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991.
Kanta Gaihre Yam Singh Upendra D. Bible Wendie Fugice Jr Job Sanabria Joaquin 《水稻科学》2020,27(5):434-444
Soil-emitted nitrous oxide (N2O) and nitric oxide (NO) in crop production are harmful nitrogen (N) emissions that may contribute both directly and indirectly to global warming. Application of nitrification inhibitors, such as dicyandiamide (DCD), and urea deep placement (UDP), are considered effective approaches to reduce these emissions. This study investigated the effects of DCD and UDP, compared to urea and potassium nitrate, on emissions, nitrogen use efficiency and grain yields under direct-seeded rice. High-frequency measurements of N2O and NO emissions were conducted using the automated closed chamber method throughout the crop-growing season and during the ratoon crop. Both UDP and DCD were effective in reducing N2O emissions by 95% and 73%, respectively. The highest emission factor (1.53% of applied N) was observed in urea, while the lowest was in UDP (0.08%). Emission peaks were mainly associated with fertilization events and appeared within one to two weeks of fertilization. Those emission peaks contributed to 65%–98% of the total seasonal emissions. Residual effects of fertilizer treatments on the N2O emissions from the ratoon crop were not significant; however, the urea treatment contributed 2%, whereas UDP contributed to 44% of the total annual emissions. On the other hand, cumulative NO emissions were not significant in either the rice or ratoon crops. UDP and DCD increased grain yields by 16%–19% and N recovery efficiency by 30%–40% over urea. The results suggested that the use of DCD and UDP could mitigate N2O emissions and increase grain yields and nitrogen use efficiency under direct-seeded rice condition. 相似文献
992.
外源一氧化氮对增强UV-B辐射后小麦幼苗膜脂过氧化系统的影响(摘要)(英文) 总被引:3,自引:0,他引:3
[目的]以硝普钠(sodium nitroprusside,SNP)作为外源一氧化氮(nitric oxide,NO)供体,研究了不同浓度一氧化氮对增强UV-B辐射胁迫后小麦幼苗膜脂过氧化系统的影响。[方法]试验设置3个组:对照组(CK)、紫外线UV-B处理组(B)、UV-B和硝酸钠(SNP)复合处理组(B+SNP),分别于处理后的第0、1、2、3、4天取样进行丙二醛(MDA)含量及CAT、POD、SOD等生理生化指标的测定,3次重复,并进行统计学分析。[结果]UV-B辐射后,小麦幼苗中丙二醛(MDA)含量上升,过氧化氢酶(CAT)、过氧化物酶(POD)、超氧化物歧化酶(SOD)活性下降,导致小麦幼苗产生氧化损伤;在UV-B辐射之后施加不同浓度的SNP,可以不同程度地缓解UV-B辐射胁迫下小麦幼苗根和叶的氧化损伤,使MDA含量下降,抗氧化酶CAT、POD、SOD活性上升。其中,0.1 mmol/LSNP对叶的氧化损伤缓解作用较明显,0.01 mmol/L SNP则对根的氧化损伤缓解作用较明显。[结论]外源NO供体SNP对小麦幼苗由于UV-B辐射引起的氧化损伤有明显的缓解作用,可增强植物对逆境胁迫的适应能力。 相似文献
993.
994.
自成骨架型氧化铁沼气脱硫剂性能研究 总被引:1,自引:1,他引:0
为实现农村沼气的高效安全利用,提高沼气的脱硫效能,本文对自成骨架型沼气氧化铁脱硫剂的脱硫性能进行研究。通过对采用扫描电子显微镜,能谱及孔径分析对其脱硫前后的表面形貌、成分、孔隙变化及硫容进行分析。结果表明,自成骨架型氧化铁脱硫剂其活性铁成份含量提高,在空速800 h-1的条件下,其初次硫容可达17.9%,再生硫容可达13.5%,积累硫容超过39%,具有较好脱硫效果,同时高活性铁含量、大比表面积,均匀孔结构均对提高沼气脱硫性有促进作用。 相似文献
995.
We investigated the effects of honey and its methanol and ethyl acetate extracts on inflammation in animal models. Rats’ paws were induced with carrageenan in the non-immune inflammatory and nociceptive model, and lipopolysaccharide (LPS) in the immune inflammatory model. Honey and its extracts were able to inhibit edema and pain in inflammatory tissues as well as showing potent inhibitory activities against NO and PGE2 in both models. The decrease in edema and pain correlates with the inhibition of NO and PGE2. Phenolic compounds have been implicated in the inhibitory activities. Honey is potentially useful in the treatment of inflammatory conditions. 相似文献
996.
From the ether extract of Porella densifolia, the first liverwort collected and chemically investigated in Vietnam, a kaurane diterpenoid, ent-kauren-15-one (1) and two sesquiterpene norpinguisone (2) and norpinguisone methyl ester (3) have been purified. Their structures were elucidated by spectroscopic analysis. In addition, an X-ray crystal structure of norpinguisone was obtained, allowing to determine its stereochemistry. Furthermore, the inhibitory activity of nitric oxide (NO) production in RAW 264.7 cells stimulated by lipopolysaccharide (LPS) of compounds 1–3 was examined with their IC50 values of 69.4, 45.5 and 1.68 μM, respectively. 相似文献
997.
998.
Dietary supplementation with high levels of zinc oxide (ZnO) is an effective method to prevent diarrhea and promote growth in weaned piglets. However, the mechanisms behind these beneficial effects are not well understood. Recent advances in this field indicated that the effects of ZnO on piglet growth are achieved through multiple regulatory pathways rather than a single pathway. This review focuses on recent advances in the effects of high level ZnO on: 1) Zn status in weaned piglets; 2) intestinal microbe flora regulation; 3) intestinal structure and function; 4) ion secretion in the intestine epithelium; 5) intestinal immunology; and 6) secretion of brain-intestine peptides. ZnO appears to regulate the intestinal microflora and decreases the release of histamine to prevent diarrhea. ZnO also increases the expression of intestinal insulin-like growth factor-1 (IGF-1) and the IGF-1 receptor to ameliorate intestinal injury associated with weaning, and mediates secretion of brain-gut peptides to stimulate food intake, to promote the growth of piglets. Better understanding of the underlying mechanisms should inspire us to supplement the diet for weaned piglets with ZnO and investigate new approaches to prevent diarrhea and enhance growth. 相似文献
999.
1000.
研究20μmol/L镧(La)处理下,NO供体硝普钠(SNP)处理对玉米叶片叶绿素含量和MDA含量、叶片中愈创木酚过氧化酶(GPX)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)以及抗坏血酸过氧化物酶(APX)活性等生理生化指标的影响。结果表明,10μmol/LSNP处理可显著缓解20μmol/LLa处理引起的玉米叶绿素含量下降,SNP通过抑制SOD活性、促进APX活性,缓解了膜脂过氧化,降低了MDA含量。SNP通过拮抗玉米中高浓度La引起的APX活性抑制,缓解了活性氧对叶绿体损伤,促进了叶绿素含量恢复。 相似文献