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References to either indigenous uses or the results of controlled assays are numerous for species of Pkyllanthus (Euphorbiaceae). These citations have been arranged by subgenus, section, subsection and species and will be published as three separate papers, followed by a paper discussing the apparent clustering of some uses or effects within taxa. This paper, the first of the series, covers the subgenera Isocladus, Kirganelia, Cicca and Emblica.  相似文献
3.
The o-diphenolic amino acid L-3,4-dihydroxyphenylalanine (dopa), the enamine alpha,beta-dehydro-3,4-dihydroxyphenylalanine (delta-dopa), and/or hydroxylated derivatives thereof, are integrated into the primary sequence of many scleroproteins and polyphenolic oligopeptides such as the celenamides, tunichromes, and halocyamines. After oxidation of N-acetyldopa ethyl ester, a low mol wt analogue of peptidyl dopa, the resultant o-quinone tautomerized to (Z)-alpha,beta-dehydro-3,4-dihydroxyphenylalanine ethyl ester. We have characterized this delta-dopa derivative and an acetate 1,4-addition product formed during the synthesis. Tautomerization of peptidyl dopa quinone to delta-dopa may be involved in the biosynthesis of delta-dopa-containing oligopeptides.  相似文献
4.
The structure of oceanapiside, an antifungal alpha, omega-bis-aminohydroxylipid glycoside from the temperate marine sponge Oceanapia sp., was elucidated by a combination of 2D NMR, chemical degradation/correlation, and MALDI MS-MS spectrometry. Oceanapiside exhibits antifungal activity against Candida glabrata at 10 micrograms/mL (MIC).  相似文献
5.
Dysidea herbacea, collected at Harrier Reef on the Great Barrier Reef, contains the novel metabolite herbacic acid as the major trichloroleucine metabolite. Herbacic acid appears to be an early product of direct free-radical chlorination of leucine and is a prototype for further transformation of the free carboxylic acid group and generation of complex trichloromethyl metabolites, including natural products of the dysidenin family.  相似文献
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The use of alternative medicine, including consumption of herbal products and dietary supplements, has been increasing substantially both in the United States and in Western Europe. One area that is garnering increased attention is the use of Oriental Medicine including Kampo, or Japanese herbal medicine. Herein, we review representative examples of research available on the most common use of Kampo medicinals, namely to improve the immune response. We also provide an extensive background on the history of Kampo. There are more than 210 different Kampo formulae used in Japan and most uses of Kampo are to modulate the immune response, i.e. to improve immunity. We have extracted data on seven common Kampo medicinals, and the data are reviewed with respect to in vitro and in vivo activities for both humans and experimental animals; the ingredients as well as the problems with classification of these materials are presented. Research suggests that Kampo herbals are biologically active and may have therapeutic potential. While it is believed that Kampo medicines have few side effects, there is a paucity of data on their toxicity as well as a relative lack of knowledge of the bioactive constituents and potential drug interactions of these agents.  相似文献
7.
Elloramycin A (1) belongs to a small family of naphthacenequinones characterized by a unique highly hydroxylated cyclohexenone moiety. A cosmid clone 16F4, harboring genes for the production of 1 from Streptomyces olivaceus Tü2353, has been previously isolated. DNA sequence analysis of a 3.2-kb fragment from 16F4 revealed four open reading frames--the elmGHIJ genes. Heterologous expressions of the elmGHI genes in either Escherichia coli or Streptomyces lividans, followed by biochemical characterizations of the ElmGHI proteins, established ElmG as tetracenomycin B2 oxygenase, ElmH as tetracenomycin F1 monooxygenase, and ElmI as tetracenomycin F2 cyclase. These results provide direct biochemical evidence for the hypothesis that the biosynthesis of 1 in S. olivaceus parallels that of tetracenomycin C (2) in Streptomyces glaucescens and support the notion that the biosynthesis of the highly hydroxylated cyclohexenone moiety in other polyketides most likely follows the same paradigm as the tetracenomycin B2 or A2 oxygenase.  相似文献
8.
The structure of the title compound, (+)-7S-hydroxyxestospongin A was solved by single-crystal X-ray diffraction analysis and the absolute stereochemistry obtained by analysis of the derived R and S Mosher's esters. The absolute configuration of xestospongin D was determined for the first time by analysis of anomalous scattering from the X-ray crystal diffraction data set. Xestospongins A, C, and D, araguspongine C, and demethylxestospongin B exhibited modest antifungal activity (MIC 30-100 g/mL) against various fluconazole-resistant Candida spp., but 7S-hydroxyxestospongin A was inactive.  相似文献
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Bleomycin (BLM) biosynthesis has been studied as a model for hybrid peptide-polyketide natural product biosynthesis. Cloning, sequencing, and biochemical characterization of the blm biosynthetic gene cluster from Streptomyces verticillus ATCC15003 revealed that (1) the BLM hybrid peptide-polyketide aglycon is assembled by the BLM megasynthetase that consists of both nonribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) modules; (2) BlmIX/BlmVIII/BlmVII constitute a natural hybrid NRPS/PKS/NRPS system, serving as a model for both hybrid NRPS/PKS and PKS/NRPS systems; (3) the catalytic sites appear to be conserved in both hybrid NRPS/PKS and nonhybrid NRPS or PKS systems, with the exception of the KS domains in the hybrid NRPS/PKS systems that are unique; (4) specific interpolypeptide linkers may play a critical role in intermodular communication to facilitate the transfer of the growing intermediates between the interacting NRPS and/or PKS modules; (5) post-translational modification of the BLM megasynthetase has been accomplished by a single PPTase with broad carrier protein specificity; and (6) BlmIV/BlmIII-templated assembly of the BLM bithiazole moiety requires intriguing protein juxtaposition and modular recognition. These results lay the foundation to investigate the molecular basis for intermodular communication between NRPS and PKS in hybrid peptide-polyketide natural product biosynthesis and set the stage for engineering novel BLM analogues by genetic manipulation of genes governing BLM biosynthesis.  相似文献
10.
A chemoselective conversion of bastadin-4 to the important Ca2+ channel modulator bastadin-5 (1a) has been achieved using cationic hydrogenation (Et3SiH, TFA, 60%). Specifically deuterated bastadin-5 (1b, >95 at. %) was prepared following this method and the simplified 1H NMR H-5/H2-6 spin system of 1b exploited to study temperature-dependent macrocyclic ring dynamics.  相似文献
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