonstrating the importance of the "apple tree" configuration for protein-like function in peptide dendrimers. 相似文献
99.
J Gallon J Esteban S Bouzbouz M Campbell S Reymond J Cossy 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(37):11788-11797
A formal convergent synthesis of dictyostatin from (R)-Roche ester is described. Synthetic highlights include a Ni-catalyzed Nozaki-Hiyama-Kishi coupling between an aldehyde and a Z vinyl iodide to assemble the two main fragments, a diastereoselective Myers alkylation, a stereoselective Evans aldolization, two asymmetric Duthaler crotyltitanations, and a stereoselective Pd-catalyzed Marshall allenylindium addition to install the stereogenic centers of dictyostatin. The synthesis of (9R)-epi-dictyostatin and a new ring-contracted dictyostatin isomer were also achieved. 相似文献
100.