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着重论述了丁家山铅锌(银)矿床的地质地球物理特征,磁法找矿的特殊作用,总结了建筑梅仙式矿床的物化探异常标导。 相似文献
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利用龙岩市1960—2013年7个国家级气象站的逐日降水资料,采用Mann-Kendall趋势和突变检验法及Morlet小波功率谱分析方法,分析龙岩市降水的时空分布规律。结果表明,龙岩市年降水量呈微弱增加趋势,年际波动振幅较大。年降水量多年平均值为1 641 mm,最小值出现在1991年(1 139.9 mm),最大值则出现在1975年(2 286.9 mm),年降水时间序列存在显著的2~8 a的周期。降水主要集中在春季,春季降水量占全年降水量的38.2%左右,其次是夏季和秋季,冬季降水量最少,仅占全年降水量的11.5%。1—6月月平降水量呈现增长趋势,8—12月呈现递减趋势。北部和南部年降水量整体变化趋势基本一致,南部地区总体小于北部地区,只有极个别年份南部地区降水量大于北部地区。 相似文献
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陇南山区小麦条锈病流行对气候偏暖的响应及对策研究 总被引:5,自引:2,他引:5
根据陇南山区 1957-2005 年气象资料和相应的小麦条锈病流行资料的对比分析得出与 1957-1995 年平均值比较,陇南各地1996-2005年年平均气温上升0.5~0.9℃,逐月平均气温也均有不同程度的上升,其中,冬季增温最为显著,为1.0℃/10a,在冬季尤以2月增幅最大,为1.3~1.6℃/10a.而陇南春季小麦条锈病流行程度与上年10月和当年1-3月平均气温正相关显著,所以,近10a冬季显著的增暖趋势与小麦条锈病流行程度逐年加重趋势相一致,由此与1990s以前相比,陇南山区冬小麦种植海拔高度及条锈病越冬越夏高界明显提高了100~300 m,致使小麦条锈病危害范围扩大,发生时间由3月提前到2月.本文结合当地特色农业经济发展战略,相应提出防御对策. 相似文献
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目的:观察三七总皂苷(PNS)对脑缺血再灌注损伤小鼠海马Bax和Bcl-2表达的影响。方法:采用双侧颈总动脉夹闭法构建缺血再灌注损伤模型,选用健康的6周龄昆明小鼠33只,分为空白组、PNS组、缺血9d组(缺血再灌注9d后取脑)、缺血24h组(缺血再灌注24h后取脑)。PNS组于缺血前3d开始腹腔注射PNS[30mg/(kg·d)],直至再灌注9d后取脑,缺血9d组和缺血24h组予以等体积0.9%氯化钠注射液腹腔注射。各组取脑后制作冰冻切片,采用免疫组织化学法检测小鼠海马区脑组织Bax和Bcl-2阳性表达细胞数。结果:与空白组比较,缺血9d组Bcl-2、Bax水平均明显增高,差异有统计学意义(P<0.05)。与缺血9d组比较,PNS组Bax的表达水平平均值明显降低,Bcl-2/Bax的表达水平明显增高,差异均具有统计学意义(P<0.05);缺血9d组Bax和Bcl-2的表达均较缺血24h组增高,差异具有统计学意义(P<0.05)。结论:PNS对短暂性双侧颈动脉闭塞型小鼠缺血再灌注损伤的作用机制是早期通过降低Bax表达,增大Bcl-2/Bax比值,抑制神经元凋亡,从而对大脑海马神经元起保护作用,且再灌注第9天损伤程度可能更大。 相似文献
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Sixteen soil samples were collected from the vicinity of an abandoned lead–zinc mine in Shangyu City, eastern China, and the
heavy-metal speciation and wheat phytotoxicity in the soils were studied. The results showed that the concentrations of free
Cu2+, Zn2+, Cd2+ and Pb2+ were highly variable and ranged from <0.01 to 0.32, 0.06 to 10.62, <0.01 to 1.40 and 0.02 to 37.10 μmol l−1, respectively. The concentrations of soluble Cu, Zn, Cd and Pb ranged from 0.38 to 3.24, 0.72 to 78.74, <0.01 to 1.95 and
0.15 to 639.34 μmol l−1, respectively. The general trend of mean solid/liquid partition coefficient and percentage of free metal ion to total soluble
metal concentration were Cu > Pb > Zn > Cd and Cd > Zn > Cu > Pb, respectively. Stepwise multiple linear regression with pH,
log(total metal) and log(organic matter) showed that log(total metal) was an important factor that controlled log(free metal
ion) and log(soluble metal). Of the variability in log(free Cu2+), log(free Cd2+) and log(free Pb2+), 55.2, 58.6 and 64.3% could be explained by log(total Cu), log(total Cd) and log(total Pb) alone, respectively. Of the variability
in log(soluble Cu) and log(soluble Cd), 77.1 and 72.5% could be explained by log(total Cu) and log(total Cd) alone, respectively.
Wheat root length was controlled by the various metals with different free and soluble concentrations, and 99.2% of the variability
in root length could be explained by concentrations of free and soluble Pb, soluble Cu and total Zn in the soils. 相似文献
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NR1D1和NR1D2转录因子属于核受体转录因子家族,二者通过调控靶基因表达参与众多生物学过程,尤其在昼夜节律调节中发挥重要作用。本研究通过分析NR1D1和NR1D2的蛋白质分子特征以及在冷胁迫下珍珠龙胆石斑鱼(Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂)的基因调控关系以及它们所参与的通路,揭示它们在鱼类低温环境中的功能作用。生物信息学比较分析显示〖STBX〗NR1D1和NR1D2〖ST〗基因序列均有23个开放阅读框,编码的蛋白质均属于不稳定的亲水性蛋白质。NR1D1和NR1D2蛋白质均含有ZF C4类锌脂蛋白结构域和Hormone_Recep核激素受体的配体结合域,主要配体为含铁原卟啉IX。这两种蛋白主要在细胞核中发挥调控基因表达的作用,且与昼夜节律通路的多个关键基因有直接作用关系。结果表明,在冷胁迫下NR1D1和NR1D2作为转录因子可通过调控靶基因的表达,参与昼夜节律调节并促进糖脂代谢、线粒体氧化等过程,为珍珠龙胆石斑鱼提供必要的能量,有助于增强其耐寒性。 相似文献
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ABSTRACT The impact of both initial and parameter errors on the spring predictability barrier (SPB) is investigated using the Zebiak Cane model (ZC model). Previous studies have shown that initial errors contribute more to the SPB than parameter errors in the ZC model. Although parameter errors themselves are less important, there is a possibility that nonlinear interactions can occur between the two types of errors, leading to larger prediction errors compared with those induced by initial errors alone. In this case, the impact of parameter errors cannot be overlooked. In the present paper, the optimal combination of these two types of errors [i.e., conditional nonlinear optimal perturbation (CNOP) errors] is calculated to investigate whether this optimal error combination may cause a more notable SPB phenomenon than that caused by initial errors alone. Using the CNOP approach, the CNOP errors and CNOP-I errors (optimal errors when only initial errors are considered) are calculated and then three aspects of error growth are compared: (1) the tendency of the seasonal error growth; (2) the prediction error of the sea surface temperature anomaly; and (3) the pattern of error growth. All three aspects show that the CNOP errors do not cause a more significant SPB than the CNOP-I errors. Therefore, this result suggests that we could improve the prediction of the E1 Nifio during spring by simply focusing on reducing the initial errors in this model. 相似文献