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71.
M. Yaeesh Siddiqi Bhupinder Malhotra Xiangjia Min Anthony D. M. Glass 《植物养料与土壤学杂志》2002,165(2):191-197
Effects of varying the proportions of NO3— and NH4+ in the growth medium on seedling growth and tomato fruit yield (Lycopersicon esculentum L. cv. Trust F1) were investigated in greenhouse hydroponic experiments. The presence of NH4+ as the sole N source (11 mM) was toxic: it curtailed growth and decreased chlorophyll content of the leaves. However, at low concentration (10 % of total N), the presence of NH4+, with or without added dissolved inorganic carbon (DIC), increased vegetative growth and fruit yield by ˜ 15 %, and enhanced taste/flavor of the fruits. In DIC‐enriched treatment, pH was maintained at 5.8 by addition of KHCO3 or as CaCO3. The presence of NH4+, at 10 % of total N, inhibited NO3— uptake rates by ˜ 27 %. The rates of uptake of NO3— and NH4+ were comparable (13.3 and 14.2 mmol plant—1 d—1, respectively, in the presence of DIC, and 14.7 and 14.0 mmol plant—1 d—1, respectively, in the absence of DIC), despite such a large difference in their concentrations in the nutrient feed solution. A higher proportion of NH4+ (up to 50 % of total N) had no further significant effect upon early vegetative growth, but in a long‐term experiment resulted in a high incidence of blossom end‐rot (BER) disease, thereby severely curtailing fruit yield. The presence of even 1.1 mM NH4+ reduced Ca2+ and Mg2+ accumulation in the leaves as well as in fruits. 相似文献
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73.
在开花期,用0、50、100和200mg/kg黄腐酸溶液喷洒白菜型油菜(BrassicaCampestris),结果表明,黄腐酸能提高叶绿素含量,降低叶片电导率,提高叶片相对含水量,降低其水分饱和亏缺,从而增强了油菜抗旱能力.喷洒黄腐酸还显著提高油菜的干物质积累量和籽粒产量。 相似文献
74.
AIM: To explore the effect of water extract propolis (WEP) from Taishan on apoptosis of human umbilical vascular endothelial cells (HUVECs) induced in vitro by tumor necrosis factor-α (TNF-α). METHODS: HUVECs were collect by digestion-perfusion and cultivated. TNF-α at concentration of 50 μg/L was administrated to induce the apoptosis of HUVECs. After injury, HUVECs were treated with WEP at concentrations of 50, 100, and 200 mg/L, respectively, for 24 h. Apoptosis was evaluated by terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL) and flow cytometry (FCM). RESULTS: Apoptosis index in injured group was significantly higher than that in control group, and decreased significantly after treating with WEP at concentrations of 50, 100, and 200 mg/L, respectively (P<0.01). CONCLUSION: WEP may be useful for protection of vascular endothelial cells by inhibiting apoptosis. 相似文献
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AIM: To investigate the balance of Treg/Th17 in synovium of collagen-induced arthritis (CIA) and the impact of tumor necrosis factor α(TNF-α) blockage therapy. METHODS: Rat CIA model was established by bovine II collagen injection. The pathological score was evaluated by HE staining and toluidine blue staining. The TNF-α level in plasma was measured by ELISA. The expression of Treg/Th17 in synovium was detected by double staining immunofluorescence. RESULTS: The plasma level of TNF-α in CIA group was significantly higher than that in control group and TNFR-Fc treatment group (P<0.01), whereas no significant difference was found between TNFR-Fc treatment group and control group (P>0.05). No significant difference between CIA group and control group in the ratio of CD4+Foxp3+Treg cells/CD4+ cells in synovium (23.12%±4.93% vs 24.66%±5.82%, P>0.05) was observed, whereas the ratio in TNFR-Fc treatment group was significantly increased(33.07%±5.14%). The ratio of CD4+RORγt+Th17 cells/CD4+ cells in CIA group was significantly higher than that in control group and TNFR-Fc treatment group (9.74%±2.23% vs 1.00%±0.59%, 5.63%±1.76%, P<0.01). CONCLUSION: Differentiation disturbance of Treg/Th17 exists in the synovium of CIA rats. TNFR-Fc may restore the balance of Treg/Th17 by inhibiting Th17 cell differentiation and inducing the production or accumulation of Treg. 相似文献
77.
粘附素蛋白是金黄色葡萄球菌感染早期最重要的致病因子,研究根据金黄色葡萄球菌聚集因子A(c1fa A)基因,设计合成特异性引物,以国内奶牛乳腺炎临床分离株金黄色葡萄球菌基因组为PCR模板,进行c1fa A基因的克隆,并连接入pMD18-T载体进行测序和序列分析,然后经BamH I和Xba I双酶切后构建真核表达载体并进行鉴定。结果表明,以金黄色葡萄球菌标准株为对照,国内分离株多数在990bp处扩增到特异性条带,经测序鉴定,与Genebank发表的金黄色葡萄球菌c1fa A序列同源性为99%;构建的真核表达质粒通过PCR和双酶切鉴定证明构建成功,为研究核酸疫苗奠定基础。 相似文献
78.
AIM: To investigate the role of miR-181b in the expression of Bcl-2 and SP1 at mRNA and protein levels in the human hepatoma G2 cells (HepG2), and to explore the effect of miR-181b on the regulation of HepG2 cell proliferation. METHODS: The synthetic double-strand complementary DNA based on the sequence of miR-181b was inserted into the vector of miRNASelectTM pEGP-miR. The microRNA high-expression plasmid was cloned, and the sequences were identified. The miR-181b plasmid was transfected into HepG2 cells with liposomes. The stable cell line was screened by puromycin. The mRNA and protein levels of Bcl-2 and SP1 were measured by RT-PCR and Western blotting, respectively. Methyl thiazolyl tetrazolium (MTT) method was used to analyze the proliferation of HepG2 cells. RESULTS: The Western blotting results showed that miR-181b inhibited the protein expression of Bcl-2 and SP1. The result of RT-PCR also indicated that the mRNA expression of Bcl-2 and SP1 was suppressed. Compared with the control, the growth rate of HepG2 with high expression of miR-181b was significantly decreased.CONCLUSION: miR-181b inhibits the proliferation of HepG2, which may be related to the down-regulation of Bcl-2 and SP1. 相似文献
79.
赵洁 《农业图书情报学刊》2019,31(9):69-74
目的 通过对中国30种科技期刊中外引文的数量及其各种分布情况的调查,揭示引文数量和质量与不同学术水平期刊之间的对应关系以及对中国科技期刊的评价效用。方法 采用统计分析方法,对不同学术水平期刊中外引文的数量和质量指标进行比较和分析。结果 学术期刊的引文数量和质量均高于普通期刊,而普通期刊由于中文引文比例大,对中国科技期刊学术评价的贡献度大于学术期刊,但学术评价效用不高。结论 引文作为论文的重要组成部分和学术质量的保证,应该纳入中国科技期刊综合评价指标体系中的独立指标,中国科学引文数据库来源期刊应进行适当调整,注重质量,可吸收一些相关的国际期刊。 相似文献
80.