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71.
Heritability of fumonisin B1 production in Gibberella fujikuroi mating population A. 总被引:4,自引:4,他引:0
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A E Desjardins R D Plattner D D Shackelford J F Leslie P E Nelson 《Applied microbiology》1992,58(9):2799-2805
Fumonisins are mycotoxins produced by strains belonging to several different mating populations of Gibberella fujikuroi (anamorphs, Fusarium section Liseola), a major pathogen of maize and sorghum worldwide. We studied the heritability of fumonisin production in mating population A by crossing fumonisin-producing strains collected from maize and sorghum in the United States with fumonisin-nonproducing strains collected from maize in Nepal. Random ascospore and tetrad progeny from three of these crosses were analyzed by gas chromatography-mass spectrometry and high-performance liquid chromatography for their ability to produce fumonisins on autoclaved cracked maize. In all three crosses, the ability to produce fumonisins, predominately fumonisin B1, segregated as a single gene or group of closely linked genes. Intercrosses between appropriate progeny and parents were poorly fertile, so we could not determine if the apparent single genes that were segregating in each of these crosses were allelic with one another. Mating type and spore-killer traits were scored in some crosses, and each segregated, as expected, as a single gene that was unlinked to the ability to produce fumonisins. We conclude that G. fujikuroi mating population A provides a powerful genetic system for the study of this important fungal toxin. 相似文献
72.
Generation of antibodies reactive with fumonisins B1, B2, and B3 by using cholera toxin as the carrier-adjuvant. 总被引:3,自引:2,他引:1
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J I Azcona-Olivera M M Abouzied R D Plattner W P Norred J J Pestka 《Applied microbiology》1992,58(1):169-173
Murine polyclonal antibodies reactive with fumonisins B1, B2, and B3 were produced after a novel immunization procedure with cholera toxin as both a hapten carrier protein and adjuvant. Immunization of mice with two 7.5-micrograms doses of fumonisin B1-cholera toxin conjugate without adjuvant resulted in the production of fumonisin B1-specific antibodies in all mice within 15 days when intraperitoneal, subcutaneous, and intravenous routes were used. In contrast, conventional immunization procedures with fumonisin B1-bovine serum albumin conjugates with and without Freund's adjuvant were largely ineffective. Fumonisin antibodies could be readily mass-produced in ascites fluid by using cholera toxin as a carrier-adjuvant. A competitive indirect enzyme-linked immunosorbent assay (ELISA) was devised whereby immobilized fumonisin B1-ovalbumin and free fumonisin B1 competed for antibody binding. The detection limit for fumonisin B1 in the ELISA was 100 ng/ml. The antiserum cross-reacted with fumonisins B2 and B3 but not with the hydrolyzed backbone of fumonisin B1 and tricarballylic acid. Concentrations of fumonisins B1, B2, and B3 required for 50% binding inhibition were 260, 300, and 650 ng/ml, respectively. These polyclonal antibodies should find wide usage in the ELISA for fumonisins in foods, feeds, and tissues. 相似文献
73.
Rina Plattner Nyla A. Heerema Shivanand R. Patil Patricia N. Howard-Peebles Catherine G. Palmer 《Human genetics》1991,87(3):290-296
Summary Seven dicentric bisatellited marker chromosomes, ascertained at amniocentesis, chorionic villus sampling, and in blood from an abnormal liveborn were characterized cytogenetically. All seven markers demonstrated brilliant bands by the DA/DAPI technique corresponding to C-band positive regions. Although some dicentric DA/DAPI-positive bisatellited markers have been identified as inverted duplicated 15s, recent literature has suggested that DA/DAPI lacks specificity for chromosome 15. Our evaluation of DA/DAPI-positive bisatellited marker chromosomes by in situ hybridization shows that some originate from chromosome 15 whereas DA/DAPI negative bisatellited markers may not be derived from 15. The morphological variations noted in our studies are discussed with respect to nomenclature. 相似文献
74.
This is an overview of the mutant strain Clostridium beijerinckii BA101 which produces solvents (acetone–butanol–ethanol, ABE) at elevated levels. This organism expresses high levels of amylases
when grown on starch. C. beijerinckii BA101 hydrolyzes starch effectively and produces solvent in the concentration range of 27–29 g l−1. C. beijerinckii BA101 has been characterized for both substrate and butanol inhibition. Supplementing the fermentation medium (MP2) with
sodium acetate enhances solvent production to 33 g l−1. The results of studies utilizing commercial fermentation medium and pilot plant-scale reactors are consistent with the results
using small-scale reactors. Pervaporation, a technique to recover solvents, has been applied to fed-batch reactors containing
C. beijerinckii BA101, and solvent production as high as 165 g l−1 has been achieved. Immobilization of C. beijerinckii BA101 by adsorption and use in a continuous reactor resulted in reactor productivity of 15.8 g l−1 h−1. Recent economic studies employing C. beijerinckii BA101 suggested that butanol can be produced at US$0.20–0.25 lb−1 by employing batch fermentation and distillative recovery. Application of new technologies such as pervaporation, fed-batch
culture, and immobilized cell reactors is expected to further reduce these prices.
Journal of Industrial Microbiology & Biotechnology (2001) 27, 287–291.
Received 12 September 2000/ Accepted in revised form 27 January 2001 相似文献
75.
Calmodulin in Paramecium tetraurelia: localization from the in vivo to the ultrastructural level 总被引:4,自引:0,他引:4
M Momayezi H Kersken U Gras J Vilmart-Seuwen H Plattner 《The journal of histochemistry and cytochemistry》1986,34(12):1621-1638
Monospecific polyclonal antibodies against Paramecium tetraurelia calmodulin were prepared and labeled for calmodulin localization on different levels of resolution: by microinjection into living cells; with isolated cell surface complexes (cortices); on the ultrastructural level, using Lowicryl sections of non-permeabilized cells (with colloidal gold-protein A labeling of antibodies bound); or using permeabilized and gently fixed cells for incubation with peroxidase- or microperoxidase-tagged antibodies. Sites selectively labeled above cytoplasmic background largely coincided, irrespective of the method used, although sensitivity, resolution, and liability to redistribution of antigen were quite different. (The methodological diversification applied allowed for their mutual control.) Nonspecific binding can be largely excluded, since all these methods gave negative results with pre-immune sera. We reached the following conclusions on sites with selective calmodulin binding (above cytoplasmic background level) in P. tetraurelia cells. A pool of calmodulin co-localized with F-actin, not only in the cortex (including fibrous materials around ciliary basal bodies) but also around food vacuoles (phagosomes) and, to a lesser degree, around the buccal cavity. Trichocyst docking sites on the cell membrane, and coated pits also displayed calmodulin labeling, thus indicating the potential involvement of calmodulin in exo-endocytosis processes. Calmodulin was also enriched on membranes of compartments with presumable ion (possibly Ca2+) transport capacity, such as trichocysts and the osmoregulatory system. Not selectively labeled were nuclei, mitochondria, and some small lysosomal organelles (as identified in vivo by rhodamine 123 or acridine orange fluorescence, respectively). 相似文献
76.
S Cohen HP LIN 《Journal of neurochemistry》1972,19(2):513-523
Abstract— The diethyl ester of α-fluoroglutarate (DEFG), an inhibitor of glutamate dehydrogenase, was prepared, and its effect on glutamate and phosphates in slices of rabbit cerebral cortex was examined. The primary effect of the drug on cortical slices incubating in a Krebs-Ringer glucose medium was to decrease the tissue levels of glutamate in association with decreased levels and turnover of high-energy phosphates. Assimilation of exogenous glutamate by the slices was partially blocked in the presence of the drug and severely depressed oxidative phosphorylation resulted when glutamate and DEFG were both present in the incubation mixture. The results suggested a significant relationship between the activity of cerebral glutamate dehydrogenase and oxidative phosphorylation. During incubation in a Krebs-Ringer glucose medium the endogenous pool of free amino acids in the cortical slice partitioned with the medium. Little or no glutamate, aspartate or GABA was present in the medium after incubation, but glycine, alanine, threonine, serine and glutamine did partition to varying degrees, with over one-half of the glutamine present in the incubation medium. With the exception of ‘leakage’ of aspartate, the partitioning patterns were relatively unaffected by the presence of added glutamate or DEFG. 相似文献
77.
78.
Duan M Kazmierski W Crosby R Gartland M Ji J Tallant M Wang A Hamatake R Wright L Wu M Zhang YK Ding CZ Li X Liu Y Zhang S Zhou Y Plattner JJ Baker SJ 《Bioorganic & medicinal chemistry letters》2012,22(8):2993-2996
A novel series of P3 oxo-modified macrocyclic hepatitis C virus NS3/4A serine protease inhibitor was designed, synthesized and biologically evaluated. The hydroxy-substituted inhibitor 10 demonstrated high potency in genotype 1a and 1b replicon and in the panel of HCV protease mutants. Interestingly, the t-butyl carbonate analog 9c, while not the most potent one in this series, exhibited a virtually flat potency profile in the panel of HCV protease mutants, thus providing opportunity for further optimization. 相似文献
79.
Lin X Rico AC Chu DT Carroll GL Barker L Shawar R Desai MC Plattner JJ 《Bioorganic & medicinal chemistry letters》2006,16(17):4692-4696
Synthesis of C(12) des-methyl ketolide is developed featuring an intramolecular epoxide formation/elimination process to establish the C(12) stereocenter. These ketolides are potent against several key respiratory pathogens, including erythromycin resistant erm- and mef-containing strains of Streptococcus pneumoniae. 相似文献
80.
Eva-Maria Ladenburger Ivonne M. Sehring Iris Korn Helmut Plattner 《Molecular and cellular biology》2009,29(13):3605-3622
A database search of the Paramecium genome reveals 34 genes related to Ca2+-release channels of the inositol-1,4,5-trisphosphate (IP3) or ryanodine receptor type (IP3R, RyR). Phylogenetic analyses show that these Ca2+ release channels (CRCs) can be subdivided into six groups (Paramecium tetraurelia CRC-I to CRC-VI), each one with features in part reminiscent of IP3Rs and RyRs. We characterize here the P. tetraurelia CRC-IV-1 gene family, whose relationship to IP3Rs and RyRs is restricted to their C-terminal channel domain. CRC-IV-1 channels localize to cortical Ca2+ stores (alveolar sacs) and also to the endoplasmic reticulum. This is in contrast to a recently described true IP3 channel, a group II member (P. tetraurelia IP3RN-1), found associated with the contractile vacuole system. Silencing of either one of these CRCs results in reduced exocytosis of dense core vesicles (trichocysts), although for different reasons. Knockdown of P. tetraurelia IP3RN affects trichocyst biogenesis, while CRC-IV-1 channels are involved in signal transduction since silenced cells show an impaired release of Ca2+ from cortical stores in response to exocytotic stimuli. Our discovery of a range of CRCs in Paramecium indicates that protozoans already have evolved multiple ways for the use of Ca2+ as signaling molecule.Ca2+ is an important component of cell activity in all organisms, from protozoa to mammals. Thereby Ca2+ may originate from the outside medium and/or from internal stores (7, 18). Ca2+ release from internal stores is mediated by various Ca2+ release channels (CRCs), of which the inositol-1,4,5-trisphosphate receptor (IP3R) and ryanodine receptor (RyR) families have been studied most extensively (8, 9, 29, 63). IP3Rs and RyRs have been identified in various metazoan organisms (reviewed in references 9, 28, and 104). According to these reviews, there exist three genetically distinct isoforms of each receptor type in mammals and orthologues have been identified in various nonmammalian vertebrates, e.g., frogs, chickens, and fish. RyRs and IP3Rs were also cloned and sequenced in the invertebrates Drosophila melanogaster and Caenorhabditis elegans, which possess one copy of each receptor type.Functional evidence for Ca2+ release in response to ryanodine or IP3 receptor agonists has been described in several unicellular systems. Treatment of permeabilized Plasmodium chabaudi parasites with IP3 results in Ca2+ release, which is inhibited by the IP3 receptor antagonist heparin (69). Another apicomplexan parasite, Toxoplasma gondii, responds to agonists and antagonists of both, ryanodine and IP3 receptors, by mediating increases in intracellular Ca2+ concentration ([Ca2+]i) (56). Stimulation of Trypanosoma cruzi with carbachol results in increased [Ca2+]i and IP3 (59). IP3 and cyclic ADP-ribose induces Ca2+ release in Euglena gracilis microsome fractions in a dose-dependent manner (61). In the giant algae Chara corallina and Nitrella translucens, IP3 produces action potentials involving increased [Ca2+]i (93). Treatment of vacuolar membrane vesicles from Candida albicans with IP3 results in Ca2+ release, blocked by heparin and ruthenium red (14). IP3 generates and maintains a Ca2+ gradient in the hyphal tip of Neurospora crassa and the IP3-sensitive channels have been reconstituted and characterized with the planar bilayer method (87). In summary, these publications suggest that IP3-dependent signaling pathways are conserved among unicellular organisms, including protozoa.Despite these data, the molecular characterization of IP3 or ryanodine receptors in low eukaryotes is currently a challenge since the identification of orthologues has not been possible thus far, probably because of evolutionary sequence divergence (66). Traynor et al. (96) identified an IP3 receptor-like protein, IplA, in Dictyostelium discoideum, which possesses regions related to IP3R sequences, but thus far no evidence for IP3 interaction exists. We have recently described an IP3R in the ciliated protozoa Paramecium tetraurelia (referred to here as P. tetraurelia IP3RN) (53), with features characteristic of mammalian IP3Rs in terms of topology and ability for IP3 binding. The expression level of P. tetraurelia IP3RN is modulated by extracellular Ca2+ concentrations ([Ca2+]o) and immunofluorescence studies reveal an unexpected localization to the contractile vacuole complex (CVC), the major organelle involved in osmoregulation (2). The ionic composition of the contractile vacuole fluid by ion-selective microelectrodes (91) suggests that the organelle plays a major role in expelling an excess of cytosolic Ca2+. Therefore, these IP3Rs may here mediate a latent, graded reflux of Ca2+ for fine-tuning of [Ca2+]i and thus serve [Ca2+] homeostasis (53).Besides [Ca2+] homeostasis, the Paramecium cell has to regulate a variety of well-characterized processes (75). This includes exocytosis of dense-core secretory vesicles (trichocysts) (71, 74, 99). Each cell possesses up to 1,000 trichocysts attached to the cell membrane. Their contents can be extruded synchronously in response to natural stimuli, i.e., predators (34, as confirmed by Knoll et al. [49]), to artificial polyamine secretagogues such as aminoethyldextran (AED) (78), to caffeine (48) or to the ryanodine substitute, 4-chloro-meta-cresol (4-CmC) (46). Their expulsion strictly depends on Ca2+ (10) and is accompanied by an increase of intracellular [Ca2+]i (24, 47). This Ca2+ signal originates from rapid mobilization of cortical stores, the alveolar sacs (33, 64, 74), superimposed by Ca2+ influx (46, 72). It thus represents a SOC-type mechanism (SOC, store-operated Ca2+ entry) known from mammalian systems (81).Upon exocytosis stimulation ∼60% of their total Ca2+ is released from alveolar sacs (33). These are Ca2+ stores (90) represented by flat membrane compartments tightly attached at the cell membrane surrounding each trichocyst docking site. They possess a SERCA-type pump located at the membrane facing the cell center (36, 37) and a luminal high-capacity/low-affinity CaBP of the calsequestrin type (73). Thus far, Ca2+ release channels of these stores were identified only indirectly as cells respond by exocytosis to the RyR activators caffeine (54, 48) and 4-CmC (46). However, an involvement of conserved RyRs has remained questionable as ryanodine is not able to activate Ca2+ release from alveolar sacs, as is the case with IP3 (54). Therefore, one of the most intriguing questions is the elucidation of the molecular nature of the channels mediating Ca2+ release from alveolar sacs upon stimulated exocytosis.In the present work we describe a novel family of CRCs (P. tetraurelia CRC-IV-1), whose members display several properties of the channels postulated above. In detail, the identified CRC-IV-1 channels localize to the alveolar sacs. Functional and fluorochrome analyses after gene silencing reveal that they are essential for mediating Ca2+ release and exocytosis in response to AED, caffeine, or 4-CmC. Their classification as “novel” CRC type is based on a restricted relationship to the C-terminal channel domains of IP3Rs and RyRs. The overall size and the number of putative transmembrane domains resemble IP3Rs, but N-terminal parts of CRC-IV-1 channels do not show any conservation, such as an IP3-binding domain. Therefore, CRC-IV-1 channels represent distant relatives of IP3Rs and RyRs and may belong to an ancestral Ca2+ signaling pathway. 相似文献