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排序方式: 共有268条查询结果,搜索用时 15 毫秒
81.
82.
户用风水光直流微电网控制策略与实现 总被引:1,自引:0,他引:1
分布式能源、微电网和智能电网都是当前电力行业的热点课题。现有微电网研究集中在并网控制、潮流计算、建模与仿真、拓扑结构与控制等方面,实际投入运营的系统不多。该文在利用现有研究成果基础上,设计并研制了一套面向户用的微电网系统。该系统由风水光等电源、储能蓄电池、逆变器等单元构成,由微网调度器和远程SCADA系统进行监控和调度。通过系统分析、建模仿真和完善的功能设计,实现了智能调度与功率自动平衡、故障自愈和即插即用等功能,并在某农村投入试运行。研究成果对智能电网的智能能量管理和调度控制研究也具有借鉴意义。 相似文献
83.
Lin KH Lin CY Liu CC Chou MY Lin JK 《Journal of agricultural and food chemistry》2011,59(7):3420-3428
The areca nut is the most widely consumed psychoactive substance in Taiwan, India, and Southeast Asia. It is considered to be an environmental risk factor for the development of oral submucous fibrosis and cancer. Arecoline, the major alkaloid of areca nut, has been known to cause cytotoxicity and genotoxicity in various systems. However, the active compound accounting for arecoline-induced damage in normal human oral cells is still uncharacterized. The present study was undertaken to identify the active metabolite of arecoline that might induce damage in human oral tissues and cause mutagenicity in Salmonella typhimurium tester strains TA 100 and TA 98. It is interesting to find that the major metabolite of arecoline, arecoline N-oxide, is moderately mutagenic to these Salmonella tester strains. This mutagenicity was potently inhibited by sulfhydryl compounds, namely, glutathione, N-acetylcysteine, and cysteine, whereas methionine is inactive in this inhibition. The mutagenicity of arecoline N-oxide was strongly inhibited by the N-oxide reducing agent titanium trichloride. The possible role of arecoline N-oxide in the induction of oral carcinogenesis by areca nut chewing is discussed. 相似文献
84.
Chen PN Chu SC Kuo WH Chou MY Lin JK Hsieh YS 《Journal of agricultural and food chemistry》2011,59(8):3836-3844
Epithelial to mesenchymal transition (EMT) is critical for the progression, invasion, and metastasis of epithelial tumorgenesis. Here, we provided molecular evidence associated with the antimetastatic effect of green tea polyphenol epigallocatechin-3 gallate (EGCG) in an oral squamous cell culture system by showing a nearly complete inhibition on the invasion (P < 0.001) of squamous cell carcinoma-9 (SCC-9) cells via a reduced expression of matrix metalloproteinase-2 (P < 0.001) and urokinasetype plasminogen activator (P < 0.001). EGCG exerted an inhibitory effect on cell migration (P < 0.001), motility (P < 0.001), spread, and adhesion (P < 0.001). We performed Western blot to find that EGCG inhibited p-focal adhesion kinase (p-FAK), p-Src, snail-1, and vimentin, indicating the anti-EMT effect of EGCG in oral squamous cell carcinoma. EGCG was also sufficient to inhibit phorbol-12-myristate-13-acetate-induced cell invasion and matrix metalloproteinase-9 expression, as evidenced by its inhibition on the tumor growth of SCC-9 cells in vivo via cancer cell xenografted nude mice mode. These results suggested that EGCG could reduce the invasion and cell growth of tumor cells, and such a characteristic may be of great value in developing a potential cancer therapy. 相似文献
85.
为对细鳞裂腹鱼幼鱼不同水体的人工饲养提供理论依据,利用金沙江水体(水温16.5℃,pH8.20)设置NH4Cl浓度50.12mg/L、56.23mg/L、63.10mg/L、70.79mg/L、79.43mg/L、89.13mg/L、100.00mg/L 7个等对数间距梯度浓度;自来水体(水温14.3℃,pH 8.05)设置NH4Cl浓度112.20mg/L、125.89mg/L、141.25mg/L、158.49mg/L、177.83mg/L、199.53mg/L 6个等对数间距梯度浓度对细鳞裂腹鱼幼鱼进行急性毒性试验。结果表明:金沙江水体中氨氮对细鳞裂腹鱼幼鱼的半致死浓度为81.92mg/L,安全浓度为8.19mg/L;非离子氨的半致死浓度为2.20mg/L,安全浓度为0.22mg/L。自来水体中氨氮对细鳞裂腹鱼幼鱼的半致死浓度为119.15 mg/L,安全浓度为11.91 mg/L;非离子氨半致死浓度为1.89mg/L,安全浓度为0.189mg/L。氨氮对细鳞裂腹鱼幼鱼的毒性效应与浓度呈正相关,与作用时间无相关性,细鳞裂腹鱼幼鱼对氨氮具有较强的耐受性。 相似文献
86.
A previously unknown solid phase of H2O has been identified by its peculiar growth patterns, distinct pressure-temperature melting relations, and vibrational Raman spectra. Morphologies of ice crystals and their pressure-temperature melting relations were directly observed in a hydrothermal diamond-anvil cell for H2O bulk densities between 1203 and 1257 kilograms per cubic meter at temperatures between -10 degrees and 50 degreesC. Under these conditions, four different ice forms were observed to melt: two stable phases, ice V and ice VI, and two metastable phases, ice IV and the new ice phase. The Raman spectra and crystal morphology are consistent with a disordered anisotropic structure with some similarities to ice VI. 相似文献
87.
Summary Electronmicroscope microanalyser (EMMA-4) analysis of Poria monticola colonising pine wood treated with a copper-chrome-arsenate preservative has shown that the fungus removes copper chromium and arsenic from the wood and stores these elements within the hyphae to the extent of 3–4% on a mycelial dry weight basis. The total uptake of each element varies from spot to spot examined (each 0.2 m dia.) but is on an average correlated with the concentration of the element in the impregnated wood. It appears that the rate of copper uptake is higher than of arsenic uptake. 相似文献
88.
William Kem Ferenc Soti Kristin Wildeboer Susan LeFrancois Kelly MacDougall Dong-Qing Wei Kuo-Chen Chou Hugo R. Arias 《Marine drugs》2006,4(3):255-273
Nemertines are a phylum of carnivorous marine worms that possess a variety of alkaloidal, peptidic or proteinaceous toxins that serve as chemical defenses against potential predators. The hoplonemertines additionally envenomate their prey with a mixture of proboscis alkaloids delivered with the help of a calcareous stylet that punctures the skin of the victim. Anabaseine, the first of these alkaloids to be identified, stimulates a wide variety of animal nicotinic acetylcholine receptors (AChRs), especially the neuromuscular [e.g., α12β1γδ (embryogenic) or α12β1γɛ (adult)] and α7 AChRs that are inhibited by the snake peptide α-bungarotoxin. A synthetic derivative, 3-(2,4-Dimethoxybenzylidene)-Anabaseine (DMXBA; also called GTS-21), improves memory in experimental animals and humans and is currently in clinical trials to determine whether it can ameliorate cognitive problems associated with schizophrenia. Here we summarize present knowledge concerning the chemistry and mechanisms of action of these two substances (anabaseine and DMXBA) on AChRs, especially those found in the mammalian brain. 相似文献
89.
宁南半干旱退化山区抗旱造林技术研究 总被引:3,自引:0,他引:3
通过在年降水量仅为300~500mm地区的抗旱造林中,集成现有的新材料、新方法、新技术,提高造林成活率,为半干旱退化山区人工营造水土保持林、薪炭林、饲料林、用材林、水源涵养林等的植被恢复、改善生态环境、发挥林业可持续发展提供科技支撑。 相似文献
90.
Wei-Ta Fang Bai-You Cheng Shang-Shu Shih Jui-Yu Chou Marinus L. Otte 《Paddy and Water Environment》2016,14(1):185-197
Farm ponds provide a home for birds and numerous species of aquatic animals in Taoyuan, Taiwan. Urbanization and development of infrastructure resulted in the gradual disappearance of these ponds. Currently, only 3800 ponds originally approximately 15.4 % remain, and 84.6 % of the surface area of the ponds has vanished. Aiming to protect avian diversity, this study used logistic regression analysis and the geostatistical approach to analyze the relationship between avian diversity and landscape structure, in an effort to elucidate the spatial driving force of avian diversity. We detected that regression-kriging (RK) was even more accurate than logistic regression (LR). In addition, the value of diversity (H′) measures may decrease instead of increase when evenness (J′) is increased. The results of this study also indicated that an exceedingly strong relationship existed among avian diversity and landscape scale, agricultural landscape indices, and pond landscape indices. The models predict that preservation of large areas of waterscapes and paddy landscapes result in greater diversity of avian species. Spatial estimation of the research area indicated that human activity substantially affected avian ecology, leading to reductions in avian diversity. Thus, the reduction of the area of ecological corridors due to urban development is expected to further reduce avian diversity in the Taoyuan region. Our approach can be used to effectively analyze the correlations between characteristics of ecosystems and the environmental landscape, to ensure that pondscapes can be appropriately maintained and ecological reserves designated to prevent further decline in avian diversity. 相似文献