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71.
基于GIS技术的荔城平原区耕地土壤重金属污染程度及其风险评价 总被引:2,自引:0,他引:2
在空间插值基础上,利用Hakanson潜在生态风险指数法,研究了荔城平原耕地土壤重金属的污染程度及其潜在生态风险。结果表明,研究区8种重金属中汞污染指数最高,综合污染指数均值为0.897,处于警戒线水平,但总体上较清洁;在重金属潜在生态危害指数中,汞危害系数较高,达到47.496,处于中度危害水平,其余重金属元素的潜在危害系数为0.362~12.058,均处于轻度危害水平;综合潜在风险指数介于27.742~127.344,均值为68.129,处于轻度危害;并利用GIS软件绘制出污染风险评价分区图。 相似文献
72.
Source-sink Characteristics and the Translocation of Assimilates in New Plant Type and Intersubspecific Hybrid Rice 总被引:1,自引:0,他引:1
Both new plant type (NPT) and intersubspecific hybrid rice (IHR) had large sink size (total number of spikelets per m2), however, poor grain filling limited their potential in the grain yield. Compared to the three-line indica hybrid of Shanyou 63 (CK), NPT and IHR showed higher photosynthetic potential,higher dry matter accumulation and higher ratio of dry weight to spikelets (total dry wt./total number of spikelets) from heading to harvest. But both exhibited a low export percentage and transfer ratio of assimilates, low partitioning of 14C to grains from labeled flag leaves, low harvest indices and low physiological activities (IAA content and activities of ATPase and starch synthase) of grains at early grainfilling stage. The physiological activities of grains at early filling stage were significantly correlated with the export percentage and transfer ratio of assimilates, ripened-grain percentage and grain plumpness (r = 0.85 *- 0.95* * ). The source-sink ratio (dry matter wt./spikelet and nonstructural carbohydrate/spikelet) at heading was positively correlated with physiological activities of grains (r = 0.84* - 0.97 * * ). It is suggested that low physiological activities of grains at early filling stage is attributed to low source-sink ratio at heading, and the low sink activity weakens the ability to remobilize assimilates into grains, and leads to poor grain filling in NPT and IHR. 相似文献
73.
在分析小麦免耕播种机作业性能要求的基础上,研制在玉米秸杆覆盖下小麦免耕播种的结构特征、工作原理,以带状粉碎防堵装置为核心的免耕播种机,通过粉碎轴粉碎玉米秸杆和田间杂草,有效地解决了开沟器缠草堵草的问题。 相似文献
74.
黄土丘陵区不同年限柠条林地土壤质量变化 总被引:1,自引:0,他引:1
在野外调查和室内分析的基础上,探讨了0、10、22、26和30 a时间序列柠条林地土壤物理、化学及酶活性的动态变化.结果表明柠条林可提高土壤粘粒、粉粒含量,10~26 a土壤容重显著降低;除全磷表现为减少趋势外,随生长年限延长,柠条林地有机质、全氮、硝态氮、铵态氮、速效磷和速效钾含量均呈现增加趋势;土壤蔗糖酶、碱性磷酸酶、脲酶和过氧化氢酶活性随柠条生长年限增加呈增加趋势,但各种酶表现最佳状态的时间不同,且蔗糖酶和碱性磷酸酶对柠条林地土壤变化的敏感性高于脲酶和过氧化氢酶. 相似文献
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78.
Bemisia tabaci(Gennadius) is a serious pest in many cropping systems worldwide and occurs in different biotypes. The mtDNA COI gene of the 12 Bemisia tabaci (Gennadius) populations from different regions and countries were analyzed.Based on mtDNA COI sequences, their biotypes were characterized and phylogenetic relationships among these populations were established with the method of UPGMA. The results indicated the genetic similarity between those populations from Beijing, Zhengzhou, Zaozhuang, Nanjing, Shanghai, Haikou, and the B-biotype populations from California, Texas, Arizona reached 99.8-100%, which meant the nation-wide infested populations of B. tabaci in China in recent years were B-biotypes. Another population collected from Kunming of Yunnan Province showed very high similarity with Q-biotype B. tabaci from Spain and Morocco, which meant the Kunming population was Q-biotype. This is the first report on the invasion of Q-biotype into China. 相似文献
79.
ZHANG Jing-ge CHEN Hai-ying QIN Jin CONG Bin LI Qiao-xia JIA Xian-xian MA Chun-ling YU Feng 《园艺学报》2011,27(3):545-549
AIM: To observe the immunoregulatory effects of prostaglandin E2 receptor (EP) subtypes EP2/EP4 on the B-cells of collagen-induced arthritic(CIA)mice. METHODS: DBA/1 mice were immunized with chicken type II collagen emulsified in Freunds complete adjuvant to induce arthritis. B-cells were isolated from the splenocyte suspension by positive selection using anti-CD19 monoclonal antibody immunomagnetic beads. The expression of MHC II, CD 80 and CD86 was examined by flow cytometry. The mRNA levels of EPs, interferon γ (IFN-γ), tumor necrosis factor α (TNF-α), IL-6, IL-4, IL-10 and transforming growth factor-β (TGF-β) were detected by real-time RT-PCR. RESULTS: The rank of the mRNA levels of EPs was EP2>EP1>EP3>EP4 in B-cells and EP2/EP4 mRNA expression was obviously increased in CIA mice. EP2 antagonists inhibited the expression of MHC II, CD80 and CD86. EP4 antagonist had little effect on CD80. EP2/EP4 antagonists inhibited the mRNA expression of IFN-γ, TNF-α, and IL-6 (P<0.05 or P<0.01) and increased the expression of IL-10 (P<0.01 or P<0.05). Furthermore, the antagonists of EP2 and EP4 also increased the mRNA expression of IL-4 and TGF-β (P<0.01), respectively. CONCLUSION: PGE2 modulate the pathogenesis of CIA via EP2/EP4 by regulating the expression of surface molecules and cytokines in B-cells. EP2/EP4 may be a new therapeutic target for treating rheumatoid arthritis. 相似文献
80.
为鉴定鸡羽髓上皮细胞感染马立克氏病病毒(MDV)前后差异表达的蛋白,本研究以MDV强毒GA株人工感染SPF鸡,并通过双向电泳技术进行分析.结果显示:在病毒感染后4 d、7 d、14 d和21 d显著差异表达的蛋白点分别有2个、8个、25个和9个;而通过质谱技术鉴定出29种蛋白质,其中包括能量代谢相关蛋白、增殖和凋亡相关蛋白、细胞骨架蛋白、信号传导蛋白、转录相关蛋白、免疫相关蛋白和其他功能蛋白质.本实验首次对鸡羽髓上皮细胞感染MDV后各时期蛋白表达水平的变化进行研究,鉴定了多种差异表达蛋白质,为进一步揭示MDV与宿主的相互关系、感染性病毒粒子的成熟和致病机制提供了依据. 相似文献