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51.
Liver cells were isolated from 6 fish fed a diet containing 12.1 g methionine/kg, 11.02 mg vitamin B6/kg, 0.20 mg vitamin B12/kg and 7.80 mg folate/kg (named high‐1C diet). These cells were compared to liver cells isolated from 6 fish fed a diet containing 6.7 g methionine/kg, 7.01 g vitamin B6/kg, 0.15 mg vitamin B12/kg and 2.60 mg folate/kg (named low‐1C diet). Isolated cells were plated on 6‐well plates in Leibovitz medium and treated with 10 mM metformin, 10 mM metformin for 24 hr followed by 0.4 mM oleic acid (OA) for 24 hr or only 0.4 mM OA for 24 hr. The cells were compared to untreated controls added only the medium. All cells were harvested 48 hr after being plated. Cells isolated from Atlantic salmon fed low‐1C diets showed higher gene expression of MGAT‐2 (p < .0001), CPT‐1 (p = .028), FAS (p = .0006), LXR (p = .020), ACC (p = .032) and MnSOD (p < .0001). The low‐ or high‐1C diets fed prior to cell isolation had no effect on gene expression of ApoB100, PPARa, CD36, SREBP‐2 or Bcl‐2. Metformin treatment increased the expression of the anti‐apoptotic protein Bcl‐2 (p = .0001) indicating an anti‐apoptotic effect. Metformin generally increased the expression of genes associated with lipid oxidation and transport, but decreased the expression of genes associated with cholesterol metabolism confirming our earlier results using this model.  相似文献   
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To investigate the role of polyamines in pre- and post-harvest fruit development of 'Akatsuki' peach (Prunus persica (L.) Batsch.) we measured polyamine concentrations, activities of polyamine biosynthetic enzymes and expression of genes encoding these enzymes. Concentrations of the free polyamines, putrescine (Put), spermidine (Spd) and spermine (Spm) in pre-harvest fruit peaked 16 days after full bloom (DAF) and then progressively decreased until harvest with the exception of Put, which showed a second peak at 94 DAF, just before the onset of ethylene production. In post-harvest fruit, minor changes in concentrations of Spd and Spm were observed, whereas Put concentration peaked on the harvest day, followed by an abrupt decrease and a subsequent 2-fold increase, which was opposite to the fluctuating pattern of ethylene production. Activities of arginine decarboxylase (ADC) and ornithine decarboxylase (ODC) peaked during the first stage of fruit development and then decreased until 80 DAF, after which the activities were below detection limits, suggesting that Put is synthesized during the early stage of fruit development. Activity of S-adenosylmethionine decarboxylase (SAMDC) decreased progressively until the end of S2. Expression levels of five putative polyamine biosynthetic genes, ADC, ODC, SAMDC, spermidine synthase (SPDS) and spermine synthase (SPMS), in pre-harvest and post-harvest fruit did not coincide precisely with the observed changes in enzymatic activities and polyamine concentrations. The possible role of polyamines during peach fruit development and the relationship between polyamines and ethylene biosynthesis are discussed.  相似文献   
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The loss of developmental competence and the glutathione (GSH) content of maternally heat‐stressed mouse oocytes and zygotes were determined. In experiment 1, zygotes were collected from female mice that were heat‐stressed at 35°C for 10 h after hCG injection (oocyte maturation stage), or for 12 h on Day 1 of pregnancy (zygote stage), followed by in vitro culture. To minimize the effects of heat stress on the fertilization process, heat‐stressed oocytes that were fertilized in vitro were also included in this experiment. In experiment 2, heat‐stressed oocytes and zygotes were assayed for GSH content. The application of heat stress to the oocytes resulted in a significant decrease in the percentage of zygotes that developed to morulae or blastocysts, both for naturally fertilized oocytes (56.9% for heat‐stressed vs 85.4% for control) or in vitro‐fertilized oocytes (54.5%vs 73.6%). In the heat‐stressed zygotes, the disruption of embryonic development was more drastic (24.3%vs 90.3%), with the majority of zygotes being arrested at the two‐cell stage. In contrast, the GSH content decreased significantly in heat‐stressed zygotes, but not in heat‐stressed oocytes. These results demonstrate that the loss of developmental competence of early embryos is associated with a decrease in the GSH content of maternally heat‐stressed zygotes, but not of maternally heat‐stressed oocytes.  相似文献   
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1-Aminocyclopropane-1-carboxylate (ACC) synthase and oxidase activities, their gene expression, and ethylene production in apple fruit [Malus sylvestris (L.) Mill. Var. domestica (Borkh.) Mansf.] treated with a synthetic auxin 2,4-dichlorophenoxy-propionic acid (2,4-DP) and n-propyl dihydrojasmonate (PDJ), a jasmonic acid derivative, has been investigated to clarify the action of auxin and jasmonates on ethylene production. The fruit was harvested at 103 d after full bloom (preclimacteric). The expression of MdACS4 messenger RNA (mRNA) at 48 and 96 h after treatment was higher in fruit treated with 2,4-DP than in the untreated control, but those of MdACS1 and MdACO1 were not affected by treatment. The ethylene production in 2,4-DP-treated fruit increased at 96 h after treatment. In contrast, expression of mRNAs hybridized with MdACS1 and MdACO1 probes in the skin of PDJ-treated fruit were higher than those in the untreated control. In addition, ACC synthase activity and ethylene production also increased after treatment. These results show that the ethylene production rate may differ with the kind of genes which were stimulated by auxin or jasmonates.  相似文献   
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Cell‐cell fusion has been a great technology to generate valuable hybrid cells and organisms such as hybridomas. In this study, skeletal muscle myoblasts were utilized to establish a novel method for autonomous xenogenic cell fusion. Myoblasts are mononuclear myogenic precursor cells and fuse mutually to form multinuclear myotubes. We generated murine myoblasts (mMBs) expressing green fluorescent protein (GFP) termed mMB‐GFP, and the chick myoblasts (chMBs) expressing Discosoma red fluorescent protein (DsRed) termed chMB‐DsRed. mMB‐GFP and chMB‐DsRed were cocultured and induced to differentiate. After 24 h, the multinuclear myotubes expressing both GFP and DsRed were observed, indicating that mMBs and chMBs interspecifically fuse. These GFP+/DsRed+ hybrid myotubes were able to survive and grew to hyper‐multinucleated mature form. We also found that undifferentiated mMB‐GFP efficiently fuse to the chMB‐DsRed‐derived myotubes. This is the first evidence for the autonomous xenogenic fusion of mammalian and avian cells. Myoblast‐based fusogenic technique will open up an alternative direction to create novel hybrid products.  相似文献   
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Plants naturally infected with Cucumber mosaic virus (CMV) were collected and analyzed by electrophoresis of the replicative form of dsRNA and by Northern blot hybridization using CMV RNA-specific probes. Some of the CMV-infected plants, especially winter crops, contained two kinds of RNA 1 segments or RNA 2 segments (or both), suggesting that mixed infections of CMV occurred naturally. Single-aphid-transmitted isolates (SATIs) from the field isolate containing two RNA 1 segments were grouped into three types by the electrophoretic mobility of RNA 1 (i.e., those containing one slow segment, those containing one fast segment, and those containing both). Furthermore, SATIs and single-lesion isolates, generated from the plants inoculated with a mixture of two CMV isolates that could be differentiated by their electrophoretic dsRNA profiles, were analyzed by dsRNA, indicating that nonparental progenies were observed. These results suggested that genetic reassortment of CMV RNA may occur in nature and that this is an important mechanism in CMV evolution.  相似文献   
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