Effects of Biological Soil Crust on Soil Enzyme Activities and Nutrients Content in Wind-water Erosion Crisscross Region,Northern Shaanxi Province,China

论文以陕北水蚀风蚀交错区六道沟小流域的生物结皮为对象,研究分析了其对土壤酶活性和土壤养分特征的影响。结果表明:生物结皮对土壤酶活性和土壤养分的影响主要体现在结皮层。结皮层的土壤脲酶和过氧化氢酶活性分别为下层(0～2 cm)土壤的1.56和1.31倍,碱性磷酸酶活性提高幅度最大,为结皮下层的3.72倍;生物结皮能显著提高结皮层土壤有机质、全氮及速效氮含量(P<0.05),研究中结皮层土壤有机质、全氮、速效氮含量分别为15.67 g.kg-1、0.65 g.kg-1和22.51 mg.kg-1,而其下0～2 cm层土壤则分别为5.54 g.kg-1、0.30 g.kg-1和14.6 mg.kg-1;生物结皮对土壤速效磷和速效钾的影响不明显(P>0.05);生物结皮层土壤pH值为8.08,低于其下0～2 cm层土壤(pH值为8.32,P<0.05)。总之,生物结皮的形成和发育可以改善表层土壤的生物化学性质,对该区植被的恢复与重建具有积极意义

Luminescent properties of Er~(3+)/Yb~(3+) co-doped oxyfluoride glass ceramic microsphere with the tapered fiber-microsphere coupling system

采用高温煅烧法制备了Er3+/yb3+共掺的氟氧玻璃陶瓷新材料(41.2SIO2-29.4Al2O3-17.6nA2CO3-11.8lAf3-0.5Erf3-2.5ybf3),并制作了透明带柄微球.提出了用锥光纤微球耦合系统研究Er3+/yb3+共掺的氟氧玻璃陶瓷材料发光特性的新方法.它具有所需激发光功率低、制备简便和便于测试的特点.用锥光纤作为耦合器将976 nM激光高效耦合入微球,并将产生的荧光和激光耦合出微球输到光谱分析仪,测量到了强的522,545和657 nM上转换荧光,也测到Er3+产生的1562 nM激光振荡光谱图.分析了Er3+/yb3+共掺氟氧玻璃陶瓷微球中Er3+上转换发光的机理、发光效率高的机理,分析了在氟氧玻璃陶瓷微球中产生激光振荡阈值比在SIO2基质微球中高的机理.We prepare Er3+/Yb3+co-doped oxyfluoride glass ceramic samples by high temperature calcination method(41.2SiO2-29.4Al2O3-17.6Na2CO3-11.8LaF3-0.5ErF3-2.5 YbF3), and also fabricate transparent microspheres each with a handle.We propose a new method of studying the luminescent properties of Er3+/Yb3+co-doped oxyfluoride glass ceramic with the tapered fiber-microsphere coupling system.The method has characteristics such as low excitation optical power, easy preparation and testing.We couple the 976 nm laser into the microspheres with the coupler of optical tapered fiber, then the fluorescence and laser are connected to spectrum analyzer with the optical tapered fiber.The strong up-conversion fluorescences at 522, 545 and 657 nm are obtained, and the laser oscillation spectra generated by Er3+ions at 1562 nm are also measured.The up-conversion luminescence mechanism of Er3+, the mechanism of high luminescence efficiency in Er3+/Yb3+co-doped oxyfluoride glass ceramic microsphere, and the mechanism of higher laser oscillation threshold in the oxyfluoride glass ceramic microsphere than in the SiO2matrix microsphere are all analyzed

Study on luminescent properties of Yb~(3+)-doped phosphosilicate microsphere

本文采用双锥光纤与微球腔耦合系统研究成分为55.93P2O5-3.57Al2O3-15nA2CO3-20SIO2的掺yb3+磷硅酸盐微球腔的合作上转换发光、下转换激光振荡及其级联拉曼激光振荡等发光特性.本实验采用中心波长为976 nM、线宽为0.15 nM的单纵模半导体激光作为抽运光源,在掺yb3+磷硅酸盐微球腔中测得中心波长为476.1 nM的蓝色合作上转换荧光,并运用合适的理论模型来解释该合作上转换产生11.9 nM蓝移效应的原因.同时,在1058.26 nM和1060.02—1126.08 nM处分别测得了由于微球腔谐振产生的下转换单纵模及多纵模激光振荡.另外,本文首次在同一微球腔中测得了由yb3+下转换激光激发产生的多级级联拉曼激光.在抽运功率为8.53 MW时,产生的级联拉曼激光可以达到两级,且波长延伸至1300 nM附近.Cooperative luminescence, down-conversion laser oscillation and cascaded Raman laser in Yb3+-doped 55.93P2O5-3.57Al2O3-15Na2CO3-20SiO2 phosphosilicate glass are studied in the biconical fiber-microsphere coupling system in this paper.A single-mode semiconducter laser with the center wavelength at 976 nm and line-width 0.15 nm is used as a pump source.The blue-shifted cooperative luminescence centered at 476.1 nm is obtained in the Yb3+-doped phosphosilicate microsphere.And a suitable model may be applied to explain the reason for the 11.9 nm blue-shift in this process.Meanwhile, the single-mode laser(at 1058.26 nm) and multimode laser oscillations(from 1060.02 to 1126.08 nm) have also been obtained as the result of resonant oscillation in microsphere cavity.In addition, for the first time so far as we know a self-stimulated cascaded Raman laser is observed in the same phosphosilicate microsphere, which is generated by the down-conversion laser of Yb3+.When the pump power is 8.53 mW, a two-order cascade Raman laser is generated,which extends the laser wavelength to near 1300 nm

青海湖裸鲤(湟鱼)鱼骨产出层位及其耳石微化学对明朝青海湖水位的指示

鱼耳石是硬骨鱼类内耳中的生物碳酸盐矿物, 其组成可以记录鱼体生活水体的物理和化学状况. 以青海湖鸟岛附近发现的青海湖裸鲤鱼骨及耳石为研究对象, 通过古代和现代耳石微化学组成的对比分析, 结合裸鲤鱼骨及耳石AMS-~(14)C 定年、产出层位和周边地形, 认为这些裸鲤是小冰期时青海湖高湖面退却形成的残余湖内生长的. 通过保存的青海湖裸鲤鱼骨和耳石的AMS-~(14)C 定年, 确定这些裸鲤生活的时代距今300~680年左右, 即我国历史上的明朝时期. X 射线衍射图谱表明, 青海湖裸鲤古代微耳石的矿物是纯文石, 这与现代微耳石一致, 说明埋藏后微耳石的矿物类型没有发生变化, 可用于对比分析. 微化学分析结果表明, 古代微耳石的Mg/Ca 比值((70.12&plusmn;18.50)&times;10~(-5))和&delta;~(18)O 值(1.76&permil;&plusmn;1.03&permil;)均明显高于现代微耳石(Mg/Ca 平均值为(3.11&plusmn;0.41)&times;10~(-5), &delta;~(18)O 平均值为-4.82&permil;&plusmn;0.96&permil;). 这反映了明朝时青海湖裸鲤生活的水体具有比现代青海湖高得多的Mg/Ca 和&delta;~(18)O值, 这是与大湖隔离后强烈蒸发浓缩的结果, 类似于现代的尕海等. 根据裸鲤鱼骨产出的层位和海拔高度, 推断明朝时期青海湖的湖面海拔至少达到3202 m, 经计算当时的湖面面积至少为4480 km~2, 比现在大5%左右.</p

中国毒理学会会议论文集

目的:通过慢性应激模型和药理学手段研究NR2B亚基在抑郁症发病中的作用,选择性拮抗NR2B亚基的快速抗抑郁样作用及其神经生物学机制。方法:采用大鼠慢性应激抑郁模型,通过核团微注射方法研究内侧前额叶皮层内谷氨酸能NMDA受体不同亚基功能与抑郁样行为的关系。通过微透析技术及Western blot方法来检测内侧前额叶皮层内谷氨酸水平及相关分子的变化;通过多个抑郁模型及多种行为学测试(包括强迫游泳测试,&nbsp;</p