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31.
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Total 26 modern soil samples were collected from various regions under different climate conditions from tropical to arid temperate in China and systematically analyzed for their organic matters by GC/MS in order to evaluate climatic impacts on soil organic components. Abundant lipids molecules were recognized, including n-alkanes, n-alkenones, and long-chain branched alkanes. We find the predominance of main peaks of long-chain n-alkanes (nC29,nC31,nC33) and short-chain ones(nC16,nC17,nC18) records information of soil generation in warm-humid and cold-dry regions. The proportion of n-alkanes(nC16+nC17+nC18)to(nC29+nC31+nC33)varies in good agreement with moisture-heat conditions and thus probably can serve as a new index for climate change. The ratios of C21-/nC22+,nC17/nC31 and (nC15+nC17+nC19)/(nC27+nC29+nC31)of n-alkanes, indicating respectively input ratios of lower bacterial alga, aquatic organisms, and higher plants and terraneous organisms, co-vary well in different climate regions from forest to grassland and desert, suggesting that they have also reflected the difference of climates between monsoon region and inland one. The C21-/C22+ ratio of n-alkan-2-one records largely the discrepancy of temperature from north to south of China bordered by the Qinling Mountains, but less humidity. The C21-/C22+ ratio of n-alkan-3-ones changes well with climatic factors, such as temperature and humidity. The biogenic source of series A-D long-chain branched alkanes may be derived from some kinds of special epiphyte that most likely live in weak oxic-anoxic and moisture-heat environments, suggesting their distribution record as well some information on climatic change. All these researches demonstrate that the distributions of lipids molecules in modern soils in China record well signals of climates from quite different climatic regions, and can serve as important climatic proxies to reveal climatic change over China. 相似文献
33.
在Matlab编程环境下模拟了单分子定位显微的纳米分辨成像,在传统实验参数条件下,对不同间隔分子带模型进行了模拟成像.模拟结果表明,单分子定位显微方法可以区分中心相隔20 nm的两个分子带.同时,也分析了不同像元大小对单分子定位精度的影响.此外,通过单分子定位显微方法在IX71倒置荧光显微镜上实现了纳米分辨,系统极限分辨率,即半高全宽为48 nm.在该系统上,获得了HeLa细胞突起中微丝束结构的纳米分辨图像.从重构获得的图像中可以看到微丝束的直径为75—200 nm. 相似文献
34.
Extreme ultraviolet (EUV) resonance fluorescence of the (0,v″) bands of the c′41Σu+→X1Σg+ and the (1,v″) bands of the b′ 1Σu+→X1Σg+ transitions of N2 has been observed by photon excitation of N2 in the vicinity of 95.8 nm. The integrated fluorescence intensities of the c′4→X (0,v″) emission become saturated at N2 pressures higher than ∼0.16 mTorr. The emission features in the spectral region between 105 and 130 nm become progressively significant as the N2 pressure is increased. The (1,v″) progression for v″ up to 11 of the b′→X transition and two progressions of the Lyman-Birge-Hopfield (LBH) system have been identified. The multiple scattering processes apparently cause significant reduction in the c′4→X (0,0) emission rates. The present results may be useful in the explanation of the weak c′4→X (0,0) fluorescence as well as the significant c′4→X (0,v″) features in the dayglow of the Earth observed by the Far Ultraviolet Spectroscopic Explorer. 相似文献
35.
36.
P. Sriramachandran R. Shanmugavel S. P. Bagare N. Rajamanickam 《Astrophysics and Space Science》2009,323(1):41-49
A high resolution spectrum of a sunspot umbra is used for identification of rotational lines due to (0, 0) band of the A
2Π–X
2Σ+ system and (0, 0), (1, 1), and (2, 2) bands of the B
2Σ+–X
2Σ+ system of the molecule SrF. The published sunspot umbral spectrum obtained with Fourier Transform Spectrometer and solar
telescope of National Solar Observatory/National Optical Astronomy Observatory at Kitt Peak was used for the study. The new
identification of more than 200 SrF lines in the umbral spectrum confirms that this molecule accounts for the majority of
lines in the spectral range 15050 to 15360 cm−1 and 17240 to 17300 cm−1. Equivalent widths have been measured for well-resolved lines of these bands and the effective rotational temperatures have
been estimated for which the presence is confirmed. 相似文献
37.
为探讨直接/间接作用模式下土壤常驻菌对蒙脱石层间距、层电荷及层间介质的影响,从绵阳地区紫色土壤中分离选取1株短小芽孢杆菌,利用透析袋,建立土壤菌与蒙脱石"接触"与"非接触"体系进行相互作用实验。作用5 d后的结果表明,蒙脱石样品层间距变小,样品M-1和M-2的d001值从1.486 nm分别减小到1.246 nm和1.257 nm,单位半晶胞层电荷数减少,且ξMMTξM-2ξM-1,FTIR分析显示作用后蒙脱石样品出现来自蛋白质酰胺Ⅱ带及蛋白质分子甲基的新特征峰,层间水分子3434 cm-1、1637 cm-1处的峰发生偏移,此外阳离子交换容量也发生明显改变。土壤菌的生物作用能改变蒙脱石的层间距、层电荷及层间介质,使其结构和性质发生改变。对比2种作用方式与作用后蒙脱石层间域特性的改变分析可知,接触作用对蒙脱石层间域特性的改变效果强于非接触作用。 相似文献
38.
白细胞介素10(Interleukin 10,IL-10)是一种抗炎细胞因子,可以抑制机体免疫反应。本研究经过分析大黄鱼基因组数据库发现了IL-10同源基因,并对其cDNA编码区序列和基因组DNA序列进行了克隆分析。大黄鱼IL-10(LycIL-10)基因由5个外显子和4个内含子构成,其序列全长1 869bp,其开放阅读框(ORF)长555bp,编码184个氨基酸,其N端的22个氨基酸残基为预测的信号肽,成熟肽由162个氨基酸残基组成,包含了脊椎动物IL-10标志性保守序列。LycIL-10的氨基酸序列同其他已知物种的IL-10氨基酸序列的一致性为26.49%~77.01%。Real-time PCR分析发现LycIL-10在检测的组织中为组成型表达,在脾脏和肌肉中转录水平相对较高。三联灭活细菌疫苗和聚肌苷酸胞苷酸(poly(I∶C))刺激后,大黄鱼头肾和脾脏中LycIL-10mRNA的转录水平会显著升高,表明LycIL-10可能参与抑制大黄鱼由细菌和病毒引起的炎症反应。 相似文献
39.
The published sunspot spectrum obtained with National Solar Observatory/Kitt Peak laboratory’s high signal to noise ratio telescope and high resolution Fourier Transform Spectrometer were used for the study. A search was made for the prominent lines of the (0, 0) and (1, 1) A2Δ − X2Π for Silicon hydride isotopomers which lie between 23500 cm−1 and 24500 cm−1. The presence of lines from the (0, 0) and (1, 1) A2Δ − X2Π transition of SiH molecule coincided with the sunspot umbral lines suggest that Silicon hydride appears to be a non-negligible component of sunspot umbrae. However, the presence of A2Δ − X2Π (0, 0) and (1, 1) bands of SiD was found to be doubtful because of the lack of number of well identified lines in sunspot umbral spectra. Equivalent widths have been measured for well-resolved lines and, thereby, the rotational temperatures have been estimated for the band systems for which the presence is confirmed. 相似文献
40.
分流比对烃类单分子氢同位素分析的影响 总被引:1,自引:0,他引:1
在单体烃的氢同位素系统测定中,以甲烷为样品,选择不同的分流比(0.1、0.5、1.0、2.0、5.0、10.0),采用气相色谱-高温热转换-同位素比率质谱对相应的氢同位素比值进行研究。结果表明,不同的分流比对峰形、出峰面积及单体烃的氢同位素值有不同程度的影响,总体上随着分流比的增大,峰宽及峰面积呈现指数方式递减;特别是当分流比较小(小于1)时,导致氢同位素值测定结果的不确定度增大;分流比较大时,氢同位素值趋于稳定。文章对造成这种现象的原因进行了分析,认为在单体烃的氢同位素的分析中,选择较大的分流比不会导致明显的同位素分馏,从而对样品分析更为有利。 相似文献