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401.
Isolation,Structure Elucidation,and (Bio)Synthesis of Haprolid,a Cell‐Type‐Specific Myxobacterial Cytotoxin
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Heinrich Steinmetz Dr. Jun Li Dr. Chengzhang Fu Dr. Nestor Zaburannyi Dr. Birgitte Kunze Dr. Kirsten Harmrolfs Viktoria Schmitt Dr. Jennifer Herrmann Prof. Dr. Hans Reichenbach Prof. Dr. Gerhard Höfle Prof. Dr. Markus Kalesse Prof. Dr. Rolf Müller 《Angewandte Chemie (International ed. in English)》2016,55(34):10113-10117
Myxobacteria are well‐established sources for novel natural products exhibiting intriguing bioactivities. We here report on haprolid ( 1 ) isolated from Byssovorax cruenta Har1. The compound exhibits an unprecedented macrolactone comprising four modified amino acids and a polyketide fragment. As configurational assignment proved difficult, a bioinformatic analysis of the biosynthetic gene cluster was chosen to predict the configuration of each stereocenter. In‐depth analysis of the corresponding biosynthetic proteins established a hybrid polyketide synthase/nonribosomal peptide synthetase origin of haprolid and allowed for stereochemical assignments. A subsequent total synthesis yielded haprolid and corroborated all predictions made. Intriguingly, haprolid showed cytotoxicity against several cell lines in the nanomolar range whereas other cells were almost unaffected by treatment with the compound. 相似文献
402.
We report here the first example of an SRN1 reaction on propargylic chloride in heterocyclic series. The reaction of 4-(3-chloroprop-1-ynyl)-1,2-dimethyl-5-nitro-1H-imidazole with nitronate anions led to both the formation of the C-alkylated product through an SRN1 mechanism and the predominant ethylenic compound resulting from nitrous acid elimination on the C-alkylated product. Interestingly, in contrast to our previous works on SRN1 reactivity, no O-alkylated product was observed. 相似文献
403.
404.
Sakonwan Kuhaudomlarp Linda Cerofolini Sabrina Santarsia Emilie Gillon Silvia Fallarini Grazia Lombardi Maxime Denis Stefano Giuntini Carolina Valori Marco Fragai Anne Imberty Alessandro Dondoni Cristina Nativi 《Chemical science》2020,11(47):12662
Two orthogonal, metal free click reactions, enabled to glycosylate ubiquitin and its mutant A28C forming two protein scaffolds with high affinity for BambL, a lectin from the human pathogen Burkholderia ambifaria. A new fucoside analogue, with high affinity with BambL, firstly synthetized and co-crystallized with the protein target, provided the insights for sugar determinants grafting onto ubiquitin. Three ubiquitin-based glycosides were thus assembled. Fuc-Ub, presented several copies of the fucoside analogue, with proper geometry for multivalent effect; Rha-A28C, displayed one thio-rhamnose, known for its ability to tuning the immunological response; finally, Fuc-Rha-A28C, included both multiple fucoside analogs and the rhamnose residue. Fuc-Ub and Fuc-Rha-A28C ligands proved high affinity for BambL and unprecedented immune modulatory properties towards macrophages activation.Metal free click reactions used to glycosylate ubiquitin and its mutant A28C afforded two protein scaffolds with high affinity for Burkholderia ambifaria lectin (BambL). 相似文献
405.
406.
Influence of actinic wavelength on properties of light‐cured interpenetrating polymer networks
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![点击此处可从《Journal of polymer science. Part A, Polymer chemistry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Feyza Karasu Caroline Rocco Maxime Lecompère Céline Croutxé‐Barghorn Xavier Allonas Yujing Zhang A. Catarina C. Esteves Leendert G. J. van der Ven Rolf A. T. M. van Benthem Gijsbertus de With 《Journal of polymer science. Part A, Polymer chemistry》2016,54(10):1378-1390
Interpenetrating polymer networks (IPNs) composed of different acrylate/epoxide ratios, were synthesized under UV and visible‐LED curing conditions. The formation of the IPNs was explored in terms of phase separation, polymerization mechanisms, final mechanical properties and surface morphology. For these purpose, we uniquely combined results of miscibility investigations, confocal Raman microscopy, dynamical mechanical analysis and atomic force microscopy. Transparent films were obtained for all compositions and both irradiation sources. The thermo‐mechanical properties of different IPNs were associated to the presence of acrylate‐ or epoxide‐rich phases, as well as, mixed interphases, resulting from the high interpenetration between both networks. Although the final conversions were similar under UV and visible‐LED irradiation, we have found evidence that the visible‐cured samples provide higher IPN homogeneity and lower Tg, for a higher epoxide content. To explain this trend, the mechanisms and sequence of the acrylate or epoxide networks formation, under UV or LED irradiation, is discussed. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1378‐1390 相似文献
407.
408.
Maxime Beau Sunhee Lee Sooyeon Kim Won‐Sik Han Olivier Jeannin Marc Fourmigu Emmanuel Aubert Enrique Espinosa Ie‐Rang Jeon 《Angewandte Chemie (International ed. in English)》2021,60(1):366-370
Crystal engineering based on σ‐hole interactions is an emerging approach for realization of new materials with higher complexity. Neutral inorganic clusters derived from 1,2‐dicarba‐closo‐dodecaborane, substituted with ‐SeMe, ‐TeMe, and ‐I moieties on both skeletal carbon vertices are experimentally demonstrated herein as outstanding chalcogen‐ and halogen‐bond donors. In particular, these new molecules strongly interact with halide anions in the solid‐state. The halide ions are coordinated by one or two donor groups (μ1‐ and μ2‐coordinations), to stabilize a discrete monomer or dimer motifs to 1D supramolecular zig‐zag chains. Crucially, the observed chalcogen bond and halogen bond interactions feature remarkably short distances and high directionality. Electrostatic potential calculations further demonstrate the efficiency of the carborane derivatives, with Vs,max being similar or even superior to that of reference organic halogen‐bond donors, such as iodopentafluorobenzene. 相似文献
409.
Cystobactamids: Myxobacterial Topoisomerase Inhibitors Exhibiting Potent Antibacterial Activity
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Dr. Sascha Baumann Dr. Jennifer Herrmann Dr. Ritesh Raju Dipl.‐Ing. Heinrich Steinmetz Dr. Kathrin I. Mohr Dr. Stephan Hüttel Dr. Kirsten Harmrolfs Prof. Dr. Marc Stadler Prof. Dr. Rolf Müller 《Angewandte Chemie (International ed. in English)》2014,53(52):14605-14609
The development of new antibiotics faces a severe crisis inter alia owing to a lack of innovative chemical scaffolds with activities against Gram‐negative and multiresistant pathogens. Herein, we report highly potent novel antibacterial compounds, the myxobacteria‐derived cystobactamids 1 – 3 , which were isolated from Cystobacter sp. and show minimum inhibitory concentrations in the low μg mL?1 range. We describe the isolation and structure elucidation of three congeners as well as the identification and annotation of their biosynthetic gene cluster. By studying the self‐resistance mechanism in the natural producer organism, the molecular targets were identified as bacterial type IIa topoisomerases. As quinolones are largely exhausted as a template for new type II topoisomerase inhibitors, the cystobactamids offer exciting alternatives to generate novel antibiotics using medicinal chemistry and biosynthetic engineering. 相似文献
410.
René R. E. Steendam Maxime C. T. Brouwer Evelien M. E. Huijs Michaël W. Kulka Dr. Hugo Meekes Dr. Willem J. P. van Enckevort Dr. Jan Raap Prof. Dr. Floris P. J. T. Rutjes Prof. Dr. Elias Vlieg 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(42):13527-13530
Here we demonstrate that deracemization of isoindolinones using Viedma ripening is possible starting from a racemic mixture of conglomerate crystals. Crystals of the enantiopure isoindolinones lose their chiral identity upon dissolution even without the need for a catalyst. This enabled complete deracemization of the reported isoindolinones without a catalyst. 相似文献