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1.
Dimethylmethyl phosphonate (DMMP), dimethyl phosphite (DMPI), trimethyl phosphite (TMPI) and trimethyl phosphate (TMP) were investigated using H2O and D2O atmospheric-pressure ionization (API) tandem mass Spectrometry. All daughter ions could be explained by losses of one or a successive number of stable molecules as opposed to losses of radicals such as the hydride, methyl and methoxy species. Losses of neutral methanol and dimethyl ether and of protonated methanol and formaldehyde ions from all four organophosphorus pseudo-molecular ions were observed. The DMMP and DMPI MH+ pseudomolecular ions produced the losses of neutral C2H6 and water, respectively. Formaldehyde loss was not observed for the MH+ ions, but it was well represented in the decomposition pathways of daughter ions. The D2O reagent gas highlighted the role of the ionizing proton/ deuteron in the various daughter ions, including m/z 95, 79, 65, 49, 33, 31 and 47. The last ion was found to be isobaric in that m/z 47 and 48 both appeared with similar abundances in the D2O-API daughter ion mass spectra of TMPI and TMP. 相似文献
2.
Lainton JA Allen MC Burton M Cameron S Edwards TR Harden G Hogg R Leung W Miller S Morrish JJ Rooke SM Wendt B 《Journal of combinatorial chemistry》2003,5(4):400-407
Efficient and general procedures have been developed for the solution-phase preparation of substituted morpholine derivatives, and a library has been produced around generic structure 1. This library was designed with proprietary modeling software for use as a general screening library. The 30 R1 reagents were phenols, and the 275 R2 reagents were taken from five different reagent classes, giving a variety of product classes in the final library of 8250 potential products. All of the library members were generated from a common intermediate, mesylate (5), which was synthesized efficiently, in bulk, in three steps from N-benzylethanolamine (2). High-throughput chemistry using robotics was carried out to produce the 7907 library members, which were individually characterized by reversed-phase LC/MS analysis. 相似文献
3.
M. Sangermano R. Bongiovanni G. Malucelli A. Priola J Olbrych A. Harden N. Rehnberg 《Journal of polymer science. Part A, Polymer chemistry》2004,42(6):1415-1420
The cationic photopolymerization of oxetane‐based systems containing silicon monomers was investigated. For this purpose, three new silicon‐containing oxetane monomers were synthesized through a simple and straightforward synthetic method. The silicon‐containing monomers were added to a typical oxetane resin, 3,3′‐[oxydi(methylene)]bis(3‐ethyloxetane), in concentrations of 1–5 wt %. They exploited a certain surface tension effect without affecting the rate of polymerization. Enrichment only on the air side was achieved, which induced hydrophobicity in the photocured films, depending on the monomer structure and concentration. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1415–1420, 2004 相似文献
4.
M. Shepherd E. R. Weaver P. G. Ledig Aktiebolaget Carba K. Melanby H. L. Harden P. Borinski H. Murschhauser R. Staufer R. Krais H. Markert H. Mogilnickij H. Heinicke K. Heimberger L. C. Mc Nair H. C. Gull St. Hediger E. Lieber R. Rosen K. M. Watson und N. H. Ceaglske 《Fresenius' Journal of Analytical Chemistry》1933,92(1-2):31-40
Ohne Zusammenfassung 相似文献
5.
W. W. Haldane Gee A. Harden und Myers 《Fresenius' Journal of Analytical Chemistry》1901,40(12):791-792
Ohne Zusammenfassung 相似文献
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Harden JD Ruppel JV Gao GY Zhang XP 《Chemical communications (Cambridge, England)》2007,(44):4644-4646
Cobalt, supported by porphyrin ligands, is capable of catalyzing intermolecular nitrene insertion of sp(3) C-H bonds with bromamine-T as the nitrene source, forming the desired tosyl-protected amines with NaBr as the by-product. 相似文献
9.
We elucidate the stereo-controlling factors of the asymmetric intramolecular hydroalkoxylation of terminal olefins catalyzed by bulky Brønsted acids [Science2018, 359 (6383), 1501–1505] using high-level electronic structure methods. The catalyst–substrate interaction is described using a dispersion-driven induced-fit model, in which the conformational changes of the catalyst and of the substrate in the transition states are governed to a large extent by London dispersion forces. The distortion energy of the catalyst is dominated by the change in the intramolecular dispersion interactions, while intermolecular catalyst–substrate dispersion interactions are the major stabilizing contribution in the transition state. This model provides a new general framework in which to discuss the stereoselectivity of transformations catalyzed by such confined organocatalysts.We elucidate the stereo-controlling factors of the asymmetric intramolecular hydroalkoxylation of terminal olefins catalyzed by bulky Brønsted acids [Science2018, 359 (6383), 1501–1505] using high-level electronic structure methods. 相似文献
10.
A rapid gas chromatography-tandem mass spectrometry (GC-MS/MS) analytical method was developed for the simultaneous analysis of 7 estrogenic hormones (17α-estradiol, 17β-estradiol, estrone, mestranol, 17α-ethynylestradiol, levonorgestrel, estriol) and 5 androgenic hormones (testosterone, androsterone, etiocholanolone, dihydrotestosterone, androstenedione) in aqueous matrices. This method is unique in its inclusion of all 12 of these estrogens and androgens and is of particular value due to its very short chromatographic run time of 15 min. The use of isotope dilution for all analytes ensures the accurate quantification, accounting for analytical variabilities that may be introduced during sample processing and instrumental analysis. Direct isotopically labelled analogues were used for 8 of the 12 hormones and satisfactory isotope standards were identified for the remaining 4 hormones. Method detection levels (MDLs) were determined to describe analyte concentrations sufficient to provide a signal with 99% certainty of detection. The established MDLs for most analytes were 1-5 ngL(-1) in a variety of aqueous matrices. However, slightly higher MDLs were observed for etiocholanolone, androstenedione, testosterone, levonorgestrel and dihydrotestosterone in some aqueous matrices. Sample matrices were observed to have only a minor impact on MDLs and the method validation confirmed satisfactory method stability over intra-day and inter-day analyses of surface water and tertiary treated effluent samples. 相似文献